Dear All,

I am faced with a challenging issue on an Ammonia plant for a Spiral Freezer. The compressor is a Kobelco Compressor (Screw). I was called upon from the client since they lost the PLC program for the entire system - Once the program was back online (the original one from Frigo-technica who basically supplied the skid) we started the compressor which worked fine till it stopped pulling down the temperature somewhere at -20C (around 1.6 bar).

Being 100% loaded; the system keeps struggling to pull the load down but doesn't manage it.

The ammonia Pump is off for supplying to the spiral, I tried closing the liquid inlet to see if there is too much vapor ingress instead of liquid; I manually shut down the startup bypass valve and also played with the oil return from the oil separator but nothing helped.

The condensing pressure stays at 12.5~13.5 bar with liquid injection oil cooling.

Any ideas pointers to diagnose this one would be highly appreciated!less