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lraja
19-01-2008, 01:54 AM
Hi

Ice forms around the level indicators and valve stems connected to low pressure receivers, intercooler vessels, and other pressure vessels handling low temperature liquid ammonia (Please see the attached picture). In most cases this is an unavoidable situation.


Is this something acceptable for the refrigeration practice in the industry or if not how to get around the problem

cheers

raja

Josip
19-01-2008, 02:22 AM
Hi, raja :)


Hi

Ice forms around the level indicators and valve stems connected to low pressure receivers, intercooler vessels, and other pressure vessels handling low temperature liquid ammonia (Please see the attached picture). In most cases this is an unavoidable situation.


Is this something acceptable for the refrigeration practice in the industry or if not how to get around the problem

cheers

raja

It is not acceptable....but exist on many many plants due to lack of money or maybe due to bad design...seems this one is an old system where you can always see and be sure about your ammonia level within vessel...;)...BTW it is not executed in proper way...lower pipe under level switch should be with big slope to the vertical pipe...to drain oil...

First what is possible to do is to insulate that pipe or you can install indirect (oil or electronic type) systems for level switches....preferably electronic what is normally in use nowadays....easy connection to PLC units.....

Best regards, Josip :)

US Iceman
19-01-2008, 02:52 AM
While ice formation is useful to see the liquid level inside of a pipe or vessel operating below the freezing temperature of water, it can also promote corrosion.

Since we should be using level indicators for this purpose we should not forget the use of insulation and vapor retarders to prevent water from reaching the pipe/vessel surfaces.

Corrosion is a main problem in refrigeration systems, which is why mechanical integrity and inspection are so important.

Corrosion can contribute to leaks or sudden failure/ruptures if not controlled, so for this reason insulation is a critical component we sometime take for granted.

Brads
19-01-2008, 09:27 AM
Raja,
Define not acceptable, Control columns and level switches should be insulated not only to avoid corrosion but also ensure correct operation the controls. The heat ingress causes boiling of the liquid which can result in incorrect level readings

lraja
19-01-2008, 09:52 AM
Brad

I meant acceptable broadly in the aspects of

good practice of refrigeration,
technical issues and
performance

of the refrigeration system under consideration

raja

mcalko
23-01-2008, 12:30 AM
Hello, In our plant this same scenario is seen on our intercooler vessel level control. In the fifteen years I have been in this plant it has never caused a problem. With subcooled liquid inside the piping and tank it is normal, moisture in the atmosphere is freezing to the piping and the pipe being uninsulated, ice forms.