nairobi, kenya steam and condensate audit 11253-ser2 …...oct 04, 2010 · kg/hr. a combustion...

GlaxoSmithKline Nairobi, Kenya

STEAM AND CONDENSATE AUDIT

11253-SER2-KE

P 30246

Rossen IVANOV + 32.42.40.90.89 [email protected]


11253-SER2-KE P30246

GLAXOSMITHKLINE Nairobi, Kenya

Date : 13/09/2010

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To the attention of Wily M Njeru Established by Eric MONTREER

TABLE OF CONTENTS GLAXOSMITHKLINE ..............................................................................................................................................................1

1 EXECUTIVE SUMMARY .................................................................................................................................................3

2 STEAM BUDGET AND SUMMARY OF POTENTIAL SAVINGS ............................................................................4

3 OPTIMIZATION PROJECTS ..........................................................................................................................................5

ECM1: REDUCE BOILER BLOW DOWN RATE ..........................................................................................................................6 ECM 2: IMPROVE BOILER COMBUSTION .................................................................................................................................9 ECM 3: REPLACE LIKONI BOILER BY A NEW BOILER .............................................................................................................11 ECM4: INSULATE STEAM PIPES ANCILLARIES .......................................................................................................................13 ECM5 IMPROVE CONDENSATE DRAINAGE ...........................................................................................................................15 ECM6: INSTALLATION OF PROPERLY SIZED DRAIN POCKET AND TRAPS ON INLET OF PLANT STEAM CONTROL VALVES, EJECTORS AND HEADERS .......................................................................................................................................................17

4 COMPLETE CHECK LIST OF ALL VERIFICATIONS DONE DURING THE AUDIT .....................................20

5 STEAM / CONDENSATE NETWORK ........................................................................................................................22

5.1 STEAM PRODUCTION ...............................................................................................................................................22 5.2 STEAM DISTRIBUTION ...............................................................................................................................................39 5.3 STEAM CONSUMERS ................................................................................................................................................40

5.3.1 Nutrition area .....................................................................................................................................................42 5.3.2 Carbon dioxyde tank room ..............................................................................................................................47 5.3.3 Liquide manufactoring and packaging area .................................................................................................48 5.3.4 Oral care manufacturing ..................................................................................................................................50 5.3.5 Kitchen and changing room ............................................................................................................................52 5.3.6 Granulation area ...............................................................................................................................................53 5.3.7 Laboratories ......................................................................................................................................................53

APPENDIX ................................................................................................................................................................................54

EFFICIENCY CALCULATIONS ...........................................................................................................................................57

RADIATION LOSSES CALCULATIONS ............................................................................................................................58

MISASSEMBLE .......................................................................................................................................................................60

STEAM TRAP SURVEY .........................................................................................................................................................68


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1 Executive summary Armstrong Service has conducted from 7th to 10st of September 2010 a complete audit of your steam installation. GSK Nairobi is using around 250 kg/h of 6 bar steam, for a total consumption of about 1700 T/ year. Steam production is handled by 2 fire tube boilers running alternatively. 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 (optimisation of the combustion, recovery on exhaust gas…) - Improvements on the heating devices drainage - Improvements on the heating control - Correction of design mistakes

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 burner and reducing a little bit the bottom blow down when the water analysis are good (a daily analysis must be done).

A new 3 passes boiler with burner control could increase the efficiency by 10%, but the payback is quite important based on energy savings only.

On network and steam users, drip legs should be added, especially before control valves to avoid condensate accumulation and valve/seat erosion.

Steam users must be controlled by control valves. You could use lower pressure and increase the global efficiency by using assistance drainage to ensure better condensate elimination.

The operation of steam trap on process heat exchangers must be improved.

All steam ancillaries must be protected with insulation jackets.

Potential energy savings of at least 45% of the current yearly steam budget, which represents a yearly saving of about 170 tonnes of steam, 876 MWh, 266 tons of CO2 and KShilling 5 495 000 (these figures do not include savings from leaking traps).


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2 Steam budget and summary of potential savings Based on Taking in consideration the last 12 months steam consumption, we have estimated the yearly budget for steam.

Average cost 6 735KShilling/T Yearly steam consumption 1 700 tons/year* Annual cost (fuel cost) 11 450 000 KShilling

Note: The fuel invoice for the first 7 months is: 8 016 350 KShilling The annual cost will be: 13 740 000 KShilling Summary of identified energy-saving optimizations and their estimated yearly results:

Savings Investment Payback CO2 savings

Mwh/year KShilling/year KShilling months T/year

1. Reduce blow down 15.16 94 200 100 000 12 7

2. Optimise combustion 516.3 3 207 600 500 000 2 157

3. Install new boiler 168.5 1 046 402 100 000 000 114 51

4. Insulate steam pipes ancillaries 184.68 1 147 230 15 000 000 16 56

5. Drainage assistance on heating devices - 650 000 -

6. Improvement of steam quality - 600 000 -


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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: 6800h for the factory (corrected for different devices) • average steam flow: 250 Kg/h • fuel cost: 6 212K shilling/MWh • steam generation global efficiency: 70% • steam cost: 6735KShilling/T • annual CO2 emissions (84,7 kg/GJ / 304,8 kg/MWh HHV)


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ECM1: Reduce Boiler Blow down Rate Current System Description and Observed Deficiency The plant operates two shell boiler at a steam pressure of 6 bar (g). The average steam load is 0.25 t/h.

Currently, the boiler blow down is controlled by:

- Opening a manual bottom valve 1 or 2 times per day for 30 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 micromhos/cm to

4500 micromhos/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 Boiler

Water Feed Water Blow down %

Conductivity µs/cm 4000 5 to 170 4.4

Silica ppm

Alkalinity ppm

Chlorine ppm


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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.


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Table 1 : Water Chemistry for Firetube Boilers - ASME Guidelines

Recommended Optimization Armstrong recommends to reduce the blow down rate by :

- Increasing the boiler water analysis

- Opening the bottom valve in accordance with the analysis

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

program.

Estimated Investment and Payback Decreasing your blow down rate from 5 to 2.5 % will save 94200 KShilling/yr of fuel.

The CO2 emissions reduction resulting of improving the blow down is 2.35 ton/year Estimated investments: The investment is estimated at 100000 KShilling It is just internal analysis.


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ECM 2: Improve Boiler Combustion Current System Description and Observed Deficiency The plant operates a Shell tube boiler rated for 1T/hour at 6 bar. The average steam generation is 250

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 320

Ambient Temperature °C 30 CO2 % 5,02 Efficiency % 62 Excess Air % 200 O2 % 14,38 CO ppm 0

Technical Discussion Essentials of low excess air boiler operation:

Combustion is a chemical reaction in which a fuel constituent reacts with oxygen and releases its heat

in reaction. As a result, all fuels need oxygen, and the natural available oxygen source is air. However,

air contains nitrogen that has no role in the combustion reaction except absorption of a portion of the

released heat of reaction. Every cubic foot of oxygen brings four cubic feet of nitrogen along with it.

This unwanted nitrogen leaves the boiler stack as a part of the waste flue gases, taking with it a portion

of the heat released from the fuel. Hence, the quantity of unwanted nitrogen has to be kept at a

minimum by controlling the oxygen level in stack gases.

There is an optimum range for O2 in the boiler. Too little will cause inefficiency due to incomplete

combustion, while too much will cause inefficiency due to high exhaust flow rates.


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Recommended Optimisation Armstrong recommends checking the burner and input the correct parameters for the fuel valve and the

air supply damper, so the proper amount of air is used at high and low firing.

Estimated Benefits Lowering the oxygen (excess air) in the boilers flue gas from the observed level down to 9% O2 will

increase the boiler efficiency from 62% to 81% and will save KShilling 3207600 annually. The savings

are calculated based on 2010 annual fuel consumption and the respective calculated efficiencies.

Existing Proposed Savings Steam Generation Kg/h 250 250 same Excess O2 % 14 9 5 Flue Stack Temperature 320 280 40 Boiler Efficiency (HHV) 62 81 19Operating Time h/year 7000 7000 same Fuel Consumption Mwh/year 2201,3 1685,0 516,3 Fuel Cost K Shilling/year 13674500 10466900 3207600 CO2 emissions t/year 670,95 513,59 157,36

The CO2 emission reduction from burner maintenance is 157 metric tons/year..

Estimated Investment and Payback

The investment is estimated at K Shilling 500000. It includes:

• Boiler tuning

• Spare parts

• Labor for installing the spare parts

• The payback of this installation is expected to be 2 months.


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ECM 3: Replace Likoni boiler by a new boiler Current System Description and Observed Deficiency The plant operates a Shell tube boiler rated for 1T/hour at 6 bar. The average steam generation is 250

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

analysis are as follows:



On the Dakar boiler, after burner maintenance, the new combustion analysis was



Technical Discussion The two boilers are old. The design are not the best to obtain very high efficiency, single passe and

reverse flame boilers.

The stack temperature is high and can’t be reduced. The chimney on the Dakar boiler is too small and

the pressure drop of the economizer damages the combustion.

The boiler insulation is not efficient anymore.

There is no sensor to control the combustion


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Recommended Optimisation Armstrong recommends to remove the Likoni boiler and use a more efficient one.

We suggest the installation of a new small boiler (800Kg/h is enough) that will be used as often as

possible.

Estimated Benefits By using a new boiler with 91% combustion efficiency instead of the Likoni boiler, you can save 1046402 KShilling/year which can be add to 3207600 KShilling/yearfrom ECM2 .

Existing Proposed Savings Steam Generation Kg/h 250 250 same Excess O2 % 9 4 5 Flue Stack Temperature 280 200 80 Boiler Efficiency (HHV) 81 91 10Operating Time h/year 7000 7000 same Fuel Consumption Mwh/year 1685,0 1516,5 168,5 Fuel Cost K Shilling/year 10466900 9420498 1046402 CO2 emissions t/year 513,59 462,22 51,37

The CO2 emission reduction from burner maintenance is 51 tons/year

Estimated Investment and Payback

The investment is estimated at 10000000 K Shilling. It includes:

• Boiler

• Chimney

• Installation

The payback of this installation is expected to be 9 years, if we consider the saving of

1046402KShilling, but 2.5 years if we consider the total savings.


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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 28 500 W that is equivalent to a steam loss of about 40 kg/h, more

than 15% of your steam consumption.


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Estimated Benefits ,

Savings calculation Energy loss 28500 W Operating hours 6480 hours Yearly losses 184,680 Mwh/year Fuel cost 6212 KShilling/Mwh Yearly savings 1147230 KShilling /year C02 saving 56,3 T/year

Working on insulation would lead to a saving of 1147230 KShilling /year.

Estimated Investment and Payback Budgetary cost to insulate pipes and add insulated jackets is 1500000 KShilling. It includes:

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

Pay back time is about 16 months.


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ECM5 Improve Condensate Drainage

Current System Description and Observed Deficiency Some heat exchanger or tank (calorifier) have set point at low temperature. The steam pressure could be very low to maintain the temperature.

Technical Discussion The latent heat of steam is increasing when the pressure decreases.

− 2201KJ at 1 bar − 2108Kj at 4 bar

Heat transfer increases when low steam pressure is used (+4.4% in the example) . Condensate at about 60°C is locally drained due to stalling condition and insufficient condensate pressure.

Recommended Optimization It is recommended to either install a double duty or pump trap combination to pump out The condensate from PHE is efficient at any percentage of valves openings. Below is a schema with Double duty pump trap.


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An air vent on the dead end of temperature control valve outlet steam supply line is required It should be installed preferably on horizontal run of pipe at end. In the above arrangement, one can connect pump trap vent line to either steam inlet:

- header dead end after temperature control valve near air vent (preferred location) or

- condensate reservoir as shown above. This arrangement requires a filling head of at least 300mm from pump trap top to heat exchanger drain point. This requires either having a pit for pump trap or lifting this PHE.

This pump will discharge condensate to existing condensate recovery line.

Estimated Benefits

This will decrease your steam consumption by 4%

Savings calculation Energy consumed 30 KW Operating hours 2000 hours Yearly consumption 60 Mwh/year Yearly saving 2,4’ Mwh/year Fuel cost 6212 KShilling/Mwh Yearly savings 15000 KShilling /year C02 saving 0,73 T/year

Estimated Investment and Payback The Budgetary cost to install a Double duty pump with all equipment (Air vent, drip leg at motive stealm line). Is estimated at 650000 KShilling It includes:

• equipments supply • Installation


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ECM6: Installation of properly sized drain pocket and traps on inlet of plant steam control valves, ejectors and headers

Current System Description and Observed Deficiency 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. In seasoning section, 6 nos. ejector steam supply

headers do not have proper drain pocket and drain traps.

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


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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 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.

Recommended Optimization 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 600000

Kshilling,

It includes:

• Installation of 6 properly sized drain pocket

• Installation of 6 steam trap stations with connector and integral blow down valve.


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4 Complete check list of all verifications done during the audit

Potential optimisation Status Comments

STEAM GENERATION Steam pressure setting ok 6 Bar(g) Maximum boiler pressure Feed water temp. to the boilers ok Stack temperature Not ok 3 passes boiler will be better Combustion air temperature ok Ambient temperature is high Oxygen rate Not ok Dakar chimney to small Boiler sizing Not ok Boilers are oversized. Boiler blow down rate Not ok No daily control 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 Boiler stand-by time and volatility of steam demand

ok 1 boiler only in service

Boiler blow-down recovery ok Too small blowdown STEAM DISTRIBUTION

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

ok Ok, system is generally well maintained

System design, trapping points etc. ok The general design of the system is good and trapping points, separators etc are generally fitted where required.

Insulation Not ok No Insulation on steam equipments. Steam quality poor Blocked (orifice) steam traps on drips and

separators compromise steam quality. High risk for erosion, corrosion and water hammering issues.

Steam pressure level Not ok Distribution lines ok but some steam users have no PRV


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Potential optimisation Status Comments

STEAM USERS Condensate drainage and air venting from heat exchangers

Not ok Orifice traps combined with modulating controls on heat exchangers form potential H&S risk. Closed loop pumping trap arrangements for heat exchangers in a stall condition must replaced orifice traps

Steam traps Not ok See trap survey results. Orifice traps appear to block up regularly on site and some other are leaking in process application.

CONDENSATE AND FLASH STEAM RECOVERY Condensate recovered ok Condensate return rate is correct. Condensate

return is collected locally in buildings and returned to the boiler house whenever possible.

Sizing of condensate return lines ok Flash steam recovery ok No process with high temperature set point. Water hammering ok No water hammering observed;


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5 Steam / Condensate Network

5.1 Steam Production

Water treatment Make up water is mixed with condensates in injection in the feed tank. 3 condensate lines are connected to the feed tank.

Feed tank

We have recorded temperature on inlet water pipe just in front of the Boilers pumps. A correction in temperature of 7 to 8°C has to be done on values recorded.


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Inlet water boiler ”Likoni” – September 7th afternoon and September 8th morning The temperature decreases during the night when the process is stopped.

Inlet water boiler ”Dakar”- September 8th afternoon, September 9th all day, September 10th morning The boiler was out of service during the night, the water temperature goes down during this period. When the process is working, the inlet water temperature is between 60°C and 70°C.


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It could be higher if you reduce slightly the make- up water by reducing the start up bottom blow down and repairing the sub cooling steam traps There was no flash at the vent of the feed tank.

Steam generation Steam production, at 6 bar, is handled by 2 fire tubes Perkins Patomatic boiler.

Each boiler has a nominal capacity of 2,000 lb/hr (907 kg/hr) and is fitted with a Nu-Way burner burning light fuel oil with high/low/off modulation. The boiler “Dakar” is a reverse flame dry back construction The boiler “Likoni” is a single pass construction.

r Dakar Likoni You had never done any “Combustion efficiency measurement” before March 2010. You found a very bad combustion analysis for the “Dakar boiler”. The excess air was very high, more than 400% at low flame and more than150 % at high flame. You made other analysis in August and the value was always very bad.


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Following the analysis, carried out by Energy Pak company, you replaced one solenoid valve and one fuel injector. The first day, this maintenance operation gave a good optimisation, but a problem occurred during the night and you have never obtained a good result since then. The result of the combustion analysis is on table below. date 08/09/2010 08/09/2010 09/09/2010 10/09/2010 10/09/2010

before modification after first

modification new solenoide

valve new calibration new calibration Flame HIGH LOW HIGH LOW HIGH LOW HIGH HIGH LOW LOW HIGH

T amb °C 29,6 30,1 30,6 29,6 32,6 32,2 32,4 30,8 30,8 33,1 34,4T gas °C 270 241 342 189 266 188 269 285 220 238 266O2 V% 14,9 19,4 15,7 6,6 9 7,7 11,7 11,9 8,6 9,6 11,8CO PPM 7 689 16 102 2 661 1838 1034 4CO2 V% 4,5 1,2 3,9 10,6 8,8 9,7 6,8 6,7 9,1 8,4 6,7CO‐0% PPM 24 9185 65 180 4 1522 3115 1905 10Qa % 28,5 92,5 42,5 8,6 14,9 9,1 18,9 20,7 11,7 13,7 18,8Eta % 71,5 7,5 57,5 91,4 85,1 90,9 81,1 79,3 88,3 86,3 81,2Lambda 3,44 4 1,46 1,75 1,58 2,25 2,3 1,69 1,84 2,2T dew P °C 26 23 43 39 41 34 34 40 38 34

These modifications were made during the audit, the 02 after modification decrease, but some leaks appeared inside of the burner, and after new maintenance operation and the replacement of the solenoid valve, you never obtained the good analysis. The CO value is always too high. During our audit, another specialist has been contacted in order to check again the burner. It was important to obtain the same parameters as September 8th afternoon.

Energy recovering systems The Dakar Boiler has an economiser installed in the chimney. This economiser heats a first time the water of the calorifier, and after the feed-tank. You have decided to stop the water loop. A problem occurred because you didn’t drain the economiser. As consequence, the energy from the stack vaporises the water and there is a stress in the tube and risk of leaks.


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This economiser was installed some months ago but the height of the chimney has not been modified. It could be the reason of a bad combustion. The building just behind the boiler house is higher than the chimney and limits air velocity. The suction is not good. Regarding the flue gas temperature, we installed a probe in the chimney in order to get information about the ratio in low, high or off fire. The result of the recorder is in graphs below.


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Red curves show the Likoni Boiler flue gas temperature. Each graph covers a period of 06 hours. 1st period: September 7th (between 1.00 pm and 7.00 pm): the burner started 11 times per hour. There was small steam consumption 2nd period September 8th (between 7.00 pm and 1.00 pm): you used more steam during 15 minutes (just before 8.00 pm) and during 35 minutes (between 8.40 pm and 9.15 pm). After that, the burner started 10 times per hour. 3rd period September 8th (between 1.00 am and 7.00 am,): you used more steam during 30 minutes (1.30Aam and during 7 minutes (after 2.00 am) After that, the burner started 8 times per hour, then 09 times per hour.


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Blue curves show the Dakar Boiler flue gas temperature. Each graph covers a period of 06 hours. 1st period: September 8th (between 1.00 pm and 7.0 0pm): the burner started at 3.30pm during 2.30 hours. 8 start-up per hour, then modulating between low and high flame during 20 minutes; then 30 minutes no flame and another 15 minutes modulated. There was steam consumption when the burner modulated. 2nd period, September 9th (between 7.00 am and .1.00 am) you used steam during 45 minutes just after 8.30am. After that, the burner started 8 times per hour. 3rd period, September 9th, (between 1.00 pm and 7.00 pm), you used steam during 40 minutes at 1.40pm. After that, the burner started 8 times per hour, and then you stopped the burner. 4th period, September 9th (between 7.00pm and 10 September 1 AM the burner started 7 times per hour, then we modified the range of the pressure switch, the burner started 6 times per hour, then you stopped the burner. 5th period, September 10th (between 1.00 pm and 4.30 pm): you used steam 40 minutes at 2.00 pm, before and after this period, the burner started 8 times per hour.


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We will compare the situation before and after modification of the set range.

Before modification

After modification


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The burner runs longer and the number of start-up decreases. You will reduce the pre venting of the combustion and increase the global efficiency. The stack temperature and the excess air are lower at low flame, the global efficiency in this new configuration is better. Howether, when we analyse all the curves, we observe that the boiler capacity is higher than the steam demand. You have some peaks of consumption during maximum 40-45 minutes, when you heat tanks for production or CIP. If you install a new boiler, we recommend you to sellect a lower capacity, closer to your peak demand.


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BOILER EFFICIENCY COMPARISON

Boiler 1 is Likoni Boiler with very high stack temperature. Boiler 2 is Dakar Boiler before modification, with high excess air and high stack temperature Boiler 3 is Dakar Boiler after modification, with medium excess air and medium stack temperature.


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With a new 3 passes boiler with modulating burner, it would be possible to obtain a global efficiency of about 87%.


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Boilers blow down Blow downs are handled by bottom manual valves. The valve is opened a few seconds each day, not necessarily related to the water analysis. You could decrease a little your blow down with daily analysis. A too high blow down rate results in energy losses, a too low rate can have consequence on the quality of steam. Actually, Johnson Diversey Company carry out a water analysis each month. The TDS value of the feed water was very strange, minimum 5.34 PPM in February, maximum 1325 PPM in January. We recommend to carry out water analysis each day per your laboratory.


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Steam-water-fuel flow graph

You note each day the quantity of fuel, steam and water used. You indicate also the running time of the boiler. This chart summarizes the value between April and September. Make-up water consumption is between 1.5 and 4m3/day Steam consumption is about 7T/day in April and May and 4.3T/day in June, July and August. Fuel consumption is about 690l/day in April and May and 510l/day in June, July and August. The ratio Kg steam/l fuel decreased since beginning of June, when the consumption is lower. You used the Likoni Boiler more than 50% during this period. The % of condensate returns is about 55% calculated only when the Dakar Boiler is in service. It seems very low if we consider that you have no direct injection in the product. Note: The steam flow meter is only installed on the Dakar pipe. The accuracy is not very good, the small vibration of the line (when the burner starts) increases the measured flow.


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We proposed to modify the installation.

Modification:


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5.2 Steam distribution Steam is delivered to the different process from the main header in the Dakar boiler house.

None of the valve is insulated. A large quantity of energy is lost by radiation. We have calculated the global losses of the ancillaries steam equipments. You will find the chart in appendix. 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 Nutrition area - One line DN 65 at 6 bar to Liquids Manufacturing and Packaging area - One line DN 65, then 25 at 6 bar to the Kitchen

You have drip legs on the different line with Gem steam traps. We have calculated the maximum flow that can be delivered at 6 bar pressure.


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You can deliver 775 kg/h of 6 bar steam in the DN50 pipe, with a velocity of 30m/s. You can deliver 195 kg/h of 6 bar steam in the DN25 pipe, with a velocity of 30m/s. Your steam pipes are correctly designed considering the steam flow recorded. . 5.3 Steam consumers The site is divided in several buildings:

• Nutritionals • Liquid manufacturing and packaging • Kitchen

Operating hours depends on each building but generally the boiler house runs 24h/24h, 6 days/week, 45 weeks/year.


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Steam is mainly used for:

Area Equipment

Nutritionals Grangemouth Bottle Washer APV Pasteurizer

CIP Machine

Mixing Tank No. 1 and No. 4

Tetrapack Steri-drink pasteurizer TBA filling machine

Purified water Sec Loop Tank Heat Exchanger and Primary Loop Carbon Filter

Oral Care Manufacturing CIP Machine (awaiting commissioning) Liquids Manufacturing and Packaging

Miraclean Bottle Washer

1000 litres Manufacturing Tank 3000 litres Manufacturing Tank

Granulation Aeromatic Fluid Bed Drier (not in service) Laboratories Hot water Calorifier (not in service)Kitchen and changing rooms Hot Water Calorifier Boiling pans and servery


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5.3.1 Nutrition area The 6 bar line feeds a PRV station protected by a strainer and a separator.

None of the ancillaries is insulated. It is the same for each process equipment. This PRV station feeds:

• Grangemouth Bottle Washer no more in service


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• APV Pasteurizer

This heat exchanger is only used per batch during production. The set point is 96°C. A second PRV station reduces the pressure to feed this exchanger at 3 bar. The operator opens the drain valve during the start-up to obtain quickly the temperature. The heat exchanger is full of condensate when the process is stopped. There is a risk of water hammer at start up. This pasteurizer is designed to heat 1900l/h of product from 27°C to 97°C. The steam pipe DN 20 can’t delivered the design flow (260kg/h) but only 85kg/h CIP Machine

This exchanger is only used per batch during cleaning application. The set point is 85°C. A PRV station reduces the pressure to feed this exchanger at 4 bar.


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There is no control valve. The operator opens the pneumatic valve to obtain quickly the temperature. This exchanger is designed to heat 200l of water from 25 to 85°C in 10 minutes. The nominal steam flow to do this is 140kg/h. The pipe and ancillaries are oversized, they can deliver more than 330kg/h. This heat exchanger is drained per a Float steam trap. Mixing Tank No. 1 and No. 4

These tanks are only used per batch to heat water during process application. The set point is 65°C. A PRV station per tank reduces the pressure to 4 bar. There is no control valve and no drip leg to protect the PRV. The operator opens the valve to obtain the temperature. The temperature information is a thermometer with bulb. The sensors are in pocket, not empty of conduct fluid. The reading temperatures are not correct. This application is designed to heat 700l of water from 25 to 65°C in 20 minutes. The nominal steam flow to reach that is 165kg/h, the pipe and ancillaries are correctly designed. If you increase the time to obtain the temperature, you will go beyond the set point. If you put more water, you must increase the time to obtain the set point.


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Tetrapack Steri-drink pasteurizer

This exchanger is only used per batch during production. The set point is 92°C. A PRV station reduces the pressure to feed this exchanger at 4 bar, but the bypass valve is opened. This pasteurizer is designed to heat 4000l/h of product from 30 to 90,. In fact you maintain a loop at 92°C, and the steam flow is around 50kg/h. The steam pipe DN 25 can deliver only 200kg/h.


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TBA filling machine

Steam is just used for sterile barriers after a PRV station at 2 bars. It seems that the Gem steam trap is installed after one TLV float trap! The steam consumption is very low.

Purified water Sec Loop Tank Heat Exchanger

This exchanger is only used per batch to heat water for CIP. The set point is 85°C. A PRV station reduces the pressure at 3 bar. There is no drip leg to protect the PRV. This application is designed to heat 2000l of water from 25 to 85°C in 30 minutes. The nominal steam flow to do reach that is 470kg/h. The pipe and ancillaries are correctly designed. The process steam trap is a float trap. This application can be the most important instantaneous steam consumer.


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Primary Loop Carbon Filter

Steam is injected in the vessel for regeneration Condensate is drained to the sewer. This application works very short time in a year.

5.3.2 Carbon dioxyde tank room CO2 heat exchanger

This exchanger is only used per batch to heat C02. The set point is 30°C. A PRV station reduces the pressure to feed this exchanger at 4 bar, but it doesn’t work. There is no control valve and no drip leg. The operator opens the inlet valve to obtain the temperature.


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The drain connection top and bottom are connected on the same pipe to the steam trap. Normally the top connection must lead to an air vent. The nominal steam flow is 150kg/h, the pipe and ancillaries are correctly designed. This heat exchanger is drained per a Gem trap that is leaking. For this application with very low set point temperature, it is recommended to put a drainage system working in closed system.

5.3.3 Liquide manufactoring and packaging area Miraclean Bottle Washer no more in service 1000 and 3000 litres Manufacturing Tank

These tanks use 2 bar steam. A PRV station decreases the pressure from 6 to 2 bar. This application is not continuous; you close the valve in front of the PRV after each batch. There is no drain connection before the valve.


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These tanks are only used per batch to heat water during process application. The set point is 65°C. The capacity of the tanks can be half. You heat with one coil or one coil and a jacket. You have no control valve. The operator opens the solenoid valve to obtain the temperature. This application is design to heat 500-1000-1500-3000l of water from 25 to 65°C in 20 minutes. The nominal steam flow to reach this is 116- 232- 348- 696kg/h. The pipe is undersized to carry more than 400 kg/h. For high capacity, you must increase the time to obtain the temperature. The process Gem traps are oversized and are leaking in normal condition. The condensate from this area is collected in an Ogden pump. This pump has a small leak at the motive and vent valve.


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Ogden pump with a small leak at the vent pipe.

Process Steam traps are leaking.

5.3.4 Oral care manufacturing One connection in the liquid manufacturing pipe feeds this area.

CIP Machine not yet in service.

PRV Station


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The outside connection of the steam trap must be at the upper part of the condensate line to avoid water hammering.

The steam trap is installed upside down. You must turn top to the bottom. There is no drip leg in front of the process at low point.


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5.3.5 Kitchen and changing room The processes in the Kitchen are very small consumers working few hours per day.

• 2 Boppos cooking vessels and 2 shelves. • a PRV station decreases the pressure at 1 bar.

Hot water clarifier

This tank is heating water for sanitary application. The set point is 60°C. A PRV station reduces the pressure at 2 bar. It is controlled by a thermostatic control valve. There is no drip leg to protect the PRV. The coil was flooded and the condensate temperature was around 60°C. It could be interesting to put a double duty pumping trap to use steam under vacuum.


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5.3.6 Granulation area Building in construction

Aeromatic Fluid Bed Drier

Steam is using, after a PRV station, to heat air for the drier. This installation was not in service. There is no drip leg to protect the PRV.

5.3.7 Laboratories

Hot water calorifier

This tank is heating water for sanitary application. The set point is 60°C. A PRV station is installed after the control valve, it can’t work correctly. The temperature is controlled per a thermostatic control valve. There is no drip leg to protect the control valve.


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APPENDIX

- Steam flow calculation - Efficiency calculations - Radiation losses calculation - Misassemble - Steam trap survey


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Steam flow calculation. We calculate the steam flow of the differents process by 2 methods: Velocity of 30m/s in the inlet pipe and energy calculation

The last column is the maximum flow possible available with the two calculations


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Efficiency calculations


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Radiation losses calculations


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Misassemble

Missing drip leg :

Glucose room

Add pipe with valve to drain line at start up. The pipe can be connected to the drip leg

Put drip leg


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Liquid manufacturing area

Add pipe with valve to drain line at start up. The pipe can be connected to the drip leg


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Reverse osmosis room

Calorifier

Add drip leg

Add drip leg


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Calorifier

Bed drier

Add drip leg

Add drip leg


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CO2 room Bad erection

Add drip leg


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Oral care CIP

Turn the steam trap up side down The nut must be at the top.


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Boiler room The flow meter must be support to avoid vibration.


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All steam strainers must be turn by 90° .


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Steam trap survey

nairobi, kenya steam and condensate audit 11253-ser2 …...oct 04, 2010 · kg/hr. a combustion...

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