Tall Cyclones for Filtering and Cooling

Hi Wood Gassers,

Lately I have been posting about the wonderful heat transfer you can get off a cyclone. I bet someone is going to come up with the brilliant idea to make a REALLY tall cyclone to cool and filter the gas in one step, avoiding building a radiator. DON’T!! Been there, tried that. I made a 48 inch tall cyclone so I would have lots of heat transfer surface. The filtering was dismal. The problem was that the flow could spread out and slow down so much going around the first spin that all the centrifugal force was lost and the particles could shoot up to the exit pipe. Live and learn.

Stick with a height of 2.5 to 3 diameters.

Hopefully this saves someone some aggravation and money.



How about several tiny cyclones in parallel? Would that provide more cooling and filtering along with the added surface area?

Hi Chris,

It would probably work. Sounds like a lot of painful fabrication, however.

I am kinda-sorta toying with a two cyclone hot/dry and cold/wet combo for my big unit. As soon as the automixer is sellable I need to get on that.


John Blount had 2 small cyclones on his last US build. the welder had them on there a little cockeyed and I think he had the guy repair that. 2 of stephens would be perfect for the 318 size trucks … He still hasn’t answered whether there is a cone in the base … My first cyclone I built to spec per Dutch John … It saw too much moisture between drives and it rotted through … I made it out of a single 2’ piece of stove pipe … Pictures of it should be on the site that Chris saved the bulk of my pictures to on google.I don’t have that link handy … I always had my site sorted by date but that info got lost … I’m running the linux machine right now so can’t access jack …Mike

Hi Mike,

There is no cone inside. I just play some games with the exit hole. That is how I stay up in the +90% efficiency range. I never see any dust after the cyclone so in my mind the cyclone doesn’t warrant any more complexity.


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