Let’s talk chimneys.

Can anyone share the advantages/disadvantages of wider/narrower, or taller/shorter chimneys?

As I’ve mentioned in previous post(s), I’m putting together a modified tin-man, a brick-man, if you will. Outer oven/kiln of fire bricks, with inner stainless steel retort.

I have two possible chimneys on hand. One is a stove chimney (either galvanized or stainless), 5 1/4” (13.3cm) diameter by 34” (86.4cm) tall. The other is a copper chimney from a still, 12 1/2” (31.75cm) diameter by 38” (96.5cm) tall.

My inner stainless retort is about 15” (38cm) diameter. And the brick kiln interior dimensions will be 25.6” (65cm) length x 20.5” (52cm) width x 35.8” (91cm) height.

Having trouble attaching photos to post. Just figured out how to minimize the file size. Let’s see if this works.

This thread is highly relevant:

https://permies.com/t/223940/Experimenting-biochar-chimneys

John S
PDX OR

I think your stovepipe should be plenty good enough and that much copper is more valuable elsewhere,  even if only as scrap!

William Bronson wrote:I think your stovepipe should be plenty good enough and that much copper is more valuable elsewhere,  even if only as scrap!

It’s a fraction of the total copper I have from the still parts, and large kettles for reducing cane juice for panela, or rum 😉. I’d rather make use of it as is than scrap it.

Based on observations in another forum, on the function of chimneys, and ratio of air intake area to chimney outflow area, the copper chimney seems a better fit.

Though I am still open to further suggestions, with supporting data.

Based on my experience, my guess is that the wider chimney will work better.  I would use that one.  I don't know what the markets are for scrap copper in Ecuador, and I don't know how hard it is to get chimneys.  

My original plan with biochar was to build a brick larger oven around my 55 gallon drum, and then use it as a retort.  But then I switched from that plan.  I realized it was going to be a ton of work.  The other retorts I had seen made so little biochar, that I had to look for a different system.    Then I saw this video and realized it would be so much easier.  I don't have to move the bricks and it has lasted for 6 years, many times each year without any apparent wear:

https://www.youtube.com/watch?v=YIbGkmt1VdE&list=PLy9hFdI8EDMmQDvG_bqHQcc2nkr2INqf8


55 gallon drums are abundant and can be found cheaply, or for free, as I found mine.  If you do use this model, please reply, because I've found some adaptations that work better, but they are minor.

John S
PDX OR