boiler

ABB Lummus Global B.V.

LGN SREP 04-3001-02.008 (Rev 0, May 2005) HOUDINI PROCESS TECHNOLOGY REPORT TEMPLATE.DOT PCFS NEM_R2.doc Page 1 of 92

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120.011 04217 E-15100-TN-5306-0001

Dept./Sect. Project Document Number

SHELL EASTERN PETROLEUM (PTE) LTD. SINGAPORE

SHELL ECC PROJECT

STEAM PRODUCTION & DISTRIBUTION

CONDENSATE COLLECTION DESALINATED WATER STORAGE

DEMINERALISED WATER MAKE-UP SYSTEM

PROCESS CONTROL FUNCTIONAL SPECIFICATION

UNIT 15100

2.00 2006-10-31 Revised Approved for Design RVO GRI GDS

1.00 2006-05-31 Approved for Design RVO GRI GDS

0.00 2006-03-10 ORIGINAL DOCUMENT RVO GRI GDS

REV. DATE DESCRIPTION PREPARED CHECKED APPROVED


Client SHELL EASTERN PETROLEUM (PTE) LTD. 120.011 04217 E-15100-TN-5306-0001

Subject PROCESS CONTROL FUNCTIONAL SPECIFICATION Dept./Sect. Project Document Number Rev.


Table of Contents

1. BACKGROUND PROCESS INFORMATION 4

1.1 PROCESS AND PROJECT 4

1.2 STEAM AND POWER GENERATION / DISTRIBUTION SYSTEM 6 1.2.1 Super High Pressure (SHP) Steam 6 1.2.2 High Pressure (HP) Steam 6 1.2.3 Medium Pressure Desuperheated (MPD) Steam 6 1.2.4 Medium Pressure Desuperheated (MPD) Steam 6 1.2.5 Low Pressure (LP) Steam 6 1.2.6 Low Pressure Desuperheated (LPD) Steam 6 1.2.7 Letdown Stations 6 1.2.8 Steam Boilers 7 1.2.9 Power Generation System 7 1.2.10 Blowdown and Flash Drums 7

1.3 CONDENSATE TREATMENT AND RECOVERY SYSTEMS 7 1.3.1 Deaerators 7 1.3.2 PCC 8 1.3.3 NCC 8 1.3.4 MP Condensate 8 1.3.5 HP Condensate 8 1.3.6 Condensate Treatment 8

1.4 DESALINATED WATER 9

1.5 DEMINERALISED WATER 10

2. CONTROL DESCRIPTION 11

2.1 STEAM SYSTEM 11 2.1.1 General 11 2.1.2 SHP Steam Header 11 2.1.3 HP Steam Header 12 2.1.4 MP Steam Header 12 2.1.5 MPD Steam Header 13 2.1.6 LP Steam Header 13 2.1.7 LPD Steam Header 13

3. DETAILED CONTROL NARRATIVES 14

3.4 STEAM BOILERS, A-15101/2/3, STEAM LOAD CONTROL 14 PICA-070, PICA-071, HIC-100, HIC-200, HIC-300, Y-100, Y-200, Y-300, HS-098, 14 HS-401, UC-400, UC-401 14 3.4.1 Objective 14 3.4.2 Functional Description 14 3.4.3 Operational and Implementation Aspects 15 3.4.4 History 16

2.00


Client SHELL EASTERN PETROLEUM (PTE) LTD. 120.011 04217 E-15100-TN-5306-0001 2.00



3.5 SHP/HP STEAM DESUPERHEATER, J-15101A/B, PRESSURE CONTROL 17 PICA-063, PICA-014, PY-014, TICA-005, HS-023 17 3.5.1 Objective 17 3.5.2 Functional Description 17 3.5.3 Operational and Implementation Aspects 18 3.5.4 History 19

3.6 BOILER COMBUSTION AIR CONTROL 24 HLA10AA001, FIC-502, XC504 24 3.6.1 Objective 24 3.6.2 Functional Description 24 3.6.3 Operational and Implementation Aspects 25 3.6.4 History 30

3.7 GAS/FUEL OIL CONTROL 31 V102 – FC155, V201 – FC172, V302 – PDC165, V502 – PDC182 31 3.7.1 Objective 31 3.7.2 Functional Description 31 3.7.3 Operational and Implementation Aspects 33 3.7.4 History 39

3.8 BOILER STEAM DRUM LEVEL AND ECONOMIZER INLET TEMPERATURE CONTROL40 LAB10AA022 – FC101 LC101, LAB10AA032 - TIC-103 40 3.8.1 Objective 40 3.8.2 Functional Description 41 3.8.3 Operational and Implementation Aspects 42 3.8.4 History 46

3.9 BOILER START-UP PRESSURE CONTROL 47 LBA10AA051 - PIC302, TIC301 47 3.9.1 Objective 47 3.9.2 Functional Description 48 3.9.3 Operational and Implementation Aspects 49 3.9.4 History 52

3.10 BOILER STEAM DESUPERHEATER TEMPERATURE CONTROL 53 LAE10AA014 – TC203, TC204, LAE10AA014 – TC205, TC206 53 3.10.1 Objective 53 3.10.2 Functional Description 53 3.10.3 Operational and Implementation Aspects 54 3.10.4 History 58

3.11 BOILER DRAIN AND BLOWDOWN CONTROL 59 HAH10AA404, HAH10AA424, LBA10AA404, HAD10AA470, HAD10AA471 - LIC-401,

GAC10AA011 - TC401, HAD10AA460 59 3.11.1 Objective 59 3.11.2 Functional Description 59 3.11.3 Operational and Implementation Aspects 61 3.11.4 History 64

3.12 DRAWINGS 91

3.13 DOCUMENTS 91





1. BACKGROUND PROCESS INFORMATION

1.1 PROCESS AND PROJECT

The ten Cracking Heaters in the LOP, and three Steam Boilers, will generate Super High Pressure (SHP) steam, which is used to drive large turbines. High Pressure (HP) steam is extracted from the Cracked Gas Compressor turbine and used for various heat exchangers, smaller turbines and a number of pumps. Medium Pressure (MP) steam is mainly extracted from the Power Generator and used for process heat exchangers in all the process units. In addition, MP steam is also used as atomizing steam, for boiler soot blowing and to drive smaller turbines, pumps and fans. MP steam is also used in the flare. Medium Pressure Desuperheated (MPD) steam is produced by desuperheating MPS steam. MPD steam is required for several heat exchangers/reboilers in the PPS and LOP. LP steam is produced by various backpressure turbines, and by extraction from the C3-REF Compressor – K-11501. The remainder is produced via letdown of MPS. LP steam is used in all process units and offsite systems in heat exchangers, heating coils, Deaerators and for stripping purposes. Low Pressure Desuperheated (LPD) steam is produced by desuperheating of LPS steam, and by the Quench Oil/LP Steam Exchangers E-11133 A/B, in the LOP. LPD steam is required for several heat exchangers/reboilers in the LOP. Pressure letdown stations are provided from higher pressure to (the next) lower levels. During normal operation, pressure letdown is done as much as possible via the turbines and the amount of steam which is letdown via the letdown/desuperheater stations is minimized. The condensate treatment systems collects all the returned condensate streams and can be divided into four categories: • HP return condensate which is normally clean and not likely to be contaminated is

recycled to the Deaerators via a HP condensate flash drum and via the MP condensate system without any further treatment.

• MP return condensate which is normally clean and not likely to be contaminated is recycled to the Deaerators via a MP condensate flash drum without any further treatment.

• Potentially Contaminated Condensate (PCC) from condensed LP/MPD steam. • Normally Clean Condensate (NCC) from surface condensers PCC is collected in the PCC Flash Drum from the following sources, polished and used as BFW: • ECU • U & GF (except LPS users) • ECC Jets/Tracing • C4SHU LPD Steam Users • PHU • BEU-1 LPS Users





NCC is collected in the Condensate Surge Tank T-15101 from the following sources and used as BFW: • Turbine Steam Condenser E-151910 • Ethylene Refrig Compressor, Steam Condensate Cooler E-15613 • Charge Gas Compressor, Steam Condenser E-11212 • MP Condensate Trim Cooler E-15107 • Ethylene Refrig Compressor, Steam Condensate Cooler E-15513 • Treated PCC from Condensate Activated Carbon Filters V-15104A/B MP Condensate is collected in the MP Condensate Flash Drum V-15102 from the following sources and used as BFW: • PHU Users • BEU-1 Users • MP Condensate/Process Water Exchanger E-1132 • ECU Users HP Condensate is collected in the HP Condensate Flash Drum V-15103 from the following sources and is recycled to the MP Flash Drum: • E-13206 in the BEU-1 • Drier Regeneration Gas Heater E-11214 Desalinated water is imported from the Bukom Refinery’s desalination plant and stored in the Desalinated Water Storage Tank. The Desalinated Water is used to: • Supply Desalinated Water to the Demineralised Water Package • Supply Desalinated Water to Industrial Water Distribution (Not normal flow) • Supply Desalinated Water to the maintain Fire Water ring main pressure (Not normal

flow) • Supply Desalinated Water to the Fire Water Pumps (Not normal flow)

The feed to the Demineralised Water System consists of Desalinated Water. The Demineralised Water System sends Demineralised Water to the Demineralised Water Storage Tank. It can also be sent to the Waste Water Equalisation Tank, if required, or it is sent to NCW. The Demineralised Water is pumped from the tank to: • Continuous BD Drum Interchanger • Condensate Treatment Package • Waste Water Neutralisation Sump The regenerant waste streams from the PCC/NCC treatment are sent to the waste water neutralisation sump before being pumped to the Plant Outfall.





1.2 STEAM AND POWER GENERATION / DISTRIBUTION SYSTEM

Steam is generated and used at six pressure/temperature levels, namely the SHP, HP, MP, MPD, LP and LPD levels.

1.2.1 Super High Pressure (SHP) Steam

The LOP unit’s cracking heaters and the steam boilers generate the SHP steam. The SHP steam is used to drive the following three turbines: • Cracked Gas Compressor (CGC) turbine K-11201 • Propylene Refrigeration Compressor (PRG) turbine K-11501 • Power Generation (PG) turbine GT-15190

All three turbines are designed as a combination of extraction/condensing type turbine to meet the needs of steam and power for the complex.

1.2.2 High Pressure (HP) Steam

HP steam is extracted from the CGC turbine and used: • for various equipment in the LOP units. • to drive backpressure turbines and produce LP steam. • for various process heat exchangers in the process units. • to support the MP steam system.

1.2.3 Medium Pressure Desuperheated (MPD) Steam

MP steam is extracted from the PG turbine and used: • for various equipment (e.g. heat exchangers, turbine drives) in all the process units. • to drive an air compressor turbine. • for export to the Bukom Refinery. • to support the LP steam system. • as dilution steam for the LOP cracking heaters.

1.2.4 Medium Pressure Desuperheated (MPD) Steam

MPD steam is extracted from the MP steam system and used: • for the MP condensate collection system. • to provide heating for the process water stripping in the LOP units.

1.2.5 Low Pressure (LP) Steam

Low Pressure (LP) steam is produced by various backpressure turbines and used to provide heating for all process units and offsite systems, e.g. heat exchangers, reboilers, Deaerator, equipment heating and storage tank heating.

1.2.6 Low Pressure Desuperheated (LPD) Steam

LPD steam is extracted from the LP steam system and also generated in the gasoline fractionator area. It is used to provide heating for various equipment, e.g. reboilers, in all the process units.

1.2.7 Letdown Stations

Pressure letdown stations are provided from each pressure level to the next lower level. From each pressure level steam can also be vented to the atmosphere, except for SHP.





1.2.8 Steam Boilers

Three steam boilers are provided to generate the required quantity of SHP steam during normal operation with all three boilers in operation. The steam boilers are normally fired with fuel oil, which is produced by the LOP units as Ethylene Cracker Residue (ECR). Natural gas is used as primary back-up fuel for the boilers. Cracked Gas Oil (CGO) is used as secondary back-up fuel and can also be blended with ECR. One motor driven and steam turbine driven forced draft fan for each steam boiler supply the necessary combustion air. Each boiler system comprises a steam drum, a furnace box, a superheater, an economizer, one FD fan, flue gas ducts and exhaust stack.

Two Deaerators are provided to produce the necessary boiler feed water (BFW). The BFW is pumped to the boilers by means of both turbine driven and motor driven pumps. The BFW is also treated by injecting various chemicals such as an oxygen scavenger, amine and phosphate.

1.2.9 Power Generation System

A power generator driven by an extracting/condensing steam turbine is provided to supply the electricity required. The generator electricity produced will be integrated with the site electrical system. Only one power turbine/generation set is provided. Any problem associated with the steam power generation will require the Cracker Complex to switch its power supply to the outside power source from the Bukom Refinery.

1.2.10 Blowdown and Flash Drums

A continuous blowdown drum V-15105 is provided to collect and flash the continuous blowdown from the three steam boilers and the twelve LOP cracking heaters. The collected water is cooled and re-used as wash water and dilution water, or in case of surplus, sent to the intermittent blowdown drum V-15104. This common intermittent blowdown drum, collects the intermittent blowdown from the LOP cracking heaters. The flashed steam is vented, to atmosphere, while the liquid is discharged to the LLOD, via the AOC system.

Several flash drums operating at different pressure levels are provided to receive the condensate streams from the various steam users. The flashed steam is re-used at a lower pressure level and the condensate is cooled and treated, before it is either re-used, or disposed.

1.3 CONDENSATE TREATMENT AND RECOVERY SYSTEMS

1.3.1 Deaerators

Two Deaerators V-15120 A/B will be provided to produce all required BFW for the Cracking Heaters, Steam Boilers, Desuperheaters and other steam generators. During normal operation, two Deaerators are available and are operating at about 77% of their design capacity each. In the event that one Deaerator is shutdown for maintenance and/or statutory inspection, the BFW capacity is decreased by exporting less steam to Bukom Refinery and stopping the production of electric power. The remaining Deaerator is then operated at 100% of its design capacity.





1.3.2 PCC PCC is the LP condensate returned from the heat exchangers, reboilers, heating coils etc. operating at LPS and LPD level. Due to its low pressure, the return condensate is more susceptible to hydrocarbon contamination. The PCC bottoms, from the PCC Flash Drum V-15101 are pumped by the PCC Pumps P-15109A/B through the PCC/Condensate Interchanger E-15102 where heat is exchanged with Polished Condensate from A-15140. The stream is further cooled in the PCC Trim Cooler E-15104 using Cooling Water, before being sent to the PCC Cartridge Filters S-15135A/B. The stream leaves the filters and goes through the Condensate Activated Carbon Filters V-15140A/B before entering the Condensate Surge Tank T-15101. Contaminated PCC can be sent to the PCC Emergency Basin. Flashed-off steam is condensed in the PCC Flash Drum Vent Condenser E-15101, installed on top of the vessel. In this way the flashed steam is recovered and its energy is used to heat-up demin water, which is sent to the Deaerators for BFW make-up. The cooled, flashed steam, then discharges to ASL.

1.3.3 NCC

NCC is the LP condensate returned from the surface condensers of the steam turbines, driving the big compressors and the power generator. NCC is normally clean and contains no hydrocarbons. However, it can be contaminated by inorganics in the case of cooling water leakage in the surface condensers. The Condensate Transfer Pumps P-15101A/B/C pump the tank inventory to the Condensate Treatment Package A-15140. In order to minimize ingress of O2 and CO2 in the PCC/NCC, T-15101 is provided with nitrogen blanketing. Consequently, the tank type is a Low Pressure Cone Roof storage tank. The tank material will be epoxy-coated CS.

1.3.4 MP Condensate

MP Condensate is collected in the MP Condensate Flash Drum V-15102. The flashed steam is sent to the LP Steam header and the condensate is sent to the Process Water Stripper C-11105 and to the Condensate Surge Tank T-15101. Before reaching the Surge Tank, the condensate is cooled down via the MP Condensate Cooler E-15106 and the MP Condensate Trim Cooler E-15107. The cooled down condensate without polishing, is the feed for the Deaerators V-15120 A/B. Contaminated Condensate is sent to the Emergency Basin.

1.3.5 HP Condensate HP Condensate is collected in the HP Condensate Flash Drum V-15103 from the following sources: • E-13206 in the BEU-1 • Drier Regeneration Gas Heater, E-11214 HP Condensate is collected in the HP Condensate Flash Drum V-15103. The flashed steam is sent to the MP Steam header and the condensate is sent to the MP Flash Drum. Contaminated Condensate is sent to the Emergency Basin via HP Condensate Emergency Cooler E-15108 where it exchanges heat with the MP Flash Drum bottoms exiting E-15106.

1.3.6 Condensate Treatment Pre-treatment All rust, debris and hydrocarbons are removed from PCC in the pre-treatment section. The PCC is sent to the PCC Cartridge Filter S-15135 A/B and the Activated Carbon Filters V-15140 A/B. In order to detect any hydrocarbon breakthrough, a TOC-analyser is installed downstream the Activated Carbon Filter.





Polishing The PCC is sent through the Cation Exchangers and Mixed Bed Polishers where all hardness, alkalinity, other inorganic compounds and humic acids are removed in the Condensate Cation Exchangers V-15151A/B and the Mixed Bed Polishers V-15151A/B. A sodium-analyser is installed downstream the Cation Exchangers in order to monitor whether the cationic resin is still active, or has to be regenerated. In order to monitor any breakthrough of compounds which shall be adsorbed by the Polishers, a silica-analyser, conductivity-analyser and a pH-analyser are installed downstream the Mixed Bed Polishers. The Mixed Bed Polisher exit stream is heated in PCC/Condensate Interchanger E-15102 and the MP Condensate Cooler E-15106. After being heated, the stream is goes to the Deaerators as BFW. Backwash & Regeneration Regeneration of the Cation Exchangers is done by diluted acid, followed by backwashing with demin water. The Mixed Bed Polishers are regenerated by diluted caustic / diluted acid, and are backwashed with demin water. Diluted acid is made on-line by mixing demin water and 98% Sulphuric acid coming from P-16104 A/B. Diluted caustic is made on-line by mixing demin water and 50% caustic coming from P-16103 A/B. The regeneration waste is discharged and neutralised in the Waste Neutralisation Sump A-15110, before being sent to the Plant Outfall. At the end of the regeneration cycle water is pumped out of the sump. If the pH at the pump discharge is not between 6.5 and 9, the sump pump discharge valve remains closed and the water is recirculated back into the sump. The pH is then adjusted and when it is between 6.5 and 9, it is pumped to the plant outfall.

1.4 DESALINATED WATER This tank contains hold-up for Demineralised Water production as well as firewater storage. Two Desalinated Water Distribution Pumps P-15105 A/B are used to transfer desalinated water to the Demineralised Water Package. One pump is the operating duty pump and the other pump is the operator selected standby pump. The Desalinated Water Distribution Pumps also keep the firewater ring main under pressure. In the event that the downstream Desalinated Water Package is not operating, the pressure is maintained by circulating the water over the tank using the pump’s minimum flow. In the event of a low pressure in the fire water system, an auto-start signal will start the standby pump. In order to minimise ingress of O2 and CO2 to the Desalinated Water Tank T-15105 is provided with nitrogen blanketing. Consequently, the tank type is a Low Pressure Cone Roof Storage Tank and the tank material is epoxy-coated CS. The Desalinated Water System also serves as a backup water source for the industrial water distribution system.





1.5 DEMINERALISED WATER

The Demineralised Water System consists of: • Demineralised Water Package A-15165. • Low pressure demin water storage tank T-15103. • Demin Water Transfer Pumps P-15103A/B/C • Regeneration and Backwash Pumps P-15106A/B. • Waste Water Neutralisation Sump A-15110. • Neutralised Waste Transfer Pump P-15108. Desalinated water is pumped from the Desalinated Water Tank to the Demin Water Package A-15165, by using pumps P-15105A/B. The Demin Water Package A-15165 consists of a large number of ‘stacks’ in parallel. A stack comprises a number of dual-chambered cells, sandwiched between two electrodes. Within each cell there are two different chambers: a dilute (“D”) chamber through which the desalinated water is fed for de-ionisation and a concentrate (“C”) chamber used to collect and remove the extracted ions. Demin water is stored in the Demin Water Storage Tank T-15103. During normal operation, the tank is operated full, at constant liquid level. The tank type is a Low Pressure Cone Roof storage tank. The tank material will be epoxy-coated CS Demin Water from the Storage Tank is pumped by the Demin Water Transfer Pumps P-15103A/B/C to the Continuous Blowdown Drum Interchanger E-15103. Two of the three pumps are running and one is spare. In the event of an NCC and/or PCC/NCC failure , the third demin water pump must/can be switched on to maintain sufficient make-up to the Deaerators The Demin Water is also pumped, by the Regeneration and Backwash Pumps P-15106A/B as Backwash Water, to the Condensate Treatment Package A-15140. Two streams are taken from the pumps discharge line, one is mixed with 98% Sulphuric Acid and the other is mixed with 50% Caustic. The dilute Acid stream and the dilute Caustic stream are sent to both the Condensate Treatment Package and the Waste Water Neutralisation Sump. The regenerant waste streams from the PCC/NCC treatment are sent to the waste water neutralisation sump A-15110, where it is neutralised by mixing with a dilute Acid and Dilute Caustic, before being pumped to the plant outfall by the Neutralised Waste Transfer Pump P-15108.





2. CONTROL DESCRIPTION

2.1 STEAM SYSTEM The main control objectives for the Steam/BFW/Condensate and Power Generation System can be summarized as follows: • Maintain the pressure/temperature in all six steam headers (SHP, HP, MP, MPD, LP and

LPD). • Provide a boiler feed water control system for the steam boilers A-15101/2/3 and

Cracking Heaters F-10100-11000 where the supply of water matches the steam production rate such that the level in the steam drums is maintained around midpoint.

• Provide a control system to maintain the level and pressure in the Deaerator V15120A/B during boiler load variations.

• Provide a burner management system that includes: • Load control on steam pressure (by steam boiler vendor). • Ratio control of fuel and combustion air with lead/lag function (by steam boiler

vendor). • Low and high pressure protective control of the fuel supply (by steam boiler

vendor). • Adequate removal/re-use of the condensate from the blowdown drums and condensate

flash vessels V-15101/2/3/4/5. • Provide an electrical system for the turbine-generator controls. • Provide MP Steam Export flow- and temperature control. • Provide sufficient storage capacity for Newater, Demin Water and returned Condensate. • Neutralization control of regeneration waste from Demin and Polisher Unit prior to

discharging to sea. 2.1.1 General

The pressure in each of the five steam headers (SHP, HP, MP, LP and LPD) is controlled in each header by means of a set of pressure controllers. This makes it possible to split the operating window for each header into various pressure ranges and for each range to take specific control actions. The general setup for the control actions is as follows: • Under normal operating conditions, the SHP Steam header pressure is controlled by

adjusting the load of the steam boilers, the pressure in the HP Steam, MP Steam and LP Steam headers are controlled by adjusting the steam extraction flows from the steam turbines and the pressure in the MPD Steam and LPD Steam is controlled by steam letdown via the desuperheaters.

• On the lower side, when the steam pressure in the header is decreasing, additional steam can be taken in via a letdown station from the higher pressure level.

• On the higher side, when the steam pressure in the header is increasing, the surplus of steam can be letdown to a lower pressure level also via a letdown station.

• On the higher side, when the steam pressure is increasing too much, steam is vented to the atmosphere, except for SHP.

For each steam header this approach will be described in more detail in the next paragraphs. The MPD steam header is only temperature controlled.

2.1.2 SHP Steam Header

The pressure in the Primary SHP steam header is maintained under normal operating conditions by adjusting the load of one of the steam boilers A-15101/2/3. All three boilers will be in operation, whereby two of them run on a fixed load approximately 75%, while the third boiler reacts on the pressure variations as set by the pressure controller.





The signal from a pressure controller PICA-070 (or PICA-071) is sent to the burner management system of the relevant boiler, along with the ECR/CGO flow rate, Natural gas flow rate, the air flow rate and the stack Oxygen content. In the event that the capacity of the boiler under pressure control reaches a constraint (for example the boiler is at its minimum turndown or the boiler is at 100% MCR), the load of the second and third boiler is adjusted. A further decrease in the Primary SHP steam header pressure will result in the second pressure controller PICA-068, reducing the steam demand on the Power Generation (PG) turbine. The signal from the pressure controller is therefore sent to the control system of the Steam Turbine/Generator Package. If the pressure, in the SHP steam header becomes high, a third pressure controller PICA-069 will open the SHP/HP steam desuperheater/letdown valve J-15101A or B and SHP steam is letdown to the HP steam header.

2.1.3 HP Steam Header

There are five pressure controllers PICA-013 until PICA-017 on the HP Steam Header. The PV for all pressure controllers is derived from a MOO3 configuration with three pressure tappings. The pressure in the HP Steam Header is normally controlled by pressure controller PICA-017, which manipulates the steam extraction control valve of the Cracked Gas Compressor (CGC) Steam Turbine KT-11201. In the event that the pressure in the HP Steam Header decreases, PICA-014 will open the SHP/HP Steam Desuperheater/letdown valve J-15101A or B. SHP Steam is then letdown from the SHP Steam Header to the HP Steam Header via high signal selector PY-014. Shall the pressure continue to fall in the HP Steam Header, PICA-015 will open via high signal selector PY-015 SHP/HP Steam Desuperheater/letdown valve J-15109A or B and more SHP steam is then letdown from the SHP Steam Header to the HP Steam Header. At the other hand in the event that the pressure in the HP Steam Header increases, PICA-016 will send a singal to high signal selector 151PY-022 in order to open HP/MP Steam Desuperheater/letdown valve J-15102A or B and HP steam is then letdown to the MP steam header, via high signal selector PY-022. A continued increase in pressure in the HP Steam Header will result in PICA-013 opening a vent control valve to ASL. The temperature controller TICA-005 is used to control the exit temperature of the SHP/HP Steam Desuperheaters J-15101A or B, by manipulating the amount of BFW added to the SHP/HP Steam Desuperheater. TICA-006 is used to control the exit temperature of SHP/HP Steam Desuperheater J-15109A or B.

2.1.4 MP Steam Header

There are five pressure controllers PICA-021 until PICA-025 on the MP Steam Header. The PV for all pressure controllers is derived from a MOO3 configuration with three pressure tappings.





The pressure in the MP Steam Header is normally controlled by pressure controller PICA-025 which manipulates the steam extraction control valve of the Power Generation Steam Turbine GT-15190. In the event that the pressure in the MP Steam Header decreases, PICA-022 will open the HP/MP Steam Desuperheater/letdown valve J-15102A or B. HP Steam is then letdown from the HP Steam Header to the MP Steam Header, via high signal selector PY-022. Shall the pressure continue to fall in the MP Steam Header, PICA-023 will open HP/MP Steam Desuperheater/letdown valve J-15110A or B. More HP steam is then letdown from the HP Steam Header, to the MP Steam Header. At the other hand in the event the pressure in the MP steam Header increases, pressure controller PICA-024 will open the control valve PICA-031CV (via high signal selector PY-031), installed upstream the MP/LP Steam Desuperheater J-15103. MP steam is then letdown to the LP Steam Header. A continued increase in pressure in the MP Steam Header will result in PICA-021 opening a vent control valve to ASL. The temperature controller TICA-010 is used to control the exit temperature of the HP/MP Steam Desuperheaters J-15102A or B, by manipulating the amount of MBFW added to the HP/MP Steam Desuperheater. TICA-011 is used to control the exit temperature of MP/LP Steam Desuperheater J-15110A or B.

2.1.5 MPD Steam Header

The temperature controller TICA-014 is used to control the exit temperature of the MP/MPD Steam Desuperheater J-15105, by manipulating the amount of MBFW added to the MP/MPD Steam Desuperheater.

2.1.6 LP Steam Header

There are three pressure controllers PICA-030, PICA-031 and PICA-032 on the LP Steam Header. The PV for each pressure controller is derived from a MOO3 configuration with three pressure tappings. The pressure in the MP Steam Header is normally controlled by PICA-030 which manipulates the steam extraction control valve of the Propylene Refrigeration Compressor Steam Turbine KT-11501. In the event that the pressure in the LP Steam Header decreases PICA-031 will open the control valve upstream of the MP/LP Steam Desuperheater J-15103 via high signal selector PY-031. MP Steam is then letdown from the MP Steam Header to the LP Steam Header. A high increase in pressure in the LP Steam Header will result in PICA-032 opening a vent control valve to ASL. The temperature controller TICA-015 is used to control the exit temperature of the MP/LP Steam Desuperheater J-15103, by manipulating the amount of MBFW added to the MP/LP Steam Desuperheater.

2.1.7 LPD Steam Header

There are two pressure controllers PICA-036 and PICA-037 on the LP Steam Header. The PV for each pressure controller is derived from a MOO3 configuration with three pressure tappings.





Upon decreasing pressure in the LPD steam Header, pressure controller PICA-036 will open the control valve upstream the LP/LPD Steam Desuperheater J-15104. LP steam is then letdown to the LPD steam header. Upon increasing pressure in the LP Steam Header, pressure controller PICA-037 will opening a vent control valve to ASL. The temperature controller TICA-017 is used to control the exit temperature of the LP/LPD Steam Desuperheater J-15104, by manipulating the amount of MBFW added to the LP/LPD Steam Desuperheater.

3. DETAILED CONTROL NARRATIVES 3.4 STEAM BOILERS, A-15101/2/3, STEAM LOAD CONTROL

PICA-070, PICA-071, HIC-100, HIC-200, HIC-300, Y-100, Y-200, Y-300, HS-098, HS-401, UC-400, UC-401

UFS E-00000-TN-2366-0026 E-15100-TN-2396-0001 Deaerator and SHP Steam Production UEFS E-00000-TN-2395-0075 BFW and SHPS Distribution – Sheet 10 E-15100-TN-2395-0004 SHP Steam Boilers

3.4.1 Objective

The objective is to balance the steam production with the steam demand, by controlling the SHP Steam Header pressure with the firing rate and by distributing the load over the three boilers. This control scheme determines the set point for the boiler firing control scheme. The load of the boilers is maintained between 72 ton/h and 180 ton/h steam per steam boiler. Below 72 ton/h (40 % MCR) is not allowed as this is the minimum stable turndown of the steam boiler. Above 180 ton/h is not allowed as this is above 100 % MCR of the steam boiler. Additional provisions guarantee steam production during upsets.

3.4.2 Functional Description

Two of the three boilers operate at an operator set fixed steam production rate, as a percentage of MCR, set by HIC-100 (boiler A-15101), HIC-200 (boiler A-15102), and HIC-300 (boiler A-15103). The 3rd boiler, selected by the operator through HS-401, is in balancing mode. One of the two boilers at fixed rate will be set as backup balancing boiler by the operator through HS-401. The signals from HIC-100, HIC-200 and HIC-300 are sent to the boiler load calculation blocks Y-100, Y-200 and Y-300 respectively. The SHP steam pressure controller switch HS-098 receives a measurement from either PICA-070 (normally active) or PICA-071. The operator selects the active pressure controller. PICA-071 is only used when the primary SHP Steam Header controller PICA-070 is out of service due to maintenance and/or inspection. The output of switch HS-098 is sent to the calculation blocks Y-100 (boiler A-15101), Y-200 (boiler A-15102), Y-300 (boiler A-15103) and to the Steam Generation Load Control 151UC-400 ????????





The signal from HS-401 determines the position of the calculation blocks Y-100, Y-200 and Y-300. The boiler in balancing mode selects the signal from HS-098, the other boilers select the signal from their respective HIC. The output of the three calculation blocks Y-100, Y-200 and Y-300 is sent to the burner management system of respectively boiler A-15101, A-15102 and A-15103. The steam production rate of the two boilers at fixed load will automatically be adjusted in parallel when the MCR of the balancing boiler exceeds a fixed high value, or falls below a fixed low value. The signal from the Primary SHPS Header pressure controller PICA-070 or the Secondary SHPS Header pressure controller PICA-071 is sent to the proportional-only controller UC-401, depending on the position of the hand switch HS-098. When this signal is higher than the fixed low value, and lower than the fixed high value, the controller will not be active. PV Tracking will make the setpoint equal to the measurement. When the measurement exceeds the fixed high value, or falls below the fixed low value, the controller will be made active with the setpoint having the value of the fixed high value or the fixed low value respectively. The output of the direct acting, proportional only controller UC-401 is sent as a bias signal to HIC-100, HIC-200 and HIC-300. Trip signals from the three boilers A-15101, A-15102 and A-15103 are sent to HS-401 through 151UZ-xx1, 151UZ-xx2 and 151UZ-xx3 respectively. In case that the balancing boiler trips, HS-401 will switch the backup balancing boiler to balancing mode. In case that the backup balancing boiler trips, HS-401 will switch the boiler at fixed rate to backup balancing mode.

Control Valve Tag Name Alg Action PV-Tracking Name PICA-070 PID Reverse Yes - PICA-071 PID Reverse Yes - HS-098 MAN-SEL - - - HS-401 MAN-SEL - - - HIC-100 - - - - HIC-200 - - - - HIC-300 - - - - Y-100 - - - - Y-200 - - - - Y-300 - - - - UC-401 PID Direct Yes - UC-400 ??? ??? ??? -

NEM comment: Controller UC-400 to add?????? 3.4.3 Operational and Implementation Aspects 3.4.3.1 Operational Modes

Each of the three boilers can be in either balancing mode, backup balancing mode, or fixed production mode. Selection is made by the operator through switch HS-401. The boiler in backup balancing mode operates as it is in fixed production mode, but switches to balancing mode when the boiler in balancing mode trips. The boiler in fixed production mode switches in this case automatically to backup balancing mode through HS-401. In case that the boiler in backup balancing mode trips, the boiler at fixed production will be set to backup balancing mode automatically, through HS-401.





3.4.3.2 Start up N/A.

3.4.3.3 Normal Steady State

The manual input stations HIC-100, HIC-200 and HIC-300, and the switch HS-401 will always be in AUTO. The calculation blocks Y-100, Y-200, Y-300 will always be in CAS. Controller UC-401 cannot be switched to MAN.

3.4.3.4 Crippled Mode Operation

When PICA-070 or PICA-071 becomes BAD, the controller shall be set to MAN with its last good output value.

3.4.3.5 Shutdown

When a trip signal from the boiler in balancing mode is received, the boiler in backup balancing mode will be switched to balancing mode through HS-401. The boiler in fixed production mode shall be switched to backup balancing mode. When a trip signal from the boiler in backup balancing mode is received, the boiler in fixed production mode shall be switched to backup balancing mode through HS-401.

3.4.3.6 Calculations

N/A.

3.4.3.7 Initialisations

When the switch Y-100, Y-200, or Y-300 switches from UC-401 to the corresponding manual input station (HIC-100, HIC-200 or HIC-300 respectively), the HIC shall absorb any difference to ensure bumpless transfer.

3.4.3.8 Interfaces

Trip signal 151UZ-HOLD from boiler A-15101, trip signal 151UZ-HOLD from boiler A-15102 and trip signal 151UZ-HOLD from boiler A-15103 shall be connected to switch HS-401. When a boiler trip signal is received, the output of the respective manual input station (HIC-100, HIC-200 or HIC-300 for boilers A-15101, A-15102, A-15103 respectively) shall be set to 0%. The respective switch (Y-100, Y-200 or Y-300) shall be switched to select the input from the manual input station. See for further functional requirements paragraph 3.4.3.1, Operational modes.

3.4.3.9 Operator Interfaces

The operator can access UC-401, HIC-100, HIC-200 and HIC-300 only through the normal DCS interface.

3.4.3.10 Special Considerations

The manual input stations HIC-100, HIC-200 and HIC-300, and controller UC-401 shall have high and low output limits at 180 ton/h steam and 72 ton/h steam respectively. Controller UC-401 shall have a proportional only PID algorithm.

3.4.4 History

Date Author Description





09-05-2006 GRI Original Document

3.5 SHP/HP STEAM DESUPERHEATER, J-15101A/B, PRESSURE CONTROL

PICA-063, PICA-014, PY-014, TICA-005, HS-023 UFS E-15100-TN-2396-0001 Deaerator and SHP Steam Production E-15100-TN-2396-0003 HP Steam Distribution UEFS E-15100-TN-2395-0006 SHP/HP Steam Desuperheaters

3.5.1 Objective To protect SHP steam header against high pressure and to protect HP steam header against low pressure. Both objectives are achieved by SHP to HP steam letdown through the SHP/HP Steam Desuperheater J-15101. When for low pressure protection this line of defence is not sufficient a separate pressure controller activates a second SHP to HP steam letdown through the SHP/HP Steam Desuperheater J-15109. For detail specification see section 3.11. The objective for TICA-005 is to maintain a steady temperature for the desuperheated steam, regardless of the Desuperheater load.

3.5.2 Functional Description The protective pressure controller PICA-069 protects the SHP steam header against high pressure. Pressure controller PICA-069 operates one of the control valves PICA-014CVA/B, which manipulates the SHP/HP steam letdown flow through the SHP/HP Steam Desuperheater J-15101A/B. The protective pressure controller PICA-014 protects the HP steam header against low pressure. Pressure controller PICA-014 also operates one of the control valves PICA-014CVA/B. Both the controllers PICA-069 and PICA-014 send the output signal to the high signal selector PY-014, which in turn selects one controller to operate one of the control valves PICA-014CVA/B. The temperature controller TICA-005 operates one of the control valves TICA-005CVA/B, which manipulates the HBFW flow to the SHP/HP Steam Desuperheater J-15101A/B. With manual selector swith HS-023 the operator is able to select the right control valves, corrresponding to the SHP/HP Steam Desuperheater J-15101A or J-15101B in operation. In case manual selection HS-032 switch is in position “J-15101A”, the high signal selector PY-014 sends a signal to control valve PICA-014CVA and temperature controller TICA-005 sends a signal to control valve TICA-005CVA. Otherwise when manual selection switch HS-023 is in position “J-15101B”, the high signal selector PY-014 sends a signal to control valve PICA-014CVB and temperature controller TICA-005 sends a signal to control valve TICA-005CVB.

Control Valve Tag Name Alg Action PV-Tracking Name PICA-069 PID Direct No - PICA-0141 PID Reverse No - PY-014 H-SEL - - -





TICA-005 PID Direct Yes - HS-0232 - - - TICA-005CVA/

PICA-014CVA HS-0233 - - - TICA-005CVB/

PICA-014CVB NOTE: 1: The pressure controller uses the output (OP) of Moo3 PY-012 as PV. 2: Describes control with manual selection switch in position “J-15101A”. 3: Describes control with manual selection switch in position “J-15101B”.

3.5.3 Operational and Implementation Aspects 3.5.3.1 Operational Modes

This control scheme is required to be operational during start up and normal operation.

3.5.3.2 Start up

3.5.3.3 Normal Steady State During normal operation the pressure controllers PICA-069 and PICA-014 and the calculation block PY-014 shall be in AUTO. The temperature controller TICA-005 shall be in AUTO.

3.5.3.4 Crippled Mode Operation If the SHP steam header pressure measurement PI-069 is BAD, the mode of the pressure controller PICA-069 shall be set to MAN and its output shall be frozen. If all HP steam header pressure measurements PI-012A/B/C are BAD, the mode of the pressure controller PICA-014 shall be set to MAN and its output shall be frozen. If the HP steam header temperature measurement TI-005 is BAD the mode of the temperature controller TICA-005 shall be set to MAN and its output shall be frozen.

3.5.3.5 Shutdown


N/A.

3.5.3.7 Initialisations To prevent the protective pressure controllers PICA-069 and PICA-014 from winding-up, apply external reset feedback from the output of low signal selector PY-014, when not selected.

3.5.3.8 Interfaces

N/A. 3.5.3.9 Operator Interfaces

Operator can access tags on the DCS.





3.5.3.10 Special Considerations The setpoint of the protective controllers PICA-069 and PICA-014 cannot be changed by the operator. The mode of these protective controllers shall always be AUTO.

3.5.4 History

Date Author Description 10-03-2006 RVO Original Document





NEM General comments:

1. Please also provide input for Section 2, ‘Control Description’. 2. We have checked this document towards your ‘Process Control Diagrams’ (PCD’s). Many

calculation blocks/functions are not described in this document. Please give a (brief) description of all calculation blocks/functions.

3. We assume that selection of the atomizing medium is done in/via the Burner Management System

(BMS). NO, in DCS 4. Add a separate section for the sootblowing sequence control.

5. Add a separate section for the Cooling Air Fans Automatic take-over 6. Add a separate section for the control and safeguarding of the FD Fan K15161, including:

• Steam Turbine KT-15161 • Lube Oil System • Automatic “clutch” system, i.e. switch-over system from steam turbine to electric motor and vice

versa

7. The configuration of the DCS (by Yokogawa) will be done via the NEM logics and the “Shellified” P&ID’s made by J.V. We will send you our “Shellified” P&ID’s so that you know how we understand and interpret your intended control and safeguarding.





3.6 BOILER OPERATION AND CONTROL

INTRODUCTION This document describes the fired steam boiler for the Ethylene Cracker Complex (ECC) to be installed at Shell Eastern Petroleum Plant. It should be read in conjunction with the piping and instrumentation diagrams (P&ID's), which are mentioned as reference documents. The document describes the controls, system protection, settings etc. in general for items within the responsibility and scope of NEM. See also process control diagrams 36005-646-01. All instrument tag numbers will have prefix ‘151’. (The Logic Diagrams and Loop Diagrams shall describe these in detail and are always leading above this document). The boiler forms an integral part of the plant and produces SHP superheated steam for the plant by firing different fuels. This SHP steam is fed to the steam header of the plant at the following normal operating conditions: Flow: 72 - 180 t/h (40 – 100% MCR) Pressure: 120 – 125 bar(g) Temperature: 515 – 525 °C The boiler operates at single pressure with natural circulation and is fed by FW pumps. The operation of the boiler and its associated equipment is carried out by the following systems: System DCS Local panel Boiler control/start/stop emergency stop Fuels/Burners/atomizing control/start/stop start/stop FD fan (incl. ST) control/start/stop start/stop Motor drive FD fan start/stop start/stop Seal and cooling air fan start/stop Sootblower start/stop The boiler is designed for operation from the plant CCR. At the boiler and FD Fan local panel only start-stop of the burners and FD fan unit is possible. Control and monitoring of the boiler is performed by the DCS. The safeguarding with interlocks is integrated in the plant ESDS (including BMS). All relevant signals in the ESDS are also monitored in the DCS. The detailed procedure on the start-up and shutdown, and operation of the burners can be found in the following documents: Burner System Description: 36005-824-04-148 Logic Diagrams: 36005-824-04-304-001 Cause and Effect Diagram: 36005-824-04-307 Logbook The boiler is operated through a DCS. This DCS is capable to supply interactive communication between the operators and the installation. It also supplies trends of process values and stores a database of previous operating conditions and boiler status. The owner of the boiler is obliged to register all relevant data of the boiler in a logbook. As a minimum the different operating situations are noted: HP steam header conditions, boiler start/stop, boiler load, boiler steam conditions, fuel and air flow conditions, malfunctioning of systems/equipment and other process conditions.





This logbook will be very helpful also in case of malfunctioning of a part to assure fast and adequate NEM response. Note: 1) In this document reference is made to equipment or parts of the plant not in NEM scope. This document does not change NEM’s scope. Here it has the purpose to explain the functionality of the NEM scope integrated in the total plant. The NEM scope is also defined in the P&ID’s (see reference documents)





OPERATION AND DESIGN CRITERIA Regulations and Design Codes The system is designed and fabricated according to the applicable rules: 1. ASME I Edition 2004, including addenda 2005 2. ASME VIII Edition 2004, including addenda 2005 3. ASME B31.1 Edition 2004 4. ASME B31.3 Edition 2004 5. NFPA85 Edition 2004 Supervision The system is designed for constant supervision from a CCR in the vicinity of the boiler. Operation The boiler is designed for a life time of 20 years. The operating schedule for each unit is 8760 hr of service per year. The boiler plant consists out of three (3) boilers operating simultaneously. In case one of the boilers is out of service the remaining boilers will operate at 100%MCR. Within the life time of the boiler the number of start-up/shutdowns are based on cold conditions and limited to: Type of cycle Number Definition of cycle Cold start-up and shut down 2000 boiler at ambient conditions Performance The boiler is designed to meet the performance as noted in NEM’s Performance Table documents 36005-103-01/36005-103-38. For these documents it is referred especially to the cases ECR (100% MCR, guarantee) and ECR (70% MCR, normal). At MCR the steam production of each boiler is 180 t/hr. The boiler turn down range is 40 – 100% MCR load. The steam temperature is controlled for 40 – 100% MCR load. Dynamic Characteristics The boiler is designed to follow boiler load fluctuations during normal operation. However, the boiler pressure and temperature gradients may never exceed the allowable values. Degree of Automation The degree of automation is described in more detail in the chapters below. Protection Concept Dangerous situations shall be avoided by safety relief valves and by the safety oriented protection system. Control System Requirements The control of the boiler shall be realized with a control system, which is commonly used in power plants. The control system shall be capable of handling the dynamics of the system without limiting the performance. Environmental Conditions The boiler is located outdoors. Reference documents DEP 32.24.20.38-Gen Standard drawing S24.030-C





3.7 BOILER COMBUSTION AIR CONTROL

HLA10AA001 (IGV FD Fan), FC-202B (Combustion Air), QC-021 (Oxygen)

P&ID 36005-105-02 Fluegas System PCD 111 UEFS E-15100-TN-2395-0031 Steam Boiler Package A-15101 – Flue Gas System

3.7.1 Objective The air flow and air/fuel ratio control take care for an optimal and safe combustion of fuel oil (ECR/CGO), Natural gas (NG) or a combination of fuels. Depending on boiler load (firing rate) measured air and fuel flows are used for this control with the O2 content measured at the stack inlet as correction parameter.

3.7.2 Functional Description The desired boiler load is compared with the total measured fuel and air flow load in a minimum respectively maximum value selector. The operator has to select the control mode for the fuels (one fuel in fixed load mode, one fuel in control mode or both fuels in control mode and atomization medium (if applicable).

The min/max selection takes care for having under all load conditions, and during load increase and decrease that the air/fuel ratio is held on a predefined value to assure proper and complete burning. This is achieved during load increase by determination of the desired fuel flow via the measured air flow and during load decrease by determination of the desired air flow via the measured fuel flow. The air flow is controlled by the IGV of the FD Fan using the air flow measured in the FD Fan suction duct.

When firing fuel oil the total fuel load is composed from the measured ECR/CGO flow and atomizing gas flow. During dual fuel firing the measured total fuel load is composed from the measured ECR/CGO flow and added with the measured NG flow and atomizing gas flow. When firing oil and gas together the required air/fuel ratio for oil will be used to determine the required air flow. To control the air/fuel ratio under all operating situations in a correct manner the following corrections are incorporated: • Boiler load • Number of burners in operation • Number of air doors not closed opened • Fuel temperature (HOLD) • Igniter in operation (HOLD) • Variations in heating value (HOLD) • Natural Gas density (HOLD)





Please briefly describe all calculation blocks, switches, High or Low Selectors, etc.

DCS – Analogue Control Valve

Tag name Service Action PV-Tracking Name FC-202B PID Direct No FICA-202 QC-021 PID Direct No Y-202A Automatic start

up function - No -

NOTE:

DCS - Discrete Control Tag name Service Limit Action Valve/Controller HS-204 Switch to gas or steam

atomising. Calculation to Combustion air equivalent is dependant on atomisation.

PDIC-216/PC-216 or PDIC-227/PC-227 are on AUTO

Operator PDIC-216 or PDIC-227

NOTE:

IPS - Discrete Control Tag name Service Limit Action Valve/Controller FZA-201 Combustion Air flow LL Boiler trip Natural gas

Fuel Oil Atomising valves

NOTE: 1) IPS (SIL1)


This control scheme is required to be operational during start up and normal operation and shutdown.

3.7.3.2 Start up At starting of the boiler the controllers FC-202B and QC-021 are in MAN mode, output 0%. When all the burners are started and on AUTO, the controllers FC-202B and QC-021 will be switched to AUTO and receive their set points from the overall load control. See also section 3.19


During normal operation controllers FC-202B and QC-021 shall be in AUTO.






Instrument Tag Name Output Controller Action Output FZA-2011) BAD IPS Boiler trip Freeze FICA-202 BAD FC-202B Mode to MAN Freeze TI-201 BAD - - Freeze PIA-203 BAD - - Freeze TI-202 BAD - - Freeze PIA-202 BAD - - Freeze TIA-203 BAD - - Freeze TIA-204 BAD - - Freeze QICA-0212) BAD QC-021 Mode to MAN Freeze PI-204 BAD - - Freeze NOTE: 1) IPS

2) In JVN Scope

3.7.3.5 Shutdown It is only for a limited time (maximum 60 seconds) allowed keeping the combustion air flow through the boiler when the boiler is not in operation anymore. The air will forcibly cool down the boiler in a rapid time, may be too fast with respect to temperature gradients in the steamdrum and superheater headers. See also section 3.19


Output (y) Input (x1,x2,x3) TAG Calculation 1x 2x 3x Y-202 21202 xorxCy Y ∗= −

Low SEL and SP Calculation stochiometric air equivalent [kg/h]

Y-100 Boiler load % MCR value

TC-202 Steam temp. gradient

FZA-201 1201 xCy ∗=

Conversion to kg/h

HLA10CF001 N/m2 1)

FICA-202 1202 xCy ∗=

Conversion to kg/h

HLA10CF002 N/m2 1)

HY-261A )21(6

1xxn +=∑

n burners in operation

NG burner in operation

CO burner in operation

HY-261B BCxxy 261)21( ∗−=

Air flow leakage correction for n air doors closed

Number of air doors

Air doors not closed

Correction value C261B

HY-261C CCxxy 261)21( ∗−=

Air flow leakage correction for n air doors not closed and n burners in operation

Number of NG/CO burners in operation

Air doors not closed

Correction value C261C





HY-261D 321 xxxy ++= Total air flow leakage correction for n air doors not closed and n burners in operation

HY-261A HY-261B HY-261C

HY-261E 2/1 xxy = Air flow leakage correction factor for n air doors not closed and n burners in operation

HY-261D HY-261A

HY-260A AA CxCy 260260 211 +∗=

Excess air depending on boiler load [%MCR]


HY-260B High SEL in case of combined fuel firing

Minimum excess air factor for NG

Minimum excess air factor for CO

HY-260C High SEL excess air factor HY-260A HY-260B HY-260D Low SEL excess air factor HY-260C Maximum

Excess air factor

HY-260E High SEL excess air factor HY-260D QY-021C FY-202A 2/1 xxy =

Calculation Air/Fuel Ratio

FICA-202 FY-502D

HY-202B 2*1 xxy =

Calculation total excess air factor

HY-260 HY-261E

FY-202B 2/1 xxy = Calculation stochiometric air requirement

FICA-202 kg/h

HY-202B

FY-202C 2*1 xxy = SP calculation air requirement

HY-202B FY-211B kg/h

FY-211A Low SEL or SP and PV combustion air equivalent

Y-202 kg/h

FY-202B kg/h

FY-211B High SEL or SP and PV of total combustion air equivalent

Y-202 kg/h

FY-205D kg/h

FY-205A

)

,(**1

NO

COSCOGNG

Cor

CCCxy =

Combustion air equivalent atomizing gas, steam or no atomising

FI-207 kg/h

HC-205B CNG

HC-206C/D/E CCOG, CCOS or CNO

FY-205B 10001∗∗= xCy NG

Combustion air equivalent NG

FIC-205 t/h

HC-205B CNG

FY-205D If firing mode is COMBINED: 21 xxy +=

if firing mode is NOT COMBINED:

).2,1( xxSELHighy = # burners

FY-205B kg/h

FY-206B kg/h

FY-206B 1xCy CO ∗=

Combustion air equivalent CO

FIC-206 kg/h

HC-206B CCO





FY-212A 21 xxy −= Combustion air equivalent CO

FY-211A kg/h

FY-205B kg/h

FY-212B 21 xxy −= Combustion air equivalent correction for atomizing gas

FY-212A kg/h

FY-205A kg/h

FY-212C

21 xxy −= Combustion air equivalent NG

FY-212G kg/h

FY-206B kg/h

FY-212D COCxy /1=

Calculation stochiometric air flow to CO flow in kg/h

FY-212B kg/h

HC-206 CCO

FY-212E NGCxy /1=

Calculation stochiometric air flow to NG flow in kg/h

FY-212C kg/h

HC-205 CNG

FY-212F 1000/)21( xxy −= NG flow correction for atomizing gas flow in t/h

FY-212E kg/h

FY-206A kg/h

FY-206A )(1 OSOG CorCxy ∗=

Contribution atomizing medium

FI-207 kg/h

HC-206C/D COG or COS

QY-021 021021 211 CxCy +∗=

O2 vol % depending on boiler load [%MCR]


QY-021B Low SEL excess air factor QC-021 Maximum excess air

QY-021C High SEL excess air factor QC-021B HY-260B HY182n )1(. xfCy CONCON= 1) HC182

HY182g )1(. xfCy COGCOG= 1)

Please consider to use the output of flowmeter installed in gas atomizing line

HC182

NOTE: 1) Square root operation in DCS


Ranges TAG Description Range Units FC-202B Combustion air Controller 30 - 100 % QC-021 Oxygen outlet boiler controller 0 - 2 Excess Air Y-202 Calculation block combustion air 0 – 216000 Equivalent

comb. Air [kg/h]

NOTE:





Alarms

TAG Description Level Value Units FICA-202 A- Indication 108000 kg/h PIA-203 A+ Indication 90 mBar(g) PIA-202 A+ Indication 30 mBar(g) PIA-202 A- Indication -10 mBar(g) TIA-203 A+ Indication 390 °C TIA-204 A+ Indication To follow °C QICA-021 A- Indication 1.1 % FA-202A A+ Indication 1.6 - FA-202A A- Indication 1.05 - NOTE:

Trips

TAG Description Level Value Units FZA-201 Z-- IPS – SIL1 90000 kg/h FZA-201 A- HOLD IPS – SIL1 108000 kg/h FZA-202A Z-- ?????????? 1.0 - NOTE:

Settings TAG Description Value Units HC182 Lower Heating Value common

Oil By JVN MJ/kg

CY-202 Conversion from MCR value to CA equivalent flow

2016 kg/h

C201 Conversion from ∆p measurement to flow in kg/h

To follow Kg/s/√(bar) HOLD

C202 Conversion from ∆p measurement to flow in kg/h

To follow Kg/s/√(bar) HOLD

HC-205B CNG

CNG Stochiometric air flow factor 16.4 -

HC-206B CCO

CCO Stochiometric air flow factor 13.0 -

HC-206C CCOG

CCOG Calculation factor for gas atomization

1 -

HC-206D CCOS

CCOS Calculation factor for steam atomization

0 -

HC-206E CNO

CNO Calculation factor for no atomization

0 -

C261B Air flow factor for cooling when air door is closed (leakage)

0.1 -

C261C Air flow correction factor for air door is not closed but burner out of operation (flame front resistance)

1.1 -

C1260A Conversion for excess air depending on boiler load [%MCR]

-0.0137 -





C2260A Conversion for excess air depending on boiler load [%MCR]

2.05 -

C1021 Conversion for O2 % depending on boiler load [%MCR]

-0.16 -

C2021 Conversion for O2 % depending on boiler load [%MCR]

12.7 -

HS-021 O2 vol % 1.1 (min.) 7.0 (max)

% (vol)

C502b Influence of firing mode on excess air

To follow %

CCOG Conversion factor from PV CO flow to required CO flow (with gas atomization) Please consider to use the output of the flowmeter, which is installed in the gas atomizing line.

To follow -

NOTE:

3.7.3.8 Interfaces

With SHP steam load controller Y100 3.7.3.9 Operator Interfaces

Operator can access tags on the DCS. 3.7.3.10 Special Considerations

During purge, start up and shutdown the air flow through the FD Fan will be limited by means of a mechanical minimum stop. The control system and air/fuel ratio computation counts for the number of burners in operation and number of air doors NOT closed. In case one or more burners are out of operation the oxygen controller (QC-021) is put to MAN, 0% output. Counting for the burners will be based on “oil flame on” or “gas flame on” or both signals healthy for individual burner (see also DEP 32.24.20.38). If oxygen controller QC-021 is forced to MAN it shall retain its last output setting unless manually changed by the operator.

3.7.4 History

Date Author Description 20-07-2007 HuR/WiH Original Document





3.8 GAS/FUEL OIL CONTROL

PC-209A / PC209B / FC-205 (NG), PC-214A / PC214B / FC206 (CO), PDIC-227 / PC-227 (Atomizing Steam), PDIC-216 / PC216 (Atomizing Gas) P&ID 36005-105-17 P&ID Piping burner system 36005-824-04-151-002/003/004 P&ID Common skid 36005-824-04-151-005/006/007 P&ID Local burner fuel system PCD 112 UEFS E-15100-TN-2395-0039 Steam Boiler Package A-15101 – Fuel Control System Reference document 36005-824-04-148 Burner system description

3.8.1 Objective The fuel flow control takes care for an optimal and safe combustion of fuel oil (ECR/CGO), Natural gas (NG) or a combination of fuels. Depending on boiler load the measured fuel flow is used for this control.

3.8.2 Functional Description The measured fuel flow will be compared with the required fuel flow as determined by the combustion air control system and the output signal will be used to control the fuel by the control valves PICA-209 and/or PICA-214. In case the fuel pressure becomes too low the master control will be override by the slave controller and the fuel is controlled at a minimum pressure. Similarly, when the fuel pressure becomes too high the fuel is controlled at maximum pressure. The control system will count for the number of burners in operation and the number of air doors open. In the DCS the operator has to select the control mode for the dual fuel firing (one fuel in fixed load mode, one fuel in control mode or both fuels in control mode). Always one fuel shall be in the AUTO control mode. Depending on the fuel(s) to be fired the operator has also to select from DCS the atomizing medium (no atomizing, steam or NG atomizing) and fuel ratio. Selection to start/stop each burner, selection for fuel and atomizing medium can also be made at the local burner panel. Atomizing gas or steam will be supplied at a pressure just above the fuel oil pressure. The atomizing medium amount is controlled by a pressure difference controller. The controller compares the fuel and atomizing medium pressure and the output signal will adjust the position of control valves PDIC-216 or PDIC-227. The amount of atomizing steam or atomizing gas depends on the nozzle characteristic and medium pressure above the fuel oil pressure. The atomizing gas flow will be used for monitoring and will be used in the fuel/air control of the total flow of the different fuels. Before starting on fuel oil the atomizing medium differential pressure control should be on AUTO. The atomizing medium pressure follows the oil pressure with a pressure difference of about 1 - 1.5 bar. At low loads (below 30% MCR) the atomizing medium pressure will be kept on a minimum fixed value.






DCS - Analogue Control Valve Tag name Service Action PV-Tracking Name FC-205 PID Direct Yes PICA-209 PC-209A PID Indirect Yes PICA-209 PC-209B PID Indirect Yes PICA-209 FC-206 PID Direct Yes PICA-214 PC-214A PID Indirect Yes PICA-214 PC-214B PID Indirect Yes PICA-214 PDIC-216 PID Indirect No PDIC-216 PDIC-227 PID Indirect No PDIC-227 PC-216 PID Indirect Yes PDIC-216 PC-227 PID Indirect Yes PDIC-227 NOTE:

DCS - Discrete Control

Tag name Service Limit Action Valve/Controller HS-270 Switch NG to AUTO or MAN SP N.A. Operator PICA-209/

FC-205 HS-269 Switch CO to AUTO or MAN SP N.A. Operator PICA-214/

FC206 HS-227 See general note 3

Switch to gas or steam atomising N.A. Operator PDIC-216/ PDIC-227

Y-209 Automatic set point adjustment for start up

Start program

PICA-209

NOTE:

IPS - Discrete Control Tag name Service Limit Action Valve/Controller PZA-2101) NG pressure too low LL NG trip NG TSO Block

valves PZA-2121) NG pressure too high HH NG trip NG TSO Block

valves PIA-2112) NG pressure low

NG pressure high L H

NG trip if Leak test failed

NG TSO Block valves

PIA-2322) NG pressure low NG pressure high

L H

Atomising Gas trip if Leak test failed

NG TSO Block valves

PZA-2131) CO pressure too low LL CO trip CO + atomizing TSO block

valves PZA-2152) Atomizing steam pressure too low LL CO trip CO + atomizing

TSO block valves

PZA-2172) Atomizing gas pressure too low LL CO trip CO + atomizing TSO block

valves NOTE: 1) IPS (SIL1) 2) IPS






This control scheme is required to be operational during start up and normal operation and shutdown. General operation aspects: Operation modes The boiler is able to operate with different fuels in a load range of 40 – 100% with all six burners in operation. Normal operation is based on ECR with natural gas as atomizing medium. For the normal start up with Natural Gas an automatic start up procedure is incorporated, however manual start up with ECR or CGO is possible. Natural gas and/or CGO will be used as back up fuel in case no ECR is available. It is also possible to fire the fuel combinations ECR/CGO, ECR/NG or NG/CGO. Atomizing steam will be available as back up for NG atomization. Operating limits The turndown ratio of the burner system with six burners in operation is: ECR/CGO 5:1 NG 6:1 The maximum/minimum Heat Input per burner is: ECR/CGO 26.7/5.34 MWth NG 26.7/4.45 MWth Viscosity for ECR within 8 – 10 CSt @ 190°C. Viscosity for CGO within 0.8 – 1.3 CSt @ 100°C Air/fuel ratio for NG minimum 1.075 Air/fuel ratio for ECR/CGO minimum 1.1 Air/fuel ratio for dual fuel firing minimum 1.1 Viscosity When firing ECR the fuel must heated to 190°C to me et the required viscosity range of 8 – 10 CSt. To ensure a proper combustion the viscosity of the ECR must stay within the mentioned viscosity range. To meet the required viscosity range ECR may be mixed with CGO. Air doors The burners are equipped with manually operated air doors with limit switches. Prior to start up all airs doors must be proven open to allow a start up. In case a burner is tripped or taken out of operation the operator can decide to close the air door of the specific burner. To operate safely, the control system accounts for the number of burners in operation and the number of not closed air doors. Atomizing medium When firing ECR, CGO or a mixture of ECR/CGO atomizing steam or NG must be available. Either all burners have gas atomizing or steam atomizing. Remote or local operation (preliminary) Following operator limitations are applicable: • Controls AUTO/MAN only from DCS • Priority concerning local or remote start/stop is at DCS • Fuel ratio adjustment only possible from DCS • Set point adjustments only possible from DCS





Fuels: When firing fuel oil (ECR, CGO) always atomizing gas or steam is required. Starting a burner on fuel oil must always be done with a clean (purged) oil gun. This means that the oil gun must be purged with steam at the end of the stop/trip sequence of each burner. When firing NG only the fuel oil gun has to be cooled by steam (steam tip cooling). Firing mixed fuels Following mixed fuel firing modes can be distinguished: • Fuel combinations: ECR/CGO in any proportion. • Dual fuel: ECR/CGO/NG or ECR/NG or CGO/NG, simultaneous on the same burner 1) • Dual fuel, simultaneous on different burners 2) For dual fuel firing on the same burner both fuels (oil and gas) one fuel will can be in AUTO control mode simultaneously or with and one fuel is at in MAN mode at a fixed load. For dual fuel firing mode this mode of operation the operator has to select in the DCS the fuels, operating mode per burner (oil or gas) and control mode (AUTO/MAN). Also the fuel ratio has to be selected which can be adjusted manually in the DCS. 1) In case of dual fuel firing the air flow and air/fuel ratio will be based on the air/fuel

ratio requirements for fuel oil. 2) The burners will be able to fire mixtures of fuels across the boiler (i.e. one on oil, one

on gas, one on oil/gas etc. However this operation mode is not recommended. Fuel changeover (main to secondary): Boiler load control mode The boiler can be operated in load control mode, fixed load mode or balancing mode. In three operation modes the air and fuel systems are in AUTO mode. In this case the main fuel flow will be controlled by the boiler load controller. To start the changeover, the operator can start the second fuel from DCS or local panel. The second fuel must be started at minimum load per burner. When taking the second fuel in operation the During start up of the second fuel is on pressure control. Therefore the set point of the maximum pressure controller (PC209B or PC214B) is lowered to the value required for start up. The flow controller (FC-205 or FC-206) of the second fuel is in MAN mode 0% output at a flow set point just above minimum burner load. Further, the burners have to be taken into operation one by one with sufficient time delay to let the system accommodate to the new situation. When adding the second fuel the load of the main fuel is automatically decreased by the combustion air control boiler load controller. With all the required burners in dual fuel mode When the second fuel flow set point is > minimum, the second fuel control will be changed from pressure to switched to manual flow control mode by increasing the pressure control set point for the maximum pressure controller of PC-209B or PC214B to its normal value. By increasing the fuel flow set point of the second fuel changing the fuel ratio (NG/OIL) the second fuel will be increased while the main fuel is automatically decreased. When the main fuel is at minimum load the fuel AUTO mode control has to be switched-over to the second fuel. The main fuel supply to each burner can be stopped and the changeover is completed. Boiler fixed flow control





In this case the main fuel flow will be controlled by the boiler steam flow controller set to a fixed value. To start the changeover, the operator can start the second fuel from DCS or local panel. The second fuel must be started at minimum load per burner. During start up of the second fuel is on pressure control. Further, the burners have to be taken into operation one by one with sufficient time delay to let the system accommodate to the new situation. When adding the second fuel the load of the main fuel is automatically decreased by the boiler load controller. When the second fuel flow set point is > minimum, the second fuel will be switched to pressure control for the maximum pressure controller. By changing the fuel ratio (NG/OIL) the second fuel will be increased while the main fuel is automatically decreased. When the main fuel is at minimum load the fuel supply to each burner can be stopped and the changeover is completed. Note: (HOLD) After a burner is taken into operation with the second fuel at minimum load the excess air amount will temporally decrease. Sub-stochiometric conditions however will not occur due to the limited fuel flow of the added second fuel. After the combustion air control system has been accommodated to the new heat input the air/fuel ratio is corrected to the required value. Atomizing medium changeover: Changeover from NG to steam atomising and v.v. is not permitted during operation with fuel oil due to the timing to open and close valves, causing flame instabilities and potential flame out situation. If a changeover is required the next the general procedure should be followed: • Changeover the fuel to single firing of NG • When operate at NG select required atomizing medium • Changeover to oil or dual fuel firing Steam Tracing: Steam tracing will be used to compensate for heat loss of the oil system or avoid clogging of the oil system when fuel oil is not in service. When steam tracing is taken into operation following manual actions is required: • Open shut off valves in oil system • Open shut off valve in steam line To allow for thermal expansion of the oil system with steam tracing in operation the manual operated valves are locked open and pneumatic operated stop valves (UZ-502 and UZ-507) must be opened by the operator.

HOLD Note: When UZ-507 should be closed than a safety r elief valve is required.

3.8.3.2 Start up To discuss: fuel temperature control (for ECR, ECR/ CGO and CGO) prior to start up. See conference notes April 3, 2007 (mechanical) and several e-mails about this subject

HOLD: decision by JV Basically the start up with NG will follow an automatic sequence. The start up with fuel oil will be done manually.





Start up with NG When starting the boiler the pressure controllers PC-209A and PC-209B are in AUTO. Flow controller FC-205 is in MAN mode output 0%. When starting the first burner the minimum stop at the fuel control valve will ensure sufficient NG to light-off the burner. The NG vent valve UZ-506 is open to create flow to be able to control the NG on pressure. This valve will be closed after the first burner is in operation. The NG control valve is positioned by the start sequence program (or when in manual mode by the operator). The set point of controller PC-209B is set to a low value (by the start program) corresponding with the required burner start load. When three (3) burners are in operation at the required load the set point of PC-209B will be gradually increased to its normal set point (maximum pressure set point). At the same time flow controller FC-205 is put in AUTO and FC-205 controls the flow at the predefined boiler load (given by the start sequence program). During start phase air controller FC-202B will be switched to AUTO when all burners are in operation (HOLD). When the boiler is connected to the steam grid the load controller will be switched to AUTO (pressure or flow) and receive their set points from the overall load control. Start up with fuel oil Prior to start up with oil the supply temperature and viscosity must be correct. Therefore the oil system will be circulated. The oil to the burners will be branched off from the common circulation system (JV-scope). To achieve the required conditions for starting the burners the supplied oil is circulated via UZ-502 and UZ-507. When the oil conditions are good the first burner can be started. When starting the boiler the pressure controllers PC-214A and PC-214B are in AUTO. Flow controller FC-206 is in MAN mode output 0%. Controllers PC-227 and PDIC-227 or PC-216 and PDIC-216 are in AUTO (depending on selection atomizing medium). When starting the first burner the minimum stop at the fuel control valve will ensure sufficient fuel oil to light-off the burner. The fuel oil return line with valve UZ-507 is open to create flow to be able to control the fuel oil pressure. This valve will be closed after the first burner is in operation. The fuel oil control valve is positioned by the operator. The set point of controller PC-214B is set to a low value corresponding with the required burner start load. When three (3) burners are in operation at the required load the set point of PC-214B will be gradually increased to its normal set point (maximum pressure set point). At the same time flow controller FC-206 is put in AUTO and FC-206 controls the flow at the predefined boiler load. During start phase the air controller FC-202B will be switched to AUTO when all burners are in operation (HOLD). When the boiler is connected to the steam grid the load controller will be switched to AUTO (pressure or flow) and receive their set points from the overall load control. See also section 3.19

3.8.3.3 Normal Steady State During normal operation one the fuel controller shall be in AUTO. The selected atomization controller is on AUTO in case atomization is effective.






Instrument Tag Name Output Controller Action Output FIC-205 BAD FC-205 Mode to MAN Freeze PICA-209 BAD PC-

209A/B Mode to MAN Freeze

PZA-210 BAD IPS NG trip Freeze PIA-211 BAD IPS Abort Leakage

Proofing / NG trip

Freeze

PZA-212 BAD IPS NG trip Freeze FIC-206 BAD FC-206 Mode to MAN Freeze TIA-222 BAD - - Freeze PICA-214 BAD PC-

214A/B, PDIC-227, PDIC-216

Mode to MAN Freeze

PZA-213 BAD IPS CO + Atomising trip

Freeze

PICA-227 BAD PDIC-227 PC-217

Mode to MAN Freeze


Freeze

PICA-216 BAD PDIC-216 PC-216

Mode to MAN Freeze


Freeze

PIA-232 BAD IPS Abort Leakage Proofing / CO + Atomising trip

Freeze

NOTE:

3.8.3.5 Shutdown Basically shutdown of the boiler has to be done manually by decreasing the boiler load to 20% MCR. As soon as the boiler load is < 20% MCR first the top burners and finally the bottom burners are stopped consecutively. When firing in dual fuel mode first the fuel at fixed load must be taken out of operation prior to boiler load decrease. See also section 3.19


Output (y) Input (x1,x2,x3) TAG Calculation 1x 2x 3x FY-205 Low SEL

Limits the maximum flow for NG FY-212F HIC-272 HC205A

FY-206 Low SEL Limits the maximum flow for CO

FY-212D HIC-271 HC206A

PY-209A High SEL Limits the minimum flow for NG

FC-205 PC-209A





PY-209B Low SEL Limits the maximum flow for NG

PY-209A PC-209B

PY-214A High SEL Limits the minimum flow for CO

FC-206 PC-214A

PY-214B Low SEL Limits the maximum flow for CO

PY-214A PC-214B

PY-216 High SEL Limits the minimum atomising gas pressure

PDIC-216 PC-216

PY-216A 21 xxy −= PICA-216 PICA-214

PY-227 High SEL Limits the minimum atomising steam pressure

PDIC-227 PC-227

PY-227A 21 xxy −= PICA-227 PICA-214

NOTE:


Ranges TAG Description Range Units FC-205 NG Controller 0 – 100 % PC-209A NG min. pressure controller 0 - 100 % PC-209B NG max. pressure controller 0 - 100 % FC-206 CO Controller 0 – 100 % PC-214A CO min. pressure controller 0 - 100 % PC-214B CO max. pressure controller 0 - 100 % PDIC-227 Atomizing steam pressure

controller 0 - 100 %

PC-227 Atomizing steam minimum pressure controller

0 - 100 %

PDIC-216 Atomizing gas pressure controller

0 - 100 %

PC-216 Atomising gas minimum pressure controller

0 - 100 %

Y-209 Automatic set point adjustment for start up

HOLD Bar(g)

NOTE:

Alarms TAG Description Level Value Units TIA-222 A- Indication 180 °C PICA-209 A+ / A- Indication To follow Bar(g) PIA-211 A+ / A- Indication To follow Bar(g) PICA-214 A+ / A- Indication To follow Bar(g) PICA-227 A- Indication To follow Bar(g) PICA-216 A- Indication To follow Bar(g) PIA-232 A+ / A- Indication To follow Bar(g) NOTE:





Trips

TAG Description Level Value Units PI163 Z++ IPS – SIL1 To follow Bar(g) PZA-210 Z-- IPS – SIL1 To follow Bar(g) PZA-212 Z++ IPS – SIL1 To follow Bar(g) PIA-211 A+ / A- IPS – SILa To follow Bar(g) PZA-213 Z-- IPS – SIL HOLD To follow Bar(g) PZA-215 Z-- IPS – SILa To follow Bar(g) PZA-217 Z-- IPS – SILa To follow Bar(g) PIA-232 A+ / A- IPS – SILa To follow Bar(g) NOTE:

PZA-213: SIL classification to be defined by JV

Settings

TAG Description Value Units C402 NG flow per ignition burner To follow Kg/s HC-205A SP NG maximum load To follow t/h HIC-272 SP NG when in MAN mode By operator t/h HC-209A SP min. pressure NG To follow Bar(g) HC-209B SP max. pressure NG To follow Bar(g) HC-206A SP CO maximum load To follow kg/h HIC-271 SP CO when in MAN mode By operator kg/h HC-214A SP min. pressure CO To follow Bar(g) HC-214B SP max. pressure CO To follow Bar(g) HC-227A SP steam atomization ∆p 1.5 Bar HC-227 SP min. atom. steam pressure To follow Bar(g) HC-216A SP gas atomization ∆p 1.5 Bar HC-216 SP min. atom. Gas pressure To follow Bar(g) NOTE:

3.8.3.8 Interfaces



During start up and shutdown the position of the following valves will be limited by means of a mechanical minimum stop (based on one burner at minimum load): 1. Natural Gas control valve 2. ECR/CGO fuel oil control valve 3. NG atomising gas control valve 4. Atomising steam control valve

3.8.4 History






3.9 BOILER STEAM DRUM LEVEL AND ECONOMIZER INLET TEMPERATURE CONTROL

LAB10AA022 (TIC-207A) – FICA-203 – LICSA-202 LAB10AA032 (TIC-207B) - TC-207B HAD15AA001 (US-532) – HAD15AA002 (US-531) P&ID 36005-105-03 Economizer System 36005-105-04 Evaporator System PCD 113 UEFS E-15100-TN-2395-0032 Steam Boiler Package A-15101 – Economiser System E-15100-TN-2395-0033 Steam Boiler Package A-15101 – Evaporator System

1. Can “Heat Input On” – LY101d (Y-202) – be taken as a signal from the BMS? Note: NEM expect the signal from DCS • Does flowmeter LAB10 CF101 (BFW supply) have a local read-out? (DELETED) • We have added a “Steam Boiler Start-up & Shutdown Block”. This block is configured in the DCS.

Via a selector switch the operator can select the following modes: 1. Cold Start-up OK 2. Warm Start-up 3. Hot Start-up 4. Steady Operation OK 5. Shutdown Furthermore, this control block receives a signal from the BMS which equals the steam boiler load at that time.

Note: NEM expect the signal from DCS This control block will send the following signals:

1. Signal to drum level controller to inform wether the boiler load is above or below 10% MCR

(i.e. P-control or P&I–control). OK 2. Signal to FS-103, which opens/closes ON/OFF valves HAD15 AA001 and HAD15 AA002. 3. Signal to temperature controller LAB10 CT003 (TIC-207) OK 4. Signal to pressure controller LBA10 CP001 (PC-207) (SHP Steam line) OK

3.9.1 Objective

Drum level The drum level control has the objective to maintain the required drum water level within the specified limits, irrespective of load fluctuation and during start-up and shutdown procedures. This is to avoid evaporator damage due to a lack of water or steam system damage due to water carry over. Excessive boiler water shall be dumped with the blow off valve HAD10 AA471 (LICS-202A) to the intermittent blowdown drum. Economizer inlet temperature Due to the firing of sulphur containing fuels the flue gas leaving the boiler can cause corrosion to the ducting and tubes if the flue gas temperature becomes too low. Therefore the feedwater temperature at the inlet of the external economizer is controlled at minimum level by mixing hot and cold feedwater. By raising the feedwater temperature the flue gas temperature to the stack will also increase which avoid sulphur dew point corrosion. The mixed temperature will be controlled at a set point of 150°C.






Drum level The drum level controller is designed as a three-element controller using the drum level as the primary control variable. The steam and feedwater flows are used as feed forward. The drum level will be controlled by regulating the feedwater flow to the boiler with feedwater control valve LAB10 AA022 (TIC-207A). For fast response and more stable operation of the control loop, the difference between steam and feedwater flow is used as feed forward signal in the drum level controller. To avoid instability at low flows this feed forward signal is activated at steam/feedwater flows higher than 20% MCR.

Feed forward at loads > 20% MCR to be incorporated by JV When starting the boiler the water level and set point of the controller will be set to start level (SL) to allow level swell when boiler starts to produce steam. In this situation no feedwater is supplied to the drum. Drum level swell compensation is incorporated to avoid wrong actions of the feedwater control valve if swell or shrink, caused by pressure changes in the drum, occurs. Hereto the differentiated steam flow is added to the output of the level controller.

Swell compensation to be incorporated by JV Once the start-up swell is over the set point of the level controller is brought to normal level (NL) of the drum and stays here as long as the boiler is in operation. Changeovers from start level to normal level and from normal level to start level, when the boiler is taken out of operation, are part of the start-up or shutdown procedure.

Automatic set point adjustment to be incorporated b y JV During start of the boiler when no steam is leaving the drum, drum level control should be proportional to avoid too high levels as a result of the integrator action. When the steam flow is higher than 10 % of MCR the controller is changed over to Proportional and Integral control (P+I). � signal from BMS is send to Control Block 151US-230 “Steam Boiler Start-up & Shutdown”. From this block, a signal is send to LY101c. NOT CLEAR When the drum level exceeds the highest allowable level the feedwater supply will be shut-off by closing valve LAB10 AA010 (LZA-201). Upon trip by LZA-201 High High, controller FICA-203 to MAN, output to 0%. Economizer inlet temperature To control the feedwater temperature at the economizer inlet the total flow coming from the feedwater system is divided into two flows. One part will pass through the feedwater control valve LAB10 AA022 (TIC-207A) while the other (smaller) part flows through control valve LAB10 AA032 (TIC-207B) which is heated in the feedwater pre-heater LAD10 AC001 in the drum. The flows will be joined upstream of the external economizer to get a uniform mixed temperature. Interaction between both control loops Variations of drum pressure and drum level will have effect on both control valves. Variation of the drum pressure will cause a variation in drum temperature and consequently also the feedwater temperature at the outlet of pre-heater LAD10 AC001. To control the feedwater temperature at 150°C the flow through LAB10 AA032 (TIC-207B) will change. This effect will change the total feedwater flow and drum level, but is compensated by the feedforward and/or drum level control. Variations of the drum level will cause a change of the feedwater flow through LAB10 AA022 (TIC-207A). This will also influence the controlled feedwater temperature for the economizer inlet and hence the flow through LAB10 AA032 (TIC-207B) will also change. To keep the control loops stable a deviation of the drum level is also forwarded to control valve LAB10 AA032 (TIC-207B).






DCS - Analogue Control Valve Tag name Service Action PV-Tracking Name LICSA-202 PID Indirect Yes - FICA-203 PID Direct Yes TIC-207A TC-207B PID Indirect Yes LZA-201 LY-101b FF balance - Yes - TY-103a BFW CV

correction - Yes -

NOTE:

DCS - Discrete Control Tag name Service Limit Action Valve/Controller XS-203 Switch to activate feedforward

control if load > 35 t/h - Switch -

FS-213 Close eco circulation valves if BFW flow is high enough during start-up

HH - -

FS-213 Close eco circulation valves if BFW flow is high enough during start-up

H Close US-531 US-532

FS-213 Open eco circulation valves if BFW flow becomes too low during shutdown

L Open US-531 US-532

NOTE:

IPS - Discrete Control Tag name Service Limit Action Valve/Controller LZA-201A1) LZA-201B1) LZA-201C1)

Steam drum level too high HH Close LZA-201

LZA-201A2) LZA-201B2) LZA-201C2)

Steam drum level too low LL Boiler Trip Natural gas, Fuel Oil and

Atomising TSO valves

NOTE: 1) SIL 1 2) SIL 2



3.9.3.2 Start up During start up of the boiler control valve LAB10 AA032 (TIC-207B) will be forced to close. When the boiler load < 15% the output of temperature controller TC-207B and control valve TIC-207B is in MAN mode, output 0% We have put it on the P&ID as follows:

• In Control Block 151US-230 “Steam Boiler Start-up & Shutdown”, the steam boiler mode is selected by operator. In case of start-up, a signal is send from control block 151US-230 to temperature controller LAB10 CT003. When boiler load < 15%, then:





- Output temperature controller LAB10 CT003: 0% - Output of control valve LAB10 AA032: 0%

When boiler load > 15%, then: - Temperature controller and control valve LAB10 AA032: AUTO-mode

When the boiler load > 15%, then the temperature controller TC-207B and control valve TI-207B are put in AUTO mode During start up phase the drum level set point has to be raised gradually from SL to NL. See also section 3.19


During normal operation the temperature controllers LICSA-202, FICA-203 and TC-207B shall be in AUTO.


Instrument Tag Name Output Controller Action Output FT-203 BAD FICA-203 Mode to MAN Freeze TI-205 BAD - - Freeze TI-206 BAD - - Freeze TICA-207 BAD TC-207B Mode to MAN Freeze LZA-201A1) BAD - - Freeze LZA-201B1) BAD - - Freeze LZA-201C1) BAD - - Freeze LT-202A BAD Freeze LT-202B BAD Freeze LT-202C BAD

LICSA-202 3oo3: Mode to MAN

Freeze PIA-206 BAD LICSA-202 - Freeze PT-2051) BAD - - Freeze PICA-207 BAD - - Freeze FI-204 BAD FICA-203 Mode to MAN Freeze TICA-217 BAD - - Freeze NOTE: 1) IPS

3.9.3.5 Shutdown

When the boiler is shutdown and burners are out operation the drum level set point has to be gradually decreased from NL to SL. See also section 3.19






Output (y) Input (x1,x2,x3) TAG Calculation 1x 2x 3x FY-204

designxxxCy ρρ /)3,2(1204 ∗∗=

Pressure and temperature correction for steam flow

FI-204 1)

t/h PICA-207 TICA-217

LY-202 )3,2,1( xxxMeanValuey = LT-202A mmwc

LT-202B mmwc

LT-202C mmwc

LY-202A )2,1( xxctionLevelCorrey = 2) PIA-206 Bar(g)

LY-202 mmwc

-

LY-202B )1(int xLevelSetpoy = 3) HEAT INPUT ON

LY-202C 21 xxy += LY-202B t/h

FY-204A t/h

FY-203 ),(/),2(1 ddd ptpxxy ρρ∗=

Temperature correction for feedwater flow 4)

FT-203 t/h

TI-205

LZA-201 )3,2,1(32 xxxooy = LZA-201A mmwc

LZA-201B mmwc

LZA-201C mmwc

LZA-201 )2,1( xxctionLevelCorrey = 2) PT-205 Bar(g)

LZA-201 mmwc

-

LY-206 21 xxy += FY-210 t/h

LICSA-202 t/h

TY-207A 21 xxy −= FICA-203 %

TC-207B %

TY-207B 21 xxy += FICA-203 %

TC-207B %

TY-207C 21 xxy −= HC-207C %

TC-207B %

FY-210 21 xxy += FY-204 t/h

FI-210 t/h

NOTE: 1) Square root operation in DCS 2) Calculation is drum connection layout dependant. Will be supplied on separate sheet 3) If burners are out of operation the level set point is at (low) start level (SL). During normal operation the level set point is at NL. During start-up the set point is raised from SL to NL. During shutdown from NL to SL. 4) Uncorrected flow (t/h) is calculated in vortex transmitter.


Ranges

TAG Description Range Units FY-204A D-action anti swell

compensation HOLD t/h

LICSA-202 Level Controller 0 – 180 t/h FICA-203 BFW flow controller 0 - 100 % TC-207B Temp. Controller 0 – 100 % NOTE:





Alarms

TAG Description Level Value Units FY-203 A+ Indication 190 t/h LZA-201A A- Indication -150 mm LZA-201B A- Indication -150 mm LZA-201C A- Indication -150 mm LT-202A A- Indication -150 mm LT-202B A- Indication -150 mm LT-202C A- Indication -150 mm LT-202A A+ Indication +150 mm LT-202B A+ Indication +150 mm LT-202C A+ Indication +150 mm LZA-201A A+ Indication +150 mm LZA-201B A+ Indication +150 mm LZA-201C A+ Indication +150 mm PIA-206 A+ Indication 135 Bar(g) PIA-206 A- Indication 0 Bar(g) NOTE:

Trips

TAG Description Level Value Units LZA-201A Z-- SIL2 -525 mm LZA-201B Z-- SIL2 -525 mm LZA-201C Z-- SIL2 -525 mm LZA-201A Z++ SIL1 +295 mm LZA-201B Z++ SIL1 +295 mm LZA-201C Z++ SIL1 +295 mm NOTE:

Settings

TAG Description Value Units C204 Flow constant for conversion to

t/h To follow Type flow measurement not decided yet

-

ρdesign Density at design parameters flow element

To follow Type Flow measurement not decided yet

Kg/m3

pd Boiler feedwater pressure in design case

158 Bar(a)

td Boiler feedwater temperature in design case

117 °C

FS-213 (HH) BFW flow high enough to switch over to feedforward control

35 t/h

FS-213 (H) BFW flow high enough to close eco circulation valves

15 1) t/h

FS-213 (L) BFW flow low enough to open eco circulation valves

12 2) t/h





FY-203A Gain for TIC-207A HOLD - FY-207D Gain for TIC-207B HOLD - FY-207E Gain for TIC-207A HOLD - LY-202B Normal level (from centerline) -25 mm LY-202B Start level (from centerline) -400 mm HC-207B SP BFW temp. before ext. eco 150 °C NOTE: 1) Flow > 15 t/h for at least 60 seconds 2) Flow < 12 t/h for at least 60 seconds

3.9.3.8 Interfaces



During start up and shutdown of the boiler the economizer circulations valves HAD15 AA001/002 have to be opened and closed. Opening of the valves makes the economizer part of the evaporator system and so temperature differences between economizer and evaporator will be negligible. When the measured feedwater flow comes above a predefined value the valves have to be closed. In case of a shutdown the valves have to be opened when the measures feedwater flow falls below the predefined value. This function is defined via Steam Boiler Start-up & Shutdown Block 151US-530.

3.9.4 History Date Author Description 20-07-2007 HuR/WiH Original Document





3.10 BOILER START-UP PRESSURE CONTROL

LBA10AA051 (PICA-207), PC-207, TC-254 P&ID 36005-105-06 Main Steam Line System PCD 115 UEFS E-15100-TN-2395-0035 Steam Boiler Package A-15101 – Main Steam Line

3.10.1 Objective Pressure control is required to gradually increase boiler pressure, temperature and flow during start-up independently from the conditions of the common steam grid. This is achieved by controlling the valve position LBA10 AA051 (PICA-207) with pressure controller PC-207. For start-up following situations are distinguished: 1. Cold start-up (boiler at atmospheric conditions) 2. Warm start-up (conditions after a shutdown of more than 2 hours, but t_drum > 100°C) 3. Hot start-up (conditions after a shutdown of 2 hours, t_drum > 300°C) The Operator can select the above the above mentioned modes in the “Steam Boiler Start-up & Shutdown” control block 151US-530 via selector switch 151HS-265: • Start up • Normal operation (connected to steam grid) This selector switch is represented by PY-265A and PY-265B shown at PCD115 Incoming signals to this control block are: • Operation mode (selector switch 151HS-265) • Boiler load (% MCR) from BMS 151UZ-500 FROM DCS? JV TO CHECK • Operating pressure ‘Main Steam Line’ – 151PICA-207 JV TO CHECK • Operating temperature ‘Main’ Steam ‘Line’ – 151TICA-217 JV TO CHECK Signals from this control block are sent to: • Pressure controller 151PICA-207 • Level controller 151LICSA-202/calculation block 151LY-202B • BFW Flow Switch FS103 (151FS-xxx) • BFW Temperature controller 151TIC-207 Furthermore, an indication is given when the boiler is (still) in start-up mode or is at normal operation. Normal operation is considered if the following conditions are met: • Normal operating pressure is reached • Normal operating temperature is reached • Boiler load between 40 and 100% MCR • Boiler connected to the SHP steam grid Furthermore the Operator has to input the: • ‘Pre-safety pressure’ (i.e. pressure at which the vent valve opens in order to avoid too

quickly open of the safety releief valve(s) • Intended pressure when Steam Boiler is connected with the SHP Steam grid





Additional to the main function of the pressure control system following functions are incorporated: • Limiting too high pressure/temperature gradients in the drum and superheaters during

start up. • Pre-safety function in case of too high steam pressure. (HOLD) • Limiting too low pressure when the boiler is shutdown (prevent vacuum conditions)

(HOLD)

3.10.2 Functional Description Depending on the pressure in the boiler the pressure the set point will be put in memory has to be set to at the actual pressure via an automatic switch when the first burner is started with a minimum of 2 bar(g). During Heat Input by the burners the boiler will be heated, produce steam and pressure will rise. After the set point of the controller is reached the start-up valve will be opened and pressure is controlled until an opening position for LBA10 AA051 (PICA-207) of 30% is reached. Valve PICA-207 will stay in this position until the steam pressure reaches normal operating set point. When the steam pressure has reached the normal set point pressure controller PC-207 is switched to MAN mode and at the same time the opening limit of PICA-207 is removed. Pressure controller PC-207 is put in AUTO mode after a certain time and then controls the pressure at normal the operating value. The start-up sequence is ended when all of the following conditions are met: - Normal operating pressure is reached - Normal operating temperature is reached - Boiler load at 40% MCR - Start up valve controls steam pressure at set point (normally 120 bar(g)) After or during start-up phase the main steam line and common grid can be pressurized and pre-heated by opening of valve LBA10 AA005 (manually). At the moment that the pressure difference over main steam valve LBA10 AA003 (MOV-201) is lower than 2 bar the main steam valve will be released to be opened (manually by the operator). The start up valve controls the boiler steam pressure through pressure controller PC-207. When there is a steam demand of the grid the boiler steam pressure tends to decrease but will be kept constant by further closing of the start up valve. When valve MOV-201 is open and start up valve (PICA-207) is closed the master control system has to be released to control the boiler load (boiler steam pressure or flow control) and output of controller PC-207 is put to MAN, 0%. When LBA10 AA051 is closed the set point will be increased to a value of Y bar above the actual set point of the main steam pressure.

DCS – Analogue Control Valve Tag name Service Action PV-Tracking Name TC-254 PID Indirect No -

PID Direct Yes PICA-207 Temperature gradient steam drum too steep 1)

Low output limitation

Yes PICA-207 PC-207

Ramp-up pressure too slow 1)

High output limitation

Yes PICA-207

NOTE: 1) See explanation at section start up





DCS – Discrete Control Tag name Service Limit Action Valve/Controller HS-201 Permission to open main steam

block valve MOV-201 if pressure difference is low enough

L Permission MOV-201

XY-207 Automatic set point switch-over for start-up with timer

See settings Switch + timer

PC-207

HS-265 Switch set point during start-up sequence

See section initializations

SP change PICA-207

HS-098 Switch input signal to PDS-204 from PICA-070 or PICA-071

See JVN section

NOTE:

IPS - Discrete Control Tag name Service Limit Action Valve/Controller N.A. NOTE:



3.10.3.2 Start up At starting of the boiler the set point of the pressure controller PC-207 is set switched to an appropriate value depending on the remaining pressure in the boiler � the mode which is selcted by the Operator in Steam Boiler Start-up & Shutdown block 151US-530 (i.e. Cold Start-up, Warm Start-up or Hot Start-up, CHECK). The heat input will cause steam production and a pressure/temperature raise in the boiler. This raise is limited by the allowable steam drum water/steam temperature gradient and superheater (outlet Sec. SH) steam temperature gradient. Controller TC-254 will force open or limiting the start up valve position and so prohibiting controller PC-207 to close the start up valve under a certain value. On the other side opening of the start-up valve must be not too much to keep the start-up time limited. At the moment this limitation is reached the set point of PC-207 is switched to that pressure value at which the boiler needs to be connected to the steam grid. The maximum opening restriction HY-264 is switched-off when the steam pressure has reached the set point value. Controller PC-207 will be switched to MAN, 0% output when: • Valve PICA-207 is closed and • Valve MOV-201 is open For steam temperature gradient see section 3.11 For start up see also section 3.19


During normal operation pressure controller PC-207 shall be in MAN, output 0% AUTO at a value of Y bar above normal operating pressure. Temperature controller TC-254 shall be in AUTO.






Instrument Tag Name Output Controller Action Output PIA-206 BAD TC-254 Mode to MAN Freeze PICA-207 BAD PC-207 Mode to MAN Freeze PICA-070/ PICA-071

BAD Y-100 Mode to MAN Freeze

NOTE:

3.10.3.5 Shutdown It is not necessary to close the MOV-201 when taking the boiler out of operation. The check valve will keep the line shut in boiler direction. See also section 3.19


Output (y) Input (x1,x2,x3) TAG Calculation 1x 2x 3x TY-251A

dt

xdy

)1(= 2) TY-251

TY-251B maxmax 1 cxfy +∗≤ 1) PIA-206

Bar(g)

TY-251C minmin 1 cxfy −∗≥ 1) PIA-206

Bar(g)

TYA-254 (H) 21 xx ≥ 1) TY-251A °C/min

TY-251B °C/min

TYA-254 (L) 21 xx ≥ 1) TY-251A °C/min

TY-251C °C/min

PDS-204 dPxx ≤− 21 1) PICA-207 PICA-070/ PICA-071

PY-265A High SEL Start up steam pressure

HC-265A HC-265B

PY-207A Low SEL Start up valve opening limited

PC-207 HY-264

PY-207B High SEL Start up valve opening limited

PY-207A TC-254

PY-264 High SEL SP reached then start up valve opening limiter removed

PICA-207 PY-265A/B

HY-264 Start up valve opening limiter PY-264 NOTE: 1) See settings.

2) Sampling time may be up to one minute.


Ranges TAG Description Range Units PC-207 Boiler pressure Controller 0 – 100 % TC-254 Steamdrum temp. gradient

controller 0 – 100 %

NOTE:





Alarms

TAG Description Level Value Units PICA-207 A+ Indication 130 Bar(g) PICA-207 A- Indication 115 Bar(g) TYA-254 High

A+ Load increase

Indication See calculations

°C/min

TYA-254 Low

A- Load decrease

Indication See calculations

°C/min

NOTE:

Trips TAG Description Level Value Units N.A. NOTE:

Settings

TAG Description Value Units fmax Gradient for drum temperature

increase (start up) 0.0538 -

cmax Gradient for drum temperature increase (start up)

7 °C/min

fmin Gradient for drum temperature decrease (shutdown)

0.0577 -

cmin Gradient for drum temperature decrease (shutdown)

8 °C/min

dP Permission to open main steam valve (MOV-201) if pressure drop across valve is low enough

2 Bar

HC-265A Min. SP steam pressure at cold start-up (PICA-207)

2 Bar(g)

HC-207 SP steam pressure start-up (PICA-207)

120 Bar(g)

XY207timer Timer to switch PC-207 from MAN to AUTO

30 seconds

AC-265B SP steam pressure at start up Automatic switch puts the measured pressure (PICA-207) in memory (set point) when the first burner is started.

0 - 125 Bar(g)

PY-265A Boiler Steam outlet pressure at start-up (PICA-207)

Actual pressure

Bar(g)

PY-265B Intended boiler steam outlet pressure to connect with steam grid

120 Bar(g)

PY302c Pre-safety pressure 125 (HOLD) Bar(g) HY-264 Maximum valve opening during

start-up 30 %

NOTE:





3.10.3.8 Interfaces



During start-up following critical process parameters must be kept within allowable limits: • Steamdrum water/steam temperature gradient • Steam temperature gradient (see also section 3.11) • Steam flow through the superheater to cool the superheater tubes (CHECK) • Pressure gradient at boiler outlet to limit the start-up time

3.10.4 History






3.11 BOILER STEAM DESUPERHEATER TEMPERATURE CONTROL

LAE10AA014 (TICA-214), TC-212, TC-214 LAE20AA014 (TICA-215), TC-215, TC-215B

TC-202 P&ID 36005-105-05 Superheater System PCD 116 UEFS E-15100-TN-2395-0034 Steam Boiler Package A-15101 – Superheater System

3.11.1 Objective The steam temperature control has the objective to control the final superheater temperature and to limit the superheater tube wall temperatures. This is to avoid lifetime reduction and/or damage to the steam system. Steam temperature control is achieved by regulating the spray water flow to two (2) inter-stage desuperheaters. This spray water is taken from the feedwater line to the boiler upstream of the feedwater control valve. The boiler is designed to control the steam temperature at the superheater outlet at a constant value within the boiler load range of 40% - 100% MCR. The normal set point is 525°C.

3.11.2 Functional Description For steam temperature control two cascade control loops are used. The first controller controls the final steam temperature at the outlet of the tertiary superheater by means of control valve LAE20 AA0014 (TICA-215). The second controller is controlling the steam temperature at the outlet of the secondary superheater by means of control valve LAE10 AA0014 (TICA-214). Both control loops are controlling the steam temperature in such a way that the total spray water flow to control valves LAE10 AA014 (TICA-214) and LAE20 AA014 (TICA-215) is as much as possible divided equally over both control valves. The set point to control the steam temperature at outlet of the secondary superheater will be load dependent. The firing/steam unbalance occurs during load variations where the fuel input is not corresponding with the steam pressure. The firing/steam unbalance will be used as a feed forward signal to both control valves to anticipate on load variations. The effect of the firing/steam unbalance can be adjusted by the gains TY-253A and TY-253B. To avoid entrance of not evaporated water into the superheater sections behind the desuperheater the set point of both controllers is limited such that the steam temperature will not become lower then a predefined value above saturation temperature. Also when the steam temperature at the outlet of both desuperheaters becomes too high the steam temperature will be limited. In case the steam temperature falls below its minimum the spray water supply will be shut-off by closing valves LAE10 AA011 (UZ-552) and/or LAE20 AA011 (UZ-562). Upon a trip of UZ-550 and/or UZ-560 also controller TC-214 and/or TC-215 will be put to MAN, output to 0%. In case the final steam temperature becomes too high the boiler will be tripped.





The steam temperature at the outlet of the secondary superheater is controlled by the slave controller but has also a steam temperature gradient controller (TC-202). This controller limits the heat input to the burners during start up, normal operation and shutdown if the steam temperature gradient exceeds allowable limits.

DCS - Analogue Control Valve Tag name Service Action PV-Tracking Name TC-212 PID Direct Yes - TC-214 PID Direct Yes TICA-214 TY204a,b FF & SEL - Yes - TC-215B PID Direct Yes - TC-215 PID Direct Yes TICA-215 TY206a,b FF & SEL - Yes - TC-202 PID Indirect Yes - NOTE:

IPS - Discrete Control

Tag name Service Limit Action Valve/Controller TZA-2111) Steam Temperature too close to

saturation. LL Close UZ-552

TZA-2131) Steam Temperature too close to saturation.

LL Close UZ-562

No BFW supply

LL Close Close MAN - 0%

LAE10AA011 LAE20AA011

TC205 TZA-2181) Steam Temperature too high HH Boiler trip Natural gas

Fuel Oil Atomising valves

NOTE: 1) IPS (SIL1)



3.11.3.2 Start up See also section 3.19

3.11.3.3 Normal Steady State During normal operation the temperature controllers TC-212/TC-214, TC-215/TC-215B and TC-202 shall be in AUTO.


Instrument Tag Name Output Controller Action Output TIA-210 BAD - - Freeze TICA-214 BAD TC-214 Mode to MAN Freeze TZA-2111) BAD - - Freeze TIA-212 BAD TC-212 - Freeze





TICA-215 BAD TC-215 Mode to MAN Freeze TZA-2131) BAD - - Freeze TICA-217 BAD TC-215B Mode to MAN Freeze TZA-2181) BAD - - Freeze NOTE: 1) IPS

3.11.3.5 Shutdown

See also section 3.19


Output (y) Input (x1,x2,x3) TAG Calculation 1x 2x 3x TY-202A

dt

xdy

)1(= 2) TIA-212

TY-202B (H)

maxmax 1 kxhy +∗≤ 1) PIA-206

TY-202C (L)

minmin 1 kxhy −∗≥ 1) PIA-206

TYA-202 High

21 xxy −= TY-202A TY-202B

TYA-202 Low

21 xxy −= TY-202A TY-202C

TY-252 )1(xeTemperaturSaturationy = PT-205

TY-251 )1(xeTemperaturSaturationy = PIA-206

TY-253

1

)12(

x

xxy

−= PV SHP steam flow (in %)

PV Fuel flow (in %)

TY-214A )2,1( SATTxxMAXy ∆+=

High SEL

TY-214B °C

TY-251 °C

TY-214B 21 xxy −= TC-212 °C

TY-253B °C

TY-214C )2,1( xxMAXy = For NG only TY-214A HC-214D

TY-253A AGxy 2531 ∗= TY-253

TY-253B BGxy 2531 ∗= TY-253

TY-215A )2,1( SATTxxMAXy ∆+=

High SEL

TY-215B °C

TY-251 °C

TY-215B 21 xxy −= TC-215B °C

TY-253A °C





TY-212 )1(xTy =

)/1261(;1 11 htxifTxMy STST ≤+∗=

)/1261(;1 22 htxifTxMy STST >+∗=

Load(%) Steam(t/h) Temp. 40 72 482 70 126 478 100 180 495

PV SHP steam (t/h)

UZ-550 )21( SATTxxifCLOSEy ∆+<= TZA-211 TY-252

UZ-560 )21( SATTxxifCLOSEy ∆+<= TZA-213 TY-252

NOTE: 1) See settings. 2) Sampling time may be up to one minute.


Ranges

TAG Description Range Units TC-212 Master Sec. Superh. Inlet

temperature controller 370 – 400 °C

TC-214 Slave Sec. Superh. Inlet temperature controller

0 - 100 %

TC-215B Master Tert. Superh. Inlet temperature controller

440 – 480 °C

TC-215 Slave Tert. Superh. Inlet temperature controller

0 - 100 %

TC-202 Sec. Superh. Gradient controller 0 - 100 % NOTE:

Alarms

TAG Description Level Value Units TIA-210 A+ Indication 440 °C TICA-214 A- Indication 360 °C TICA-214 A+ Indication 395 °C TZA-211 A- Indication 360 °C TIA-212 A+ Indication 505 °C TICA-215 A- Indication 360 °C TICA-215 A+ Indication 475 °C TZA-213 A- Indication 360 °C TICA-217 A- Indication 510 °C TICA-217 A+ Indication 535 °C TZA-218 A+ Indication 535 °C TYA-202 (H) A+ Indication See

calculation °C/min

TYA-202 (L) A- Indication See calculation

°C/min

NOTE:





Trips

TAG Description Level Value Units TZA-211 Z-- SIL1 330 °C TZA-213 Z-- SIL1 330 °C TZA-218 Z++ SIL1 540 °C NOTE:

Settings

TAG Description Value Units hmax Gradient for superheater

temperature increase (start up) 0.4344 -

kmax Gradient for superheater temperature increase (start up)

22 °C/min

hmin Gradient for superheater temperature decrease (shutdown)

0.4098 -

kmin Gradient for superheater temperature decrease (shutdown)

55 °C/min

SATT∆ Required temperature difference above saturation.

30 °C

TMAX Maximum temperature outlet secondary superheater

500 °C

LHV205 Lower heating value NG 47.6 kJ/t LHV206 Lower heating value CO 39500 kJ/kg G253A Gain for feedforward signal to

temperature control HOLD -

G253B Gain for feedforward signal to temperature control

HOLD -

MST 1 Flow constant for load dependent set point

-0.08 -

TST 1 Temperature constant for load dependent set point

488 -

MST 2 Flow constant for load dependent set point

0.3 -

TST 2 Temperature constant for load dependent set point

440 -

HC-215B Set point SHP steam temperature outlet boiler

515 - 525 °C

HC-214D Low SEL (Maximum temperature in case of NG firing)

380 °C

NOTE:





3.11.3.8 Interfaces



The setpoint of the controller TC-215B may be changed, but only to a temperature between 515 and 525 °C, by the operator. The mode of this cont roller shall always be AUTO. Closing the block valves LAE10 AA011 (UZ-552) and LAE20 AA0011 (UZ-562) upstream the desuperheaters is a SIL 1 application.

3.11.4 History






3.12 BOILER DRAIN AND BLOWDOWN CONTROL

HAH10AA404 (FIC-204A), HAH10AA424 (FIC-204B), LBA10AA404 (TICA-217), HAD10AA470 (LICS-202), HAD10AA471 (LICS-202A), GAC10AA011 (TICA-219), HAD10AA460 (QISA-202) P&ID 36005-105-04 Evaporator System 36005-105-07 Drain System 36005-105-08 Blow Down System 36005-105-09 Sample unit PCD 117 UEFS E-15100-TN-2395-0036 Steam Boiler Package A-15101 – Blowdown & Drain System E-15100-TN-2395-0043 Steam Boiler Package A-15101 – Sample Unit

3.12.1 Objective Condensate will be formed in the superheaters and connecting piping if the boiler is shutdown and during start-up. The boiler drain control has the objective to discharge this condensate to the intermittent blowdown drum during start up of the boiler. A continuous blowdown (HAD10 BR460) is provided to control the quality of the drum water and to avoid scaling on the heat transfer areas of the drum, to avoid foaming and to assure the quality of the produced SHP Steam. The boiler intermittent blowdown (HAD10 BR470) might be opened during start up (swell) and is also opened during normal operation upon a high level in the steam drum. Industrial water (GAC10 BR010) is supplied to the water outlet of the intermittent blowdown drum to reduce the water temperate to the sewer.

3.12.2 Functional Description Condensate: As condensate can occur during different start up conditions the control valve opening position is pressure depended. To assure that all condensate is removed the main steam drain valve LBA10 AA404 (TICA-217) will be closed if superheated conditions have been reached. The drain valves HAH10 AA404 (FIC-204A) and HAH10 AA424 (FIC-204B) will be closed when the boiler steam flow becomes > HC-202 t/h (see setting list below) � According to PCD117 these valves close at a certain steam flow. Steam flow is measured and is pressure and temperature compensated. TS404 gets a signal from FY102 which is P,T compensated. Intermittent blowdown: Intermittent blow down control is used during start-up and in normal operation if the water level in the drum becomes too high and is carried out by means of a proportional controller. The set point for this controller is adjusted to the same value as for the drum level high alarm. The Gain for the controller can be set to 100% divided by the difference between NWL drum level and drum level H alarm setting HOLD. The intermittent blow down control is normally designed to allow sufficient blow down when the drum is at low pressure. To avoid a too high blow down flow when the drum is pressurized the output to the control valve (HAD10 AA471- LICS-202A) is limited based on the square root of the drum pressure in





accordance with the formulaPdrum

Cvalve .

In this formula the constant Cvalve is the drum pressure where the control valve is allowed to open fully at controller output of 100% (Cvalve see setting list below). This limitation shall always be present to avoid damage to the blow down tank; also when the blow down control is in MAN mode. The HP intermittent blow down valve LICS-202B is on AUTO after valve LICS-202B is opened (ZS = 100%). The HP intermittent blow down control valve LICS-202A is set to –10% opening (MAN 0% output) as soon as drum level is at NWL for a certain time (tclose see setting list below). The HP intermittent blow down valve LICS-202B is closed after control valve LICS-202A is closed (ZS = 0%) for a certain time (tclose see setting list below). Continuous blowdown At normal operation boiler water from the drum will be discharged via the continuous blowdown valve to an external system. The amount depends on the water quality in the drum. The flow has to be manually adjusted by valve HAD10 AA461. Based on the results of the water quality samples the operator can choose to adjust the valve opening of HAD10 AA461.

PENDING Valve HAD10 AA460 (QISA-202) will be opened/closed by the measured conductivity. Decision by JV

The design blowdown capacity will be < 2% of the maximum economizer flow and is measured by HAD10 CF101 (FI-210). Blowdown water temperature: Blowdown water of 100°C will be mixed with industri al water to limit the temperature to the sewer system to 50°C. Temperature control of the mi xed flows is achieved by temperature controller TC-219. A too high temperature will be alarmed.

DCS - Analogue Control Valve Tag name Service Action PV-Tracking Name LC-207 PID Direct No LICS-202A TC-219 PID Direct No TICA-219 FC-202 PID Direct No FIC-204A/B TC-217 PID Direct No TICA-217


Tag name Service Limit Action Valve/Controller ZS-202B LC-207 in AUTO if LICS-202B is

open 100% AUTO LC-207

ZS-202A LICS-202B to close if LICS-202A is closed for tIBD-valve

0% Close LICS-202B

TS-403 Close main steam line drain valve if steam flow is enough superheated during start-up

H Close LBA10AA404

TS-404 Close superheater drain valves if steam flow is during start-up

H Close HAH10AA404 HAH10AA424

LS-207 Open Close IBD block valve LICS-202B in case the level becomes too high is low enough

H Open Close

LICS-202B





QIS-202 Open CBD valve QISA-202 for t202 minutes if the conductivity in the drum is too high Close CBD valve if conductivity after timer t202 is elapsed. This CBD valve is working “discontinuously”. Please consider to install a “continuously” working CBD valve. If this is not possible or not preferred by NEM, please explain. PENDING (decision by JV see conference notes 2007-04-03)

H t202

Open Close

QISA-202

QISA-202

NOTE:

IPS - Discrete Control Tag name Service Limit Action Valve/Controller N.A. NOTE:



3.12.3.2 Start up

See also section 3.19 3.12.3.3 Normal Steady State

During normal operation the controllers LC-207, TC-219, FC-202 and TC-217 shall be in AUTO.


Instrument

Tag Name Output Controller Action Output LIA-203 BAD - - Freeze TICA-219 BAD TC-219 Mode to MAN Freeze FI-210 BAD - - Freeze LY-202A BAD LC-207 Mode to MAN Freeze QIA-202 BAD - - Freeze QIA-203 BAD - - Freeze QIA-204 BAD - - Freeze QIA-205 BAD - - Freeze NOTE:





3.12.3.5 Shutdown See also section 3.19


Output (y) Input (x1,x2,x3) TAG Calculation 1x 2x 3x TS-403

%100

T )2(1(%0 SAT

=∆+>=

yelse

xTSATxify

DELETED

LBA10 CT001

LBA10 CP001

TY-217 ) T )1( SAT∆+= xTsaty

SP for temperature controller at which valve TICA-217 is closed

PICA-207

TY-217A

1217

xCy A=

PICA-207

TY-217B ))(2),(1( digitalxdigitalxMINy =Low SEL

TC-217 TY-217A

TS-404

%100

%)1(%0

=>=

yelse

xxify

DELETED

FY-102

FY-202A

1202

xCy A=

HOLD

PIA-206

FY-202B ))(2),(1( digitalxdigitalxMINy =Output limiter

FS-202 FY-202A

LY-206A Explain function

ALxy 2061 ∆+=

Signal to open IBD control valve if drum level exceeds ∆L mm above SP

LICSA-202

TS-404

%0

) 21(%100 401b

=∆+>=

yelse

Lxxify

DELETED

FY102

PY-207

1207

xCy =

HOLD

PIA-206

LY-207 )2,1( xxMINy =

Low SEL

LC-207 PY-207

QIS-202

%0

1

min)(%100

202

202

=>

=

yelse

Kxif

tfory

PENDING (decision by JV see conference notes 2007-04-03)

QIA-202

NOTE:





Please describe: TY403b � Low Selector? NO, is output limiter YES, Low SEL TY404b � Low Selector? NO, is output limiter YES, Low SEL


Ranges TAG Description Range Units TY-403 Switch close/open 0/100 % TY-404 Switch close/open 0/100 % FC-202 Steam flow controller drain

valves FIC-204A/B 0 - 100 %

TC-217 Steam tempeprature controller drain valve TICA-217

0 - 100 %

TC-219 Industrial water temperature controller

0 - 100 %

LC-207 IBD level controller 0 - 100 % NOTE:

Alarms

TAG Description Level Value Units LIA-203 A+ Indication 1400 mm (above

bottom TL) QIA-202 A+ Indication 50 µs QIA-203 A- Indication 9.8 pH QIA-203 A+ Indication 10.2 pH QIA-204 A+ Indication 0.15 µs QIA-205 A+ Indication 0.15 µs TICA-219 A+ Indication 55 °C NOTE:

Trips

TAG Description Level Value Units N.A. NOTE:

Settings

TAG Description Value Units HC-202 Set point flow controller at which

drain valves FIC-204A/B will be closed

15 t/h

Cvalve Constant Cvalve is the drum pressure where the control valve LICS-202A is allowed to open fully at controller output of 100%

0.2 Bar(g)

tclose Timer for set point -10% (MAN 0% output) opening IBD control valve LICS-202A after NWL is reached

60 seconds





tIBD-valve Timer for to close valve LICS-202B after IBD control valve LICS-202A is closed

60 seconds

SATT∆ Required temperature difference above saturation.

30 °C

C217A Constant which limits opening of the valve at higher pressures

To follow √(Bar)

C202A Constant which limits opening of the valve at higher pressures

To follow √(Bar)

AL206∆ Level margin to open IBD block valve LICS-202B

150 mm

aL401∆ Level margin to close IBO valve 160 mm

C207 Constant which limits opening of the valve at higher pressures

To follow √(Bar)

t202 Timer for opening CBD valve QISA-202 PENDING (decision by JV see conference notes 2007-04-03)

4 Initial, to be finalized during operation

hours

LC-207 Gain for LC-207 (100%/150mm) HOLD

0.67 HOLD

-

K202 Maximum allowable conductivity As alarm from transmitter

µs

HC-219 SP temperature controller 50 °C NOTE:

3.12.3.8 Interfaces



A too high level in the intermittent blowdown drum will give an alarm.

3.12.4 History






3.13 DUAL DRIVEN FD FAN

P&ID 36005-560-04-151 36005-560-04-151-002 36005-105-13 PCD UEFS E-15100-TN-2395-0041 Steam Boiler Package A-15101 – Dual Driven FD Fan E-15100-TN-2395-0044 Steam Boiler Package A-15101 – Lube Oil System Reference documents 36005-560-04-148 Operating procedure 36005-560-04-148-001 Control Narratives

3.13.1 Objective The objective for the dual driven FD Fan is to supply combustion air to the boiler in a controlled manner. The fan will be driven by a steam turbine as main driver and in case the steam turbine is not available or tripped the driving function is taken over by an electric motor.

3.13.2 Functional Description The FD fan capacity is controlled with the IGV damper, which receive its signal for the required air flow from the combustion air flow controller FC-202B. The speed of the FD Fan and steam turbine will be kept constant over the operating range by control of the steam flow through the steam turbine. The speed controller (UC-580) of the steam turbine controls the position of the steam governor valve. The lube oil is supplied by the shaft driven oil pump to the bearings of the whole FD Fan train. The oil pressure to the bearings is controlled by pressure controller PIC-225. Following control/safeguarding blocks: 1. KT-15161 Woodward Governor 151UC-xxx (start/stop turbine/motor & turb. control) 2. KT-15161 Bentley Nevada 151UZ-xxx (monitoring/safeguarding) 3. KT-15161 FD Fan Operation 151US-xxx (driver selection)

DCS - Analogue Control Valve Tag name Service Action PV-Tracking Name UC-580 PID Direct Yes UC-581 PIC-225 PID Direct Yes PIC-225


Tag name Service Limit Action Valve/Controller PISA-222 Lube oil pressure to bearings L Start aux.

oil pump

UC-580 ST-206

R.p.m. turbine and fan 0 Stop aux. oil pump

TA-258 Lube oil temperature in tank H Switch heater off





TA-258 Lube oil temperature in tank L Switch heater on

NOTE:

IPS - Discrete Control Tag name Service Limit Action Valve/Controller UC-580 Steam turbine speed H Trip

turbine UC-581 UC-???

TISA-249 Steam turbine inlet temperature S Trip turbine

UC-581 UC-???

FD Fan bearings HH Trip Fan PZA-223 Lube oil pressure to bearings LL Trip Fan Lube oil pressure to bearings HH Trip Fan NOTE:

Note: Trip steam turbine TISA-249 HOLD. High temper ature is a SILa classification Decision by JV


This control scheme is required to be operational during start up, shutdown, normal operation, and take-over. Start up/shutdown: Start up and shutdown of the FD Fan unit can be done automatically from the DCS and manually from a local panel (see also section start up below). Normal operation: The FD Fan is dual driven by a steam turbine or electric motor. The FD Fan is normally driven by the steam turbine. The steam turbine will keep the speed constant over the load range by admit more or less steam to the turbine. The electric motor serves as a back up. When the steam turbine is in operation the electric motor is decoupled and v.v. The FD Fan train runs at the following speeds: • Steam turbine: 4762 rpm • FD Fan: 1500 rpm • Electric motor: 1500 rpm Steam for the steam turbine is coming from the HP steam system. The steam turbine outlet is connected to the LP steam system. Automatic take-over: With the steam turbine in operation an automatic take-over takes place in case of a steam turbine trip. At steam turbine trip the steam to the turbine is immediately shut off. The FD Fan operation is continued by automatic start of the electric motor (starting time approximately 17 seconds). In general the driver with the highest speed will drive the FD Fan. Automatic clutches will engage the driver with the highest speed and disengage the driver with the lower speed. The trip signal will ramp down the speed set point of the turbine to zero. When the turbine speed indicates no speed (for x seconds HOLD) the steam governor switches to shutdown and the steam governor valve (UC-581) will than be closed.





Manual take-over: A planned take-over from steam turbine to electric motor or from electric-motor to steam turbine has to be done manually (from DCS or local panel). From steam turbine to electric motor (Preliminary) For take over from steam turbine to electric motor next procedure has to be followed: • Start permissive when electric motor temperatures is within operating range • Start electric motor to full speed • Auxiliary lube oil pump will start automatically if PISA-222 is LOW 1) • Speed set point is ramped to zero (slow rate) • When set point is zero, valve limiter is stepped to zero 1) Manual start from local panel also possible From electric motor to steam turbine (preliminary) The take-over from E-motor to steam turbine needs additional local, manual actions (pre-heating steam lines to and from steam turbine, valves in correct position etc.). The steam turbine will be started according the normal start up procedure and when the steam turbine reaches his normal speed the electric motor can be switched off. During take-over, generally the driver with the highest speed will drive the FD Fan. For take over from electric motor to steam turbine start up procedure (see 3.13.3.2) has to be followed: Trip/stop electric motor A trip or stop of the electric motor leads to a shutdown or trip of the boiler. A manual take-over takes to much time and in this case a boiler start up procedure has to be initiated.

3.13.3.2 Start up

Start up and preparations prior to start up have to be done manually with local actions and supervision of the operator (i.e valves in correct position, emergency cooling water available, lube oil system ready, steam systems available, etc). Prior to start up a selection has to be made which driver should be started. General permissive • Verify steam conditions are within operating range • Steam lines pre-heated. • Valves in correct position • Lube oil system ready • Verify steam turbine doesn’t accelerate/run if steam inlet/outlet valves are opened 2) • Emergency cooling water system in circulation Note: 2) If turbine starts running close steam valve LBG10 AA010/015 FD Fan permissive • Verify IGV FD Fan closed to minimum stop • Verify impeller is not rotating • Verify FD Fan bearing temperatures are within operating range. Steam turbine/Gearbox permissive • Verify steam turbine/gearbox bearing temperatures are within operating range. • Verify Woodward governor is shutdown (governor valve closed) • Emergency trip is reset (if required) (DCS or LOCAL) • Steam turbine housing preheated (preferred but not required).





E-motor permissive • Verify bearing temperatures are within operating range. • Verify is FD Fan speed is 0 rpm or 1500 rpm Lube oil unit permissive • Verify emergency cooling water conditions (press/temp) are within operating range • Lube oil reservoir level > LOW Start lube oil unit (DCS or LOCAL) • Lube oil system to be started with the auxiliary lube oil pump (motor driven). • Verify lube oil pressure (PISA-222) within operating range • Verify differential pressure (PDIA-226) lube oil filter < HIGH • Verify water content (QIA-206) < HIGH • Verify bearing and gearbox temperatures are within operating range Start steam turbine operation (DCS or LOCAL) • Put governor in start function • Start steam turbine • Governor will ramp up turbine to nominal speed to minimum operating speed (500 rpm

HOLD). • Check differential temperature between steam turbine inlet and outlet (dT < 177°C) • Check oil temperature outlet oil/water cooler E-15163 (Toil < 49°C) Ramp up of the steam turbine to nominal speed will be done according a programmed sequence. During start up conditions of steam turbine and FD Fan need to be checked (i.e. oil temperatures, pressures, vibrations, noise). If excessive conditions occur the steam turbine must be shutdown. The governor valve position will be controlled by the speed controller. The turbine runs for (15 minutes at 500 rpm HOLD), meanwhile checking conditions of the FD Fan unit Steam turbine in normal operation • Governor at will ramp up speed to nominal speed (4762 rpm) • When the oil pressure of main pump PISA-222 is within operating limits the auxiliary

lube oil pump can be switched off manually. • Verify steam turbine, FD Fan and lube oil temperature is within operating range. • Verify lube oil pressure when running with main pump (shaft driven) • Verify gearbox vibration is within operating range Start electric motor operation When the electric motor is selected, start can be released when: • Electric motor temperatures within temperature range. • Lube oil system is in operation and conditions are verified. • Electric motor permissive and lube oil permissive are fulfilled. Note: The number of starts with the E-motor is limited (see section 3.13.3.10). FD Fan operation After steam turbine or electric motor is in stable operation the FD Fan runs with IGV’s in minimum opening position.





Controls Steam turbine/motor/lube oil unit At starting of the steam turbine the turbine speed controller (UC-580) is in start up mode. When the speed reaches normal set point the controller will be switched to AUTO. The pressure controller PIC-225 in the lube oil system will always be on AUTO. FD Fan At starting of the boiler the controllers FC-202B and QC-021 are in MAN mode, output 0%. Both controllers can be put on AUTO when: • All burners are in operation HOLD • FD Fan unit is in stable operation The controllers FC-202B and QC-021 receive their set points from the overall load control. See also section 3.19

3.13.3.3 Normal Steady State During normal operation the steam turbine speed controller (UC-580), oil pressure controller (PIC-225) and controllers FC-202B and QC-021 shall be in AUTO.


Instrument Tag Name Output Controller Action Output TIA-231A & TIA-231B

BAD - Manual Stop steam turbine 1) Freeze

TIA-232A & TIA-232B


TIA-233A & TIA-233B


TIA-234A & TIA234B


TIA-235A & TIA-235B & TIA-235C


TIA-236A & TIA-236B


TIA-237A & TIA-237B


TIA-238A & TIA-238B & TIA-238C


TIA-239 BAD - Manual Stop FD-Fan 2) Freeze TIA-240 BAD - Manual Stop FD-Fan 2) Freeze TIA-241 BAD - Manual Stop E-motor 3) Freeze TIA-243 BAD - Manual Stop E-motor 3) Freeze XIA-201 BAD - Manual Stop steam turbine 4) Freeze ST-202A & ST-202B

BAD UC-580 Mode to MAN Freeze

ST-204 BAD - - Freeze TI-201 BAD - - Freeze





LISA-204 BAD - Note 5) Freeze TA-258 BAD - Note 6/7) Freeze PDIA-226 BAD - Note 8) Freeze QIA-206 BAD - Note 9) Freeze PISA-222 BAD - Note 10) Freeze PZA-223 BAD - Note 11) Freeze PT-225 BAD PIC-225 Mode to MAN Freeze NOTE: 1) When two/three signals are BAD stop turbine manually and start E-motor if possible 2) Steam turbine and E-motor must be stopped 3) Start steam turbine if possible 4) When signal is BAD stop turbine manually and start E-motor if possible 5) Shut off heater and check oil level 6) When HIGH switch heater off 7) When LOW switch heater on 8) Switch-over to other filter 9) Check oil system and replace oil content 10) Automatic start aux. lube oil pump 11) Check/adjust control valve PIC-225

3.13.3.5 Shutdown

Shutdown with steam turbine The normal shutdown procedure of the turbine has to be followed. • IGV FD Fan to minimum position • Activate steam turbine stop • Speed set point is ramped to zero (slow rate) • Auxiliary lube oil pump will start automatically if PISA-222 is LOW 3) • When set point is zero, valve limiter is stepped to zero • If steam turbine speed is zero, governor is shutdown and governor valve closes. • When the speed of Steam Turbine and FD Fan = 0 rpm stop the auxiliary lube oil pump

after 60 seconds • Close steam valves LBG10 AA010 and AA015 3) Manual start from local panel also possible. During shutdown the auxiliary lube oil pump is started if the lube oil pressure (PISA – 222 or PIS – 227/327/427) is < L. Shutdown with electric motor • IGV FD Fan to minimum position • Activate E-motor stop • When the electric motor is switched off and the speed of FD Fan = 0 rpm stop the

auxiliary lube oil pump after 60 seconds Note It is only for a limited time allowed to keep a combustion air flow through the boiler when the boiler is not in operation anymore. The air will forcibly cool down the boiler in a rapid time, may be too fast with respect to temperature gradients in the steamdrum and superheater headers. See also section 3.19






Output (y) Input (x1,x2,x3) TAG Calculation 1x 2x 3x ?????

)sec02&1(

lub.

ondstforrpmxx

ifpumpoileauxstopy

stop==

UC-580 ST-204

NOTE:


Ranges TAG Description Range Units PIC-225 Lube oil pressure controller 0 - 100 % UC-580 Speed controller 0 - 100 % NOTE:

Alarms

TAG Description Level Value Units ST-204 A+ Indication 1550 rpm TISA-249 A+ Indication 400 °C TIA-231A/B A+ Indication 1) 110 °C TIA-232A/B A+ Indication 1) 110 °C TIA-233A/B A+ Indication 1) 105 °C TIA-234A/B A+ Indication 1) 105 °C TIA-235A/B/C A+ Indication 1) 105 °C TIA-236A/B A+ Indication 1) 105 °C TIA-237A/B A+ Indication 1) 105 °C TIA-238A/B/C A+ Indication 1) 105 °C TIA-239 A+ Indication 2) 80 °C TIA-240 A+ Indication 2) 80 °C TIA-241 A+ Indication 3) 80 °C TIA-243 A+ Indication 3) 80 °C XIA-201 A+ Indication 4) 58840 or

6 mm/s2 or G

LISA-204 A- Indication 5) 250 mm TA-258 A+ Indication 6) 70 °C TA-258 A- Indication 7) 5 °C PDIA-226 A+ Indication 8) 1.5 Bar(a) QIA-206 A+ Indication 9) 100 ppm PISA-222 A+ Indication 10) 2.25 Bar(g) PISA-222 A- Indication 11) 1.75 Bar(g)





NOTE: 1) When two/three signals are BAD stop turbine manually and start E-motor if possible 2) Steam turbine and E-motor must be stopped 3) Start steam turbine if possible 4) When signal is BAD stop turbine manually and start E-motor if possible 5) Shut off heater and check oil level 6) When HIGH switch heater off 7) When LOW switch heater on 8) Switch-over to other filter 9) Check oil system and replace oil content 10) Automatic start aux. lube oil pump 11) Check/adjust control valve PIC-225

Trips

TAG Description Level Value Units UC-580/ UZ-571

Z+ - 5450 rpm

SS-207 1) Z+ - 5500 rpm TISA-249 S SILa 430 °C PZA-223 2) Z-- SIL1 1.5 Bar(g) PZA-??? 3) Z- - 0.62 Bar(g) NOTE: 1) Mechanical trip 2) Trip FD Fan and driver 3) Mechanical trip

Note: Trip steam turbine TISA-249 HOLD High tempera ture is a SILa classification Decision by JV

Settings

TAG Description Value Units tstop Timer to stop auxiliary lube oil

pump 60 seconds

ST-204 Fan speed for permissive to start E-motor

0 or 1500

rpm

NOTE:

3.13.3.8 Interfaces


Operator can access tags on the DCS. Following functions/signals are present:

151HS-xxx Switch in DCS To select type of driver: steam turbine or motor 151HS-xxx Switch in DCS To start/stop KT-15161 151HS-xxx Switch on local

panel To start/stop KT-15161

151HS-xxx Switch in DCS To start/stop KM-15161 151HS-xxx Switch on local

panel To start/stop KM-15161

151HS-xxx Switch on local To start/stop KT-15161





panel 151XI-xxx Switch on local

panel To start auxiliary lube oil pump

151XI-xxx Switch on local panel

To stop auxiliary lube oil pump

151XI-xxx Indication in DCS Indication that KM-15161 is ready to start 151XI-xxx Indication on local

panel Indication that KM-15161 is ready to start

151XI-xxx Indication in DCS Indication that KT-15161 is running 151XI-xxx Indication on local

panel Indication that KT-15161 is running

151XI-xxx Indication in DCS Indication that KM-15161 is running 151XI-xxx Indication on local

panel Indication that KM-15161 is running

Signal 151US-xxx

Signal Signal to MCC to start KM-15161

Signal 151US-xxx

Signal Signal from MCC to confirm that KM-15161 is running

Signal 151US-xxx

Indication in DCS Indication any failure

Signal 151US-xxx

Indication on local panel

Indication any failure

151TIZA-239 Signal Trip FD Fan (stop electric motor KM-15161) upon High High temperature HOLD (to be discussed with NEM; refer to TZA19 and TZA20 on NEM P&ID. We know that the steam turbine will be tripped anyway, but we don’t know if the Fan on motor is also the be tripped/stopped )



151PZA-223 Signal Trip FD Fan (stop electric motor KM-15161) upon Low Low and High High pressure HOLD (to be discussed with NEM; refer to PZA06 on NEM P&ID. We know that the steam turbine will be tripped anyway, but we don’t know if the Fan on motor is also the be tripped/stopped )

151UZ Signal Signal from BMS 151UZ-500 to stop the Fan 151US Switch on local

panel Emergency stop of the Fan

151US-xxx Signal Permissive signal to KT-15161 Woodward Governer - 151UC-XXX that the steam turbine is allowed (or not) to be started

151UZ-xxx Signal Running confirmation of steam turbine from KT-15161 Woodward Governer - 151UC-XXX





3.13.3.10 Special Considerations During purge, start up and shutdown the air flow through the FD Fan will be limited by means of a mechanical minimum stop. Cooling water for the lube oil system will be supplied from the emergency cooling water system. The number of consecutive starts with the E-motor is limited to: • 3 cold starts • 2 warm starts When a start is not succeeded after 3 cold or 2 warm starts a waiting time of 300 minutes is required to cool-down the motor sufficiently.

3.13.4 History


On this P&ID we have shown/made three (3) control/safeguarding blocks:

4. KT-15161 Woodward Governer - 151UC-XXX 5. KT-15161 Bentley Nevada – 151UZ-xxx 6. FD Fan KT-15161 Operation – 151US-xxx

We will send you our “Shellified” P&ID for your consideration. FD Fan KT-15161 Operation – 151US-xxx In this block the Operator has to select the type of driver for FD Fan K-15161. The steam turbine KT-15161 will be started/stopped from the “KT-15161 Woodward Governer - 151UC-XXX”. The electric motor will be started/stopped from this block.





3.14 COOLING AIR FANS K-15162A/B AUTO TAKE-OVER

P&ID 36005-105-12

PISA - 205, KM - 15162A, KM - 15162B, US-540

UEFS E-15100-TN-2395-0038 Steam Boiler Package A-15101 - Cooling Air Viewports

See typical control loop PUMP AUTO TAKE-OVER in General Functional Specification, doc. E-00000-TN-5306-0001. � I don’t know if this is still applicable to a FAN. J.V. to advise.

3.14.1 Objective The fans supply cooling air to the boiler view ports and burner igniters. The air will also be used as seal air for the sootblower wall box and to prevent ingress of flue gas into the sootblower lance when the sootblower is not blowing steam.


To start the standby fan KM - 15162B or KM - 15162A on detection of a low discharge pressure PISA-205 or a discrepancy alarm on the duty fan. US-540: Cooling Air Fans Auto Take-over Input Logic Description Action PISA-205 OR KM - 15162A.DIS_ALARM OR KM - 15162B.DIS_ALARM

PISA-205.LO = SET OR KM - 15162A.DIS_ALARM = SET OR KM - 15162B.DIS_ALARM = SET

KM - 15162A = START KM - 15162B = STOP OR KM - 15162B = START KM - 15162A = STOP


This control scheme is required to be operational during start up, shutdown, normal operation, and take-over.


3.14.3.3 Start up


Instrument Tag Name Output Controller Action Output PISA-205 BAD - - Freeze NOTE:





3.14.3.5 Shutdown



Alarms

TAG Description Level Value Units PISA-205 A- Indication HOLD Barg(g) PISA-205 A-- Indication HOLD Barg(g) NOTE:

Low discharge pressure switch PISA-205 will be automatically reset when the pressure rises above the low switch setting.

3.14.3.8 Interfaces 3.14.3.9 Operator Interfaces


3.14.4 History






3.15 SOOTBLOWER SYSTEM

P&ID 36005-105-10 36005-105-11

PISA-208, TISA-220, TISA-221

UEFS E-15100-TN-2395-0037 Steam Boiler Package A-15101 – Sootblower System Reference document 36005-553-04-118 Sootblower Logic Diagram

3.15.1 Objective The sootblowers will be used to keep the heating surfaces of superheaters and economizers in the boiler free from soot and dust as much as possible. Especially during firing of fuel oil the sootblowers will blow MP steam to the heating surfaces within a certain time interval. Always one sootblower at a time is in operation. Seal air is supplied the sootblower wall box to prevent flue gases escaping from the boiler and to prevent ingress of flue gas into the sootblower lance when the sootblower is not blowing steam.


The sootblowers operate normally a few minutes each day so the normal position for the steam valve is to be closed and the drain valves to be opened. The sootblower sequence will be started by the operator from the DCS. The operator can select for either a fixed programmed sequence to be followed or a manual random sequence. When starting the sequence warming up will commence (typically 10 to 15 minutes) and valves HCB10 AA001 (KBS-211), HCB10 AA010 (KBS-212)and HCB10 AA030 (KBS-213) are automatically opened. If the steam temperature is satisfied the warming up valves HCB10 AA010 (KBS212) and HCB10 AA030 (KBS-213) are closed and steam blowing can be started. Sootblowers will operate one by one usually from the hot to the cold parts. During sootblow operation the steam lines will be kept at the required temperature via the orifices RO-203 and RO-205 in steam lines HCB10 BR013 and BR033. When the sootblower is inserted the steam valve is open. In retracted position the steam valve is closed.

DCS - Discrete Control Tag name Service Limit Action Valve/Controller PISA-208 Steam supply pressure LOW

(S) Retract sootblowers and stop sequence

KBS-211

TISA-220 Steam temperature at drain valve HIGH (S)

Close valve KBS-212

TISA-221 Steam temperature at drain valve HIGH (S)

Close valve KBS-213

NOTE:






The boiler can be claeaned by an automatically fixed sootblowing sequence or by manual/individual sootblowing.

3.15.3.2 Normal Steady State 3.15.3.3 Start up

Automatically blowing sequence: This sequence will start with the boiler sootblowers in lane 1. Subsequently the sootblowers in lane 2 up to 7 will be started. The sequence ends with the sootblowers of the external economizer of lane 8 and 9. • Power on • Check all sootblowers in retracted position • If not retracted press retract/fault reset button • All sootblowers in retracted position • Drain valves HCB10 AA010 (KBS-212) and HCB10 AA030 (KBS-213) are opened • Steam supply valve HCB10 AA001 (KBS-211) is opened • Preheating steam line • If steam temperature TISA 220 > HIGH (S+), drain valve HCB10 AA010 closes • If steam temperature TISA 221 > HIGH (S+), drain valve HCB10 AA030 closes • If drain valves closed, check steam pressure PISA 208 > HIGH (S+) • Select ‘ALL’ button (AUTO sequence selected) • Press start button • Sequence started for lane 1 up to 9 (individual sootblower operation) • Sootblower motor energized • Sootblower inserted • Sootblowing in advance • When limit switch position ‘close’ is reached motor is switched to reverse action • Sootblower is retracted • When limit switch position ‘open’ is reached sootblower motor is switched off • Sequence starts next sootblower • Sequence continues up to last sootblower • Wait for timer is finished • Check for all sootblowers retracted • Steam supply valve HCB10 AA001 (KBS-211) is closed • Drain valves HCB10 AA010 (KBS-212) and HCB10 AA030 (KBS-213) are opened • Power off Manual blowing sequence: The sequence can be started random. After the first of the selected sootblowers is finished subsequently the other selected sootblowers will be started automatically. • Power on • Check all sootblowers in retracted position • If not retracted press retract/fault reset button • All sootblowers in retracted position • Drain valves HCB10 AA010 (KBS-212) and HCB10 AA030 (KBS-213) are opened • Steam supply valve HCB10 AA001 (KBS-211) is opened • Preheating steam line





• If steam temperature TISA 220 > HIGH (S+), drain valve HCB10 AA010 closes • If steam temperature TISA 221 > HIGH (S+), drain valve HCB10 AA030 closes • If drain valves closed, check steam pressure PISA 208 > HIGH (S+) • INDIVIDUAL sootblowers selected • Press start button • Sequence started (individual sootblower operation) • Sootblower motor energized • Sootblower inserted • Sootblowing in advance • When limit switch position ‘close’ is reached motor is switched to reverse action • Sootblower is retracted • When limit switch position ‘open’ is reached sootblower motor is switched off • Sequence starts next sootblower • Sequence continues up to last sootblower • Wait for timer is finished • Check for all sootblowers retracted • Steam supply valve HCB10 AA001 (KBS-211) is closed • Drain valves HCB10 AA010 (KBS-212) and HCB10 AA030 (KBS-213) are opened • Power off


Instrument Tag Name Output Controller Action Output PISA-208 BAD - Open valve KBS-211 Freeze TISA-220 BAD - Close valve KBS-212 Freeze TISA-221 BAD - Close valve KBS-213 Freeze NOTE:

3.15.3.5 Shutdown

See start up above.



Alarms TAG Description Level Value Units PISA-208 A- Indication 17 Barg(g) TISA-220 A+ Indication 350 °C TISA-221 A+ Indication 350 °C HOLD (MAX blowing time elapsed)

A+ Indication 15 minutes

NOTE:

Settings TAG Description Value Units PISA-208 Retract sootblowers & stop

sequence if pressure < LOW (S-) 18 Bar(g)





TISA-220 Close drain valve KBS-212 if steam temperature > HIGH (S+)

280 °C

TISA-221 Close drain valve KBS-213 if steam temperature > HIGH (S+)

280 °C

TISA-220 Sootblowing suspended if steam temperature < LOW (S-)

260 °C

TISA-221 Sootblowing suspended if steam temperature < LOW (S-)

260 °C

HOLD (Blowing time)

Sootblower operating will retract and suspended if MAX blowing time (insert + retract time) is elapsed

10 minutes

NOTE: 3.15.3.8 Interfaces 3.15.3.9 Operator Interfaces

Operator can access tags on the DCS.

Following functions/signals are present:

151HS-xxx Switch in DCS Power on/off 151HS-xxx Switch in DCS Emergency retract/fault reset push button 151HS-xxx Switch in DCS Selection sequence ‘ALL’ or ‘INDIVIDUAL’ button 151HS-xxx Switch in DCS Start button 151HS-xxx Switch in DCS (Emergency) stop button

3.15.3.10 Special Considerations

3.15.4 History






3.16 ATOMIZING STEAM CONTROL LBG30AA011 (PICA-115)

LBG30AA016 (TICA-081) P&ID 36005-105-14 PCD 114 UEFS E-15100-TN-2395-0004 Steam Boiler Package A-15101 – Atomising Steam System

3.16.1 Objective To supply MP steam to the fuel skid with a constant superheated temperature used for atomizing of the fuel oil in the burners.

3.16.2 Functional Description To supply MP steam of the required conditions to the fuel skid MP steam and MP desuperheated steam will be mixed. To mix the two flows with nearly equal pressures a pressure controller PC-115 controls the MPD steam to a fixed pressure downstream of the control valve. Temperature control of the mixed flows is achieved by temperature controller TC-081. Too low or high pressures and temperatures will be alarmed. If atomizing gas or no atomizing medium is selected (NG selected) the controllers will be in MAN mode 0% output. If atomizing steam is selected both controllers will be switched to AUTO mode.

DCS - Analogue Control Valve Tag name Service Action PV-Tracking Name PC-115 PID Direct Yes PICA-115 TC-081 PID Direct Yes TICA-081


Tag name Service Limit Action Valve/Controller N.A. NOTE:

IPS - Discrete Control

Tag name Service Limit Action Valve/Controller N.A. NOTE:







3.16.3.2 Start up 3.16.3.3 Normal Steady State

During normal operation the controllers PC-115 and TC-081 shall be in AUTO.


Instrument Tag Name Output Controller Action Output PICA-115 BAD PC-115 Mode to MAN Freeze TICA-081 BAD TC-081 Mode to MAN Freeze NOTE:

3.16.3.5 Shutdown


Output (y) Input (x1,x2,x3) TAG Calculation 1x 2x 3x N.A. NOTE:


Ranges TAG Description Range Units PC-115 Pressure controller 0 - 100 % TC-081 Temperature controller 0 - 100 % NOTE:

Alarms

TAG Description Level Value Units PICA-115 A+ Indication 20 Bar(g) PICA-115 A- Indication 16 Bar(g) TICA-081 A+ Indication 320 °C TICA-081 A- Indication 215 °C NOTE:

Trips

TAG Description Level Value Units N.A. NOTE:

Settings

TAG Description Value Units HC-115 SP pressure controller 18 Bar(g) HC-081 SP temperature controller 237 °C NOTE:





3.16.3.8 Interfaces



The maximum allowable mixed temperature (324°C) is lower than the design temperature of the MP steam (400°C). If the mixed temperature exceeds the allowable temperature the opening of the MP steam control valve will be limited.

3.16.4 History






3.17 BOILER START UP AND SHUTDOWN

HLA10AA001, FIC-502, XC504 (HOLD) P&ID 36005-105-?? (HOLD) PCD (HOLD) Question to JV: Will there be a check on conditions as a release signal for start up? - Fuel supply OK - Feedwater conditions OK - MP and LP steam conditions for steam t urbine OK - Industrial water conditions OK - Cooling water conditions OK - Instrument air conditions OK - Atomizing steam conditions OK - Sootblower steam conditions OK

3.17.1 Objective To start up and shutdown the boiler according specific procedures. An automatic sequence is incorporated for start up with NG. Manually start up with other fuels is possible. Boiler shutdown will be done manually.

3.17.2 Functional Description When starting the fuel control valves are positioned by the start sequence program or operator. During start phase the fuel and air control will be switched to AUTO when all burners are in operation. The boiler is disconnected from the grid by main steam valve LBA10 AA003 (MOV-201) which is closed. The steam pressure will controlled by controller PC-207. Start up is ended when the boiler is at 40% MCR. From that point the boiler can be connected to the steam grid. When the boiler is connected to the steam grid the load controller will be switched to AUTO (pressure or flow) and receive their set points from the overall load control Several controllers are in MAN or AUTO mode as described in the specific start up sections above.

Please briefly describe all calculation blocks, switches, High or Low Selectors, etc. For DCS control see other sections above.






3.17.3.2 Start up

CHECK UPS PRIOR TO START PROGRAM • Auxiliary systems standby at the required conditions for normal operation, i.e.

feedwater, cooling water, industrial water, auxiliary steam systems, oil system FD fan, fuel system, chemical dosing systems, plant/instrument air.

• Boiler equipment standby. • All valves in correct position. • Boiler is vented and drum level is brought to start level. • Burner system and fuel lines standby. • The water level in the intermittent blowdown drum is brought to minimum level by

supplying industrial water. START UP MODES As far as applicable three different start up modes are distinguished: • Cold start up: defined as t drum < 100°C • Warm start up: defined as t drum ≥ 100 and < 300°C • Hot start up: defined as t drum ≥ 300 °C START PROGRAM Purging The boiler shall be purged prior to the burner start according NFPA 85. Start of the FD fan at minimum required combustion airflow would purge the boiler. Minimum purging conditions are described in the table below. Furthermore, all burner air dampers (6 in total) need to be open during purging. More details can be found in the Burner System Description.

Purging due to Minimum purge flow (m3/s)/kg/h

Maximum purge air temperature (°C)

Minimum time (min)

Boiler + duct purge volume (once) (m3)

Excl. Stack

Boiler 18.7/90000 35 6 1300

Table 1. Purge conditions After purging, the 6 burner air dampers remain open with at least the minimum purge flow. Fuel selection The fuel selection is set in the DCS system. There are two options: 1. Natural Gas selection (for automatic start up procedure) 2. Oil selection (for manual start up procedure) Mixed fuel operation during start up is not recommended. NG will always be used as ignition fuel.





Boiler start-up At starting of the boiler the set point of the pressure controller PC-207 is, via an automatic switch, put in memory to the remaining pressure in the boiler with a minimum of 2 bar(g) The boiler start-up is initiated by setting the desired boiler load from the DCS with a maximum of 40% MCR. This will initiate a starting sequence of the burners (for NG). During the start program is running other actions will be initiated such as open and closing of drains, level increase of the drum level from SL to NWL, activate of control functions. Details can be found in the Functional Control Diagrams (HOLD). Burner start The burner start is described in the Burner System Description. Each burner start is performed from the DCS or burner local panel. Burner starting sequence The burner starting sequence as described in this paragraph needs to be followed to start-up the boiler in the correct manner. Once more it is noted that the boiler has six (6) burners located at the front side of the furnace divided into 2 rows with each 3 burners. The bottom row burners will be started first, and later on the top row burners, in order to heat up the boiler as gradually as possible. Furthermore, two holding points are included to start-up the boiler correctly. The burner starting sequence is described in the table 2 below. Burner front is shown in figure 1 below. Step Burner

number Action Nr of bur-

ners on Load per burner (%)

boiler load (%)

Hold point

1 Burner 5 1st burner start 1 25 4.2 2 Burner 4 2nd burner start 2 25 8.3 3 Burner 6 3rd burner start 3 25 12.5 1 4 Increase load 3 burners 3 79.9 40 8 Burner 2 4th burner start 4 59.9 40 10 Burner 1 5th burner start 5 47.9 40 12 Burner 3 6th burner start 6 40 40 2 13 Increase load 6 burners 6 100 100

Table 2. Burning starting sequence





Figure 1. Burner front (seen from burner platform) Load to 12.5% boiler load (final value to be defined during commissioning) The load of the boiler is set to 12.5% MCR. The first three (3) burners are started in the sequence as given in table 2. At that point a hold point (1) is applied to heat up the boiler gradually. Furthermore, the condensate in the superheater tubes needs to be removed. The hold point (1) needs to be maintained until the following conditions are met: • Drum level HAD10 CL004/5/6 (LT-202A/B/C) is constant for at least 120 seconds. • Drum pressure HAD10 CP001 (PIA-206) is > 2 bar(g) and stable for at least 120

seconds. • Drum temperature gradient within allowed range. • Main steam temperature gradient within allowed range. • Maximum start up valve opening = 30% During this stage, steam temperature and pressure will increase. The boiler load and or steam pressure will be limited when the allowable gradients are exceeded. (HOLD) A too high steam temperature gradient will limit the load increase. A too high medium temperature in the drum will be limited by further opening of the start up valve. Load increase can recommence as soon as the gradients are acceptable. This means that the load is reduced as soon as the allowable gradients has been passed. Load increase can recommence as soon as the gradients are acceptable. (HOLD) Load to 40% As soon as the above conditions for hold point (1) are met, the load of the HP auxiliary boiler is gradually increased to 40%. When the load is at 40% the last three (3) burners are started in the sequence as given in table 2. During this stage, steam temperature and pressure will increase further. The boiler load increase is controlled by: • Allowable HP steam drum temperature gradient • Allowable HP main steam temperature gradient. During this stage, steam temperature and pressure will increase. The boiler load and or steam pressure will be limited when the allowable gradients are exceeded. (HOLD) A too high steam temperature gradient will limit the load increase. A too high medium temperature in the drum will be limited by further opening of the start up valve. Load increase can recommence as soon as the gradients are acceptable. This means that the load is reduced as soon as the allowable gradients has been passed. Load increase can recommence as soon as the gradients are acceptable. (HOLD)

Burner 1 (A) Burner 2 (B) Burner 3 (C)

Burner 4 (D) Burner 5 (E) Burner 6 (F)





The steam pressure will reach the set point of the start up blow off valve LBA10 AA051 (PICA-207) and the valve will control the steam pressure at 120 bar(g). Feedwater control valves during start up To close and open control valve LAB10 AA032 (TIC-207B) see section 3.9.3.2. During start up of the boiler control valve LAB10 AA032 will be forced to close. When the boiler load < 15%, then: • Output temperature controller LAB10 CT003: 0% • Output of control valve LAB10 AA032: 0% When boiler load > 15%, then: • Temperature controller and control valve LAB10 AA032: AUTO-mode Warming up steam lines As soon as the steam production starts the superheater and main steam line will be warmed up by the steam/condensate discharged via the start up drain valves HAH10 AA402/424 and LBA10 AA404. The start up drain valves will be closed during the start up procedure. ECO circulation valve during start-up The ECO circulation valves HAD15 AA001 (US-532) and HAD15 AA002 (US-531) can be closed as soon as the following conditions are met: • FW flow LAB10 CF101 is > 15 t/h for at least 60 seconds. (HOLD) Start-up steam blow off CV LBA10 AA051(PICA-207) during start-up (0-40% load) The control valve opens at 2 bar(g) minimum or actual pressure and controls the actual pressure until a maximum open position of 30% is reached. With increasing boiler load, the steam flow, pressure and temperature will rise. When the steam pressure has reached normal set point pressure controller PC-207 is switched to MAN mode and at the same time the 30% opening limit of PICA-207 is removed. Pressure controller PC-207 is put in AUTO mode after a certain time (to stabilize) and then controls the pressure at normal the operating value of 120 bar(g). Warming up common steam system during start-up (0-40%) The common steam system is the system downstream boiler valve LBA10 AA003 (MOV-201) and can be warmed up by opening bypass valve LBA10 AA005 of main steam valve LBA10 AA003 (MOV-201). Note: Draining of the steam system downstream boiler main steam valve is required. Open main steam valve LBA10 AA003 (MOV-201) As soon as the following conditions are met the main steam valve can be opened (and the start-up blow off valve LBA10 AA051 (PICA-207) is closed): • Steam line pressure LBA10 CP001 (PICA-207) is ≥ 120 bar(g) • Main steam temperature LBA10 CT001 (TICA-217) ≤ 525 °C • Differential pressure over boiler HP steam valve LBA10 AA003 (MOV-201) < 2 bar Note: The temperature of steam lines downstream main steam valve LBA10 AA003 should have an acceptable level.





Close start up valve LBA10 AA051 (PICA-207) The valve will automatically close as soon as there is a steam demand from the common steam system respectively steam turbines. Controller PC-207 will be switched to MAN, 0% output when: • Valve PICA-207 is closed and • Valve MOV-201 is open If valve LBA10 AA051 is closed the set point of the valve will be increased with a upset of 2 bar to 122 bar(g). (HOLD) Boiler control Control can be performed in two different manners. 1. Pressure control by master pressure control system. 2. Boiler steam flow control. Master pressure control or flow control can be activated if: • Valve PICA-207 is closed and • Valve MOV-201 is open Transfer from 40% load to 100% load The boiler load can be transferred from 40% to normal operation as soon as the following conditions are met: • Boiler load is 40% MCR. • Main steam valve LBA10 AA003 (MOV-201) is opened. • Start up valve LBA10 AA051 (PICA-207) closed. • Boiler steam temperature and pressure control on AUTO • Steam drum temperature gradient < allowable • Steam temperature gradient < allowable • Main steam line pressure LBA10 CP001 (PICA-207) is ≥120 bar(g) • Main steam temperature LBA10 CT001 (TICA-217) ≤ 525 °C

IN OPERATION STATUS The boiler is in operation status during normal operation. The HP auxiliary boiler is at a load between 40 to 100 % MCR and produces steam with a constant pressure of 120 bar(g) (maximum 125 bar(g)). The boiler produces steam with a constant steam temperature over the boiler load range of approx. 40 to 100%. The boiler is in operation at pressure or flow control.

3.17.3.3 Normal Steady State N.A.

3.17.3.4 Crippled Mode Operation For crippled mode operation see sections above.





3.17.3.5 Shutdown In order to shut down the boiler, the following actions need to be taken: • Open manual steam blow off valve LBA10 AA050 • Adjust set point for pressure controller PC-207 to an appropriate value just above of the

actual pressure in main steam line (to avoid steam blow off) • Put pressure controller/start up valve PICA-207 on AUTO • Reduce boiler load slowly to approximately 20% MCR (with constant steam header

pressure) • The HP steam line MOV LBA10 AA003 (MOV-201) can be closed (manually from CCR)

as soon as the boiler load is < 40%. Potential stored heat can be released by the start up valve LBA10 AA051 operating as pre-safety valve.

• As soon as the boiler load is < 20% MCR the top burners and finally the bottom burners are stopped consecutively

• As soon as all burners are out of operation FD Fan HLB10 AN001 (K-15161) will automatically stopped by activating the stop program of the steam turbine or electric motor

• The economizer circulation valves HAD15 AA001/002 are opened automatically as soon the FW flow LAB10 CF101) < 12 t/h for at least 60 seconds

• The drum level will be brought from normal level to start level • Close continuous blowdown valve HAD10 AA460 (QISA-202) • Put pressure controller/start up valve PICA-207 on MAN, 0% output • The start up valve set point will follow the actual steam pressure (with a margin of 2 bar)

during boiler cool down Forced cooling of the boiler by running the FD Fan should be kept to a minimum. An alarm is given in case the allowable steam drum pressure gradient during cool down is exceeded.


For calculations see sections above.

3.17.3.7 Initialisations For initialisations see sections above.

3.17.3.8 Interfaces 3.17.3.9 Operator Interfaces


During purge, start up and shutdown the air flow through the FD Fan will be limited by means of a mechanical minimum stop. Allowable temperature gradients: See section 3.10.3.6/ 7 and 3.11.3.6/7 above.

3.17.4 History






REFERENCES 3.18 DRAWINGS

PID’s 36005-104-01 Legend and symbols for P&ID's 36005-104-02 Legend and symbols for P&ID's 36005-105-01 PFD and material balance 36005-105-02 P&ID Flue gas system 36005-105-03 P&ID Economiser system 36005-105-04 P&ID Evaporator system 36005-105-05 P&ID Superheater system 36005-105-06 P&ID Main steam line 36005-105-07 P&ID Drain system 36005-105-08 P&ID Blow down system 36005-105-09 P&ID Sample unit 36005-105-10 P&ID Sootblower system boiler 36005-105-11 P&ID Sootblower system economizer 36005-105-12 P&ID Cooling air view ports 36005-105-13 P&ID Steam lines turbine 36005-105-14 P&ID Atomizing steam desuperheater station 36005-105-15 P&ID Cooling water 36005-105-16 P&ID Instrument air 36005-105-17 P&ID Burner piping system 36005-560-04-151 P&ID Dual drive Fan 36005-560-04-151-002 P&ID Lubrication system (dual drive fan) 36005-824-04-151-002/003/004 P&ID Common skid 36005-824-04-151-005/006/007 P&ID Local burner fuel system

3.19 DOCUMENTS

Operating data 36005-103-01 Performance data 36005-103-38 Material balance 36005-646-01 Process control diagrams Reference documents 36005-824-04-148 Burner system description (including control and safeguarding) 36005-560-04-148 Operating procedure Dual Driven FD Fan 36005-560-04-148-001 Control Narratives Dual Driven FD Fan 36005-553-04-118 Sootblower Logic Diagram 36005-646-01 Functional Control Diagrams (LATER)

boiler

Documents

steam load control pica

medium pressure mp steam

shphp steam desuperheater

pressure control pica

boiler steam drum level

process units

process heat exchangers

project e