Any new small charcoal retorts out there?

[daveatdave]

at first glance I thought it was a steam powered truck.

as I have said before this thread is way over my head but I keep reading the posts and trying to learn a bit

[Woodworks]

Continuing test burns. Now it's being run at more modest temperatures there are periods of the burn where there is smoke from the chimney and I would like to limit this. I noticed the Hookway has some system where the excess gasses burn in the flue. Any idea how this achieved?

 

Thanks

[SteveA]

Continuing test burns. Now it's being run at more modest temperatures there are periods of the burn where there is smoke from the chimney and I would like to limit this. I noticed the Hookway has some system where the excess gasses burn in the flue. Any idea how this achieved?

 

Thanks

 

Far as I can gather, the Hookway retort works on a similar principle to a rocket stove. If you search Rocket Stove on YouTube it'll come up with lots of examples.

 

Also worth looking up Rocket Mass Heaters.

 

For both of the above getting the correct dimensions can make a huge difference to the efficiency of the burn.

 

cheers, steve

Edited April 27, 2017 by SteveA

[TreeMuggs]

This is how I make my own charcoal:

 

 

 

 

.

[Duncansimpson]

Good idea this but I reckon he burnt £10 of logs to get £10 of charcoal. I cut the top off a 20kg gas bottle and then welded lugs so I could put the top back on. I fill this with wood and drop it into my biomass boiler and leave it until the morning. Perfect charcoal plus still getting the rhi payments. Win win

[farmer rod]

Good idea this but I reckon he burnt £10 of logs to get £10 of charcoal. I cut the top off a 20kg gas bottle and then welded lugs so I could put the top back on. I fill this with wood and drop it into my biomass boiler and leave it until the morning. Perfect charcoal plus still getting the rhi payments. Win win

 

Genius!!

 

Ive got the wrong boiler

[openspaceman]

Genius!!

 

Ive got the wrong boiler

 

Mine lends itself to this although I've never tried it.

[farmer rod]

Mine lends itself to this although I've never tried it.

 

Perhaps this is the answer to all these retorts getting too hot, fit flue gas recirculation and a lambda probe to run the afterburner

 

Out of curiosity, what is the lowest temperature that will make acceptable charcoal?

[openspaceman]

Perhaps this is the answer to all these retorts getting too hot, fit flue gas recirculation and a lambda probe to run the afterburner

 

Out of curiosity, what is the lowest temperature that will make acceptable charcoal?

 

With dry wood the temperature in my firebox is likely over 1200C at the flue exit, the grate and auger are cooled by incoming air.

 

I moved away from retorts for a number of reasons but yes some sort of recirculation and after burning the excess offgas in a separate firebox would make sense.

 

As to temperature, we have to remember that unless the wood is dry whilst some of the charge is charring some other bits are still coming up to temperature but I'd guess by the time all the charge is about 330C its charcoal .

 

The thing is if the temperature is rising uniformly through the charge then at this temperature it autolyses, i.e. as long as heat isn't lost it continues pyrolysing by itself and the temperature also rises till about 440C at which point some of the carbon changes from chain like molecules to ring like ones, I think this absorbs heat so without further heat input it would stop. In practice the load isn't homogeneous nor very dry so more complex things are happening at any time. People here seem to be reporting temperatures of 550C inside the retort.

[pileswasp]

I noticed the Hookway has some system where the excess gasses burn in the flue. Any idea how this achieved?

 

 

There's an air inlet in the base of the flue, but I don't recall it being as controllable as you seem to be thinking.

 

 

 

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