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mre212
30-05-2014, 10:43 AM
Dear All,


For ammonia low temperature application(-45 deg C) which compressor recommended to use piston type or screw type and why?


Thank you in advice

RANGER1
30-05-2014, 11:34 AM
Reciprocating or screw, both Ok.
Reciprocating has to be 2 stage, but probably small capacity depending on how much you want.
Screw can be in a 2 stage or single stage, economised system.
Screw can be small to as big as you like.
Would need to know size & requirements of plant to make a better judgement.

mre212
30-05-2014, 05:10 PM
our existing ammonia plant with Reciprocating compressor but we are thing to change some with screw compressors due to a lot of problems we are facing we have one compressor working as swing two times damaged also these compressor Always trip due to piston overheating. I heard that water in ammonia dangerous on screw compressors more than piston type because they have ball bearing not roller bearing


Thank you

Josip
30-05-2014, 07:49 PM
Hi, mre212 :)


our existing ammonia plant with Reciprocating compressor but we are thing to change some with screw compressors due to a lot of problems we are facing we have one compressor working as swing two times damaged also these compressor Always trip due to piston overheating. I heard that water in ammonia dangerous on screw compressors more than piston type because they have ball bearing not roller bearing


Thank you

Dear mre212, believe me this is not a simple to answer to make a good decision. From your question I can read that you are not a specialist in refrigeration technology, but you want to keep your plant running in the best possible way.

I suggest you to contact some good refrigeration plant designer with all data you have now, also with all your plans regarding your future business expansion and ask him to give you a few possible solutions.

It is important to make a good solution how to utilize new compressor when installing it into your existing plant .. what type of new compressor (piston or screw both are OK and reliable, but...) to install depend on real situation and your future plans.

This will cost you some amount of money, but I believe you will get few solutions with detailed explanation what you will get with each possible solution particularly.

Best regards, Josip :)

mre212
30-05-2014, 08:37 PM
Thank you Josip

we already did and he is the one not recommend to use screw compressor for low temperature application and he recommended to install water removal

I am working in this filed for 7 years and will be happy if you can give me more information about refrigeration

Regards

RANGER1
31-05-2014, 12:53 AM
[QUOTE=mre212;296412]our existing ammonia plant with Reciprocating compressor but we are thing to change some with screw compressors due to a lot of problems we are facing we have one compressor working as swing two times damaged also these compressor Always trip due to piston overheating. I heard that water in ammonia dangerous on screw compressors more than piston type because they have ball bearing not roller bearing


It sound like a more fundamental thing is wrong with the way you are running the plant & protection of each compressor.
If they are overheating for example, then something is wrong like poor water cooling, high discharge temperatures, running incorrect pressures for the machine.

Can you give us pressures of each compressor suction & discharge.

Also what brand & type of compressor, also safety controls & settings.

Water removal is important, but this mainly effects plant efficiency unless you have liquid injection on something like a screw compressor.
If you are using piston machine now, then it appears to be a medium to small system.

It would be interesting to know reasons for not using a screw compressor.
Just because there is water in the ammonia does not mean it will enter compressor.

Josip
31-05-2014, 08:54 AM
Hi, mre212 :)


Thank you Josip

we already did and he is the one not recommend to use screw compressor for low temperature application and he recommended to install water removal

I am working in this filed for 7 years and will be happy if you can give me more information about refrigeration

Regards


To give you any suggestion we need to know much more about your plant i.e.

- type, number and size of compressor for each stage ... it will be the best to upload a scheme of your plant ... where we can see all what we need .... of course it will be nice to get more info about every compressor particular .. as per RANGER_1 request ... as much data we have it is easier to give you some advice what to do and what not to do and why ..

- type and number of condensers ... receiver, suction separator vessel size, both, for first and second stage

- future expansion plan of your plant

- all problems you faced earlier and recently regarding system, compressors, .... i.e. all what you think can be helpful for us ...

- installation of water removal unit is one thing, but there is also air purger unit (usually installed whenever we have a two stage plant ... i.e. running first stage under atmospheric pressure (-35*C and lower) ... to install screw or piston compressor sometimes depends on designer preferences (what is OK) and/or on the whole plant purpose.

Hope this is of some help to you ... to get idea all about designing of ref. plant.

Best regards, Josip :)