Hi, I read a post by DJ (I think) where he mentioned that a cyclone makes a rather compact cooler. I am interested in exploring this and was wondering if having 2 or 3 cyclones in tandem (with some heat exchange enhancements) could provide the cooling drop needed to get condensation. Since the cyclones work on velocity, the inlets, diameters and height ratios would need to be optimized to remove finer and finer particles.
Here is the cyclone I am using today. I think I got the proportions off the GEK web site a couple of years ago. This one does not have any cooling enhancements on it, but it does a good job trapping the large stuff from my pellet fed gasifier.
My questions:
Is a properly designed cyclone capable of removing soot ?
I have not measured the temperature drop before and after the cyclone. Has anyone see that type of info ?
I figure it is better to ask these questions here before building a few more cyclones to try it, right ?
Gary Gilmore has a slide show on YouTube showing a grease barrel with a tangential entry at the top and then a screen at the bottom holding up a cylinder resembling a large stove pipe (with notches for gas entry). There is charcoal in the bottom of this pipe, some screens, and foam in the top part. Hot gases spin around in the barrel, enter the filter pipe at the bottom, travel up through the charcoal and foam, and exit at the top. He uses this system on a VW, at Model TT, and a generator. It does function as a cooler. The video is here: http://www.youtube.com/watch?v=VAyItWMNl2A&feature=g-like&context=G218561aALT3mZcgAKAA
Gary is a member of this forum, so he can chime in and correct me if I am wrong. I built a copy of this filter, and TIG welded to the grease barrel, not without making a few holes! I recommend you look carefully at Gary’s attachment methods to that thin-walled barrel. He has already figured it out…
The Handbook Of Biomass Downdraft Gasifier Engine Systems, page 76 shows a dimensioning example. More extensive calculations can be found in Small Scale Gas Producer Engine Systems by Kaupp and Goss. Very good book, by the way, excellent collection of classic literature and articles.
Cyclones in series could filter out all dust if the gas velocity would be constant at all times. Unfortunately this is not the case in gasification.
Thanks DJ and Chris for the references and Ray for the informative slide show on Gary Gilmore’s combination cyclone can filter. I like it a lot. A couple of years ago, I found a tool I did not quite understand how to use until today. After re-reading the cyclone section of the SERI “Handbook”, something I saw on Dutch John’s site kind of clicked… I tried running the parameters from the 10kW design example as seen in the SERI “Handbook” on page 76 (84 of 128) through this spreadsheet tool for fun. www.enq.ufsc.br/disci/eqa5313/cyclone.xls.
The spreadsheet written by Neil Stone of Esco Engineering suggests dimensions for a cyclone using just 3 inputs (flow rate, design inlet velocity and gas density) . Inputs can be in metric or Imperial and it also has a charting feature to show particle diameter and penetration.
I think I may have learned something tonight. Good way to burn an hour or two if you are interested in cyclones and learning about gas flow…
I made some external temperature measurements on my cyclone a few weeks ago and was able to document at least a 180 degree F temperature drop on my cyclone, over 200F depending on how far you measure down from the inlet. Inlet temperature was in the 525 F range, and the temperature at the bottom of the cyclone cylinder was around 330 F, and measuring about an inch or two from the top of the cone, it dropped below 200 F (like 180 F). I am not saying the gas is that cool - just taking note of the surface temperature.
Here is a link to the video showing external temperatures of my gasifier and the cyclone http://youtu.be/IiSI37xAMQc .
PS: Don’t stare at the flare too long.
When I followed the dimensions in the Handbook I ended up with a pretty big cyclone: like 9" diameter and a cone 20" tall. And it really removes soot! It removes heat as well, but not enough to get condensation. If you you cool too much in there(or before) the soot gets gooey.
It’s big and ugly, but it works.
John
Hello StephenA
Good to see your name pop up here.
You are doing great works. And videos.
The more often I can see you name in writing the more likely I am to be able to spell it correctly.
Of course you know now you’ve set yourself up for someone asking to see a picture of your cyclone you know.
