water contamination in NH3, how much is too much?

[Tycho]

I have close to similar RSW plants, spray chillers.

One has 0.4% water content, other has 0.8%

What happens is at a certain point, the chillers isn't able to produce the amount of gas the compressor is demanding, the liquid in the drop leg starts boiling, the pumps start cavitating and the pump pressure collapses.

Once the pump pressure collapses the compressor can't reduce capacity fast enough to reestablish pump pressure and it cuts out on low suction pressure.

Now the funny thing is that the plat with 0.4¤ is having major issues and have to run with reduced speed on the compressor.

the plant with 0.8% is functioning kinda like normal after I adjusted the AKVA liquid injection valves to work faster.

Spray chillers seem to be very sensitive to some kind of coating on the NH3 side of the tubes that acts kind of teflon on a non stick frying pan, making the liquid nh3 that is sprayed over it just roll right off instead of sticking to the tubes.

I've been working on these kind of RSW plants over 20 years and it's annoying me that some plant's work just fine for year after year, and then you have others that get this problem after 8-10 years for no apparent reason.

we have cleaned some chillers using a specialized company that circulate a soap solution at 80-90C for 24 hours, then there is 2 weeks running vacuum pumps and flushing with OFN.

10-12 years ago I got to look inside a chiller before and after a cleaning.



Before the cleaning the titanium pipes were dark brown, looking like what I would expect the tubes inside an oil cooler that were continuously running warm oil would look like.

Rubbing with my fingers did nothing, brake cleaner and a rag did nothing, brake cleaner and a 3m polishing mat slightly changed the color from dark brown to light brown.


After the cleaning process, the tubes were back to bright silver titanium color.


After drying it out and charging new NH3, the plant was running like brand new.

The oils used are Mobile Gargoyle Arctic 300, Reflo 68 or Mobil Gargoyle Arctic SHC NH 68, and it doesn't seem like any oil is better or worse than the rest when it comes to poor performance on the chillers.


Anyone else working on spray chillers that may have any input?

[RANGER1]

Tycho,
How much is to much

ATANZ-Catostrophic-water-containation-2015-1.pdf (gcapcoolcast.com)

Does not answer problem, but interesting reading in general.
Page 30 onwards about water etc.

http://colmaccoil.com/media/90683/co...ook-4th-ed.pdf

Page 121 mentions fouling in evaporator

https://www.alfalaval.com/globalasse...rigeration.pdf

[Tycho]

Thanks Ranger1, looks like a good read