GlaxoSmithKline - Armstrong International€¦ · GlaxoSmithKline El Salam Cairo, Egypt STEAM AND...

GlaxoSmithKline El Salam Cairo, Egypt

STEAM AND CONDENSATE AUDIT P 30432

Rossen IVANOV �� + 32.42.40.90.89 [email protected]

STEAM AND CONDENSATES PRE-AUDIT

P 30432

GLAXOSMITHKLINE

Cairo, Egypt

Date : 23/10/2012

of 80

To the attention of Mohamed Kamal Awad and Amr Mohamed Alaa Ibrahim

Established by Eric MONTREER

TABLE OF CONTENTS

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

2 STEAM BUDGET AND SUMMARY OF POTENTIAL SAVINGS .............................................................................7

3 OPTIMIZATION PROJECTS ..........................................................................................................................................8

ECM1: REDUCE BOILER BLOW DOWN RATE ..........................................................................................................................9

ECM 2: IMPROVE BOILER EFFICIENCY ..................................................................................................................................14

ECM 3: REPLACE STEAM BY HOT WATER TO HEAT 60°C HOT WATER LOOP ......................................................................25

ECM4: INSULATE STEAM PIPES ANCILLARIES .......................................................................................................................28

ECM5: STEAM TRAPS REPLACEMENT ..................................................................................................................................30

ECM6 REPLACE CONDENSATE TANK BY PUMPING TRAP PACKAGE ....................................................................................32

ECM7: INSTALLATION OF PROPERLY SIZED DRIP LEGS AND TRAPS ON THE INLET OF PLANT STEAM CONTROL VALVES, ON

HEADERS AND MAIN LINES......................................................................................................................................................35

4 COMPLETE CHECK LIST OF ALL VERIFICATIONS DONE DURIN G THE AUDIT ..........................................38

5 COMMENTS ON STEAM & CONDENSATE NETWORK .......................................................................................39

STEAM PRODUCTION .............................................................................................................................................................39

STEAM DISTRIBUTION .............................................................................................................................................................41

STEAM CONSUMERS ...............................................................................................................................................................42

5.1.1 60°C Hot water Tank ........................................................................................................................................42

5.1.2 Laundry ..............................................................................................................................................................42

5.1.3 Ceph’s ................................................................................................................................................................43

5.1.4 Factory area ......................................................................................................................................................47

CONDENSATE RETURN NETWORK .........................................................................................................................................51

APPENDIX ................................................................................................................................................................................53

RADIATION LOSSES CALCULATIONS .............................................................................................................................60

INSTALLATION MISTAKES ................................................................................................................................................62

STEAM TRAP SURVEY .........................................................................................................................................................71

LIST ON EXCEL CHART .......................................................................................................................................................71

STEAM PRESSURE CONTROLLED HEAT EXCHANGERS AT LOW LOAD .............................................................72

CURRENT SITUATION ...............................................................................................................................................................72


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Cairo, Egypt

Date : 23/10/2012

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OPTIMIZATION .........................................................................................................................................................................74

Closed loop pumping trap .................................................................................................................................................76

Posipressure system ...........................................................................................................................................................77

Safety drain........................................................................................................................................................................78

Barometric leg ...................................................................................................................................................................78

Condensate level control ...................................................................................................................................................79

Mixing valve on the product side .......................................................................................................................................80


P 30432

GLAXOSMITHKLINE

Cairo, Egypt

Date : 23/10/2012

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1 Executive summary

Armstrong Service has conducted from 9th to 14st of October 2012 a complete audit of your steam

installation.

GSK Cairo is using around 1500 kg/h of 6 bar steam, for a total consumption of about 13000 T/year.

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

The site is divided in several buildings:

• Ceph’s

• Factory

• Laundry

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

Ceph’s Pure steam generator

Distiller

Munters air Coil

Factory Munters air Coils AHU Coils

Hot water Tanks

Vertical Exchangers for Sirup

Sirup Tanks

Purified hot water Generator

Laundry Dryers

Press iron


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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 (recovery on exhaust gas and blowdown…)

- Improvements on the heating devices drainage

- Improvements on the heating control

- Correction of design mistakes

We wish to thank particularly the mechanical team, Boiler house Team and Amr Mohamed Alaa Ibrahim

for his 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, global efficiency could be enhanced by changing the adjustment of the Boilers’

burners, installing an economiser, preheating the comburant air and reducing a little bit the blow

down when the water analysis are good.

On network and steam users, drip legs instead of ½ or ¾ inch condensate pipe should be added,

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

On Ceph’s condensate network, the steam trap and pumping trap must be cancelled.

Steam on 60°C water Tank can be replaced by flash s team or condensate.

Low temperature steam users must be implemented. 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.


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All steam ancillaries must be protected with insulation jackets.

Potential energy savings could be at least 19% of the current yearly steam budget, which represents

a yearly saving of about 1835 MWh, 334 tons of CO2 and 73 426 Egypt pound.


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Date : 23/10/2012

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

Average cost 26.0 Egyptian Pound/T

Yearly steam consumption 13000 tons/year*

Annual cost (Gas cost) 337 901 Egyptian Pound

Note:

The gas invoice for the first 8 months in 2012 is: 248 463 Egyptian Pound

The annual cost will be: 390 830 Egyptian Pound

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. Reduce Boiler Blow down Rate

68 2705 0 1 12

2. Improve Boiler efficiency

556 22233 200000 108 101

3. Replace steam by hot water to heat 60°C Hot water loop

312 12490 40000 38 57

4. Insulate steam pipes ancillaries

385 15423 55000 43 70

5. Steam traps replacement

514 20575 38500 22 94

TOTAL 1835 73426 333500 55 334

6. Replace Condensate tank by pumping trap package

64000

7. Improvement of steam quality

45000


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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: 1500 Kg/h

• fuel cost: 40.0 Egyptian Pound/MWh

• steam generation global efficiency: 80%

• steam cost: 26.0 Egyptian Pound/T

• annual CO2 emissions (51 kg/GJ / 183 kg/MWh HHV)


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Cairo, Egypt

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ECM1: Reduce Boiler Blow down Rate

Current System Description and Observed Deficiency

Water treatment

Softened Make up water is mixed with condensates in injection in the feed tank.

The water flow is adjusted by a manual valve. It will be better to feed a Tank with softened water, on-

off level control and add softened water to the feed tank with a control valve.

Condensate return

2 condensate lines are connected to the feed tank one from Ceph’s and one from factory.

Feed tank

The temperature on inlet water pipe just in front of the Boilers pumps was often more than 90°C.


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Inlet water boiler ”Likoni” – September 7th afternoon and September 8th morning

When we started the audit, you were losing flash steam at the vent pipe, after the modification at

Ceph’s (see section Condensate return network) condensate return pipe, this loss was reduced.

Boilers blow down

Blow downs are controlled by bottom solenoid valves.

The valve is opened 120 seconds each 45 minutes, which is not necessarily based on the water

analysis.

You could decrease a little your blow down with correct daily analysis.

The TDS value was 2400 micro-siemens cm and you can accept 4500.

The Feed water TDS value was 370 micro-siemens cm.

The blowdown % was more than 15%.


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The plant operates two shell boiler at a steam pressure of 6 bar (g). The average steam load is 1.4 t/h.

Currently, the boiler blow down is controlled by:

- Opening a solenoide valve 32 times per day for 120 sec.

There is no heat recovery installed on the blow down. According to the plant’s water analysis, the

average values are:

The upper limits recommended by the local water treatment company are from 4000 to 4500

microSiemens/cm.

Technical Discussion Even with the best pretreatment programs, boiler feed water contains some degrees of impurities such

as suspended and dissolved solids. As water evaporates, these impurities are left behind and they

accumulate inside the boiler. The increasing concentration of dissolved solids leads to carryover of

boiler water into the steam, causing damage to piping, steam traps and even process equipment. The

increasing concentration of suspended solids forms sludge, which impairs boiler efficiency and heat

transfer capability.

To avoid boiler problems, water must be periodically discharged or “blown down” from the boiler to

control the concentrations of suspended and total dissolved solids in the boiler water. Surface water

blow down is often done continuously, to reduce the level of dissolved solids, and bottom blow down is

performed periodically to remove sludge from the bottom of the boiler.

Average Water Analysis Results

Ygnis

Boiler

Water

Cleaver

Brooks

Boiler

Water

Feed Water Blow down %

Conductivity µs/cm 2400 2200 370 18


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The importance of boiler blow down is often overlooked. If the blow down rate is too high, energy

(water, fuel, chemicals) is wasted. If high concentrations are maintained, (too low blow down) it may

lead to scaling, reduced efficiency and to water carryover into the steam, compromising its quality (wet

steam). The blow down rate is calculated with the following formula:

% Blow down = C Feedwater

(C Boiler – C Feedwater)

Where:

CFeedwater= the measured concentration of the selected chemical in the feed water (Conductivity, TDS,

Alkalinity, Chlorine)

CBoiler = the measured concentration of the same chemical in the boiler

Note that the feed water concentration depends on the make-up water quality and the condensate

return ratio.

The ASME guidelines "Consensus on Operating Practices for the Control of Feed water and Boiler

Water Quality in Modern Industrial Boilers," shown in the tables below, are frequently used for

establishing optimum blow down rates.

Table 1: Water Chemistry for Firetube Boilers - ASM E Guidelines


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Recommended Optimization Armstrong recommends reducing the blow down rate by:

- Increasing time between 2 blowdowns

- Adjust the time in accordance with the analysis

It is advised to consult your boiler water treatment vendor before changing the boiler feed water

treatment program.

Estimated Investment and Payback

Present Proposed Savings

Fuel used LSHS LSHS

Steam Demand kg/h 1500 1500

blowdown % 15 8

Boiler Efficiency

(LHV) % 79,6 80,34

Heat Required Kw 1120 1113 35.2

Hours of operation h 8700 8700

Heat Required

(HHV) Mw/year 10827 10759 68

Gas Cost Egypt Pound 40/Mwh 40/Mwh

Annual Costs Egypt Pound /year 433065 430360 2705

CO2 emissions t/year 1981 1969 12

Decreasing your blow down rate from 15 to 8 % will save 2705 Egypt Pound/yr of Gas.

The CO2 emissions reduction resulting of improving the blow down is 12 ton/year

Estimated investments: The investment is estimated at 0 Egypt Pound, as only an internal analysis is required.


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GLAXOSMITHKLINE

Cairo, Egypt

Date : 23/10/2012

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ECM 2: Improve Boiler efficiency Current System Description and Observed Deficiency

Steam generation

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

Ygnis - 5T/h - 3 passes boiler Cleaver BroOKs - 3T/h - 2 passes boiler

We did the “Combustion efficiency measurement”.


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GLAXOSMITHKLINE

Cairo, Egypt

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You found a good combustion analysis for the Ygnis boiler. The excess air was correct, 18%.

You found a correct combustion analysis for the Cleaver Brooks boiler but not so good than the other.

The excess air was more than 50%.

The burners are modulating but you work like On-Off control on Ygnis boiler.

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


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Cairo, Egypt

Date : 23/10/2012

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Ygnis Boiler

The red curve is the stack temp

The green curve is the blowdown temp

The blue curve is the feed water temp

The stack temp increases when you add feed water. The burner started each 12 minutes during 6

minutes, then stopped.

The blowdown valve opens each 45 minutes during 2 minutes.

The pump is on 2 minutes each 12 minutes. The pump flow is 8.5m3/h. The average water flow was

8.5:6=1.4m3/h


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Cleaver Brooks

The red curve is the stack temp

The green curve is the air temp

The blue curve is the feed water temp

The stack temp increases when you add feed water. The burner runs in high load each 10 minutes

during 2-3 minutes. The burner never stopped.


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Energy recovering systems

There is no economiser, no blowdown energy recovering system, no comburant air preheating

system.

The stack temperature is higher than 180°C, with na tural gas, you can decrease this temperature to

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

You can reduce the blowdown time and recover a part of the Energy to heat the softened water.

You can take the comburant air at the top of the boiler to increase the temperature

The green curve is the bottom air temp

The blue curve is the top air temp

During the day the difference is between 10 and 15°C.

During the night, the difference is between 15 and 20°C.

BOILER EFFICIENCY (see next page)


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GLAXOSMITHKLINE

Cairo, Egypt

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Boiler 1 is Ygnis with losses from burner cycling.

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


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

26 Egyptian Pound/T considered in the chapter 2.

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

Technical Discussion

The plant operates a Shell tube boiler rated for 5 T/hour at 6 bar. The average steam generation

is 1400 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

Stack

Temperature

°C 180

Ambient

Temperature

°C 30

CO2 % 10

Efficiency % 83,7

Excess Air % 18

O2 % 3,46

CO ppm 0

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.

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


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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 40 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.

• The intake air could be increase from 30 to 40°C i f you suck it from the top of the boiler.

Example of installation:


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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

Reducing the stack temperature from 180°C to 120°C will increase the boiler efficiency from

80% to 84% and will save annually 13 230 Egypt Pound.


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Present Proposed Savings

Fuel used LSHS LSHS

Steam Demand kg/h 1500 1500

Excess O2 in Stack % 3.4 3.4

Combustion air

Temperature °C 30 40

Flue Gas Temp at

Boiler Outlet °C 180 180

Flue Gas Temp at

Economizer Outlet °C NA 120

Boiler Efficiency

(LHV) % 89 93

Heat Required(LHV) Kw 1113+1118 1058 35.2

Hours of operation h 4350 8700

Heat Required

(HHV) Mw/year 10783 10227 556


Annual Costs Egypt Pound /year 431326 409093 22233

CO2 emissions t/year 1973 1872 101


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

• Economizer

• 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 9 years.


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ECM 3: Replace steam by hot water to heat 60°C Hot water loop Current System Description and Observed Deficiency

Behind the boiler house, a connection pipe from the Laundry steam pipe feeds the 60°C Hot water

Tank.

The control is done by a thermostatic valve, and the steam trap technology is a float trap.

There is no drip leg to protect the control valve.

The set point is 60°C but in fact the Tank temperat ure was more than 75°C.

The control valve is leaking even the set point temperature is OK.

You consume more steam than you expect.

The 60°C hot water Tank is heated by a steam coil, 0.1 to 0.15 T/hour at 6 bar. The Condensate Tank

has an average temperature around 90°C.

You lose a part of the energy through the flash steam at the vent.


The temperature of the 60°C water loop was more tha n 70°C, the thermostatic control valve was not

totally closed. You have possibility to replace the Steam coil by a hot water heat exchanger.

Recommended Optimisation


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Armstrong recommends replacing the steam usage by a hot water loop from the condensate Tank.

We suggest the installation of a plate heat exchanger fed by the condensate.

The return pipe after the exchanger will be connected at the vent pipe of the feed tank to condense the

flash steam. The existing system will be maintained, but used only if not enough heat is delivered by the

condensate tank.


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Estimated Benefits

By using hot water loop instead of steam, you can save 100 to 150Kg/h of steam.

Existing Proposed Savings

Steam Consumption Kg/h 100-150 0-50 50-100

Boiler Efficiency (LHV) 80 80

Operating Time h/year 8000 8000 same

Gas Consumption Mwh/year 416,0-624 208 208-416


Annual Cost

Egypt

Pound/year

16652-

25000 8326 8326-16652

CO2 emissions t/year 76-114 0 38-76


The investment is estimated at 40 000 Egypt Pound. It includes:

• Plate Heat Exchanger

• Pump

• 3 way valve

• valves

• Installation

The payback of this installation is expected to be 3 years.


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ECM4: 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/m 2 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 34 900 W that is equivalent to a steam loss of about 50 kg/h, more

than 3.5% of your steam consumption.


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Estimated Benefits

, .


Budgetary cost to insulate pipes and add insulated jackets is 55000 Egypt Pound It includes:

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

Payback time is about 40 months.


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ECM5: Steam traps Replacement


There are 47 steam traps installed on your network. A trap survey was done during our audit. 47 steam

traps were identified. 11 of the installed traps were out of service. 19 of the traps were failed (11

leaking, 8 plugged 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.


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Estimated Benefits

Fuel savings

Steam losses calculated kg/h 75

Energy loss kW 43

Operating hours hr 8700

yearly Energy used MWh/year 374

boiler efficiency % 80%

Fuel used

MWh/year

hhv 514

Fuel unit costs

Egypt

Pound/MWh

hhv 40

Fuel costs

Egypt Pound

/year 20575

CO2 savings

Energy used MWh/yr 514

CO2 emissions kg CO2/MWh 183

CO2 produced t/yr 94

Replace leaking traps would save 20575 Egypt Pound /year .


The budgetary cost for replacing leaking traps is 38 500 Egypt Pound .It includes:

- Equipments supply (traps)

- Installation by a mechanical contractor

- Project management

Payback time for replacing all failing traps, including blocked traps, is 22 Months.


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ECM6 Replace Condensate tank by pumping trap packag e


All condensate from the factory returns to an atmospheric tank.

An electric pump sucks the hot water from this tank to transfer it to the feed tank.

You have cavitation problems with the electric pump.

The capacity of the tank is high and there are also some radiation losses due to lack of insulation.

The tank temperature was more than 100°C

You have some steam trap leaking and the vent pipe diameter is too small.

You have some problem to evacuate correctly the condensate of the farthest process.

The pipe diameter after 90°C tank is 20mm and you c onnect the 4 steam traps from the Soft gelatine

Dehumidifier coils.

We recommend you to increase the diameter of this pipe from 20 to 50 mm.


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Condensate at about 100°C will flash (revaporise) a t the suction entry of the pump.

To avoid cavitation, you have to put the pump 4 m under the tank in order to create sufficient NPSH.

It is not possible in your installation.


We propose to replace the Tank by a mechanical condensate pump package


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This pump will discharge condensate to the existing condensate recovery line.

Estimated Benefits

This will decrease your electric consumption and reduce your maintenance cost.


The Budgetary cost to install a package pump with all equipment (Air vent, drip leg at motive steam line). Is estimated at 64 000 Egypt Pound with 1 pump

96 000 Egypt Pound with 2 pumps (1 for replacement) It includes:

• equipments supply • Installation


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ECM7: 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.


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


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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 necessary.

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


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Estimated investment

The preliminary estimate of the project cost to implement the above recommendations is 45 000 Egypt

Pound

It includes:

• Installation of 11 properly sized drain pocket

• Installation of 11 steam trap stations with connector and integral blow down valve.


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4 Complete check list of all verifications done dur ing the audit

Potential optimisation Status Comments

STEAM GENERATION

Steam pressure setting OK 7Bar(g) Maximum boiler pressure. Necessary for Ceph’s Process

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 (see Project 2)

Combustion air temperature OK Ambient temperature is high, but could be increased by 10°C (see Project 2)

Oxygen rate Not OK Could be improved on boiler 3T (see Project 2), OK on boiler 5T

Boiler sizing Not OK Boiler 5T is oversized, but replacement could not be justified only based on energy-savings.

Boiler blow down rate Not OK A little bit too high (see Project 1)

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 (Project 2)

Boiler stand-by time and volatility of steam demand

Not OK You change the boiler in service each 4 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 missing (see Project 7).

Insulation Not OK

No Insulation on all steam equipments (see Project 4).

Steam quality poor Blocked steam traps on drips compromise steam quality. High risk for erosion, corrosion and water hammering issues (see Project 7).

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 5).

CONDENSATE AND FLASH STEAM RECOVERY

Condensate recovered Not OK Lot of by pass to the sewer open. Condensate return rate is too low. Condensate tank could be replaced by pumping trap (see Projects 5 and 6).

Sizing of condensate return lines OK

Flash steam recovery Not OK From Ceph’s condensate temperature is high (see Project 3).

Water hammering Not OK Condensate go to the sewer to reduce water hammering (excessive pressure in the condensate return)


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5 Comments on Steam & Condensate Network

Steam Production

Steam flow You put a steam flow meter between the boiler 5T/h and the main header.

We collect the value to analyse your steam consumption.

date/hour time total steam steam flow

10-oct min kg kg/h

9H20 34276

9H47 27 34595 709 factory off Ceph's on

11H00 73 35570 801 factory off Ceph's on

12H30 90 37022 968 factory on Ceph's off



16H00 20 41351 1818 factory on Ceph's on

11-oct




Make-up water consumption is around 40m3/day, 1.6 to 1.8 m3/h.

The % of condensate returns is 0% if we consider this value.

We have calculated the % condensate return with the information from the Feed tank temperature.

The feed tank had an average temperature of 80°C.

The softened water temp is 25°C.

The condensate average temp is 120°C.

0.4x25+ 0.6x 120= 82

We can estimate that you have between 60 and 65% of condensate return and 35-40% of softened

water.

It seems very low if we consider that you have no direct injection in the product


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

return.

Note:

The steam flow meter is only installed on the Ygnis Boiler pipe.

The accuracy is not very good, the distance between the flowmeter and the elbow is not sufficient.


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Steam distribution

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

The steam trap is not installed on a drip leg, the pipe is blocked with dirt and the condensate is not

drained.

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

From the boiler room, steam is distributed by:

- One line DN 50 at 6 bar to the Laundry

- One line DN 100 at 6 bar to Factory

- One line DN 50 at 6 bar to Ceph’s

You have steam traps without drip legs on the different line to laundry and factory but no draining

points on Ceph’s line.

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


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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 the steam flow recorded.

.

Steam consumers

5.1.1 60°C Hot water Tank

For comments on this steam user, see Project 3.

5.1.2 Laundry

The 6 bar line feeds a PRV station protected by a check valve and a drip leg.

None of the ancillaries is insulated.

There is no safety valve after the PRV, you close the manual valve when you don’t use the laundries

equipments.

The TD steam trap is leaking.

This PRV station feeds:

• 2 Dryers, just one in service

• 1 Press iron

None of the ancillaries is insulated

The Press steam trap is leaking.


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5.1.3 Ceph’s The steam pipe to Ceph’s has a dilatation lira not protected by a drip leg.

The different process fed by this pipe are:

• Munters coil

A PRV station protected by a strainer (installed not correctly, see section Installation Errors).


The drain valve before the steam trap was opened.

• Clean steam generator


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This exchanger is only used when you have to do a sterilisation after maintenance operation.



• Distiller

The control valve is protected by a strainer (installed not correctly, see section Installation Errors).


The process steam trap was in incorrect position, it was leaking.


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You had a drain valve connected to the body, this valve was opened.

The pressure in the body was low, you flash a part of condensate and don’t evacuate correctly the

condensate.

You have installed it in correct position, but it was always a little leaking.


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The equipments are protected by 2 separators, one steam trap was leaking.


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5.1.4 Factory area

A PRV station decreases the pressure from 7 to 5-6 bar.

You changed the PRV valve during our audit, as previous one was failed.


The different processes fed by steam are:

• AHU

All steam traps were insulated, which could disturb their operation. Indeed, most of these were Float &

Thermostatic type which contains an air vent opening based on difference in temperature between

saturated steam and non-condensable gases.


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• Glatt Coating

• Munters dehumidification coils

On soft gelatine Munters coils, most of the steam traps were leaking, you replaced them during our

audit.

• Sirup heat exchanger


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Not in service.

The line steam trap was cold, the pipe is probably plugged.

• Sirup Tanks

Pipe to sirup Tanks, there is no drip leg before the PR Valves and On-Off solenoid valves.

The steam pipe was cold.

During operation, you drain the condensate to the sewer.

You might put 2 steam traps in parallel, one Bimetallic for start up connected to the sewer, one IB float

connected to the condensate return pipe for continuous operation.


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Purified hot water Generator

The steam trap was installed above the exchanger, not close to the drain valve.

• Double Jacket Tank

This tank is mobile, you connect the steam and condensate pipe when necessary.

There is no drip leg before the steam valve to drain the condensate when the valve is closed.


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• Hot Water Tank

Steam pipe fed the coil of the 90°C water Tank.

The control is done by a thermostatic valve, and the steam trap technology is thermodynamic.


The coil is leaking, you increase the pressure in the water loop, so you control actually the Temp

manually.

You closed the manual valve to decrease the steam pressure, but could not drain the condensate.

The water’s temperature was 65°C and not 90°C.

We propose you to replace this tank by a heat exchanger package. We need more information

concerning water flow to design this package.

Condensate return network

Condensate from Ceph’s was drained by a float trap installed in series on the main condensate pipe

DN50.

You installed a pumping trap after this float trap.

The vent of the condensate pump header was modified with a hydraulic pipe.


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You maintained the pressure in the condensate pipe and disturbed the correct drainage of the

condensate. After the pump, the condensate pipe was reduced to DN32, which increased back

pressure even further. This has disturbed the operation of the system and created flash steam in the

feedtank.

In the current configuration, the steam trap in series and the pump trap are not necessary. We have

asked you to dismantle the mechanical pump and the float trap, which was done during our audit.

The result was less flash steam at the vent of the feed tank.

You have always small pressure in the pipe due to the reduced section pipe.

Condensate from the factory returns in a condensate tank (see Project 6).


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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 calculate the steam flow of the different process by velocity of 30m/s in the inlet pipe and energy

calculation


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Efficiency calculations


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Calculation with Optimization ECM 2. The indicate cost are not euro but Egyptian Pound


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Calculation with Optimization ECM 2. 100% Time with Ygnis 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:

In place of ½’’ pipe

Main pipe to Cephs before elbow


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In the elbow before control valve

Before dilatation elbow


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before the manual valve Heat exchanger not in service

In place of ½’’ pipe


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Syrup Tank

No picture

In the elbow before manual valve


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In the elbow before manual valve


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All steam strainers must be turned by 90°.

Boiler Hose


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Factory Purified hot water Generator

Old Glatt AHU

ooL Ceph’s Munter


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Ceph’s Distiller


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Steam trap survey

There are 47 steam traps installed on your network.

47 steam traps were identified. 11 of the installed traps were out of service. 19 of the traps were failing

(11 leaking, 8 plugged or flooded).

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

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

incondensable, if the trap is insulated, the trap is not open and you don’t drain the air and you reduce

the float TRAP capacity.

The technology are :

Thermodynamic Qty13

Float Trap Qty29

Inverted Pocket Qty4

26 steam traps for process and 20 for line.

List on Excel Chart


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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.

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