Monday, December 18, 2017

Energy Audit at Dairy plant at Vadodara, Gujarat.Print


A comprehensive energy conservation study of the Dairy plant at Vadodara, Gujarat was carried out by PCRA.This Dairy is engaged in the manufacture of various qualities of milk & also other milk products like butter, ghee, in their plant.The total Annual milk processing capacity is 107710 MT. There are 3 nos. boilers- 4 TPH each, for generating steam for use in the plant. The boilers use furnace oil as fuel.Annual furnace oil consumption is 1148.21 KL. The unit takes its electricity supply from the GEB .The contract demand is 1700KVA. 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. 16.33 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 boiler be chemically descaled on the water side. This will reduce the flue gas temperature to 220 deg c on high firing & 200 deg c on low firing.
  • It is recommended that the blocked traps be rectified at the earliest. Due to the blocked traps on the main steam line, condensate is not removed from the steam line. This results in water hammering in the steam line bends/valves/flanges & results in increasing tendency for steam leakages.
  • Furnace is stored in 1 nos.main storage tank of capacity 35000 lts. 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. It is observed that the steam coil in one of the storage tanks is leaking. It is recommended that this be rectified as soon as possible.
  • Furnace oil main storage tanks should be cleaned at least once a year to remove the sludge accumulated at the bottom of the tanks.
  • Steam traps are fitted improperly on the ghee kettles & are not working. The operator ahs to keep the bypass open for maintaining the batch time in the ghee kettles. It is recommended that the steam traps be serviced & fitted properly on the ghee kettles
  • Steam traps fitted in the Gulab Jamun section have a common line. This results in back pressure on the steam traps. The operator has to open the bypass valve to maintain the temperature of the units. It is recommended that each steam trap be fitted to a separate line so that they can discharge properly.
  • The discharge temperature of ammonia discharged from the refrigeration compressors from the dairy is around 110 deg c. It is recommended that a heat exchanger be installed for recovering the waste heat from the hot discharge gas. The heat recovery is 10% of the heat rejected to the condensers. The heat recovered will be used to preheat boiler feed water. However a detailed feasibility study will have to be conducted to overcome the space constraints in installing the heat exchanger/hot water tank& the pipelines.
  • The steam is generated at a pressure of 14 kgcm2g & reduced to 3.5 kg/cm2g for use in the plant. It is recommended that a backpressure turbine be installed to generate power from this pressure drop.
  • The power factor of the plant is not satisfactory. This is due to the new refrigeration plant being installed in dairy.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.
  • In dairy, the gram freezer refrigerant gas discharge is condensed by chilled water condenser. It is recommended that cooling water condenser be installed for use instead of chilled water. The freezer manufacturer/plate heat exchanger manufacturer will have to be consulted to assess the size of the cooling water heat exchanger & whether it can be fitted into the freezer.
  • It is observed that the outside walls of the cold stores 7 & 8 in dairy are completely wet with moisture condensation. This indicates that the insulation of the outside walls is not proper. It is recommended that the outside walls of cold stores 7 & 8 be insulated properly.
  • It is recommended that auto temperature controllers be fitted on the cooling towers which will switch off the cooling tower fans when the cooling water temperature reaches below a set point. Presently, the cooling towers are shut off manually.
  • It is observed that valves/flanges on ammonia suction lines for the booster compressors are uninsulated. This results in the suction gas picking up wasteful superheat from the atmosphere. Thus the ammonia suction gas to the booster compressor carries over 30-40 deg c of superheat, This can be verified by the high discharge temperature from the booster compressors of over 70 deg c. It is recommended that the valves/flanges on the ammonia suction lines be insulated.
  • It is observed that the AHU fans in cold stores/deep freezes are kept on even when the cold store desired temperature is attained. It is recommended that the cold store fans be switched off, along with the shutting off ammonia supply to the AHU coil, when the desired temperature has been achieved.
  • Present lighting single phase voltage is 240 to 245 volts. Nowadays lighting transformers are available, which reduce the voltage to around 210 volts. The reduction in voltage also reduces power consumption with little reduction in lumens emitted by the light source.

 

For further information, please write to:

Director (I/C),
PCRA,
Sanrakshan Bhawan, 10,
Bhikaji Cama Place,|
New Delhi-110066
Telephone: +91-11-26198856
Fax. +91-11-26109668
Web site: www.pcra.org