Ammonia plant high liquid level

[bunglebear]

Have an ammonia system shutting down due to a high liquid alarm in the surge drum. It is only there on startup, well for thfirst hour. Usually it gos out 2-4 times and I had to close the valve off to pump it out today to keep it going. Once it gets off it will run with no problems all day. It's a Frick screw on a blast freezer. The oil I don't think has been drained for a while. I had a look through some old service sheets and I know at the end of September a sample was took for testing but I can't find the results. Also a small shaft seal leak was repaired. At this time a diaphragm and orifice was replaced to a valve which seemed to solve the problem but it has returned in the last day or two. My own thought was a liquid line solenoid passing causing the drum to overfill, I thought if the problem was TX valve related it would happen not only on startup. I don't want to have to change a load of bits to get it runnning but it needs it's overhaul as the 40,000 hr is getting close. It's a single stage recirculation system if that helps. I can't find a liquid pump either although I had only a quick look at the high side components as the freezer room was out of bounds so maybe hot gas dump trap. I shall return tomorrow and have a better look, as I will be able to start and stop the plant with no one in there. The closest I got to the coolers was the header and TX valve on top......another opinion would be good..

[icemeister]

If the high surge drum level only occurs at startup, it tells me that during that period the additional refrigerant in there isn't where it usually is during normal operation. It's possible that during startup the flow of refrigerant to the evaps is very high due to the pulldown load and the pumper drums can't keep up. Maybe you're having a pumper drum problem. It could be a partially plugged strainer in a liquid feed line.

Like I said, I no NH3 man, but if the juice isn't where it's supposed to be, you have to find it and bring it back.

[Out of Control]

If I was a betting man, i'd say the the liquid line solenoid is remaining partially open in the off cycle. Close the king manually at the next shut down and see if it make a difference.