Petroleum Conservation Research Association
Ministry of Petroleum & Natural Gas, Government of India
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Energy Audit at Dairy plant at Bharuch,Gujarat.Print
A comprehensive energy conservation study of the Dairy plant at Bharuch,Gujarat. was carried out by PCRA.This Dairy is engaged engaged in the manufacture of various qualities of milk & also other milk products like butter, ghee, in their plant. The total Annual production of the plant Milk – 14892.8 MT,Ghee – 78.3 MT,Butter - 74.8 MT There are 2 nos. boilers of capacity 2 TPH each for generating steam for use in the plant. The boilers use natural gas as fuel for generating steam .One boiler is in operation & the other is kept as standby. Annual natural gas consumption is 172301 NM3. The unit takes its electricity supply from the GEB .The contract demand is 250KVA. 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.
A comprehensive energy conservation study of the plant was carried out by PCRA, The identified total annual energy saving potential is around Rs. 7.84 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.
- Boiler blowdown is manual for the boiler. The raw water quality has been tested & the TDS level in raw water is around 1200 ppm. Boiler water TDS is observed to be around 10000 ppm as against the permissible level of 3500 ppm. This will lead to wet steam to the process & increase in steam leakages from PRVs/flanges as well as malfunctioning of PRV valves.
- The high TDS level in the boiler will also lead to increase in flue gas temperature due to scale deposition on the water side of the boiler. It is recommended that the r.o plant be rectified as soon as possible to preserve the life of the boiler.
- 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. Also some bare steam lines were observed. It is recommended that the bare valves/flanges/steam lines be insulated in the plant.
- Presently, no condensate recovery is conducted in the plant. Ammonia discharge gases from the refrigeration compressors are at a temperature of over 120 -130 deg c. It is recommended that this waste heat be used to generate hot water at 70 deg c for boiler feed water as well as for CIP purpose.
- The power factor of the plant is not satisfactory. The average power factor for the plant is 0.984.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.
- The contract demand for the plant is 250 KVA. The minimum billable maximum demand is 213 KVA. It is observed that the actual maximum demand for the plant has never crossed 203 KVA. It is recommended that the contract demand be reduced to 180 KVA. The actual maximum demand can be kept below 180 KVA even in peak season by proper scheduling of process machinery.
- It is observed that both the condenser pumps & all the air compressors are overloaded. It is recommended that the pumps/motors be inspected & serviced. The condenser pumps are overloaded largely due to scale formation on the impeller profile. This is due to the raw water quality which has TDS of upto 1200 ppm. It is recommended that the impeller be serviced/replaced.
- It is recommended that new KC-2 compressors be procured & operated & the leased refrigeration compressors be phased out to save on lease rentals.
- Presently, there are no liquid level controllers in the IBT accumulators. Thus there is liquid carryover into the compressor suction. It is recommended that liquid level controllers be fitted on the IBT accumulators.
- It is recommended that compressor should be operated such that the suction pressure is between 30 – 40 psig. Thus, when the suction pressure reaches 30 psig, one cylinder should be cut-off. The cylinder should once again be loaded when the suction pressure reaches 40 psig.
- It is observed that there is thick scale formation on the ammonia condenser tubes . Moreover one condenser coil is leaking & is hence not operational. Hence the discharge pressure of the compressor is on the higher side. The unit is replacing the leaking coil shortly. It is further recommended that the condenser coils be descaled completely. The unit is also advised to restart the r.o plant.
- It is observed that a section of the ammonia suction lines from cold store & deep freeze are uninsulated. This results in the ammonia vapor picking up unnecessary superheat from the atmosphere & waste of energy. It is recommended that the ammonia suction lines be insulated. It is observed that the insulation of the chilled water supply & return lines to & the from the process is damaged. It is recommended that the lines be insulated properly to reduce refrigeration load on the system.
- It is recommended that the Ahu blowers in milk cold store & butter deep freeze be shut off along with the ammonia supply to the AHu coils ,when the desired room temperature is attained.
- Compressed air is generated at a pressure of 6 to 8.5 kg/cm2g. It is recommended that the compressed air generation pressure range should be 6 – 6.5 kgc/cm2g. This will result in power savings in compressed air generation. The unit is already thinking in this direction & has a proposal for increasing the compressed air line size to 2” . This will be sufficient to take care of the pressure drop in the line & will enable the unit to reduce the generation pressure to 6.5 kg/cm2g.
- The volumetric efficiency of the air compressor no.1 is not satisfactory. It is recommended that the compressor be overhauled/serviced to increase its volumetric efficiency. It is recommended that pump up tests be conducted for all the compressors as it is a good indicator of the wear & tear that occurs in the compressor.
- 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.
For further information, please write to:
Sanrakshan Bhawan, 10,
Bhikaji Cama Place,|
Web site: www.pcra.org