purging air from condenser

[faryuki]

Dear Guys,

Do you have idea for manual purging air from condenser in the ammonia system. Recently i purging from gas inlet condenser which compressor stop and the result not to be good.

I saw from outlet evacon there is purging valve too.

Many thanks

[aawood1]

Hi Faryuki, The only time that I would purge air from an Ammonia (R717) evaporative condenser on the inlet side would be with the plant stoped. The best place to purge air is at the outlet point as the gas velocity decreases in the condenser, and the air accumulates as the gas velocity is at its lowest and the gas has cooled down. I would look into fitting an air purger unit as from some of the papers that I have seen say,to purge 1 pound of air you can waste 28 Lbs. of Ammonia. (Armstrong)
Arthur

[US Iceman]

I agree with Arthur. Purging on the gas inlet side of the condenser is a waste of time and ammonia. A Refrigerated purger is a good method to use as it purges more air than ammonia.

[ART KUHN]

Please be sure that the sevice valve is mounted on top of the pipe!!
On the bottem will be nh3 liquid.

[SteveDixey]

Dear Guys,

Do you have idea for manual purging air from condenser in the ammonia system. Recently i purging from gas inlet condenser which compressor stop and the result not to be good.

I saw from outlet evacon there is purging valve too.

Many thanks

Best practice is to fit an air purger drawing off from the liquid outlet. However, before finally persuading the accountants to let us have the money to fit a purger we did this:
To purge from the condenser inlet, you really need to look at the following:
Stop plant and run the condenser for a half-hour or more. Close all stop valves on the condenser.
Purge off slowly into a big water container so you can see air bubbles emerging off the purge pipe (ammonia will not bubble so much)
Purge for maybe 10 minutes maximum as the liquid will start to boil off in the tubes causing the air to mix.
Open up the valves, run the plant for an hour and repeat above.

It may be that you may have to take a day between purges. I had noticed that purging did not always have an immediate effect, and that one purge seemed to suddenly have the desired effect. However, you will have lost ammonia in the process.

Steve

[faryuki]

Dear guys,

thank u for the idea, i would be try

take care