3 replies to this topic

[arkae]

hi everyone,

 

i have a doubt regarding the type of cooling for a  screw compressor.

 

The site conditions are:

 

 min temp: -6 degC

avg temp: 17.6 degC

max temp: 40 degC

 

The design temp. is taken as 33 degC for compressor design.

 

For this site conditions what would be the type of cooling for a screw compressor considering performance of the compressor and initial cost associated.

 

I do know that where water is a problem, we go for air cooled compressor.

Other than this is there any other reason for going for a air cooled compressor?

 

[Art Montemayor]

Arkae:

 

If this query is not confusing, it raises a lot of questions.

 

Those of us who have done a lot of work with screw compressors know from personal experience that we (and that includes you also) don’t select the type of cooling that goes on a screw compressor.  It is the designer/manufacturer who does that.

 

Perhaps you really mean the type of intercooler cooling medium employed in a multi-stage screw compressor package.  But then, you have not stated that your screw is multi-staged.  What do you really mean to put into a question?  And while you answer that, could you furnish all the rest of the information:  gas compressed; suction and discharge pressures; gas flow rate and compressor connected horsepower.

[ankur2061]

Arkae,

 

Assuming Art's contention that by cooling you mean inter-stage cooling using heat exchangers, then the following advantages would accrue with air cooling vis-a-vis water cooling:

 

1. Water cooled heat exchangers could face freezing of water at low ambient temperatures (your min. ambient temp. is -6 deg C), specifically in piping low-points and stagnant drain connections. Such a problem would not occur with an air-cooled heat exchanger

 

2. Fouling and scaling would be much more prominent in a water-cooled heat exchanger than an air-cooled heat exchanger

 

Obviously there are advantages of using water-cooled heat exchangers also:

 

1. Water having a much higher heat capacity compared to air would ensure that your heat exchanger is smaller in size compared to an air-cooled heat exchanger for the same heat duty.

 

2. If you are already having a cooling water network with certain excess capacity and sufficient pressure then the running cost or OPEX using a water-cooled heat exchanger would definitely be lower than using an air-cooled heat exchanger with a Forced or Induced Draft fan.

 

These are very generic guidelines and specific advantages and disadvantages for your case can only be elaborated once you furnish more details as pointed out by Art Montemayor.

 

Regards,

Ankur.

[arkae]

Dear ArtMontemayor,

 

The compressor used is for supplying Instrument air to control valves.

 

Air is the fluid to be compressed and the suction is at atmospheric pressure(0.797 bar) and discharge pressure is 8 barG.

It is a two stage air compressor with a flow rate of 980 Nm3/hr.

 

Actually during proposal stage air cooling for interstage cooling was selected in the datasheet.

I couldnot get answer from the person who prepared the datasheet. That is why i have put this question in this forum.

I am not that experienced, but i think that we specify the type of cooling to the manufacturer and may be manufacturer suggests us the type of cooling after we issue him the datasheet.

 

Thankyou ankur sir and ArtMontemayor for your valuable information and waiting for your further information on the above topic.