FW: [Biochar] The missing middle scale for biochar production: moving and crushing

 

On Fri, Dec 29, 2023 at 3:40 PM Ben Discoe <bdiscoe@gmail.com> wrote:

By now, there are countless resources on how to make biochar at a small scale: pits, rings, barrels, small kilns, small retorts. There are books and YouTube videos. To unload these small volumes, you can dump or shovel the char, crush or
grind it slowly in small batches with a mesh or chipper or even put it in sacks and drive on it.

 

At the large scale, I believe, you can build a large industrial building and fill it with machines you can buy, $100k and up, which will do large batches, or even continuous production, where the char is moved along automatically from pyrolsis
through crushing and loading into trucks for distribution. If there are powerful enough machines to chip the feedstock finely before pyrolysis, you might not even need to crush the result.

 

What I cannot find is the middle scale.

 

I’m a small farm biochar producer, making ~2 cubic yards per batch, very manually: hand feeding wood, shoveling out the kiln, pushing it through a mesh into a wheelbarrow, scooping it up in buckets to fill bags. It works, but it’s slow
and labor-intensive, which means it doesn’t scale up.

 

A crucial bottleneck is unloading the char from the retort or kiln, crushing it to uniform size and depositing it in sacks.  On YouTube, there is only this very brief mention from 2013 of a mid-sized operation:

 

https://youtube.com/clip/Ugkxk1v48cfHk11YydSC-zOSjTUwFHFxekec?si=O7zONl9wjCjbr7Sp

Dan at Living Web Farms: “About scale, a better way to crush the char, well we operate on such a big scale that we can afford to use one of these, basically its a leaf vacuum, we jump in there and we vacuum it out, and it grinds it on the
way out, and we capture it in those giant super sacks. We vacuum it through a chopper.”

 

That sounds fascinating, and promising! But AFAICT, it’s the only 10 seconds on the internet about how it might work at that scale. That leaves a LOT of questions.

 

What was that vacuum machine?

Did it clog or jam or require expensive maintenance?

Would it grind char uniformly or would large chunks make it through, requiring further sifting?

This was 10 years ago, did it continue to work well or did they move to another process?

Is anyone else producing char at a similar scale today willing to share what they use?

 

Thanks,

Ben

 

From: main@Biochar.groups.io <main@Biochar.groups.io&gt;
On Behalf Of Bob Wells via groups.io

Sent: Friday, December 29, 2023 11:50 AM

To: main@biochar.groups.io

Subject: Re: [Biochar] The missing middle scale for biochar production: moving and crushing

 

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Hi Ben,

    The middle scale is indeed difficult.  The unloader that we build for the retort that you are referring to is run on a 14 HP gas engine and it is basically a slightly overbuilt centrifugal fan/blower/vacuum.  The biochar is sucked right
through the stainless impeller and smashed as it goes through.  It is immediately blown from there to a cyclone separator that drops the char into a container.  There is also an adjustable water jet built into the housing of the blower just before the impeller,so
that we can add just enough water to knock down the dust.  It only takes 10 minutes to unload the retort and the dust is pulled away from the operator as he/she works.  Properly designed, it never clogs, doesn’t wear out, is safe and easy to use, takes very
little time to run, and it partially processes the biochar.  What it doesn’t do is crush the biochar to a uniform or controlled particle size.  That requires another step.  We use a hopper fed trommel to sort out the size fractions.  Any oversize particles
go into a finger type crusher that gives us perfectly sized biochar that then goes to the next step which is inoculation and mixing.

    There are no real easy answers to all these steps.  You have to decide how much of the process you can afford to mechanize based on the cost of the equipment and the cost of the labor that it will save.  Any machine will be more cost
effective if it is used consistently, requires little maintenance, and saves lots of labor.  But sometimes the upfront cost is still hard to come up with.

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Bob Wells

New England Biochar LLC

Eastham, MA 02642, USA

T:  (508) 255-3688

bob@newenglandbiochar.com

www.newenglandbiochar.com

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