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A comprehensive energy conservation study of the Dairy plant at Gandhinagar,Gujarat.. was carried out by PCRA.This Dairy is is engaged in the manufacture of various qualities of milk & also other milk
products like butter, ghee, SMP powder, flavored milk in their plant.The Anuual Milk Processing Capacity is 86151 MT.Annual Production of the plant Powder -1834 MT,Butter - 322 MT,Ghee - 2671 MT. There are 2 nos. boilers-, one oil fired of 5 TPH & one coal fired 3 TPH , for generating steam for
use in the plant. Generally, the oil fired boiler is used in the plant. The coal fired boiler is used is
sparingly.The unit also has an air heater for the 18 TPD powder plant. Daily furnace oil consumption is 1436.4 Kl .The unit takes its electricity supply from the GEB .The contract demand is 1000KVA. Electricity is consumed in a variety of equipment in the refrigeration plant compressors & auxiliary
equipment like cooling & chilled water pumps, air compressors, water & milk pumps & lighting. Annual electricity consumption is 41.90 LakhKWH

A comprehensive energy conservation study of the plant was carried out by PCRA, The identified total annual energy saving potential is around Rs. 20.63 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 excess air level in all the boilers is satisfactory. However, some fine tuning can be done such
that the oxygen % in the flue gases is 3.0%. This will result in improvement in boiler efficiency.
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 have been cleaned 2 months back. It is recommended that at least
once a year to remove the sludge accumulated at the bottom of the tanks.
Boiler blowdown is manual for the boiler. The raw water quality has been tested & the TDS level
in raw water is around 500 ppm. Condensate is recovered from the powder plant . Make up water
addition is manual. Boiler water TDS is observed to be below 5500 ppm when the powder plant is
not in operation & is around 1800 ppm when the powder plant is in operation. It is recommended
that the blowdown frequency be adjusted such that the boiler water TDS is increased to 3500 ppm.
It is observed that the boiler operation is intermittent. The average boiler operating hours are
around 15 hours/day. When the boiler is shut off, cold air is sucked in from the blower damper &
picks up heat from the combustion chamber & leaves through the chimney. This results in cooling
down of the combustion chamber & consequently, increase in furnace oil consumption in the
boiler. It is recommended that the an automatic damper be installed in the chimney to eliminate
these losses.
The boiler is presently operating only on high firing. It is recommended that the boiler be operated on high – low mode automatically. This will reduce the number of stop starts in the boiler burner & lead to savings in furnace oil.
Steam line insulation was in good shape in the plant in. However, some the valves & flanges on
the PRV stations are not insulated in the plant. Steam line insulation was in good shape in the plant. All the valves & flanges are not insulated in the plant. Also some bare steam lines were observed. By insulating with 2" thick mineral wool with aluminium cladding, 90% of the heat loss can be minimised.
It is recommended that the identified steam leaks be eliminated as soon as possible. The ghee
kettle safety valves/bypass valves are continuously blowing steam. It is recommended that the
safety valves/PRV before the ghee kettle should be reset so that the safety valves do not blow
steam.
It is recommended that the soft water make up pump to the boiler feed water tank be operated by automatic level controller . When the level in the feed water tank falls below a certain level, the pump will be automatically operated. This will result in rise in boiler feed water temperature by at least 12 - 15 deg c & also water savings.
It is observed that cold make up water is added to the CIP tanks manually. The steam valve is also controlled manually. It is recommended that make up water addition & steam addition be
automated. This will result in virtually no cold make up water addition in the CIP tanks &
eventually in steam & water savings.
For the powder plant air heater, we are of the opinion that the supply air is leaking into the flue
gases & hence the excess air levels are high. It is recommended that the leakage be identified &
rectified. It is observed that the flue gas temperature is also high. It is recommended that the flue gas temperature should be reduced to 220 deg c.
The power factor of the plant is not satisfactory. The average power factor for the dairy is 0.949.
It is recommended that the power factor be improved to 0.999. This will result in savings in
electrical bills due to increase in rebate amount.
Presently the powder plant exhaust fan is operated with its damper 50% closed . It is recommended that a VFD drive be fitted for the exhaust fan. This will reduce the power consumption in the exhaust fan by at least 20%
The unit is thinking of soft water in the evaporative condensers in future. However, due to the
quality of raw water available , it is strongly recommended that the unit should install a DM
water/R.O water plant for use in the condensers & as boiler feed as well.
It is observed that the butter deep freeze temperature is maintained at an average of – 5 deg c with the booster compressor. A temperature of -5 deg c can easily be achieved with the high stage compressor, It is recommended that the booster compressor be stopped & the deep freeze load be taken up by the high stage compressor. This will reduce power consumption in the refrigeration section.
The compressed air leakage level is on the higher side. The milk pouch packing machines are in
operation for 20 hours a day, hence it is difficult for the unit to attend to compressed air leakages.
However, concerted efforts must be made to identify & minimize leakage levels to at least 25%.
Compressed air is generated at a pressure of 8.3 to 8.9 kg/cm2g. The compressed air pressure is
very high at over 8 kg/cm2g. This is because, there is high pressure drop in compressed air line
leading to insufficient pressure at powder packing m/c.
The main line size is 2”diameter. It is recommended that the compressed air main line diameter be increased to 4”. This will reduce the pressure drop to a negligible level & allow the compressed air generation pressure to be dropped to 6.5 kg/cm2g.
It is recommended that mechanical pouch packaging machines be installed for replacing the 2nos
pneumatic machines presently in operation in the pouch packing section.
Present lighting single phase voltage is 250 to 260 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 30% of the power consumption.