Four steps in the use of parallel compressors in cold storage

Four steps in the use of parallel compressors in cold storage

The use of parallel compressors focuses on four issues, as follows:

　　①Keep the oil level

　　② Countermeasures for liquid flood back

　　③Protection device and accessory parts device

　　④Confirmation of piping stress

step one:

　　When the compressors are used in parallel, due to the difference between the compressor's oil volume and the system's oil return volume, long-term operation will cause the compressor's oil level to change (one oil level decreases, and the other oil level rises).

　　When connecting compressors A and B of the same model, if the oil volume of compressor A is large and the oil return volume of the system is small, the oil level of A will continue to drop, and finally a state of almost no oil will appear, resulting in poor lubrication and bearing burnout. When the oil volume of compressor B is small, and the oil return volume of the system is large, the oil level of B will continue to rise, and finally the motor rotor is almost there. Immersion in oil causes the increase of input power and temperature rise of various parts.

　　 The oil level change (oil deviation to the other compressor) when the parallel compressor is running is called [oil partial]. In the worst case, the other compressor has no oil within tens of minutes.

　　Step 2:

　　 Try to make the oil volume of each compressor equal, and the suction pipeline with equal oil return can extend the time of the oil-free state, but these measures cannot completely eliminate the oil partiality of the compressor.

　　☆Design a system that is not prone to partial oil;

　　☆After the oil deviation occurs, a design must be adopted to restore the compressor oil volume to the initial state of

　　Step 3: Countermeasures to avoid partial oil

　　①Connect the compressors of the same model and capacity, and try to equalize the oil flow/return flow.

　　②The compressor's exhaust pipe to the confluence, and the branch of the suction pipe to the compressor, each system component must have the same shape, and the two compressors should try to maintain the same refrigerant + oil flow.

③In order to further suppress the oil volume of the system, an oil separator is designed on the exhaust line. It is best to take the above three countermeasures to separate the oil from the two compressors and return to the system. ① and ② are necessary and ③ necessary Time to implement. The effect is very obvious)

　　Step 4:

　　① After a certain period of operation, perform oil equalization operation;

　　②Oil equalizing operation, whether it is possible to perform oil equalizing operation through the exhaust pipe and suction pipe of both compressors, even if it can, the time required is very long;

　　③The effective method is to connect the oil storage positions of the two compressors through the oil equalization pipe and move the oil through the oil equalization pipe;

　　④ The typical oil equalization operation method is to turn on and off both compressors for a short time by the following procedure (Note 1) to correct the oil deviation.