GET
A typical drying agent will absorb 3% to 20% of its mass before regeneration
is necessary. For more accurate values, the type of adsorbent and its
experimentally determined properties are required, together with the
regeneration cycle conditions.
Refer to the following link for guidance with initial selection:
http://www.sorbentsystems.com/desiccants_charts.html
Regeneration normally takes place after 4-8 hours.
This, together with Gordons comments should allow you to calculate a rough order of magnitude estimate of your requirements.
Cheers
Steve
-----Original Message-----
From: Gordon.Reddek@Alcan.com [mailto:Gordon.Reddek@Alcan.com]
Sent: Tuesday, April 27, 2004 7:52 PM
To: PipingDesign@yahoogroups.com
Subject: Re: [PipingDesign] pls suggest me
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
To: PipingDesign@yahoogroups.com
cc:
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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