maybee it can be interessant to discuss about chargas filtering, especially dust traps…
on my mowers - 250 ccm, 480 ccm - i have made the experience how useful they are for a longer run time, or to say to prevent that the filter cloggs up…especially on small moving engines it is difficult to have a big filter with big filter surface because of space and weight problems.
also the final filter gets less dust…
actually i think for the fiat crawler for a dust trap, my idea is how shown on the design, prefer the right design with a bit more space as the left design, but what think others …?
place for the trap is in the quadratic 6x6 cm basement , what is also gas pipe…
the principle is: when the gas must make a turn from about 180 degree , dust falls off…
has someone historic documentation about dust traps? ( i think mostly of görans collection of historic material, books ecc…)
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I stuff an ammo box with scotchbright pads. You just wash them and re use them over and over. They are tough and perfect for the task. Very simple to build too.
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Hi Giorgio, im going to find some, they was very popular in the woodgas time.
One type, the Prall plate cleaner was much used.
It was built as a tube, with lots of walls inside, every wall was fitted to a center shaft, so they could be pulled out for cleaning.
In the walls/plates there was holes, placed so they dont lined up.
Principal drawing of Prall plate cleaner, there was a lot more holes than i draw.
Rinse it by just pull out the rod with the plates.
These was sometimes “moistened” with little waste motor oil, increased dust collection some.
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It will work. What you are trying to do in the design is slow the air down slow enough so the particles fall out of the air. It uses more space/volume then a cyclone(which spins the particles really fast to throw them against a wall) or a filter.
If I remember correctly, FreeCAD has a module for analyzing the flow rates which may assist in figuring out what size you need to get stuff to drop out. it just saves building time, and materials to see if what you want is actually practical.
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Here’s some i found so far, both are the type “Prall blech” cleaners, with holes “not in line”.
A charcoal gasifier, the dust trap plates(12) are mounted on the same center rod as the filter cartridge(13), in the same housing(11).
The Finland made “Otso” with four “prall plate” cleaners, as also acts as a gas cooler.
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göran, thanks for the interesting pictures…do you think with the wider spaced discs coarse dust will be collected, and with the narrower spaced discs finer dust?
gas speed decreases with the narrower plates…?
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Giorgio,
Don’t you use a disk type dust trap on one of your gasifiers? I thought I recently saw a photo of one in your response to my post on another thread.
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Hi Giorgio, that was a good question.
I believe as this also acts as a gas cooler, maybe the gas speed is somewhat similar, as the gas volume decreases?
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steve, yes i have, my first disc dust trap is in the gasifier for the tiller and for the grain mower…seeing it collects a lot of dust, but not enough for avoiding a blocked filter with smal surface(because of limited space on litttle moving engines).
so i developed a other system of dust trap with mesh inside with a 90 to 180 degree turn of the gas stream. this collects a lot of the dust and the filter not cloggs up more…
i readed in the swiss gengas book that the dust is thrown off when the gas stream makes this sharp degree turn…this was the principle thought for my design…all documented with pictures in my topics…
this actual topics goal is to see other constructions, also historic solutions…it is always to learn something new…
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Hi Giorgio, yes, that is the way to go, these dust traps have many features, gas turns, and therefor throws the dust, the dusts weight, living force makes it moving on forward.
This in conjunction with gas speed slows down, directly after the “bend” helps.
Those Prall blech cleaners works this way in series, also cools, and collects some moisture which helps bind dust.
Look at the drawing of the “Otso” gasifier, lower right, the oil bath final filter: the gas comes in fast, directly bends upwards, the dust carry on, directly to the oil in bottom.
The volume increase slows the gas down, more dust fells the the bottom, some oil is carried with gas, wetting the filter wich collects the rest.
Not 100% effective, but pretty clever?
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göran, on the otso design in the oil filter the inner lining is drawn with interrupted lines…will this say that the bended metal sheet has holes ?
the arrow through the whole design shows the gas stream… in the oil filter seems the gas passes through the oil.
maybee the holes on the bended sheet are more for startup in way the gas can pass easier , drawn by a sucking or blowing fan…when the engine sucks, than gas stream is much more stronger and is forced through the oil…
the upper declined sheets (with holes obviously) keep some mesh or wire between , as we know from old common oil bath filters from diesel engines…
what do you think about the gas stream arrow?
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Hi Giorgio, on other drawings of this oil bath filter, the pipe ends over the oil surface, not “bubbling” through the oil.
But as you say there are other oil bath filters acting exactly as you describes it: a hole or a slit for the gas to pass when running starter blower, and for idle.
Not as common on oil filters like on water scrubbers, i guess the oil really makes foam or froth, when a little condensed water appears.
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This is how I made a dropbox for my charcoal generator. I was surprised at how much dust it collected.
The metal sides also radiate a lot of heat which cools the gas.
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