glaxosmithkline - armstrong international...2012/12/06 · glaxosmithkline giza, egypt date :...

GlaxoSmithKline Giza, Egypt

STEAM AND CONDENSATE AUDIT P 30432

Rossen IVANOV �� + 32.42.40.90.89 [email protected]

STEAM AND CONDENSATES PRE-AUDIT

P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 2 of 73

To the attention of Mohamed Abdel Gelil Gadallah

Established by Eric MONTREER

TABLE OF CONTENTS

1 EXECUTIVE SUMMARY .................................................................................................................................................4

2 STEAM BUDGET AND SUMMARY OF POTENTIAL SAVINGS .............................................................................6

3 OPTIMIZATION PROJECTS ..........................................................................................................................................7

ECM 1: IMPROVE BOILER EFFICIENCY ....................................................................................................................................8

ECM2: INSULATE STEAM PIPES ANCILLARIES .......................................................................................................................19

ECM3: STEAM TRAPS REPLACEMENT ..................................................................................................................................21

ECM4: PUT ON-OFF VALVE BEFORE CONTROL VALVE ........................................................................................................23

ECM5: INSTALLATION OF PROPERLY SIZED DRAIN POCKET AND TRAPS ON INLET OF PLANT STEAM CONTROL VALVES , ON

HEADERS AND MAIN PIPE .......................................................................................................................................................24

4 COMPLETE CHECK LIST OF ALL VERIFICATIONS DONE DURING THE AUDIT ......................................27

5 STEAM / CONDENSATE NETWORK .........................................................................................................................28

STEAM PRODUCTION .............................................................................................................................................................28

STEAM DISTRIBUTION .............................................................................................................................................................30

STEAM CONSUMERS ...............................................................................................................................................................32

5.1.1 60°C Hot water heat exchangers ...................................................................................................................32

5.1.2 Lactam Purified Water Tank ............................................................................................................................34

5.1.3 Laboratory ..........................................................................................................................................................36

5.1.4 Lactam building .................................................................................................................................................36

5.1.5 Non Lactam area ..............................................................................................................................................40

APPENDIX ................................................................................................................................................................................50

RADIATION LOSSES CALCULATIONS .............................................................................................................................54

MISASSEMBLE ................................................................................................................. ERREUR ! SIGNET NON DÉFINI.

STEAM TRAP SURVEY .........................................................................................................................................................64

LIST ON EXCEL CHART .......................................................................................................................................................64

STEAM PRESSURE CONTROLLED HEAT EXCHANGERS AT LOW LOAD .............................................................65

CURRENT SITUATION ...............................................................................................................................................................65

OPTIMIZATION .........................................................................................................................................................................67

Closed loop pumping trap .................................................................................................................................................69


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 3 of 73



Posipressure system ...........................................................................................................................................................70

Safety drain........................................................................................................................................................................71

Barometric leg ...................................................................................................................................................................71

Condensate level control ...................................................................................................................................................72

Mixing valve on the product side .......................................................................................................................................73


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 4 of 73



1 Executive summary

Armstrong Service has conducted from 15th to 18th of October 2012 a complete audit of your steam

installation.

GSK Gisa is consuming around 1000 kg/h of 6 bar steam, for a total consumption of about 8000 T/year.

Steam production is handled by 2 fire tube boilers running alternatively.

The site is divided in several buildings:

• Lactam Building • Non Lactam Building • Laboratory Building

Operating hours depends on each building but generally the boiler house runs 24h/24h, 7 days/week,

52 weeks/year.

Steam is mainly used for:

Area Equipment

Lactam Building

Hot water heat exchanger for AHU

Distiller

Pure steam generator

Non Lactam Building

Glatt coating air Coils Hot water heat exchanger for AHU

Distiller

Liquid Tanks

Purified hot water Generator

Laboratory Building

Distiller

Autoclave


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 5 of 73



The aim of this audit was to clearly identify potential optimisations and savings opportunities.

Consequently, the audit was particularly focused on:

- Improvements in boiler room

- Improvements on the heating devices drainage

- Correction of design mistakes

We wish to thank particularly the mechanical team, and Boiler house team for their help during this

audit.

This audit has confirmed possibilities of improving the efficiency of your steam system and realising

additional savings on your yearly global invoice.

In the boiler house, you have to clean the tubes of the 2 T/H and use the 4 T/h in priority. Global

efficiency could be enhanced by changing the adjustment of the Boilers’ burner, and reducing a little

bit the blow down when the water analysis are good.

You can also install an economiser to recover energy from the stack.

The steam leaks from the hot water heat exchanger control valve and missing steam trap header

must be stopped.

On network and steam users, the size of the drip legs must be increased (same as the steam pipe

diameter), especially before control valves to avoid condensate accumulation and valve/seat erosion.

All failed steam traps must be changed.

Condensate drainage of low temperature steam users must be improved. You could increase the

global efficiency by using assistance drainage to ensure better condensate elimination.

The TD process steam trap must be changed by mechanical type.

All steam ancillaries must be protected with insulation jackets.

Potential energy savings could be at least 20% of the current yearly steam budget, which represents

a yearly saving of about 1491 MWh, 275 tons of CO2 and 60190 Egypt pound.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 6 of 73



2 Steam budget and summary of potential savings Taking in consideration 2011 steam consumption, we have estimated the yearly budget for steam.

Average cost 30 Egyptian Pound/T

Yearly steam consumption 9000 tons/year*

Annual cost (Gas cost) 270 000 Egyptian Pound

Note:

The gas invoice for the first 9 months in 2012 is: 208 527 Egyptian Pound

If we consider the increasing consumption since May, the annual cost for 2012 will be more than

300 000 Egyptian Pounds.

Your cost of gas and steam is relatively low, which explains the longer than usual payback for some of

the solutions proposed.

Summary of identified energy-saving optimizations a nd their estimated yearly results: ECM n° and Name Savings Savings Investment Payback CO2

saving

MWh Egyptian Pound /year

Egyptian Pound

months T/year

1. Improve Boiler efficiency

749 29970 200000 80 137

2. Insulate steam pipes ancillaries

155 6840 50000 88 31

3. Steam traps replacement

587 23380 46500 24 107

TOTAL 1491 60190 296500 59 275

4. Put On-Off valve before control valve

50000

5. Improvement of steam quality

60000


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 7 of 73



3 Optimization projects

General considerations:

Following projects are proposal of improvement of your global steam and condensate installation.

These projects can be directly linked to a countable saving or to an increase of reliability of

system or also permit to establish better practices in the follow up of your installation (monitoring

of steam/condensate flow, drawing up of check list data sheets…).

At this stage, indicated savings and investments are still estimations and are given with a

precision of:

• +/- 25% for investments; • +/- 15% for savings.

To establish our calculation, we have considered the following parameters:

• annual working time: 8700h for the factory (corrected for different devices) • average steam flow: 1000 Kg/h • fuel cost: 40.0 Egyptian Pound/MWh • steam generation global efficiency: 75% • steam cost: 30.00 Egyptian Pound/T • annual CO2 emissions (51 kg/GJ / 183 kg/MWh HHV)


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 8 of 73



ECM 1: Improve Boiler efficiency We did a “Combustion efficiency measurement”:

O2 CO CO2 T° SO2 H2

2T/H 7.3 13 7.77 330 -1 1

7.22 12 7.8 330 0 2

0.8 4300 11.44 282 -30 2477

3.78 55 9.75 297 60 500

8.49 3 7.1 316 0 4

4T/H 4 1 9.6 187 -1 4

3.6 1 9.71 188 -2 5

4.56 7 9.3 189 -9 121

4.63 2 9.5 190 -7 20

The combustion analysis for the 4 T/h boiler showed good results. The excess air was correct, between

18 and 25% (O2: 3.6 to 4.6%).

The combustion analysis for the 2 T/h boiler showed poor results. The excess air was between 50 and

60% (O2: 7.2 to 8.5%). The stack temperature is very high.

The 4 T/h Boiler’s burner is modulating but, it works like On-Off control.

We put a PT 100 probe at the chimney to follow the fluctuation of the combustion.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 9 of 73



Cleaver Brooks 4 T/h Boiler

The red curve is the air temp

The green curve is the feed water temp

The blue curve is the stack temp


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 10 of 73



The stack temp increases when the burner is running. The burner started each 12 minutes during 5-

6 minutes, then stopped.

There is 2 minutes for pre combustion. During this time you lose energy.

In this period the steam demand is higher, the burner is running during more time.

The burner load is at 40% stack temperature is 186.7°C.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 11 of 73



The burner load is at 30% stack temperature is 181.5°C.

If you can run at this average load, between 20 and 30%, you will maintain the burner on and reduce the pre combustion losses.

Cleaver Brooks 2T/h

The red curve is the air temp

The green curve is the feed water temp

The blue curve is the stack temp


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 12 of 73



The water probe was not in contact with the pipe during 6 hours.

The stack temp was between 230°C and more than 300° C. The burner runs in high load during

some period and modulates during other periods. The burner never stopped, only during small

periods.

The burner modulated during this period of 90 min

Energy recovering systems

There is no economiser, no controlled blowdown system, no blowdown energy recovering system.

There is no comburant air preheating system, the air temperature is high, more than 40°C, the air

fan is at the Top of the boiler, where the temperature is higher than in the floor.

The stack temperature is higher than 185°C, with na tural gas, you can decrease this temperature to

120°C and reduce the gas consumption around 3 %.

BOILER EFFICIENCY:


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 13 of 73




P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 14 of 73



Boiler 1 is 4T/h Cleaver Brooks with losses from burner cycling.

Boiler 2 is 2T/h Cleaver Brooks, with high excess air and high stack temperature


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 15 of 73



Note: The indicated costs are not euro but Egyptian Pound. The steam cost is a little different from

the 33 Egyptian Pound/T considered in the chapter 2.

The difference is coming from the average steam flow and gas HHV.

Boilers blow down

The TDS value was good during the audit. You have to check your TDS controller to adjust the

blowdown correctly.

There is no continuous blowdown system - you adjust the TDS value opening the bottom blowdown

valve during some minutes when it is too high.

Current System Description and Observed Deficiency

The plant operates a Shell tube boiler rated for 4 T/hour at 6 bar. The average steam generation is

1000 Kg/hr. A combustion analysis of the boiler flue gas was conducted during the Audit. The results of

the analysis are as follows:

Combustion Analysis

Boiler Load % 25 50

Stack Temperature °C 185 300

Ambient Temperature °C 40 40

CO2 % 9,6 7,8

Efficiency % 87,9 80,2

Excess Air % 23 50

O2 % 4,3 7,5

CO ppm 0 0

Technical Discussion

During combustion, the carbon from the fuel combines with the oxygen and gets converted in to

CO2. This oxidation reaction is exothermic and liberates heat. This heat is absorbed by the

water on the water-side of the boiler, which is converted into steam. The gases of this reaction

are exhausted via the stack of the boiler at a temperature close to the saturation temperature of

the steam. The energy contained in these exhaust gases accounts for a major part of the

efficiency loss of a boiler.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 16 of 73



It is therefore important to recover the maximum amount of energy out of these gases by using

economizers.

An indirect heating type economizer consists of a coil heat exchanger, with finned or un-finned

tubes, placed in the exhaust gas flow as a section of the ductwork or stack. With this type of

economizer, the water flows through the tubes and absorbs the excess heat from the flue gas.

Typically, a deaerated feedwater is used for this purpose as a heat sink.

Your Combustion analysis is very good, but you have no continuous operation.

During our analysis, the burner started each 12 minutes during 6 minutes, then stopped.

When it starts, there is a pre venting action during 120 sec and you therefore lose some Energy.

Recommended Optimisation

• Armstrong recommends checking the burner and input the correct parameters to decrease the low firing set point.

• Armstrong recommends installing a stainless steel feedwater economizer to recover the heat from boiler flue gases and improve the boiler efficiency.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 17 of 73



The system consists of an economizer with control instrumentation in the flue gas and the feed water

paths. The water passes through the tubes. The control valves maintain and modulate water flow as

per the boiler requirement. In case the boiler does not require more feed water, a secondary back

pressure control valve would open to the DA to keep the circulation of the feed water in the economizer.

A by-pass interlock on the flue gas side ensures the stack temperature stays above the specified

minimum limits.

Estimated Benefits

Using only 4 T/h Boiler with modification of the setting burner and reducing the stack

temperature from 185°C to 115°C will increase the b oiler efficiency from 87,9-80,24% to 94,4%

and will save annually 29 967 Egypt Pound.

Present Proposed Savings

Fuel used LSHS LSHS

Steam Demand kg/h 1000 1000

Excess O2 in Stack % 3.4 3.4

Combustion air

Temperature °C 40 40

Flue Gas Temp at

Boiler Outlet °C 185 185

Flue Gas Temp at

Economizer Outlet °C NA 115

Boiler Efficiency

(LHV) % 87.9+80.24 94.4

Heat Required(LHV) Kw 655+718 609,5 77

Hours of operation h 4350 8700

Heat Required

(HHV) Mw/year 6641 5292 749

Gas Cost Egypt Pound 40/Mwh 40/Mwh

Annual Costs Egypt Pound /year 265655 235688 29967

CO2 emissions t/year 1215 1078 137

Estimated Investment and Payback

The investment is estimated at 200 000 Egypt Pound. It includes:

• Economizer


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 18 of 73



• Control mechanism flue gas side

• Control mechanism on feedwater side

• Modification in ducting and piping, instrumentation

• Engineering

• Installation and commissioning

The biggest part (about 80%) of both the investments and the savings are linked to the installation of

the economizer.

The payback of this installation is expected to be 7 years.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 19 of 73



ECM2: Insulate steam pipes ancillaries Current System Description and Observed Deficiency

During the audit, we listed all pipes equipments (valves, filters, separators) that are not insulated. Non-insulated parts imply a loss of energy by radiation. It means higher fuel consumption in the boiler house.

Recommended Optimization

We advise you to install insulated jackets on all pipes equipments. They protect very well the equipments and are easy to install or remove.

Wrap: Glass fiber silicone double face Thermal resistance 270°C uninterrupted Weight: 575G/m² Insulation: Glass wool, 50mm, density 35kgs/m³ Seam: wire of teflon glass Fixing: Bent straps Details concerning equipments to insulate and energy losses are listed in appendix.

It represents a total energy loss of 15 KW that is equivalent to a steam loss of about 21 kg/h, about 2%

of your steam consumption.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 20 of 73



Estimated Benefits

, .


Budgetary cost to insulate pipes and add insulated jackets is 50000 Egypt Pound It includes:

• Statement of dimensions on site • Insulation equipments supply • Installation

Payback time is about 7 years.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 21 of 73



ECM3: Steam traps Replacement


There are 57 steam traps installed on your network: 12 of the installed traps were out of service, 23 of

the traps were failed (12 leaking, 11 cold or flooded).


Leaking steam traps mean losses of steam. It may also reduce condensate evacuation from process by

creating a back-pressure in the return lines.

Besides, steam in condensate return lines may generate water hammers which can damage your

installation and ancillaries (valves, pressure reducing valve, heat exchangers).

Blocked traps compromise steam quality and cause corrosion and erosion of steam lines and

auxiliaries, resulting in high maintenance costs and increased down time due to system failures. These

traps should be individually evaluated and should be cleaned or replaced by correctly sized and

installed traps.

We highly advise to carry out traps surveys on a regular basis (once per year) in order to insure a good

reliability of the steam and condensate network.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 22 of 73



Estimated Benefits

Fuel savings

Steam losses calculated kg/h 90

Energy loss kW 51

Operating hours hr 8700

yearly Energy used MWh/year 449

boiler efficiency % 85%

Fuel used

MWh/year

hhv 587

Fuel unit costs

Egypt

Pound/MWh

hhv 40

Fuel costs

Egypt Pound

/year 23480

CO2 savings

Energy used MWh/yr 587

CO2 emissions kg CO2/MWh 183

CO2 produced t/yr 107

Replace leaking traps would save 23480 Egypt Pound /year .


The budgetary cost for replacing leaking traps is 46 500 Egypt Pound

Including:

- Equipments supply (traps)

- Installation by a mechanical contractor

- Project management

Payback time for replacing all failing traps, inclu ding blocked traps, is 2 years.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 23 of 73



ECM4: Put On-Off valve before control valve


Many heat exchangers have actuated valve to control the temperature of the outlet fluid (see

Comments on Steam & Condensate Network).

An actuated control valve has a “normal” small leak even when it is closed, so you continue to heat the

fluid above the set point.


We proposed to install On-Off actuated valve in front of the control valve to be sure that you have no

steam through the Heat exchanger when the set point is OK.

You must add a temperature switch probe to pilot the valve.

The equipments are to be installed at:

Hot water heat exchanger in boiler House

Purified hot water heat exchangers

Hot water heat exchangers for AHU

Estimated Benefits

It is really difficult to know the steam leak through the control valve, but it might be between 1 and 10 kg/h depending of the valve size and steam pressure.

Estimated investment

The preliminary estimate of the project cost to implement the above recommendations is 50 000 Egypt

Pound

It includes:

• Installation of 5 On-Off Valves DN25-DN40

• Installation of 5 Temperature Switch Probe.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 24 of 73



ECM5: Installation of properly sized drip legs and traps on the inlet of plant steam control valves, on headers and main lines


Our study has also permitted to detect that the plant steam headers and inlet of control valves do not

have proper sized drip legs. Furthermore, in many locations, drain pocket and drain traps are missing.

As a result, plant steam is getting wet and most of the control valves are leaking from gland. It has a

bad effect on control valve trim life and profile.

Technical Discussion

The correct size of a drip leg depends on the diameter of the pipe, refer below figure and table.

Height H1 > H minimum

1. Local drained Traps

Height H1 > H minimum

2. Traps Connected to condensate Recovery

HH1


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 25 of 73



Figure 6: Proposed configuration for the drip-leg

Steam line Size D H

for Supervised Warm-up

H for Automatic

Warm-up 15NB 15NB 250 mm 710 mm

20NB 20NB 250 mm 710 mm

25NB 25NB 250 mm 710 mm

40NB 40NB 250 mm 710 mm

50NB 50NB 250 mm 710 mm

80NB 80NB 250 mm 710 mm

Table 16, Recommended Drip-leg diameter and Height

The direct savings from these corrective proposals are difficult to estimate. There is no direct steam

loss. The equipment performance after the missing drainage is affected. The plant personnel could

count the number of valves, regulators, flanges and plates that have been changed due to early

corrosion and pitting, and how much manpower for repair and replacement was necassy..

Moreover, due to moist steam, the ejector requires more steam for creating same vacuum level. It also

leads to more erosion and change in bore size of ejector nozzles which could further increase the

steam consumption, if not checked and replaced periodically.


Armstrong recommends the installation of properly sized drain pockets and a trap in missing locations

before steam control valve and steam header.

Estimated Benefits

The main benefits from this optimisation are:

• Reduced valve maintenance cost

• Reduced steam pipe erosion and corrosion

• Reduced down time

• Increased Heat transfer efficiency


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 26 of 73



Estimated investment

The preliminary estimate of the project cost to implement the above recommendations is 60 000 Egypt

Pound

It includes:

• Installation of 15 properly sized drain pocket

• Installation of 15 steam trap stations with connector and integral blow down valve.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 27 of 73



4 Complete check list of all verifications done dur ing the audit Potential optimisation Status Comments

STEAM GENERATION

Steam pressure setting OK 6 Bar(g) Maximum boiler pressure. Necessary for Distillers

Feed water temp. to the boilers OK A little bit too high

Stack temperature Not OK You can reduce the temp by installing an economiser on boiler 4 T/h (see Project 1). Boiler 2T/h very high, may be problem with scale.

Combustion air temperature OK Ambient temperature is correct

Oxygen rate Not OK Not on boiler 2 T/h, ok on boiler 4 T/h

Boiler sizing Not OK Boiler 4 T/h is oversized, but replacement could not be justified only based on energy-savings.

Boiler blow down rate Not OK Not correctly controlled

Deaerator pressure n.a. Non –pressurized hot well. High condensate return and low steam load. Pressurized DA to save chemicals not feasible

Feed-water pre-heating Not OK See stack temperature (see Project 1)

Boiler stand-by time and volatility of steam demand

Not OK You change the boiler in service each 12 hours

Boiler blow-down recovery Not OK Could be improved, but the payback is too long

STEAM DISTRIBUTION

External leaks of steam or condensate from pipes, flanges, etc.

OK OK, system is generally well maintained

System design, trapping points etc. Not OK Some drip legs are not correctly designed (see Project 5).

Insulation Not OK

Lot of steam equipments with no insulation (see Project 2).

Steam quality Poor Blocked steam traps on drips compromise steam quality. High risk for erosion, corrosion and water hammering issues (see Project 5).

STEAM USERS

Condensate drainage and air venting from heat exchangers

Not OK Closed loop pumping trap arrangements for heat exchangers in a stall condition must replace blocked traps

Steam traps Not OK See trap survey results (Project 3).

CONDENSATE AND FLASH STEAM RECOVERY

Condensate recovered OK

Sizing of condensate return lines Not OK Often too small (see Comments on Steam & Condensate Network)

Flash steam recovery N/A Steam escaping from feedwater tank vent is probably due to leaking steam traps (see Project 3).

Water hammering OK


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 28 of 73



5 Comments on Steam & Condensate Network

Steam Production

Water treatment Softened Make up water is mixed with condensates in one of the feed tank.

You have 2 feed tanks, one for each boiler.

Condensate lines are connected to the feed tanks from Lactam Building, Non Lactam Builing,

Laboratory and boiler house.

2T/h Boiler Feed tank

4T/h Boiler Feed tank

Some condensate returns to the small tank and others to the big tank.

The overflow of the smallest feed tank is connected to the bigger feed tank.


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GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 29 of 73



The average level of the bigger tank is higher than the top of the smallest tank.

The small tank must be more than 100% full to fed the bigger tank.

There is water hammering in the condensate pipe arriving in the smallest tank.

The water temperature in the tank was in some period more than 105°C.

There were a lot of leaking steam traps.

There were flash steam losses at the vent pipe.

Steam generation

Steam production, at 6 bar, is handled by 2 fire tubes boilers.

Cleaver Brooks - 4T/h - 2 passes boiler Cleaver Brooks - 2T/h - 2 passes boiler

We did the “Combustion efficiency measurement” – see project 1.

Steam flow You have no steam flow meter.

We collect the value from the gas counter to calculate the steam consumption.

date/hour time total gas gas flow gas flow Steam flow Efficiency

15-oct min m3 m3/h Nm3/h kg/h %

16H30 3544161,5

16-oct

10H15 1065 3545788 91,63 87,93 1146 87

13H20 185 3546093 98,92 94,92 1137 80

16H20 180 3546372 93,00 89,24 1163 87

17H00 40 3546433 91,50 87,80 1144 87

17-oct

09H05 965 3548046 100,29 96,24 1153 80

11H45 160 3548311 99,38 95,36 1242 87


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

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The make-up water counter was out of service, it was not possible to calculate the % of condensate

return.

We will calculate the % condensate return with the information from the feed tank temperature.

The feed tank had an average temperature of 90°C.

The softened water temp is 25°C.

The condensate average temp is 105°C .

0.2x25+ 0.8x 105= 89

We can estimate that you have between 75 and 80% of condensate return and 20-25% of softened

water.

It will be interesting for you to replace the water flowmeter to follow correctly your % of condensate

return.

It will be also interesting for you to put a steam flowmeter to manage correctly your steam

consumption.

Steam distribution

Steam is delivered to the different process from the main header.

There is no steam trap installed, it is a strainer and you closed partially the valve.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 31 of 73



You have a big steam leak.

The size of the drip leg is too small.

We followed the steam lines in order to analyse all consumers.

From the boiler room, steam is distributed by:

- One line DN 50 at 6 bar to Lactam plant

- One line DN 100 at 6 bar to non Lactam plant

- One line DN 50 at 6 bar to Laboratory

- One line DN 50 at 6 bar to Boiler House

- One line DN 50 at 6 bar to Lactam Purified water Tank

You have steam traps with small drip legs on the different lines.

We have calculated the maximum flow that can be delivered at 6 bar pressure.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 32 of 73



You can deliver 2000 kg/h of 6 bar steam in the DN80 pipe, with a velocity of 30m/s.



Your steam pipes are correctly designed considering your steam consumption.

Steam consumers

5.1.1 60°C Hot water heat exchangers

In the boiler house, a steam pipe feeds the 70°C Ho t water heat exchangers.

2 exchangers in parallel, only one in service, one control valve is out of service.

The control is done by a pneumatic valve.


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GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 33 of 73



You changed the valve by a new one, but you have a problem of setting.

Even if the temp is more than the set value the valve is a little bit open.

The set point was 70°C and you had more than 90°C.

The by- pass valve was leaking, but the main problem was the control valve which is never totally

closed.

You have to put an On-Off valve before the control valve to stop totally the steam flow (see Project 4),

and you must change the by-pass valve.

There are drip legs to protect the control valves.


P 30432

GLAXOSMITHKLINE

Giza, Egypt

Date : 23/10/2012

Page 34 of 73



The steam trap technology is inverted bucket trap for drip legs and TD for process.

You added a TD steam trap in series after the 4 processes and drip legs steam traps. We recommend

you to remove the TD trap and make sure the 4 traps upfront are working properly.

Some steam traps are leaking, due to the steam leak from the main header.

You must change the technology of the process steam trap, by float trap, or to increase the global

efficiency by double duty pump.

5.1.2 Lactam Purified Water Tank

There is a low point with a valve to drain the condensate to

the sewer.

You must install a drip leg with a steam trap to drain the condensate continuously.

The 6 bar line feeds an exchanger to heat once per week the water of the tank for pasteurization.


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None of the ancillaries is insulated.

There is no drip leg before the control valve.

The strainer is not in the good position.

This application was not in service, we could not test the steam trap.


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5.1.3 Laboratory The steam pipe to Laboratory has 3 steam traps to drain the condensate.

The Steam traps were not installed on drip legs.

The last one is just before the downpipe, it was isolated.

The steam applications are distiller and autoclaves.

You put the condensate from this area directly to the sewer.

You could return them to the condensate pipe located nearby, estimated additional quantity is 20 kg/h.

5.1.4 Lactam building

A Steam pipe is separated at the entry of the building in 2 lines.

2 separate pipes

There is a drip leg with an inverted bucket trap.

Steam trap was OK


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The top pipe fed a hot water heat exchanger.

All equipments are insulated.

We didn’t find the control valve.

The strainer is not installed in a good position.

There is a leak under the insulation, you consume steam because the wool is wet.

The hot water is used to feed AHU coils.

We put some probes to check the temperature of the inlet and outlet water pipe.


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The red curve is return water temp

The green curve is inlet water temp

The blue curve is condensate temp

There is no steam consumption before 05Hh00 in the morning, then a small peak.

You increase the water temperature at 61°C.

Normally, you just need hot water during winter.

You could put an insulated valve outside the building to close the steam pipe before the heat

exchanger when the outside temperature is OK.

The bottom pipe fed

• A Pure steam generator No problem in this equipment

• A Distiller


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You control the system with a pressure reducing valve.

You have a problem with the distiller, the steam trap was leaking.

When the control valve is closed, there is a small leak in the pipe; steam passes through the steam trap

but was blocked by the pressure in the drain pipe, coming from cooling water.

You must disconnected the outlet steam trap pipe and add a direct drain pipe to the sewer.

You have to change the technology of the steam trap.

A float trap with condensate return connection to the feed tank when you heat the water and in parallel,

a thermostatic trap connected to the sewer when the application is not heating.

New equipment:

Glatt coating

You installed this equipment some weeks ago.

You feed it by a pipe connected to Non Lactam main pipe.

There is no PRV station, the manometer range is 0 – 2 bar


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You should confirm whether the heat exchanger could work at 6 bar steam (manometer with

appropriate range to be installed) or whether a PRV (6-2 bar) should be added to match the heat

exchanger maximum allowable pressure.

You installed a condensate return pipe, but it is not yet connected.

5.1.5 Non Lactam area

This building is fed with a steam pipe with a correct number of drip legs.

The size of the drip legs and the position are not always correct.

The pots are not under the main pipe, but connected to the side.


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The dimension of the drip leg is too small. There is no drain valve before the steam trap.

You distribute the steam in 2 technical mezzanines.

• 2nd Floor Mezzanine We found a PRV station and 2 steam traps to drain the line.

PRV station with no insulation in the steam pipe and

equipments.


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Steam traps

• 1st Floor mezzanine: We found 5 steam traps to drain the line.

correct installation.


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Giza, Egypt

Date : 23/10/2012

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No drip leg before the steam trap. Connection pipe

not below the main pipe

steam trap is removed

No steam trap before the pipe going up.


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Date : 23/10/2012

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1st Floor mezzanine feds ground floor area.

The processes in ground floor area are:

• Distillers

1st strainer in bad position, 2nd is ok

Equipments are not insulated.

No drip leg before the control valves.

• Clean steam generator

No drip leg before the control valves. Equipments are not

insulated.

2nd Floor mezzanine feds First floor area.

The processes in first floor area are:

• Hot water for AHU


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You increase the pipe diameter before the control valve.

Thermostatic sensor

We measured the temperature of the water loop, it was higher than for Lactam Building,

55°C for return water temp

70°C for inlet water temp

67°C for condensate temp

You consume steam to increase the temperature after cooling water coil.

Normally this heat exchanger must be out of service in this season.

• Lysten Tray Dryer Control valve is in the mezzanine.

The set point is 45°C, you drain the coil with a TD steam trap; at this temperature, you must use a

double duty trap to avoid flooded coil.


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• Double Jacket Tanks You use steam to heat ointments and cream in double jacket tanks.

The applications were not in services during our visit.

In the Room N206, 2 tanks:

The biggest one has a TD steam trap to drain the condensate, you open the by-pass.

The smallest has no steam trap, just a valve.

• In the Room N2111A 4 tanks:

1 small with a TD Trap ½’’

3 biggest with IBT Steam trap 1’’

1 for Dissolver

1 for Melter

1 TE3

The condensate connection is at the same level than the Steam connection.

The set point temperature is certainly low to condense quickly in the double jacket.

In mechanical floor

• Driam air coils

Float traps are insulated.


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The safety valve outlet pipe is connected to the condensate

pipe.

When the On-Off valve is closed, the pressure after the PRV station increase and you have steam

going through the safety valve to the condensate pipe.


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Giza, Egypt

Date : 23/10/2012

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• XLA air coils

There is no control valve, just On-Off valve.

2 steam traps in series for process and line – 1 inverted bucket then 1 TD. We recommend removing

the TD trap and making sure the first trap works properly.

TD after IB process trap where by pass is opened.

We recommend removing the TD trap and making sure the first trap works properly.


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Giza, Egypt

Date : 23/10/2012

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• Glatt coating air Coils

No insulation around the equipments

Strainer in a bad position

Technology of the steam traps is not the best, replace them by inverted bucket or float trap.

In process rooms

• Double jacket Tanks • Purified water heat exchanger

There is no insulation around control valve and strainer


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Giza, Egypt

Date : 23/10/2012

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APPENDIX

- Steam flow calculation - Efficiency calculations - Radiation losses calculation - Misassemble - Steam trap survey - Steam Pressure Controlled Heat Exchangers at Low Load


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Steam flow calculation.

We couldn’t calculate the steam flow of the different process, you have no information concerning

the global steam flow and no sufficient data concerning the design of the equipments.

Efficiency calculations


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Calculation with Optimization ECM 2. 100% Time with 4T/h Boiler The indicate cost are not euro but Egyptian Pound


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Radiation losses calculations


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Installation Mistakes Missing drip leg:

Main header - the condensate pipe size is too small, there is no steam trap.

Pipe to laboratory - the condensate pipes size are too small.


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Pipe to Non Lactam.

The drip legs are not below the steam pipe.


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Before Hot purified water control valves.

The drip legs are not below the steam pipes.


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Non lactam pipe, the size is too small.

Before control valve.


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Before control valves.


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All steam strainers must be turn by 90°.


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Steam trap survey

There are 57 steam traps installed on your network: 12 of the installed traps were out of service, 23 of

the traps were failing (12 leaking, 11 cold or flooded).

Some steam traps are insulated, we recommend you to dismantle the insulation to increase the

efficiency of the float trap. One thermostatic element is located in the chamber of the trap, and must

drain incondensable gases. If the trap is insulated, the thermostatic element could not open and the air

cannot be drained and therefore the float trap capacity is reduced.

The technology are:

• Thermodynamic Qty17 (technology not recommended for process application) • Float Trap Qty 4 • Inverted Bucket Trap Qty 28 • Thermostatic Qty 5

25 steam traps for process and 32 for line.

List on Excel Chart


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Giza, Egypt

Date : 23/10/2012

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Steam Pressure Controlled Heat Exchangers at Low L oad

Current situation

Within the steam system, there are several pressure controlled heat exchangers operating at low loads.

Within these heat exchangers, liquids or gasses (air) are heated along with the steam. Most of the time

the desired medium temperature is below 100°C, and the heat exchanger is working at partial load.

Under these conditions, regardless of brand or model, problems may occur due to the physical

properties of the steam.

An audit is only a short visit on site, in which it is impossible to see all operating conditions. Most

problems with heat exchangers only occur at certain conditions. For instance, operation of heat

exchangers for building heating may only be a real problem during the fall and the spring, when partial

loads are typical. Due to the variability of these problems they are often not recognized in time, and can

cause process bottlenecks, loss of production, loss of temperature control and increased maintenance

costs.

Control of steam pressure can be designed in two ways: modulating or on-off. In both cases the control

valves are modulated by the measured temperature of the heated media. Steam pressure controlled

heat exchangers at low loads almost always produce sub-cooled condensate.

Modulating Controls

The steam pressure after a modulating control valve is always lower than the steam pressure in the up

steam lines, unless the system is working at full load which is a rare operating condition.

When heating a product to a temperature below 100ºC, the required steam temperature will often be

close to 100ºC, as the latent heat of the steam is used to transfer the energy as the steam condenses.

Steam temperatures lower than 100ºC, has a pressure below atmospheric pressure. If the steam

pressure after the steam control valve is less than the pressure in the condensate line, there will be no


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driving force (pressure differential) available to push the condensate out of the heat exchanger and

move it to the condensate receiver. The condensate will back up in the heat exchanger, and will

become flooded. This situation is often called a “stall situation”. As the condensate backs up in the heat

exchanger, it will exchange sensible heat with the product, where the condensate becomes sub-cooled

(matching the product temperature). The infrared pictures below show the condensate backing up in a

shell and tube heat exchanger as well as a plate and frame heat exchanger, and the resulting

temperature differences in it.

The more a heat exchanger is oversized , the sooner it will operate at a partial load and the more the

condensate will sub-cool.

During a stall condition, the output of a heat exchanger is no longer controlled by the steam pressure

and the resulting amount of steam through the control valve. In fact the output is now continuously

controlled (limited) by the condensate level inside the heat exchanger. A few centimetres change of

condensate level will have a huge impact on the heat output. A pressure change of only 10 centimetres

water column (= 0,01 Bar) on steam inlet or condensate outlet (= back pressure) can be the difference

between 0% and 100% output. In the best case scenario the control system will balance the

steam/product differential. However even the best control system cannot control the back pressure

variations in the condensate return system. Therefore, in most cases the following is observed:


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Due to the condensate backing up the amount of heated surface in the heat exchanger is reduced, and

the desired set point product temperature cannot be reached. As a reaction to this, the steam control

valve will open, thus providing enough pressure differential to push out the condensate. When this

happens all the heating surface in the heat exchanger is available again causing a sudden rise in the

product temperature. There will be an overshoot in temperature which the controls will try to correct by

closing the steam control valve. This cycle will repeat and control valves will “hunt” searching for

balance. Hunting control valves, and actuators, wear quicker and tend to leak. The most critical aspect

of cycling control valves is that the frequent changes in temperature will cause local material stresses in

the heat exchanger, which over time can cause failures and leaks (especially in stainless steel). In

addition the presence of relatively cold condensate may cause water hammer and corrosion inside the

heat exchanger which can also lead to leaks. These leaks often occur on the outside of the heat

exchanger (gasket failure), where they will be clearly visible. However these leaks can just as easily

occur inside a heat exchanger, thus causing contamination issues and even blockage of heat

exchangers.

Lowering the condensate back pressure will reduce the risk of condensate backing up in the heat

exchanger, which provides two system improvements. First, it will reduce the loss of exchanger

capacity, and second, it reduces the risk of water hammer. Often when condensate is backing up, the

condensate lines are drained to the sewer. This is only a temporary fix and is a great loss of energy and

can raise waste water temperatures above safe limits.

Optimization

A number of solutions have been developed to solve the problems with heat exchangers at low/partial

loads. Finding the most effective and efficient solution would require custom tailored engineering.

Basically there are six methods to remove the condensate from a flooded heat exchanger with steam

pressure control:

• a closed loop pumping trap

• a Posipressure system

• a safety drain trap


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• a barometric leg

• change to condensate level control

• a mixing valve on the product side


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Closed loop pumping trap

A closed loop pumping trap arrangements uses a balancing line to equalize the pressure in the heat

exchanger and the pumping trap. Condensate will drain by gravity toward the pump, and will be pushed

out using steam pressure. The diagram below shows a typical setup:


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Posipressure system

A Posi-pressure system allows air or nitrogen to push out the condensate as soon as the steam

pressure inside the heat exchanger is less than the back pressure in the condensate system. When

using a Posipressure system, the condensate return system should be able to handle small quantities

of air or Nitrogen. The steam traps applied should be inverted bucket traps, and the condensate

receiver has to be vented. The diagram below shows a typical setup for this arrangement:


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Safety drain

A safety drain is a second trap that is sized to handle the same load as the primary trap. It is located

above the primary trap and discharges into an open sewer. When there is sufficient differential

pressure across the primary trap to operate normally, condensate drains from the drip point, through

the primary trap, and up to the overhead return line. When the differential pressure is reduced to the

point where the condensate cannot rise to the return, it backs up in the drip leg and enters the safety

drain. The safety drain then discharges the condensate by gravity.

Barometric leg

A barometric leg can be created by moving the steam trap to a lower position. Every meter the trap is

positioned below the heat exchanger will generate 0,1 Bar pressure differential. Reversely, lift of

condensate after the steam trap or back pressure in the condensate return system, will reduce (or even

eliminate) the effect of the created barometric leg. Of course this option will only work if sufficient height

differential is available. A steam temperature of 60°C requires a barometric leg of 8 meters!


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Condensate level control

On condensate level controlled heat exchangers full steam pressure is applied on the heat exchanger.

The capacity of the heat exchanger is controlled by changing the level of condensate inside the heat

exchanger. The submerged part of the heat exchanger works as a condensate after cooler.

Condensate from a condensate level controlled heat exchanger is always sub cooled.

Heat exchangers have to be specially designed to work on condensate level control. There should be

sufficient height differential between minimum and maximum condensate level to allow accurate

control. Horizontal heat exchangers cannot be used for condensate level control. Furthermore the heat

exchanger should be able to handle mechanical stress due to local temperature variations, and the heat

exchanger should be able to handle sub-cooled (low pH) condensate. Most plate and frame heat

exchangers are not suitable for condensate level control. Vertical hairpin heat exchangers, with steam

and condensate in the shell and product in the tubes, work best on condensate level control.

Part of the product is exposed to maximum steam pressure and hence maximum steam temperature;

not every product can handle these high temperatures. Caution is advised on applications where the

steam temperature could exceed boiling temperature of the heated product (reboilers on distiller

columns). Due to local high temperatures inside the heat exchanger, the product will very likely start

boiling at these hot spots. The product vapours will implode again as soon as they mix with the colder

product ( cavitation). The result will be similar to water hammering on steam systems, only this time it

occurs on the product side. Both can cause leaks and provide a serious health and safety hazard.

Controlling on condensate level is a slow process. In the event the condensate level control valve (or

controls) fails, or if the controls cannot keep up with sudden load changes, live steam may enter the

condensate return system. During this event, the heat exchanger will work on full capacity. The

pressure in the condensate return system will suddenly increase, which may disturb other processes.

These events will soon be recognized by process operators. Passing live steam into the condensate

return system furthermore represents a serious safety issue. To control this safety risk, a number of

precautions can be applied:


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- A temperature alarm in front of the condensate discharge valve. This alarm closes the steam

inlet in case the condensate temperature exceeds a certain set point.

- A float switch on the shell of the heat exchanger. Low condensate level generates a signal to

close the steam inlet valve.

- Installation of a mechanical steam trap in front of the level control valve. The steam trap opens

for condensate and closes as soon as steam enters the steam trap. Advantage of this solution

is that it will secure operation, however the heat exchanger will work on full capacity.

Another risk using condensate level control, is that the heat exchanger will be fully flooded with

condensate (up to the steam inlet valve), in case there is no demand for heat. This could also induce

water hammering. This can be prevented by the following measures:

- A high condensate level switch closing the steam inlet on too high condensate levels.

- A mechanical steam trap at the highest condensate level. The excess condensate will be

discharged by this steam trap.

Mixing valve on the product side

Instead of controlling the product temperature by modulating the steam pressure, it is also possible to

fix the steam pressure and blend the heated product with cold product. In this case the steam pressure

has to be fixed at a pressure exceeding the condensate back pressure, thus securing that condensate

will be pushed out of the heat exchanger. This (too) high steam pressure will overheat the product. This

overheated product can be cooled down again by blending it with non heated product.

Caution should be taken however, as local overheating however can cause scaling and fouling issues in

heat exchangers. Furthermore the elevated steam pressures will result in elevated condensate

temperatures. As a result more flash steam will be generated, which has to be recovered to maintain

system efficiency. Also this flash steam may require enlargement of condensate return lines in order to

prevent water hammering.

glaxosmithkline - armstrong international...2012/12/06 · glaxosmithkline giza, egypt date :...

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