Gallery, Projects and General > Project Logs
Making a Desiccant Air Dryer with Silica Gel
appletree:
At the power station where I worked for 40 years in the instrumentation dept, the electrical dept used an industrial martindale hot air blower (hair drier) to blast air through desiccant tubes used as moisture absorbers in very big motors (huge). This was in the times of demarcation believe it or not, if a SWA gland (steel wire armoured) required fitting to an instrument cable, an electrical fitter was called in, (its a wonder the country did not go bankrupt) oh it did?
I do not know if it was efficient or not i.e. slow cook versus forced draft either way thats what they did.
In my workshop i would use my refrigerant compressed air drier normally used for paint spraying. But yes a container containing desiccant that can be regenerated is good however i wonder about flow rates (distance velocity). There is more than one way to skin a cat, why you wold want to is a different question.
awemawson:
Thanks for the various comments chaps :thumbup:
Appletree - my motivation making the desiccator was not to have to run the refrigerant drier for long periods. It needs to run for at least an hour before the copper coil of tubing is cold enough, by which time I would have cut whatever I'm cutting on the plasma table, and gone in for a cup of tea :lol:
awemawson:
I was so pleased with the way this drier works I made a second one :lol:
This second one takes air directly from the compressor and dries it, hence my whole air distribution system will now have properly dried air. I'm sure that there will be existing moisture in the pipework, but after a bit the newly dried air should absorb and flush it out.
Looking at the picture starting on the left is the Regulator / Water Separator taking 150 psi from the compressor and reducing it to 100 psi - the water separator is the float type that blows water down the small pipe to the outside.
This is followed by an 'oiler' that although in circuit is NOT used or filled - it happened to be integral with the regulator so stayed there.
Then comes the new desiccant filter made exactly like the previous one.
This is followed by a large volume filter / water separator, just being used as a filter, as by this stage there should be no water to separate :ddb:
Not pressured up yet as you can see from the gauges as the Loctite 542 needs another hour to go off.
awemawson:
So the time has come for the first regeneration cycle of the self indicating silica gel crystals of my main air dryer. (This is the one that all the air from the compressor flows through)
Unscrewing the housing showed that the outer layers must be most exposed to the moist air, as tipping them into a baking tray there seemed to be far less turned blue than you'd think from looking at them in situ.
They are now in the oven at 140 deg C for a couple of hours. Meanwhile the dryer is back in service, as the 3 Kgs of silica gel that I originally bought not only filled this dryer and the one I fitted to my CNC Plasma Table, but was enough to re-fill this one while the fan oven does it's stuff driving off the water.
I'm really pleased with the performance of this dryer - it's so simple and yet seems very effective.
DICKEYBIRD:
Very nice Andrew! I'm always learning new things from your threads; thanks.
I'm curious what kind of pressure drop you're getting across it. Does it get cooler as well?
If I ever do any more spray painting, I'll need to make one of those!
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