Cold storage defrosting operation rules
1. Preparation work before defrosting cold storage evaporator defrosting frequency should be based on the local timely weather conditions and the amount of product inlet and outlet, refrigeration personnel should check the temperature of the warehouse frequently, check the thickness of the evaporator frost layer frequently, and rinse the evaporator in time before the formation of ice to ensure the maximum refrigeration efficiency of the warehouse evaporator and reduce refrigeration energy consumption. When hot ammonia defrosting, it is best to contact the cold storage management department, it is best to carry out after the warehouse goods are out of the warehouse or transferred to the warehouse, especially the warehouse using the top row evaporator, if there are goods in the warehouse, the goods should be covered with canvas, MATS and other waterproof materials on the ground to prevent the goods from getting dirty and the ground from freezing. The hot ammonia defrosting of the chiller is generally accompanied by the water defrosting process, and the water temperature for defrosting is generally controlled at 18-20 ° C.
2 Check before defrosting:
2.1 Check the liquid level and pressure of the liquid drain bucket. If necessary, drain the liquid and reduce the pressure to ensure that the liquid drain bucket is in the ready working state. If the low-pressure circulation bucket is used as a liquid discharge bucket, the amount of liquid ammonia in the low-pressure circulation bucket should be adjusted so that the liquid level is not higher than 40% to accommodate the liquid returned from defrosting.
2.2 Check the water content of the frost flushing tank.
3 Defrosting operation:
3.1 When hot ammonia is defrosting, close the liquid supply valve of the regulating station 15 minutes in advance, then close the corresponding return valve of the evaporator, and disconnect the power supply of the cold air machine.
3.2 Open the pressure relief valve and inlet valve of the liquid discharge barrel and the discharge valve of the sub-regulating station, so that the ammonia liquid return route in the evaporator has been connected. Note that the opening degree of the pressure relief valve of the liquid discharge barrel is not too large.
3.3 Slowly open the hot ammonia defrosting valve to heat ammonia into the evaporator. Pay attention to adjusting the pressure gauge of the liquid drain header of the station. The pressure should not exceed 0.58MPa, and the amount of ammonia stored in the liquid drain barrel should not exceed 80%.
3.4 When the frost layer on the wall of the evaporator tube begins to melt and fall off, open the valve of the corresponding frost flushing water channel of the evaporator, open the frost flushing water pump, adjust and check the amount of frost flushing water to avoid the overflow of frost flushing water in the water tray.
3.5 Water defrosting usually takes no more than 30 minutes. After 30 minutes of defrosting, close the defrosting water valve in turn. After 5 minutes of delay, close the hot ammonia defrosting valve, the drain valve on the regulating station and the inlet valve of the drain bucket. Then the hot ammonia defrosting work is completed.
3.6 When resuming the work of the cold storage, the return valve of the sub-regulating station should be slowly opened to make the tube and evaporator
When the internal pressure is reduced to close to the evaporation pressure of the system, the liquid supply valve of the sub-regulating station is opened and the cold is turned on
Fan return to normal cooling state, and do a good frost record.
3.7 For the automatic defrosting system, it shall be carried out in strict accordance with the setting procedure, and the setting value shall not be changed at will.
To avoid security accidents.