GSK Manufacturing
Alcala de Henares, SPAIN
STEAM AND CONDENSATE ENERGY AUDIT REPORT
PROJECT N° 30284
1 Emission E. Morin R. Ivanov 06/04/2011 Item Description Established Checked out Date
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
Page 2 of 46
To the attention of MM. Lopez and De Peña Established by E. Morin
TABLE OF CONTENTS
1 Executive summary ................................................................................................................... 4
2 Steam budget and summary of potential savings ...................................................................... 6
3 Optimisation project n°1: Improve energy production efficiency in the boiler house .................. 8
3.1 CURRENT SITUATION .............................................................................................................................. 8
3.2 OPTIMIZATION ....................................................................................................................................... 8
3.3 SAVINGS CALCULATION .......................................................................................................................... 9
3.4 INVESTMENTS ...................................................................................................................................... 10
4 Optimisation project n°2: Reduce steam pressure on Hot Water heat exchangers + install a
pumping trap ................................................................................................................................... 11
4.1 CURRENT SITUATION ............................................................................................................................ 11
4.2 OPTIMIZATION ..................................................................................................................................... 12
4.3 SAVINGS CALCULATION ........................................................................................................................ 13
4.4 INVESTMENT ........................................................................................................................................ 14
5 Optimisation project n°3: Improve steam ancillaries insulation ............................................... 15
5.1 CURRENT SITUATION ............................................................................................................................ 15
5.2 OPTIMIZATION ..................................................................................................................................... 16
5.3 SAVINGS CALCULATION ........................................................................................................................ 16
5.4 INVESTMENTS ...................................................................................................................................... 16
6 Optimisation project n°4: Isolate the old condensate return line ............................................. 17
6.1 CURRENT SITUATION ............................................................................................................................ 17
6.2 OPTIMIZATION ..................................................................................................................................... 18
6.3 SAVINGS CALCULATION ........................................................................................................................ 19
6.4 INVESTMENT ........................................................................................................................................ 20
7 Summary of deviations noticed during the audit ...................................................................... 21
7.1 STEAM GENERATION ............................................................................................................................ 21
7.2 STEAM DISTRIBUTION ........................................................................................................................... 21
7.3 STEAM USERS ..................................................................................................................................... 23
7.4 CONDENSATE RETURN ......................................................................................................................... 25
8 Complete check list of all verifications done during the audit ................................................... 27
9 Recommended complementary studies................................................................................... 29
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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9.1 ADDITIONAL ENERGY-SAVING OPTIMISATIONS ........................................................................................ 29
9.2 ADDITIONAL OPERATIONAL OPTIMISATIONS ............................................................................................ 31
10 Appendix N°1: Determination of the 2010 boiler house efficiency ............................................ 32
11 Appendix N°2: Steam consumption calculations – all users .................................................... 36
11.1 DESIGN DATA ...................................................................................................................................... 36
11.2 REAL CONSUMPTION SIMULATION (MAXIMUM) ........................................................................................ 37
11.3 REAL CONSUMPTION SIMULATION (MINIMUM) ......................................................................................... 39
12 Appendix N°3 : Steam Pressure Controlled Heat Exchangers at Low Load ............................. 41
12.1 CURRENT SITUATION ............................................................................................................................ 41
12.2 OPTIMIZATION ..................................................................................................................................... 44
12.3 SAVINGS ............................................................................................................................................. 46
12.4 INVESTMENTS ...................................................................................................................................... 46
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
Page 4 of 46
To the attention of MM. Lopez and De Peña Established by E. Morin
1 Executive summary
The energy audit conducted from March 21st till March 24th 2011 by Armstrong covers the 4 parts of
the steam loop: boiler house, steam distribution, steam consumption and condensate return.
GSK factory located at Alcala de Henares, in Spain, produces medicines as liquids, tablets and
sachets.
Steam is mainly used by:
- Coils to heat air around 40-60°C in fluid bed dryers and coaters
- Heat exchangers for hot water production at 65°C (sanitary water, HVAC and CIP)
Hot water can also be produced by 2 gas-fired hot water boilers (581 kW each). Generally one boiler
is started during 2 months in winter. The rest of the time, the boilers are stopped.
Steam is distributed at 7 barg from the boiler house.
In some locations, steam pressure is reduced to 4 or 2,5 barg.
Steam is produced by one gas-fired steam boiler (1394 kW – 1,96 tons/hr). You have a second
identical boiler as back-up.
Steam production during the audit was about 450 kg/hr (2 steam users were shut down for
maintenance operations). However we estimate the factory average steam consumption between
600 and 1500 kg/hr depending on the season.
Our calculations based upon data collected during the audit show a 2010 steam price of 37,5 € per
ton and an annual steam budget estimated at 108 400 €.
Some steam and condensate lines are undersized considering design data of steam users.
Insulation of pipes is correct, however several steam ancillaries should be also insulated.
The steam distribution system is under trapped, especially in front of control valves and in “low
point”, resulting in a serious risk of steam leaks caused by corrosion, erosion and water hammering.
All Condensate that could be recovered is sent back to the boiler house using 3 pumping traps units.
Condensate return ratio was calculated to be 91% all over the year.
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
No steam trap survey has been carried out during the audit as it has been done last October. Your
trap population is about 25 traps. 3 of them was reported leaking and 1 was not installed properly
(reversed). You did replace the failed traps recently.
The savings calculated for optimization projects in this report were based upon engineering
assumptions, observations and standard engineering practices.
We estimate the potential energy savings of at least 8% of the estimated steam budget, which
represents a yearly saving of about 170 MWh, 29 tons of CO2 and 8990 €.
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
Page 6 of 46
To the attention of MM. Lopez and De Peña Established by E. Morin
2 Steam budget and summary of potential savings
The boiler house is composed by 4 boilers: 2 identical fire-tubes steam boilers and 2 hot water
boilers.
Most of the time, only one steam boiler is running. The others are stopped except during the coldest
weeks in winter.
Energy metering is being developed but currently the factory has only one gas meter for the whole
boiler house. It is therefore not possible to know the gas consumption for hot water boilers when
they run.
According to data provided for 2010 we estimate:
Boilers steam generation:
• Total yearly steam generation in 2010: 1987 MWh (2890 tons/year)
• Steam cost in 2010 : 54,5 €/MWh (37,5 €/t)
• Total yearly steam budget in 2010 : 108 400 €/year
• Efficiency estimated: 88% (see calculation in appendix n°1)
• Steam cost foreseen in 2011 for same production level : 47,1 €/MWh (32,4 €/t)
Basic data considered:
• Gas unit costs : 41,12 €/MWh hhv for year 2010
35,23 €/MWh hhv since February 2011
• Gas High Heating Value : 42.1 MJ/Nm³
• Water costs :
o 2 €/m³ for city water
o 5030 €/year for Chemicals
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
Steam consumption repartition:
According to operating hours registered for 2010 and estimated steam flows for each user, the
repartition of the consumption for 2010 is the following:
Summary of identified energy-saving optimizations and their estimated yearly results:
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
Page 8 of 46
To the attention of MM. Lopez and De Peña Established by E. Morin
3 Optimisation project n°1: Improve energy production efficiency in the
boiler house
3.1 Current situation
As calculated in appendix n°1, the normal steam production efficiency is estimated at 88%.
There is no heat recovery existing on stacks or blowdown.
Moreover, the steam boiler load is directly affected by the weather as about 56% of steam is
produced for hot water to HVAC.
When outside temperature is getting warmer, the boiler load is decreasing.
When energy demand of steam users is lower than the minimum capacity of the burner, the boiler
starts cycling: the burner stops, steam pressure decreases and when the lower point is reached, the
burner restarts. However during this phase, a period or purging with ambient air inside the fired
tubes is necessary. This purging causes energy losses.
Therefore too much cycling of the burner, due to low load, will decrease the steam production
efficiency.
During summer, we estimate your average steam need for the factory at about 250 kg/hr (see
appendix N°2) which lead to a steam production efficiency loss of 4% (due to cycling losses mainly).
3.2 Optimization
In order to improve the global steam production efficiency, we propose to:
- Use a smaller steam generator (about 850 kg/hr) modulating from 20 to 100% equipped with an
economizer on stacks. Steam production efficiency would be at least 92%
When the steam demand will increase in winter (due to the use of defrosting coils and low
outside air temperature), you can restart the existing steam boiler to increase your capacity.
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
Page 9 of 46
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- Use hot water boilers all over the year to produce hot water for HVAC and Cleaning (Sanitary
water) : 92% efficiency
This configuration will improve the global efficiency of energy production during a major part of the
year.
3.3 Savings calculation
Savings due to the improvement of steam production efficiency during 6 months per year:
SAVINGS CALCULATION for steam generation
Steam production efficiency in summer 84%
Energy demand (factory only) (spring + summer) 385 MWh/year
Corresponding gas consumption 509 MWh hhv/year
Costs 17928 €/year
CLAYTON STEAM GENERATOR efficiency 92%
Energy produced 385 MWh/year
Corresponding gas consumption 465 MWh hhv/year
Costs 16369 €/year
FUEL SAVINGS 1559 €/year
CO2 savings 2,6 t/year
Savings due to the production of hot water with hot water boiler instead of steam boiler:
SAVINGS CALCULATION for hot water generation
Current steam production efficiency 88%
Energy demand (Hot water only) 1.218 MWh/year
Corresponding gas consumption 1538 MWh hhv/year
Costs 54171 €/year
Hot Water boiler efficiency 92%
Energy produced 1.218 MWh/year
Corresponding gas consumption 1471 MWh hhv/year
Costs 51816 €/year
FUEL SAVINGS 2355 €/year
CO2 savings 3,9 t/year
WATER Treatment (chemicals) SAVINGS (estimated) 3000 €/year
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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Total savings for this optimization would be 6900 €/year.
3.4 Investments
The budgetary cost for the optimization is 70 000 €.
This cost includes:
- A New steam generator (Clayton EOG-60, 589 kW, 820 kg/hr) with economizer
- 24 hours self operation
- Installation and commissioning
The second steam boiler currently used as back-up is not necessary anymore therefore the budget
can be reduced by 50% by selling 1 existing steam boiler.
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
4 Optimisation project n°2: Reduce steam pressure on Hot Water heat
exchangers + install a pumping trap
4.1 Current situation
Two shell and tubes heat exchangers, located in the boiler
house, produce hot water at 63°C for HVAC and cleaning
(sanitary water).
These exchangers are fed with 7 barg steam.
We also noticed some slight water hammers in the condensate
return line.
Indeed on the same return line are connected condensate
from both heat exchangers and a drip trap from the 7 barg steam line.
Depending on the load of heat exchangers, condensate can accumulates and cool down at 65°C
while other is hot. This will generates water hammering and risks of damages for the installation.
Temperature measurement on Sanitary hot water exchanger:
Steam boiler shut down – gas failure
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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Red = steam inlet (after control valve) and Blue = condensate outlet (before steam trap)
Temperature measurement on HVAC hot water exchanger:
4.2 Optimization
Considering the temperature setting of hot water, these 2 heat exchangers could be fed by 3 barg
steam.
The latent heat at this pressure is higher than at 7 barg, which allows reducing the steam
consumption for hot water production.
Moreover, as shown in the measurement above, at low load condensate can accumulate in heat
exchangers. To help evacuating this condensate at any operating conditions and avoid water
hammering, several solutions exist (see appendix N°3).
Considering your situation, we recommend to install a mechanical condensate pump as described
below:
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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4.3 Savings calculation
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
This is optimization will save about 2400 €/year.
4.4 Investment
The budgetary cost for the optimization is 4000 €.
Including:
- Installation of 1 pressure reducing valve
- Move of the condensate pump from the Aeromatic dryer technical area to the boiler house
(linked to project n°4).
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
5 Optimisation project n°3: Improve steam ancillaries insulation
5.1 Current situation
Not only for safety reason, must hot surfaces have effective insulation to
prevent excessive heat loss by radiation. The basic function of insulation is
to retard the flow of unwanted heat transfer. There is more chance of part
of steam to condense during distribution if the pipelines are not properly
insulated.
There is a closely interrelated efficiency between boilers and their
distribution systems. The losses occurred in the distribution systems have
a significant impact on boiler operations. When these losses are minimized, boiler plant efficiency is
improved.
We observed some valves on steam lines which are not insulated in your steam distribution system.
The following table shows the non-insulated equipments identified during the audit:
Location Ancillaries length or DN Pressure loss
type number (mm) (barg) (W)
GLATT defrosting coil valve 1 25 7 365
Dryer Aeromatic valve 1 65 7 865
Dryer Aeromatic valve 1 65 7 865
Distribution to factory (new line) valve 2 65 7 1731
Technical area / offices valve 2 65 7 1731
Technical corridor - CIP valve 1 50 7 652
The total radiation loss is calculated at 5844 W.
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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5.2 Optimization
We recommend installing insulated jackets on all ancillaries located in
steam lines above DN25. These jackets are easy to remove in case of
maintenance operations.
5.3 Savings calculation
SAVINGS Calculation
Total radiation losses 5844 W
Operating hours 5232 h
Annual loss (time corrected) 32,5 MWh/yr
Steam production efficiency 88% (lhv)
Annual primary energy loss 36,9 MWh lhv/yr
Annual primary energy loss 41,0 MWh hhv/yr
Fuel cost 35,23 €/MWh
Annual financial loss 1445 €/yr
CO2 emissions 7,5 t CO2/year
Savings calculated are 1445 €/year.
5.4 Investments
Budgetary cost for this project is 2100 €.
Including:
- On site measurement to prepare tailor-made manufacturing of the jackets
- Supply of insulation jackets
Payback time for this optimization is less than 21 Months.
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
6 Optimisation project n°4: Isolate the old condensate return line
6.1 Current situation
During the audit, we could not find any updated drawing with the condensate lines and we were not
able to follow all condensate lines in the factory because some of them were not accessible.
However we suppose the network is the following:
In the factory, there are 3 pumping traps allowing sending condensate back to the boiler house:
- One connected to the coater 350
- One close to the Aeromatic dryer
- One in the technical room near the offices
Depending on the back pressure, condensate can return to the boiler house following 2 ways: the
new connection to the boiler house or the outdoor rack.
AC48
AC350 CIP GLATT
Aeromatic
Boiler house
Pump
Pump
Pump
DN20
DN25
DN25
DN40
DN40
DN25
Outdoor rack
Outdoor ra
ck
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
The condensate pump located in the technical room near Offices needs steam as motive fluid. As
nowadays steam is coming exclusively from the factory and not from the outdoor rack anymore,
several meters of steam line is still in use only for this application.
6.2 Optimization
There is no need to keep 2 ways to send condensate back to the boiler house. Besides it implies a
loss of energy by radiation.
We recommend isolating the condensate return line and the steam line, the closest to the branch
from CIP/GLATT/Coaters line.
The pumping trap located in the technical room near offices can be moved to replace the one close
to the Aeromatic dryer as its capacity is bigger (DN40 against DN25).
AC48
AC350 CIP GLATT
Aeromatic
Boiler house
Pump
Pump
Pump
DN20
DN25
DN25
DN40
DN40
DN25
Outdoor rack
Outdoor ra
ck
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
6.3 Savings calculation
Savings calculation is based on radiation losses by un-needed condensate lines and steam line.
Condensate pipes have been considered with 30 mm insulation and steam pipe with 40 mm
insulation.
Savings would be around 630 €/year.
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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6.4 Investment
The budgetary cost for the optimization is 2600 €.
Including:
- Insertion of isolating valves
- Move of the condensate pump from Offices technical room to the Aeromatic dryer technical
area.
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
7 Summary of deviations noticed during the audit
7.1 Steam generation
Water costs
Considering your city water last invoices and the quantity of chemical products purchased in 2010
for water treatment in the boiler house, the total cost for 1 m³ of treated water is 21,99 €.
This price seems to be really expensive.
With Nalco, you have decided to change the chemical product type, this may help reducing the
amount of chemicals needed and will reduce the treated water costs.
7.2 Steam distribution
Missing condensate drain points
Poor drainage of steam lines will cause accumulation of condensate in the steam distribution
system, especially in “low point”, thus causing a serious safety hazard for water hammering.
Also on some locations there are no drip legs installed on steam lines in front of control valves.
When these valves are in a closed position condensate will accumulate in front of these control
valves, and sub-cool. This sub-cooled condensate is aggressive (low PH) and will cause corrosion
of the valves and piping. Also there is a risk for thermo shock and water hammering. Furthermore
accumulated condensate will compromise steam quality and cause early wear of piping and
ancillaries due to erosion.
Some examples:
Steam distribution – near CIP Mix water/steam- GLATT GSW
Steam distribution – outlet boiler house
Defrosting coil – Coater 350
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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To the attention of MM. Lopez and De Peña Established by E. Morin
Note that if you improve the condensate drainage of steam lines, it will contribute increasing general
condensate return temperature (currently 80°C in the condensate tank). It will therefore improve
your steam production efficiency as feed water temperature entering the boiler will be higher.
Steam line size
From the boiler house, 2 main lines distribute steam to users:
- 1 to feed the 2 heat exchangers to produce hot water, size = DN65
- 1 to feed the users in the factory, size = DN65
Design consumption for the hot water production is 1016 kW or 1780 kg/hr 7 barg steam.
Design consumption for the factory current users is about the same: 1029 kW – 1786 kg/hr 7 barg
steam.
As the table above shows, each steam line is a little bit undersized. This may induce higher pressure
drop and increase noise.
For good operating conditions, steam flow should be less than 1380 kg/hr in each steam line:
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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In winter we estimate the maximum steam consumption for the factory at about 1330 kg/hr and hot
water production should not exceed a steam consumption of 1220 kg/hr if one hot water boiler is
started in the coldest weeks.
In conclusion, the design steam consumption is almost never reached in the existing situation;
therefore no problem is expected till the steam usage is not increased for production reasons.
7.3 Steam users
Steam users in the factory are:
- 2 fluid bed dryers (Glatt WSG360 and Aeromatic)
A first steam coil is used in winter to prevent from freezing and a second coil heats the air between
40°C and 60°C (depending on the recipe).
We noticed a steam leak in the Glatt defrosting coil. It must have been broken during the winter.
The Glatt dryer also use a mixing valve to produce hot water at 65°C for cleaning. This is the only
point of losing condensate. However this equipment is not often used.
The temperature setting point of hot air is quite low: less than 60°C. Thus steam coils may operate
often at low load and the steam pressure after control valves may be below atmospheric pressure
(<100°C). Therefore there will be no driving force (pressure differential) available to push the
condensate out of the coil and move it to the condensate return lines. The condensate will back up
Defrosting coil – Glatt WSG360
Defrosting coil – Aeromatic
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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in the coil and will become flooded. This situation can lead to water hammering. (see appendixes
n°3).
For the Aeromatic dryer the situation is improved by the mechanical
condensate pump. This equipment will help reducing the return line back
pressure and therefore the condensate evacuation.
However for the Glatt dryer we haven’t seen a condensate pump directly
linked to the condensate outlet line.
- 2 coaters (48 and 350)
Coaters also use 2 coils to heat outside air (defrosting and heating).
The temperature setting range is the same as the dryers. Therefore same flooded situations may be
observed.
The coater 350 (Manesty) steam system is equipped with a mechanical condensate pump but not
the coater 48 which is directly linked on the condensate main return line.
On the coater 48, we also noticed that condensate from the 2 coils is drained by the same trap.
Depending on the load of the 2 coils, this configuration may generate condensate accumulation and
water hammering. Each coil fed by a different control valve should be trapped by a specific steam
trap.
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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- 1 CIP unit with air dryer
This unit is used by a cleaning cabin. CIP water at 60°C is spayed in the
cabin for cleaning and hot air (80°C) is then blown for drying.
The water is heated by a vertical tube and shell heat exchanger.
A vertical heat exchanger always works flooded, thus condensate may be at
low temperature (close to the product setting temperature) and some water
hammering in condensate return lines can be generated.
7.4 Condensate return
Condensate lines size
Considering the design steam consumption, we think that some condensate lines are undersized.
Indeed condensate line from CIP, coaters and Glatt is in DN25 for 1400 kg/h condensate. If we
consider a low steam pressure after control valves (1 barg), the calculation is the following:
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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It will increase the back-pressure in condensate line of minimum 22 mm WC per meter of pipe.
However, considering the current situation, this undersized design will not disturb your condensate
system.
Pumping trap Coater 350
The piping configuration on the pumping trap near the coater 350 is the following:
The pumping trap is not working at atmospheric pressure as the equalizing line is connected to the
condensate inlet.
This configuration works, however we would recommend moving the 2 condensate lines from drip
traps to the main return line after the bypass valve. Indeed the equalizing line should never be
flooded in order to assure the pumping trap cycling.
STEAM 2.5 bars
CONDENSATE
CONDENSATE RETURNDrip trap
Coater coil
Coater coil
Drip trap
Equalizing line
Pumping
Trap
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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8 Complete check list of all verifications done during the audit
Potential optimisation Status Comments
STEAM GENERATION
Steam pressure setting OK Maximum steam pressure setting for the boiler is
13 barg. Operating at 7 barg is a good
compromise. Operate at lower pressure may lead
to risk of carry-over in the boiler
Feed water temp. to the boilers To be improved Measured temperature of feed water entering the
boiler is only 70°C. It should be around 80-90°C
minimum.
Stack temperature in front of
economizer
To be improved Stacks temperature is between 180 and 230°C.
Stack temperature after economizer NA There is no economizer to recover energy from
stacks.
Combustion air temperature OK Ambient air in the boiler house.
Oxygen rate OK Between 3 and 6% depending on the firing rate.
Boiler sizing To be improved Refer to project 1
Boiler blow down rate OK Reported to be around 3% the last 2 months
Deaerator pressure NA
Feed-water pre-heating NA
Boiler stand-by time and volatility of
steam demand
To be improved At low load (specially in summer time),boiler
efficiency may be decreased by 5%
Boiler blow-down recovery NA
STEAM AND CONDENSATE AUDIT
Project N°30284
GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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STEAM DISTRIBUTION
External leaks of steam or condensate
from pipes, flanges, etc.
OK No important leaks have been observed.
System design, trapping points etc. To be improved Missing drip legs in “low points”
Insulation OK Few valves should be insulated also
Steam quality To be improved Add some drainage point on steam lines will help
improving steam quality
Steam pressure level OK
Water hammering OK
STEAM USERS
Condensate drainage and air venting
from heat exchangers
OK
Steam traps To be improved 5 traps were not tested during the last trap survey.
Steam traps should not be insulated.
CONDENSATE AND FLASH STEAM RECOVERY
Condensate recovered OK
Sizing of condensate return lines To be improved
Flash steam recovery NA
Water hammering To be improved Water hammers have been observed in
condensate line from the hot water heat
exchangers in the boiler house
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Date: 06/04/2011
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9 Recommended complementary studies
9.1 Additional energy-saving optimisations
Replace steam by hot water:
The highest temperature needed by current steam users is 80°C, but most of temperature settings
are about 60°C. Therefore the usage of 7 barg/170°C steam is questioned.
As heating fluid, hot water at 80-90°C could be sufficient.
Moreover your factory already owns 2 hot water boilers.
Hot water production efficiency by these boilers is about 92%. By using steam, it is maximum 88%.
For the same energy production, savings would at least 4% on gas consumption +make-up water
consumption and chemicals :
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This is only energy savings. Remove steam will also lead to maintenance savings.
However, a problem of design needs to be highlighted. Hot water boilers capacity is 581 kW each,
which means a maximum energy production of 1162 kW.
If we gather all design data from current steam users, the sum of energy needed is about 2045 kW.
If we do the same calculations but with real temperature settings, the result is closer to the hot water
boilers capacity but still higher (1226 kW), especially in winter time (Refer to appendix N°2 for
calculations).
In conclusion the current design of hot water boilers is not sufficient to replace steam. A third hot
water boiler would be necessary.
Besides, to get rid of steam in the factory also implies to:
- replace all steam coils by hot water coils in coaters and dryers
- install a new hot water network distribution with several pumps
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9.2 Additional operational optimisations
Flooded heat exchangers:
Poor drainage of condensate from low temperature controlled heat exchangers could have an
impact on productivity (decreased heat exchange surface and unstable heating temperature) and on
maintenance (leaking heat exchangers due to corrosion and water hammering). The reasons for this
phenomenon and possible solutions are described in details in appendix 3. Almost all anti-freezing
coils on dryers and coaters equipments are operating under these conditions. In case flooding of
heat exchangers starts creating important productivity and maintenance problems, we recommend
studying in more details the best solution for each concerned heat exchanger.
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GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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10 Appendix N°1: Determination of the 2010 boiler house efficiency
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Date: 06/04/2011
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GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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STEAM AND CONDENSATE AUDIT
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GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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STEAM AND CONDENSATE AUDIT
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GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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11 Appendix N°2: Steam consumption calculations – all users
11.1 Design data
TOTAL Steam consumption 3567 kg/hr 2045 kW
Fluid bed dryer Aeromatic
Fluid bed dryer GLATT
Design data
Estimation design
defrosting coil 31,35 kW
defrosting coil 30 kW
steam pressure 7 barg
steam pressure 7 barg
steam consumption 55,1 kg/hr
steam consumption 52,7 kg/hr
air flow 10000 m³/h
air flow 2700 m³/h
estimated design delta T 60 °C
estimated delta T 60 °C
Energy needed 184,9 kW
Energy needed 49,9 kW
steam pressure 4 barg
steam pressure 4 barg
steam consumption 315,8 kg/hr
steam consumption 85,3 kg/hr
Total steam consumption 370,9 kg/hr
Total steam consumption 138,0 kg/hr
Coater 350
Coater 48
Design data
Estimation
defrosting coil 33 kW
defrosting coil 33 kW
steam pressure 2,5 barg
steam pressure 4 barg
steam consumption 55,3 kg/hr
steam consumption 56,4 kg/hr
Heating coils (2) 176,0 kW
air flow 7040 m³/h
air flow 4000 m³/h
estimated delta T 80 °C
estimated delta T 80 °C
Energy needed 173,6 kW
Energy needed 98,6 kW
steam pressure 2,5 barg
steam pressure 4 barg
steam consumption 290,9 kg/hr
steam consumption 168,4 kg/hr
Total steam consumption 346,3 kg/hr
Total steam consumption 224,8 kg/hr
CIP unit
Hot Water Production HVAC
Design data
Water flow 37,5 m3/h
Heat exchanger 348 kW
Temperature IN 40 °C
steam pressure 7 barg
Temperature OUT 60 °C
steam consumption 612,5 kg/hr
Energy needed 871 kW
Dryer (coil) 46,4 kW
steam pressure 7 barg
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air flow 1884 m³/h
steam consumption 1531,2 kg/hr
estimated delta T 80 °C
Energy needed 50,2 kW
Hot Water Production Sanitary
steam pressure 7 barg
Water flow 2,6 m3/h
steam consumption 88,3 kg/hr
Temperature IN 15 °C
Total steam consumption 700,8 kg/hr
Temperature OUT 63 °C
Energy needed 145 kW
steam pressure 7 barg
steam consumption 255,2 kg/hr
11.2 Real consumption simulation (maximum)
TOTAL Steam consumption 2129 kg/hr WINTER 1226 kW
TOTAL Steam consumption 1182 kg/hr SUMMER 685 kW
Fluid bed dryer Aeromatic
Fluid bed dryer GLATT
Design data
Estimation
defrosting coil 31,35 kW
defrosting coil 30 kW
steam pressure 7 barg
steam pressure 7 barg
steam consumption 55,1 kg/hr
steam consumption 52,7 kg/hr
air flow 10000 m³/h
air flow 2700 m³/h
estimated delta T 50 °C
estimated delta T 50 °C
Energy needed 154,1 kW
Energy needed 41,6 kW
steam pressure 4 barg
steam pressure 4 barg
steam consumption 263,2 kg/hr
steam consumption 71,1 kg/hr
Total steam consumption 318,3 kg/hr
Total steam consumption 123,8 kg/hr
STEAM AND CONDENSATE AUDIT
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Date: 06/04/2011
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Coater 350
Coater 48
Design data
Estimation
defrosting coil 33 kW
defrosting coil 33 kW
steam pressure 2,5 barg
steam pressure 4 barg
steam consumption 55,3 kg/hr
steam consumption 56,4 kg/hr
Heating coils (2) 176,0 kW
air flow 7040 m³/h
air flow 4000 m³/h
estimated delta T 50 °C
estimated delta T 50 °C
Energy needed 108,5 kW
Energy needed 61,6 kW
steam pressure 2,5 barg
steam pressure 4 barg
steam consumption 181,8 kg/hr
steam consumption 105,3 kg/hr
Total steam consumption 237,2 kg/hr
Total steam consumption 161,6 kg/hr
CIP unit
Design data
Hot Water Production HVAC winter
Heat exchanger 232 kW
Water flow 37,5 m3/h
steam pressure 7 barg
Temperature IN 53 °C
steam consumption 408,3 kg/hr
Temperature OUT 63 °C
Dryer (coil) 46,4 kW
Energy needed 435 kW
air flow 2153 m³/h
steam pressure 7 barg
estimated delta T 70 °C
steam consumption 765,6 kg/hr
Energy needed 46,4 kW
steam pressure 7 barg
Hot Water Production HVAC summer
steam consumption 81,7 kg/hr
Water flow 37,5 m3/h
Total steam consumption 490,0 kg/hr
Temperature IN 62,5 °C
Temperature OUT 63 °C
Hot Water Production Sanitary
Energy needed 22 kW
Water flow 0,33 m3/h
steam pressure 7 barg
Temperature IN 15 °C
steam consumption 38,3 kg/hr
Temperature OUT 63 °C
Energy needed 18,5 kW
steam pressure 7 barg
steam consumption 32,5 kg/hr
STEAM AND CONDENSATE AUDIT
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GSK MANUFACTURING Alcala, Spain
Date: 06/04/2011
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11.3 Real consumption simulation (minimum)
TOTAL Steam consumption 1205 kg/hr WINTER 725 kW
TOTAL Steam consumption 751 kg/hr SUMMER 465 kW
Fluid bed dryer Aeromatic 249
Fluid bed dryer GLATT
Design data
Estimation
defrosting coil 15,68 kW
defrosting coil 15 kW
steam pressure 7 barg
steam pressure 7 barg
steam consumption 27,6 kg/hr
steam consumption 26,4 kg/hr
air flow 10000 m³/h
air flow 2700 m³/h
estimated delta T 20 °C
estimated delta T 20 °C
Energy needed 61,6 kW
Energy needed 16,6 kW
steam pressure 4 barg
steam pressure 4 barg
steam consumption 105,3 kg/hr
steam consumption 28,4 kg/hr
Total steam consumption 132,8 kg/hr
Total steam consumption 54,8 kg/hr
Coater 350
Coater 48
Design data
Estimation
defrosting coil 16,5 kW
defrosting coil 16,5 kW
steam pressure 2,5 barg
steam pressure 4 barg
steam consumption 27,7 kg/hr
steam consumption 28,2 kg/hr
Heating coils (2) 176,0 kW
air flow 7040 m³/h
air flow 4000 m³/h
estimated delta T 20 °C
estimated delta T 20 °C
Energy needed 43,4 kW
Energy needed 24,7 kW
steam pressure 2,5 barg
steam pressure 4 barg
steam consumption 72,7 kg/hr
steam consumption 42,1 kg/hr
Total steam consumption 100,4 kg/hr
Total steam consumption 70,3 kg/hr
CIP unit
Hot Water Production HVAC winter
Design data
Water flow 37,5 m3/h
Heat exchanger 232 kW
Temperature IN 58 °C
steam pressure 7 barg
Temperature OUT 63 °C
steam consumption 408,3 kg/hr
Energy needed 218 kW
Dryer (coil) 46,4 kW
steam pressure 7 barg
air flow 2153 m³/h
steam consumption 382,8 kg/hr
estimated delta T 20 °C
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Date: 06/04/2011
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Energy needed 13,3 kW
Hot Water Production HVAC summer
steam pressure 7 barg
Water flow 37,5 m3/h
steam consumption 23,3 kg/hr
Temperature IN 62,5 °C
Total steam consumption 431,6 kg/hr
Temperature OUT 63 °C
Energy needed 22 kW
Hot Water Production Sanitary
steam pressure 7 barg
Water flow 0,33 m3/h
steam consumption 38,3 kg/hr
Temperature IN 15 °C
Temperature OUT 63 °C
Energy needed 18,5 kW
steam pressure 7 barg
steam consumption 32,5 kg/hr
NOTA : the CIP unit is a big consumer in terms of instantaneous steam flow. However this user only
runs 3 hours per day as an average. Therefore, its consumption has to be considered as a peak of
consumption.
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Date: 06/04/2011
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12 Appendix N°3 : Steam Pressure Controlled Heat Exchangers at Low
Load
12.1 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
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the steam pressure after the steam control valve is less than the pressure in the condensate line,
there will be no 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 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.
In the best case scenario the control system will balance the steam/product differential. However, in
most cases the following is observed:
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
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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.
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.
On-off controls
As with modulating controls, very similar conditions occur in an on-off control. The steam valve
opens when there is a heat demand. A positive pressure differential is created, and the condensate
in the heat exchanger is pushed out. The heating surface in the heat exchanger is exposed and the
capacity rises. Before all of the condensate is pushed out, the desired temperature is reached and
the steam valve closes. During this cycle the steam trap does not receive condensate with a
temperature above 100ºC.
When the steam valve closes, the steam in the heat exchanger will condense, thus creating a
vacuum in the heat exchanger. This vacuum will pull condensate back from the condensate line
unless there is a check valve in place. The condensate inside the heat exchanger will continue to
cool down (sub-cool). When the steam valve opens again, the hot steam will be in contact with the
relatively cold condensate. When this occurs there is a serious risk for thermal water hammer to
occur. Over time these water hammers, and the presence of cold aggressive condensate, can cause
leaks.
Installing a vacuum breaker and a check valve may eliminate the vacuum and the backing-up of
condensate, but it will also allow air to enter the system. This air has to be vented from the heat
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exchanger otherwise it will reduce the effective steam temperature, and as a result, the heat
exchanger’s capacity. Air in the condensate system will cause corrosion.
12.2 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 three 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
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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A Posipressure 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. The
diagram below shows a typical setup for this arrangement:
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.
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12.3 Savings
The installation of closed loop pumping trap systems, or a Posipressure system, will return
condensate back to the boiler house. Often on flooded heat exchangers this condensate is drained
to sewer and therefore lost. It can increase the heat exchangers capacity, and may speed up
production processes. More important are the savings achieved from improved system reliability
and controllability, however these are often difficult to quantify. The safety drain will not improve the
condensate return, but will save the coil from freezing and prevent process time downs and
maintenance labour to repair.
12.4 Investments
Average budgetary cost for the installation of a closed loop pumping trap system on an existing heat
exchanger is 14000 €.
Average budgetary cost for the installation of a Posipressure system on an existing heat exchanger
is 8000 €.
Average budgetary cost for the installation of a Safety Drain on an existing heat exchanger is 1700€.
Included:
- Equipments supply (piping, pumping trap / Posipressure, valves etc. )
- Installation by a mechanical contractor
- Engineering and project management
Payback time for these optimizations depends on the specific situation.