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I had a possible problem with liquid stacking up and not returning to the receiver. Unfortunately my compressors are liquid injection cooled and the compressors shut down on high oil temps. Does anyone out their no some possible diagnostics to prove if the liquid is actually stacking up and if so what are some solutions to help get it to return? Thank you all for any input you may be able to provide.I'm scratching my head on this one?
Too cold outside.
I agree with Magoo, liquid is most likely in condenser or condensers. Problem is probably worse during low load conditions. I've had to shut off condenser circuits or isolate whole condensers in order to drive the head pressure back up to get the liquid back. You can also run the condensers dry if the are evaporative.
Are there multiple condensers? Is there a vent line from the receiver to the condenser inlet?
Rcsac,
Can you please send us a simple drawing of the connections condensers «» receiver?
Any way, that could be caused by:
- Lack of NH3;
- Connections between multiple condensers and liquid receiver not done correctly.
Do you have one or more condensers?
Where do you have the equalizing line between the condenser(s) and receiver?
Is your system flooded? Does the electrovalve that feed the separator is sealing well?
If you can not valve off a condenser to increase your head pressure (if it is lower than normal) you may be low on charge due to service loss during the past year(i.e. oil bleeding,valve repairs or minor leaks.
Check your units for ice build up and fans for proper operation. Or, you could have liquid valves leaking by on the liquid supply lines. If your fans are off and your liquid valves are leaking by then the unit will fill up with liquid and store your ammonia not letting it make it back to be reused. It's helpful to check your receiver site glass levels daily, so you can predict or catch a problem and start looking for an answer sooner than later.
Hi,
If you can answer Sandro Baptista's questions you will get much better relevant answers to help you. However if its asmaller unit you can make use a head pressure cylcling switch. Make sure that you have the correct charge and load on your system. www.isentropictemptech.com
If you have a gas balance between receiver and hot gas to the condenser, close it and drive liquid out, if water/ evaporative condensers drain water and isolate spray pumps. Then control fan operation, natural convection will do the job.
magoo
Thanks for everybody's response, my head pressure was 155# at the time of this issue, the ambient was 57 F with a 82% humidity. We did have an unusually low load condition due to the fact that some of our spiral freezers were down, 33% to be exact. So that is definitely worth looking into. Thank you so much for pointing me in the right direction and everyone have a safe and Happy New Year.
Low load would curtainly compound your problem.
magoo
57 F isn't cold. Most likely spiral liquid solenoids are leaking and liquid is in idle evaporators.Quote:
Originally Posted by Rcsac
I've had non-condensibles holding liquid NH3 up in an evaporative condenser before.
Is this a new problem with the plant?
Just an image for reference...Quote:
Originally Posted by DTLarca
This can happen if evaporative condensers have wrong piping or air purger doesn't work properly.Quote:
Originally Posted by Superfridge
Quote:
Originally Posted by Superfridge
Despite the increase of the total pressure due to the non condensables gases partial pressure effect I can't see how this effect will influence the Rcsac main problem.
I have experienced purging non-condensibles to find an increased receiver level afterwards. I assumed the N/C's trapped above the tower drain leg U traps restricted liquid draining freely from the tower bundle.Quote:
Originally Posted by Sandro Baptista
Could be wrong.......have been before.
Rsac, would be kind/polite if you came back what happened so far. We helped you - I think - help us now also what you found.
Yah, probably you're right!Quote:
Originally Posted by Superfridge
Sorry for the delayed response guys. After gathering all the data there were a couple of factors that came in to play on this one, non condensibles was not one of them, i beleive if it was we would have seen an increase on our purger count. However, we had difficulties maintaining our temps on the prod. floor in the summer monthes because there were some unconditioned spaces that were seperated by strip curtains. The proper fix would have been to condition them, but with our tight budget we installed automated doors. Worked out great, floor temps/freezer temps but. Here comes cooler temps, low ambients with higher than usual humidity and our wonderful doors hold back the heat load that we our used to expiriancing, the liquid stacks in the piping on the roof. Thats a lot of volume you can fill. On top of that production had a line interuption and was forced to shut down, what did they do, they shut the fans off only to the spiral freezer but do not take the refrigeration controls out of refrigeration mode, great, now weve stored a considerable more amount of liquid and with an undersized receiver she ran out. Did I mention undersized, yes weve added evaporators, recirculators, condensers, oops. So the fix. Create production interupt procedures for the spiral freezers, increase the volume of the receiver, and start shutting off liquid to the production floor evaporaters. But my mind is not closed nor my ego too big. Does anyone else have some suggestions.
Sorry Rcsac,
Can you organize better/individualize the several subjects you have mentioned as well as your question?
Yes, I will have to get back to you on that one.
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I apologize Sandro, we must be struggling with some language barrier issues. Let me ask again.
1. Are there ways to tell that liquid Nh3 is stacking prior to allowing a receiver vessel to go empty?
2. What are some fixes to minimize stacking?
When I use the word STACKING I am meaning Nh3 holding up, flow slowed/stopped, a decrease in pressure
Differential, not flowing properly.
I hope this helps you sincerely.
Liqiud holding up in condensers ,sometimes liquid drains are stone cold .
In your climate this could be the case anyway.
If you have a balance line between main discharge line & top of liquid reciever as well as "P" traps on each it should'nt be to bad.
You could try carefully opening purge valve on liquid drain from each condenser to see if liqid(if you have a valve there).
You could try turning plant off to see if reciever level changes, as well as isolate balance line & purge aggresively off top of reciever (maybe hose & run to low side accumulator or similar).
Rcsac,
RANGER1 has given you good information. I advice to follow his advices
RCSAC, if you are having issues with the plant design due to add-ons and such, it would really benifit you to hire a good refrigeration consultant to do a survey on the plant and see where the problems lie and what it willtake to fix them. I know a very good and experienced consultant (P.E.) in Houston thatprovide the diagonsitic service.
Ken