Petroleum Conservation Research Association
Ministry of Petroleum & Natural Gas, Government of India
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Energy Audit at Dairy plant at Himmatnagar, Gujarat.Print
A comprehensive energy conservation study of the Dairy plant at Himmatnagar,Gujarat. was carried out by PCRA.This Dairy is is in the manufacture of various qualities of milk & also other milk products
like butter, ghee, dahi & milk powder in their plant.The Anuual Milk Processing Capacity is 271082 MT.Annual Production of the plant Liquid milk – 33614 MT,Powder – 20858 MT,Masti Dahi - 2627 MT,Shrikhand – 897 MT,Paneer – 1049 MT,Ghee - 3072 MT,Table butter – 6551 MT. There are 6 nos. boilers of various capacities for generating steam for use in the plant. The boilers use
natural gas/furnace oil as fuel.
Furnace oil is also used as fuel in powder plant air heaters .There are 3 powder plants with air heaters
of various capacities . Annual furnace oil consumption is 3240.5 KL ,Annual Fuel consumption natural gas 4667193 NM3. The unit takes its electricity supply from the GEB & also generates a part of it in its GG sets.The contract demand is 2400KVA & 200 KVA for Sabar & Sabar ETP respectively. Electricity is
consumed in a variety of equipment in the refrigeration plant compressors & auxiliary equipment like
cooling & chilled water pumps, powder plant blowers, air compressors, water & milk pumps & lighting. Annual electricity consumption is 169.86 LakhKWH
A comprehensive energy conservation study of the plant was carried out by PCRA, The identified total annual energy saving potential is around Rs. 145.79 Lakhs on a recurring basis. The energy audit has identified several areas for energy conservation in thermal & electrical energy. The steps identified for energy conservation are given below:
- The boilers are operated both on natural gas as well as furnace oil. Generally 4 nos. boilers are
operated. This results in part load operation of all the boilers with the result that the efficiency of the boiler suffers. It is recommended that the steam demand be met with only 2 nos. boilers, 10 TPH & 7.5 TPH.
- It is observed that the excess air level in all the boilers is very high. It is recommended that online oxygen monitoring & control system be installed on 2 boilers in operation most of the time, 10 TPH Revomax boiler & 2 nos. 7.5 TPH boilers.
- It is observed that the boiler flue tubes are cleaned once a year during boiler passing. The flue gas temperatures observed in the boilers during our visit were quite high. It is recommended that the boiler flue gas exit temperature be monitored & the boiler cleaned once the flue gas temperature rises by 40 deg c.
- Air – fuel ratio controller has been fitted in air heaters for PP3. It is recommended that the air-fuel ratio be tuned such that oxygen% in the flue gases is 3%. It is recommended that similar ratio controller be fitted on PP2 air heater. The PP1 air heater is small & consumes lesser fuel as compared to the other air heaters. It is also recommended that the flue gas temperature of the air heaters be monitored . The air heaters should be cleaned once the flue gas temperature rises above 220 deg c .
- It is recommended that a portable combustion analyzer be procured & combustion parameters of all the boilers/air heaters be monitored on a regular basis.
- It is recommended that the furnace oil storage & service tanks should be drained at least once a week. This will ensure that all the water is removed from furnace oil & prevent sludge formation.
- Furnace oil main storage tanks should be cleaned at least once a year to remove the sludge
accumulated at the bottom of the tanks.
- Boiler water TDS is observed to be below 2000 ppm. It is recommended that the blowdown frequency be reduced such that the boiler water TDS is increased to 3500 ppm. This will reduce the heat loss in boiler blowdown & improve the efficiency of the boilers.
- Steam line insulation was in good shape in the plant in the dairy. However, some the valves & flanges on the PRV stations are not insulated in the plant. It is recommended that uninsulated steam valves/flanges/line be insulated as soon as possible.
- It is observed that 8 steam traps is found to be blowing I.e. leaking steam. The total nos. of steam traps tested is 30. It is recommended that leaking traps should be rectified immediately.
- Condensate should also be recovered from the tubular heaters of powder plant 1 & 2.
- It is observed that the supply air quantity for all the spray dryers is on the higher side. It is
recommended that the supply air quantity for the powder plant spray dryers be minimized. This will result in savings of at least 10% of furnace oil in the air heaters.
- Presently, the milk feed temperature to the spray dryers in all the powder plants is around 45 – 50 deg c. It is recommended that the unit should raise the milk feed temperature to 70 deg c by installing a heat exchanger. The heating can be done partly by first effect condensate from the calendria. This will help in proper atomization of the milk in the spray dryer & reduce fuel consumption in the air heaters.
- It is observed that the oxygen% for all the GG sets is on the lower side. Also the carbon monoxide
level in all the GG sets is excessively higher. It is recommended that all the engines be tuned properly. This will result in improvement in specific fuel consumption by at least 10%.
- It is observed that the supply /exhaust fans in the powder plants are operated with their dampers in throttled condition. It is recommended that variable frequency drives be fitted on the supply /exhaust fans to reduce their power consumption.
- It is observed that the chilled water line to the MPG section is damaged in some section & some
portion of it is also exposed to the atmosphere/sunlight. This is confirmed by a 2 -3 deg c rise in
chilled water temperature when it reaches the MPG section. It is recommended that the damages
section of insulation be rectified as soon as possible.
- It is recommended that a well water section be installed in the buttermilk pasteurizer. Buttermilk milk is chilled from 47 deg c to 8 deg c by chilled water. By installing a wellwater section, it is possible to reduce the buttermilk temperature to 37 deg c before it enters the chilled water section. This will reduce the load on the chilled water for cooling the buttermilk.
- There are 2 nos. cream pasteurizers in the plant. One cream pasteurizer has a well water section & the second one does not have a well water section. It is recommended that the second cream pasteurizer be fitted with a well water section.
- Presently 1 no. Grasso compressor is in operation for 17 hours a day & the second one is kept as
standby in the refrigeration plant. The unit is operating 9 x 9 compressors for meeting the IBT load . It is recommended that the Grasso compressor be operated & the old inefficient 9 X 9 compressors be kept as standby. This will reduce the power consumption in the new refrigeration plant.
- It is observed that the hot condensate from the powder plants is overflowing into the cooling tower pond. This unnecessarily raises the temperature of the cooling water being sprayed on the ammonia condenser tubes thus raising the discharge pressure. It is recommended that the overflow of the hot water to the cooling water pond be stopped.
- The temperature maintained in the Dahi cold store is 0 to – 4 deg c. It is observed that the Dahi cold store AHU is presently operating from the 2 stage system. This is because the Dahi cold store has a suction line only to the two stage system. It is recommended that the Dahi cold store be operated from the 6 X 6 system . This will reduce the power consumption in the MPG refrigeration section.
- It is observed that cold air is leaking out from the AHUs in paneer section. This results in an
unnecessary chilling load on the AHU resulting in wastage of power. It is recommended that the air leakages in the paneer AHUs be eliminated.
- Compressed air leakage is 26% in MPG section. It is recommended that the leakages be identified by taking regular rounds & minimized such that the leakage % is reduced to at least 15%.
- Presently there are separate compressors in operation in all the 3 powder plants. It is recommended that centralized screw compressor be installed which will cater to the compressed air demand of all the 10 powder plants.
- Present lighting single phase voltage is 230 to 240 volts. Nowadays lighting transformers are
available, which reduce the voltage to around 220 volts. The reduction in voltage also reduces power consumption with little reduction in lumens emitted by the light source. The savings due to installation of lighting transformer is 15% of the power consumption.
For further information, please write to:
Sanrakshan Bhawan, 10,
Bhikaji Cama Place,|
Web site: www.pcra.org