section a.6 steam and water cycle equipment

PIONEER GAS POWER LIMITED

380-425 MW COMBINED CYCLE POWER PLANT APSIPL-05EPC- 3-A6

STEAM AND WATER CYCLE EQUIPMENT

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6.0 STEAM AND WATER CYCLE EQUIPMENT 6.1 General 6.1.1 The steam water and cycle equipment design shall be as per this section

including data sheets. 6.2 Surface Condenser and Accessories 6.2.1 The selected condenser together with the condenser cooling water system

shall be such that the condenser pressure, corresponding to a sustained HP-IP-LP bypass operation (nearly fully open) and turbine operation at house load at maximum cooling water inlet temperature to condenser, is less than the turbine alarm value for the high condenser back pressure by a reasonable limit.

6.2.2 The contractor shall take into account the following aspects in respect of

condenser design: (a) Water box shall be designed for integrity against maximum circulating

water transients i.e. design of circulating water system side to the circulating water pump shut-off head to next higher 0.5 kg/cm2 plus an allowance for water hammer surge, if required as verified by vendors calculation. The calculation shall be submitted for review. The water box test pressure shall be at least 1.5 times the design pressure

(b) The condenser shall be capable for part load operation of the STG unit with one half of the condenser out of service. This operation however will be for short duration only.

6.2.3 The location and design of steam and water dumps to the condenser shall

be in accordance with ASME Standard TDP-1, Part-1. 6.2.4 The condenser design shall provide for adequate bowing or sloping of

tubes to assure complete drainage of the tubes. 6.2.5 A vacuum grid shall be fitted to ensure that an average reading can be

obtained and the grid shall be fitted 300 mm from the edge of condenser tube bundle nearest the turbine exhaust for measurement of condenser vacuum.

6.2.7 Each water box shall be provided with drain valves of adequate size at the

bottom to enable the front and rear water box and tubes to be emptied of water in not more than 30 minutes.

6.2.8 Access manholes of adequate size shall be provided, one in each of

the hotwell sections. Hotwell connections to suction of condensate




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extraction pumps shall have anti-vortex baffling and the material of screen mesh shall be of stainless steel type 304.

6.2.9 A suitable means of access shall be provided inside the condenser to

permit inspection and cleaning of confined areas. An access manhole of 600 mm x 600 mm size minimum shall be provided on the shell above tubes.

6.3 CONDENSER AIR EVACUATION EQUIPMENT 6.3.1 2 X 100% duty mechanical vacuum pumps and accessories shall be

used to create vacuum by removing air and non-condensable gases from steam condenser during plant start-up and operation. The pumps shall be single stage liquid ring with an air ejector or two-stage liquid ring type. In case of a two stage pump both the stages shall be mounted on a common shaft.

6.3.2 The unit shall require no internal lubrication and shall not be damaged

by water vapour, entrained droplets or slugs of water. 6.3.3 Provision shall be made in the design of the equipment to prevent loss

of vacuum by flow of atmospheric air back into the condenser upon shutdown of the pump.

6.3.4 The control system shall be such that the entire operation from hogging

through holding can be carried out automatically. 6.4 CONDENSATE EXTRACTION PUMPS AND ACCESSORIES 6.4.1 For maximum availability between planned maintenance periods,

components of pump shall not be made of materials which are degradable and/or which will wear and need replacing within 40,000 hours with the exception of mechanical shaft seal materials, which shall be capable of operating for not less than 15,000 hours.

6.4.2 Each pump set shall:

(a) Be capable of supplying the starting requirements of the plant. (b) Satisfactorily accommodate steady and transient loadings imposed

by the main pipe work.

6.4.3 The pump characteristic curve test tolerances shall be limited to : Plus (%) Minus (%) (a) Flow at guarantee point 0 0 (b) Head at guarantee point 3 0




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(c) Efficiency at guarantee point Unlimited 0 (d) Shut-off head 5 0 These tolerances shall be the permissible variations between the

conditions as proposed initially by Bidder and the design parameters demonstrated during the acceptance tests.

6.4.4 The pump motor rating shall not be less than larger of the following :

(a) Sufficient to drive the pump through the entire range of runout flow to shut-off conditions.

(b) 110% of pump design point rating.

6.4.5 The construction shall be such as to allow removal of pump shaft and

impeller without disturbing the can. 6.4.6 The suction side vent of each cannister shall be individually connected

to condenser. Discharge side vent of each condensate extraction pump shall have its own solenoid valve operated, together with break down orifice and be connected individually to condenser.

6.4.7 The initial sealing water for the condensate extraction pumps shall be

from hotwell make-up system and during normal operation from condensate extraction pump discharge. Transfer from one sealing water source to another shall be automatic.

6.5 DEAERATING FEED WATER HEATER 6.5.1 The deaerator shall be capable of satisfactory operation under normal

operation, condition of turbine trip and bypass operation (full open) and lowest condenser pressure. Minimum condenser pressure shall not affect deaerator performance in any manner.

6.5.2 In case of spray-tray type with direct-contact vent condenser parallel

flow of steam and water is not desirable. Tray supports shall be rigid enough to withstand severe vibrations that would be caused due to water hammering during start-up and full load throw-off conditions. The sprayer shall be a spring controlled spray valve (variable flow area) which ensures fine atomisation of condensate at all loads. The sprayer device shall provide a self regulated system in which disc/piston opening adopts automatically to the changing hydraulic loads.

6.5.3 The spray type deaerator shall be Stork type or proven equivalent

construction which combines in one vessel the functions of deaerator, pre-heater, vent condenser and feed water storage tank. The design shall incorporate suitable spray valves of disc type or equivalent, splash




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plates, baffles, grids, etc. which ensures fine atomisation of incoming condensate, rapid heating up by steam and higher residence time. The rake supplying heating steam shall be suitably supported to prevent vibration. A separate heating steam rake to supply heating steam during start-up shall be provided.

6.5.4 The outlet pipes from the feed water storage tank shall be provided with

a vortex breaker and project a minimum of 75 mm above the bottom of the storage tank.

6.5.5 The vent from the continuous blow down tank (CBDT) will also be led to

the deaerator. 6.5.6 The sprayer shall be designed to ensure fine atomisation of condensate

at all loads upto 110% of the design flow. 6.6 HRSG FEED PUMPS 6.6.1 The requirements indicated here are applicable for all the HRSG feed

water pumps in steam and water circuit. 6.6.2 In designing the system, attention shall be paid to the NPSH

requirements of the pumps during normal operation and transients.. 6.6.3 Each HRSG feed pump set as a whole shall be capable of withstanding

the reverse rotational speeds which would result from non-return valve failure under the most severe condition. CONTRACTOR shall provide reverse rotation detection system to close discharge valve on detection of same.

6.6.4 Pump characteristic curve test tolerances shall be limited to : Plus(%) Minus(%) (a) Flow at guarantee point 0 0 (b) Head at guarantee point 3 0 (c) Efficiency at guarantee point Unlimited 0 (d) Shut-off head 5 0 These tolerances shall be the permissible variations between the

conditions as initially proposed by the Bidder and the design parameters demonstrated during acceptance tests.

6.6.5 Pump with high suction specific speed not proven in practice is not

acceptable. The impeller shall be designed for minimum 40,000 hours operation.




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6.6.6 The pump motor rating shall not be less than the larger of the following

:

(a) Sufficient to drive the pump through the entire range of run-out flow to shut-off conditions.

(b) 110% of pump design point rating. 6.6.7 All bearings shall be provided with a forced lubrication from a common

oil system for HP / IP or HP feed pumps. The thrust bearings shall be of tilting pad type. Also the design of lubricating oil system should take into account the oil requirements of the motor. Bearings shall be easily accessible without disturbing the pump. Each bearing housing shall have a drain plug. The balance drum leak-off shall be internal to pump

6.6.8 Each HRSG feed pump set shall be provided with flexible couplings of approved type between the motor and pumps and hydraulic coupling.

6.6.9 A forced lubricating oil system for HRSG HP / IP or HP feed pumps and motor with necessary instrumentation and control shall be supplied. The lubrication system shall include, but not necessarily be limited to, a shaft driven oil pump, a spare full capacity electric motor driven oil pump, all piping, valves, return flow sight gauges, relief valves, oil coolers, pressure and temperature switches, duplex or two simplex filters, pressure gauges, flow control devices, oil level indicators, thermometers including return oil thermometer for each bearing and on oil reservoir.

6.6.10 Mechanical Seals (a) The mechanical seals shall have a life expectancy of 15,000 hours.

(b) A cooling jacket shall be incorporated in the gland design. This

shall consist of a water circulation ring, magnetic filter and sealing water cooler. Auxiliary cooling water shall be used for the cooling and the system shall have a suitable filling, venting and draining arrangement.

6.6.11 Variable Speed Hydraulic Coupling, if applicable

(a) Bidder shall note that for steam and water cycle with HP

pressure as indicated in item 2.3.2 (a) of data sheets, hydraulic coupling shall be provided for the HP-IP pressure pumps.

(b) This shall be of Voith design or equivalent and shall be rated for

maximum duty of the main pump of the HP / IP or HP BFP set.




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The pump speed can be steplessly varied over a range 20% to 100% of pump rated speed

(c) The scoop tube shall be operated by a servo positioner which is

powered by the coupling lubricating oil system. A stepper motor shall interface with the servo positioner with a suitable linkage provided. A special requirement is the need for rapid starting and response to control signals. The coupling and its auxiliaries shall be designed to reduce inherent time lags to a minimum. The start-up time for the complete BFP set is to be not more than 15 seconds.

6.7 HP / IP / LP Bypass System 6.7.1 100% capacity HP/IP/LP bypass system shall be provided for each

HRSG to facilitate following, in case Bidder is offering dual pressure HRSGs, the HP/ LP bypass shall meet the requirements outlined here:

(a) Operation of the HRSGs when

(i) Load is either temporarily lost on the steam turbine generator or is rapidly reduced,

(ii) Steam turbine generator is tripped. (b) Rapid matching of steam and turbine metal temperatures

during start-up of the turbine. (b) Serving as a pressure relief system to reduce the risk of HRSG

safety valves lifting when rapid load reduction on the steam turbine generator occurs.

(c) Continuous operation of the steam turbine at part loads with

HRSG operating at 100% MCR condition.

6.7.2 Each pressure level of bypass station shall be designed for the maximum steam pressure, i.e. The safety valve set pressure in the respective section and sized for maximum steam capacity generated. In addition to the above, necessary margin for the condensate injection shall be considered. Each bypass station shall comprise a quick acting stop valve and a pressure control valve on steam line (operated by separate actuators), a desuperheater, a stop valve and a control valve on spray water injection line (operated by separate actuators), necessary instrumentation and control equipment, all necessary piping, valves and fittings. Bidder shall indicate the arrangement made for dumping the bypass steam into the condenser




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and the same shall be subject to Owner / Owners Representative approval.

6.7.3 The bypass control valves shall have the stroking time of not more than

3-4 seconds for fast opening and 10-15 seconds for normal stroking. The spray water system for temperature control shall be compatible with the HP bypass control valve requirements. They shall be provided with electro-hydraulic actuators. If the oil system is a self contained unit, it shall have 100% standby oil pump connected to main system with necessary valves for isolation and maintenance. Hydraulic accumulators shall be provided on the hydraulic system to ensure positive supply of oil to hydraulic actuators even when hydraulic oil pumps are not available. Accumulator shall be adequately sized to ensure supply for two complete stroking operation of all connected actuators. All control valves shall be of tight shut-off design and the actuators shall be designed for maximum shut-off differential pressure acting across the valve. Low noise trim shall be provided to limit the noise level to 85 dBA at a distance of 1.0 m from outline of valve at all operating conditions.

6.7.4 The HP-IP-LP bypass system shall rapidly shutdown upon detection of

low spray water pressure, high steam temperature downstream of desuperheating stations and high reheater / condenser pressures.

6.7.5 Special attention shall be paid to provision of warming up drains as close to

the bypass valves as possible in order to minimise thermal shock on bypass valves and upstream pipe work when bypass comes into operation.

6.7.6 The systems downstream of bypass valves shall be capable of withstanding

the thermal shock due to failure of spray water.

6.8 Excess Condensate Dump System 6.8.1 Excess condensate dump system shall dump the excess condensate in

condenser hotwell to the condensate storage tank through an excess condensate dump line downstream of condensate extraction pump discharge. The excess condensate dump line shall be provided with an excess condensate dump control valve sized for not less than 10 percent steam turbine VWO flow.

6.9 General Process Requirements for Control Valves 6.9.1 All control valves for entire contract shall be sized such that the valves are

controllable over entire operating regime viz. low load to full load. The control valves which require to be operated during cold, warm and hot start conditions shall also be controllable during this mode of operation. To meet the above requirements if CONTRACTOR provides more than one control




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valve, the controllable ranges of the control valves shall overlap to ensure bumpless transfer from one control valve to other. For other requirements of control valve refer relevant C&I sections.

6.10 General Requirements Of Auxiliary Coolers 6.10.1 All the auxiliary heat exchangers provided for the entire contract shall be

designed to meet the requirements of TEMA-R unless otherwise specifically mentioned.

6.11 General Requirements Of Centrifugal Pumps 6.11.1 All the centrifugal pumps for entire contract shall meet the requirements of

API 610 standard unless otherwise specifically mentioned.




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1.0 SURFACE CONDENSER & ACCESSORIES

1.1 Configuration - Condenser with axis perpendicular or

parallel to STG axis.

- Axial condenser with axis perpendicular

to STG.

- Side mounted axial condenser with each

half on either side of STG with axis

parallel to STG axis and interconnection

between hotwell shall be provided for

level balancing.

OR

- Bottom mounted condenser with axis

perpendicular to STG axis.

1.2 Type of condenser Two pass. Single shell with divided water

box to facilitate unit operation with one half

under maintenance for condenser with axis

perpendicular to STG axis or single shell type

for each side mounted condenser with axis

parallel to STG axis such that one side can be

isolated and unit run with only one side

mounted condenser in service.

1.3 Orientation of condenser tube axis Parallel or perpendicular to STG axis as per

item 1.1 above.

1.4 Quality of cooling water For analysis refer Project Information Section

B.

1.5 Design cooling water inlet temperature (CWIT) Same as cooling tower recooled water design

temperature after accounting for any heat gain

or loss.

1.6 Design margin on heat load at TG VWO, 0%

MU, Design CWIT

% 5

1.7 Steam bypass - Shall be designed for 100% HP-IP-LP

steam bypass operation continuously

- Condenser back pressure shall not exceed

0.15 kg/cm2 (a) at max. condenser cooling

water temperature at above conditions

1.8 Hotwell storage capacity normal level to low

level (150 mm above bottom of hotwell)

3 minutes of turbine VWO flow, 1% MU,

design CWIT

1.9 Hotwell water level - Very high water level in condenser shall

be atleast 150 mm lower than the tip of

longest blade of low pressure turbine.

- Turbine trip on very high water level.

1.10 Tube cleanliness factor % 90

1.11 Cooling water velocity in condenser tube m/s Not to exceed 2.0 m/s.

1.12 Oxygen in condensate at hotwell outlet with

3% make-up from 30% TG MCR to TGVWO

cc/litre Not to exceed 0.03




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1.13 Water box design pressure Shall be equal to the circulating water pump

shut-off head, rounded off to next higher 0.5

kg/sq.cm plus an allowance for water hammer/

surge, if required.

1.14 Shell side design pressure Turbine rupture disc pressure & full vacuum

1.15 Shell side design temperature Turbine exhaust hood temperature high trip

setting

1.16 Tube gauge in air cooling zone BWG 22

1.17 Tube gauge in condensing zone BWG 18

1.18 Minimum tube sheet thickness mm 40

1.19 Minimum tube support plate thickness mm 12

1.20 Minimum steam impingement baffle thickness mm 10

1.21 Water box lining 3mm fibre reinforced epoxy

1.22 Tube sheet coating on CW side Epoxy coating

1.23 Type of protection for tubes against

impingement of steam from

(a) Main turbine exhaust Higher thickness tubes / dummy tubes

(b) HP / IP / LP bypass exhaust Baffles / steam throw-off device (as required)

(c) Drains Baffles

1.24 Type of tube sheet to shell joint Welded

1.25 Type of condenser neck to steam turbine

exhaust joint

Welded

1.26 Lateral movement of condenser compensated

by

Spring supports

1.27 Corrosion allowance on ferrous parts mm 3.2

1.28 Materials Of Construction

1.28.1 Condenser shell, hotwell and condenser neck Carbon steel to SA 516 Gr. 70 or equivalent

1.28.2 Water box Carbon steel to SA 516 Gr. 70 or equivalent

1.28.3 Structural parts Carbon steel

1.28.4 Tube sheets Carbon steel to SA 516 Gr.70 or equivalent

1.28.5 Tubes in condensing section Aluminium brass UNS C60800

1.28.6 Tubes in air cooling section 90-10 Cupro nickel C70600

1.28.7 Tube support plates Carbon steel to SA 516 Gr. 70 or equivalent

1.28.8 Gaskets on water side Neoprene

1.28.9 Bolts ASTM A. 193-B7 or equivalent

1.28.10 Nuts ASTM A. 194-2H or equivalent

1.28.11 Dummy tubes / rods Two rows of SS 304

1.29 Accessories

Conductivity Measurement Provision cathodic

protection

Required

1.30 Codes And Standards

1.30.1 Heat Exchange Institute Standards for Steam

Surface Condensers




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1.30.2 American Society of Mechanical Engineers

1.30.3 ASME Performance Test Code for Condensers

1.30.4 American Society for Testing Materials

1.30.5 Other established material or international

codes and standards equal or superior to the

above listed standards.

2.0 CONDENSER AIR EVACUATION EQPT.

& ACCESSORIES

2.1 Number Two x 100% capacity; During normal

operation one pump will be in operation

2.2 Duty Continuous

2.3 Vapour to be handled Mixture of air, steam and non-condensable

gases

2.4 HEI standard pressure and temperature

conditions for air suction

0.034 kg/sq.cm (a) and 21.1 deg.C

2.5 Capacity

2.5.1 Capacity of pump Shall be not less than 120 percent the capacity

obtained from HEI standards

2.5.2 Capacity of pump during hogging Shall be able to maintain vacuum upto 0.35

kg/sq.cm(a) within 20 minutes with both the

vacuum pumps in operation, from atmosphere

pressure.

2.6 Source of sealing water Condensate

2.7 Type of coupling Flexible coupling

2.8 Acceptable noise level at all operating

conditions

dBA Not to exceed 85 at a distance of 1.0m from

the outline of equipment

2.9 Allowable vibration level at all operating

conditions

mm/sec 7 peak

2.10 Material of Construction

2.10.1 Vacuum pumps

(a) Casing Cast iron

(b) Shaft Carbon steel EN-8

(c) Impeller Nodular iron

(d) Shaft sleeves Nodular iron

2.10.2 Seal Water Recirculation Pumps (if

required)

(a) Casing Cast iron

(b) Shaft Carbon Steel EN-8

(c) Impeller Nodular iron

2.10.3 Heat Exchangers

(a) Shell Carbon steel

(b) Tubes Stainless Steel




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(c) Tube sheet Carbon steel with epoxy coating as required

2.11 Codes and Standards

2.11.1 HEI Standards for Steam Surface Condenser

2.11.2 HEI Standards - Performance Standard for

Liquid ring vacuum pumps

2.11.3 ASME Performance Test Code

2.11.4 TEMA Standards

2.11.5 Hydraulic Institute Standards




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1.0 CONDENSATE EXTRACTION PUMPS

& ACCESSORIES

1.1 Number of pumps 2 x 100%, One Working and One Standby

1.2 Operation Continuous at any point between minimum

flow to runout flow

1.3 Pump type Vertical cannister type

1.4 Design capacity per pump Total combined flow of normally working

pumps shall be 110 % condensate flow at

turbine VWO at maximum cooling water inlet

temp. or 105% condensate flow requirements

at design inlet condenser cooling water

temperature during a 100% HP-IP-LP bypass

operation or any other condition causing

maximum condensate flow to be a maximum

and 1% make-up plus sealing water flow to

valves plus any other spray water requirement,

rounded off to nearest higher 5 cubic metre per

hour

1.5 Minimum flow per pump Not less than twenty five (25) percent

1.6 Best efficiency point of pump Total flow of normally working pump shall

be the total condensate requirement at 100%

TG MCR and 1% MU.

1.7 Total dynamic head (TDH) at design capacity While establishing the design TDH the

following shall be considered and rounded

off to next higher 5 mlc:

(a) One twenty five percent (125%) of

deaerating feedwater heater operating

pressure at TG VWO

(b) A ten percent (10%) margin on

equipment and piping pressure drops at

TG VWO or 100% HP-IP-LP bypass

operation.

(c) Shall be selected such that pump would

be capable of meeting the TG VWO

requirement during an under frequency

operation of 47.5Hz.

1.8 Shut-off pressure Between 120% and 125% of pump design

total dynamic head and Curve shall be

continuously rising from runout to shutoff.

1.9 NPSH available (min.) Shall be based on condenser hotwell low

level

1.10 NPSH required at zero percent headbreak Shall not be greater than 80% of NPSH

available over the entire range of operation

from minimum flow to pump runout

1.11 Acceptable noise level at all operating

conditions

Not greater than 85 dBA at a distance of 1.0

m from the outline of equipment

1.12 Maximum speed rpm 1500

1.13 Maximum allowable vibration level at all mm/sec 8 (peak)




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operating conditions

1.14 Suction specific speed US units Not greater than 11,000

1.15 Condensate pH 8.6 to 9.2 during normal operation and 11 to

12 during alkaline flushing

1.16 Internal element Removable

1.17 Type of lubrication Self

1.18 Type of coupling Flexible type

1.19 Suction nozzle location Below mounting flange (top of suction piping

elevation shall be same as ground level)

1.20 Type of seals Mechanical seals

1.21 Thrust bearing type Kingsbury or equivalent

1.22 Thrust bearing location Between pump and motor

1.23 Reverse rotation protection Capable of withstanding reverse rotation due

to discharge NRV failure while system is at

maximum discharge pressure

1.24 Load sharing between pumps Not exceeding 5% over entire operating range

when operating with one or both pumps

1.25 Materials of Construction

1.25.1 Mounting flange Steel

1.25.2 Discharge elbow, Column pipe Carbon Steel

1.25.3 Suction bell, Bowl or casing, Discharge casing Cast Iron

1.25.4 Diffuser & guide vanes, cannister Carbon steel

1.25.5 Impeller Stainless steel

1.25.6 Shaft sleeves 11 - 13% chrome steel

1.25.7 Pump shaft 11 - 13% Forged chrome steel

1.25.8 Suction strainer Stainless steel


1.26.1 American Society for Testing & Materials


1.26.3 ASME Performance Test Code for Centrifugal

Pumps

2.0 HRSG FEED PUMPS & ACCESSORIES

2.1 Number of HRSG feed water pumps for each

feed water pumping system

(a) Single-shaft configuration (i.e.,

independent ST for each gas turbine)

Two, (One working and one standby)

To be deleted as it is not applicable

(b) Multi-shaft configuration 2 X 100%, (One working and one standby)

2.2 Number of feed water pumping systems

(a) Triple pressure Combined HP feed water pump system with




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inter-stage tap-off for IP feed water system

And

LP feedwater pumping system

(b) Dual pressure HP feedwater pumping system

And

LP feedwater pumping system

2.3 Type of pump set

(b) LP Pumps Direct electric drive

2.4 Mode Continuous, either in single or in parallel,

from minimum flow to runout flow

2.5 Liquid handled Feed water and undeaerated feed water during

start-up.

2.6 Minimum temperature Ambient

2.7 Rated capacity of each pump Total combined flow of normally working

pump(s) shall be 110% of the total feedwater

flow at TG VWO, 1% MU and design cooling

water inlet temperature or 100% HP-IP-LP

bypass operation, 1% MU and design

condenser cooling water inlet temperature

together with any other feedwater

requirements, or any other condition causing

maximum feed water flow to be a maximum,

rounded off to nearest higher 10 cubic metre

per hour.

2.8 Best efficiency point of each pump Shall be of at feed water flow equivalent to

100% TG MCR and 1% MU

2.9 Total dynamic head at rated capacity Shall include 10% margin on equipment and

piping pressure drops for VWO condition or

100% HP-IP-LP bypass operation and shall be

rounded to next higher 5 mlc.

Shall be selected such that :

- Normally working pump would be

capable of meeting the TG VWO

requirement during an under frequency

operation of 47.5 Hz.

- Normally working pump would be

capable of meeting the requirements of

HRSG's MCR flow when drum highest

set pressure safety valve is relieving

2.10 NPSH available at (booster) pump centre line

for HP / IP pump and pump centre line for LP

pump (min)

2.10.1 Normal operation Shall not be less than three hundred percent

NPSH required at 3% head break by booster

pump for HP / IP pumps and LP pumps




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2.10.2 Transient operation Shall not be less than one hundred and twenty

five percent the NPSH required at 3% head

break by booster pump for HP / IP pumps and

LP pumps

2.11 Design speed for pumps

2.11.1 for booster pump of HP/IP pumps and LP

pump

rpm 1500

2.11.2 For barrel type main pump of HP/IP pumps

with variable speed hydraulic coupling.

rpm Around 5000 (Max 3000 rpm only)

2.11.3 for barrel type HP pump of constant speed

type.

rpm < 3000

2.12 Maximum suction specific speed US units Preferably not greater than 9500.

2.13 Shut-off head Shall be continuously rising from runout to

shut off and shut-off head shall be not less

than 120 and not greater than 125 percent

2.14 Load sharing between pumps Not exceeding 5% over entire operating range

when operating in parallel with other pumps

2.15 Minimum capacity of low flow recirculation Not less than 25% of pump rated capacity

2.16 Type of recirculation control Separate modulating type / automatic

modulating type recirculation valve (ARC)

2.17 Maximum noise level at all operating

conditions for the pump set comprising main

pumps, hydraulic coupling, booster pump,

drive motor

Not to exceed 85 dBA at a distance of 1.0 m

from outline of equipment. If maximum noise

level exceeds same, an accoustic enclosure

shall be provided. Accoustic enclosure if

provided, shall be of pre-fabricated modular

type with ease for assembly / disassembly

2.18 Maximum vibration level at all operating

conditions

VDI 2056 group G degree Good

2.19 Type of impeller Enclosed

2.20 Seals Mechanical seal confirming to API 682

2.21 Shaft Coupling Flexible type

2.22 Type of thrust bearing Kingsbury type or equivalent type

2.23 Strainer a) Fine mesh type with mesh size such that

same is less than minimum internal

clearance of the pumps during

commissioning.

b) Normal operation coarse strainer mesh

size as recommended by manufacturer

2.24 Materials of Construction

2.24.1 Outer casing applicable for barrel type pump Forged Carbon steel

2.24.2 Inner casing applicable for barrel type pump

and all stage casings for ring section type

pump.

ASTM A743 CA 6 NM

2.24.3 Impellers ASTM A743 CA 6 NM

2.24.4 Wearing rings 13 - 17% Chrome steel (Material shall be non-

galling type with differential hardness not less




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than 100 BHN)

2.24.5 Stuffing box bushing & stuffing box 13% chrome steel

2.24.6 Pump shaft 13% forged chrome steel

2.24.7 Shaft sleeves Stellite on 13% chrome steel

2.24.8 Base plate Structural steel

2.24.9 Diffuser / Volute 13% chrome steel

2.24.10 Strainer Stainless steel mesh

2.25 Hydraulic Coupling

2.25.1 Coupling wheels Alloy steel

2.25.2 Coupling wheels casing Alloy steel

2.25.3 Scoop tube Stainless steel

2.26 Thermal insulation Lightly bonded mineral wool with cladding.

Design thickness shall be based on outer

surface temperature of 600C under still air

condition with station ambient temperature of

300C


2.27.1 API 610 Eight Edition

2.27.2 American Society for Testing and Materials

(ASTM)


(ASME)


2.27.5 ASME Power Test Code for Centrifugal

Pumps (PTC 8.2)




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1.0 DEAERATING FEED WATER HEATER

& ACCESSORIES

1.1 Type of deaerating feed water heater Spray - tray type / Spray type of Stork design or equivalent

1.2 Type of spraying arrangement Spray valves (variable flow area) / sprayer

assembly of Stork design or equivalent

1.3 Operation To match combined cycle power plant

requirements using steam supply from low

pressure line / auxiliary steam line

1.4 Design pressure of deaerator and feed water

storage tank

One hundred and twenty five (125) percent of

maximum extraction steam pressure or 4.5

kg/cm2(a) whichever is higher, rounded off to

next higher 0.5 kg/cm2 and full vacuum

1.5 Minimum design temperature of deaerator Compatible with heating sources temperature

or 2300C whichever is higher, rounded off to

next higher 50C

1.6 Minimum design temperature of feed water

storage tank

50 C higher than saturation temperature

corresponding to the design pressure or 2050C

whichever is higher, rounded off to next

higher 50C

1.7 Nett feed water storage tank capacity at 2/3rd

level (Normal) between normal level and top of

boiler feed pump suction in deaerator exclusive

of volume of any internal piping, baffles &

excluding volume of dished ends

6 minutes of feed water outflow at TG VWO,

1% MU condition with design CWIT

1.8 Other Requirements - In case desuperheater is provided on steam

line to deaerating feed water heater, the

deaerating feed water heater material shall

be selected taking into consideration the

condition of spray water failure.

- Safety valve on deaerating feed water

heater shall be sized to relieve the entire

steam quantity due to failure of control

valves on heating steam line to deaerating

feed water heater or alternatively an

additional safety relief valve shall be

provided downstream of the control valve

on the pipeline connecting deaerating feed

water heater.

1.9 Corrosion allowance over & above design code

requirements

mm 3.2

1.10 Pressure drop across spray valve assembly at

maximum condensate flow

kg/sq.cm 0.5 (max.)

1.11 Performance Guarantees Over Complete

Load Range

1.11.1 Maximum oxygen content in deaerated feed

water from 30% TG MCR to TGVWO with

1% makeup

cc/litre 0.005




Page 19 of 19

1.11.2 Maximum carbon dioxide content in deaerated

feed water from 30% TG MCR to TGVWO

with 1% makeup

Nil

1.12 Materials Of Construction

1.12.1 Deaerating shell & heads Carbon steel to SA 516 Gr. 70 or equivalent

1.12.2 Feed water storage tank shell & heads Carbon steel to SA 516 Gr. 70 or equivalent

1.12.3 Trays Stainless steel to SS 304 / SS 431

1.12.4 Tray enclosure Stainless steel to SS 304

1.12.5 Spray valves / sprayer assembly Stainless steel to SS 304

1.12.6 Steam distribution pipe (Internal) / nozzles /

condensate pipes

Carbon steel to SA 106 Gr. B or equivalent

1.12.7 Splash plates & baffle plates Stainless steel to SS 304

1.12.8 Bolts SA - 193 B7 or equivalent

1.12.9 Nuts SA - 194 2H or equivalent

1.12.10 Gaskets CAF 40

1.12.11 Internal bolting, if any Stainless steel to SS 304

1.12.12 Vent orifice Stainless steel to SS 304

1.13 Thermal insulation Lightly bonded mineral wool with cladding.

Design thickness shall be based on outer

surface temperature of 600C under still air

condition with station ambient temperature of

300C

1.14 Codes & Standards

1.14.1 Heat Exchange Institute (HEI) Standards and

Typical specifications for Deaerators

1.14.2 American Society of Testing Materials

(ASTM)

1.14.3 ASME Performance Test Code for Deaerator


1.14.5 Indian Boiler Regulations

section a.6 steam and water cycle equipment

Documents