Re: pls suggest me

From: <Gordon.Reddek@Alcan.com>
Date: Tue Apr 27 2004 - 03:52:00 EDT

GET, You should not have to do too much calculating on this one. All of the air compressor suppliers also sell units to dehydrate the compressed air and most of them have sizing tables galore that you can simply strip off the web. I just looked at the "compair" site and found this page: http://www.compair.com/index.asp?section=products&page=pacc which seems to have lots of good downloads. If they do not have what you want just surf for air compressor suppliers or "desiccant dryer" suppliers and look at their downloads.
Working out how much absorbent you need is relatively simple however but you must have details of the installation first. I find that the biggest obstacle in understanding what is going on is that people do not grasp the fact that the air changes volume dramatically in the compression cycle, but the water that remains in vapour form is always governed by one thing only, and that is its temperature. Put simply it works like this:   When the air enters the compressor it will have a certain amount of moisture which gets compressed with the air in the compressor. When the air discharges the compressor it will have reduced in volume to one eighth of its original volume (in your system) and the moisture content will be so high that the air will not be able to contain that water. The excess water will condense out in the receiver and flow to grade as water. The air in the receiver will be saturated and the amount of water passing out of the receiver will be the actual flow volume of the air (which in your case is one eighth the volume of air entering the compressor at atmospheric pressure) multiplied by the amount of water vapour at saturation conditions that can be held in a volume of air at the compressor discharge temperature( you will get this figure from steam tables). It is highly likely that you will want to absorb close to all of this moisture in your desiccant dryer. If you are drying to say 0C or -5C dew point or whatever you will find that the amount of moisture remaining is so small you can just about forget it. So ALL of the moisture leaving the receiver must be absorbed by the desiccant. Well, all you need to know is what desiccant you intend using, how much moisture it can absorb and how you intend running the dryer to work out the rest. I would be surprised if your figures did not tally well with those from suppliers.

Hope that helps,

Regards,

Gordon Reddek

GET Mithapur <getuser@tatachemicals.com> 27/04/2004 05:06 PM
Please respond to PipingDesign

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         Subject:        [PipingDesign] pls suggest me

Dear All,

I have some problem in calculating the quantity of adsorbent required to adsorb the water in 7bar Air Compressor. Can u help in finding out this. i have calculated the flowrate of air,Moisture content in that air. Still confusing .

Thanks
Pls.Revert back

GET

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[Non-text portions of this message have been removed] Received on Tue Apr 27 03:52:00 2004