Mobile Retorts

[timbernut]

Always been interested by the Adam retort and I found new(ish) YouTube of them trying a new small mobile version in Bavaria and are looking for a manufacturer/ entrepreneur to take it further

[Woodworks]

This one? [ame]

[/ame]

[timbernut]

This one?

 

 

Hats the one!

[Woodworks]

How critical is the temperature of the burn to the quality of the charcoal? I see the Exeter retort and that Bavarian one in the video all have a thermometer. On our retort I just watch to see if the wood is giving off it's its gas. If these flames die back a bit I feed the fire and if it keeps going I leave it. No brown ends and no ash but maybe there is more to it than that.

Edited May 1, 2015 by Woodworks

[openspaceman]

How critical is the temperature of the burn to the quality of the charcoal? I see the Exeter retort and that Bavarian one in the video all have a thermometer. On our retort I just watch to see if the wood is giving off it's its gas. If these flames die back a bit I feed the fire and if it keeps going I leave it. No brown ends and no ash but maybe there is more to it than that.

 

This is a how long is a piece of string question. You can make a low temperature char at 400C which can have 45% of the dry matter yield in a high lignin feedstock but much of the content is higher tars rather than fixed carbon. Fixed carbon is checked by raising the sample in an inert atmosphere to 900C and will be about 15% of the dry matter.

 

Where indigenous peoples use char for cooking, often in towns indoors, they will prefer a high temperature char that just glows. In UK for barbecues people accept a high volatiles char that would be too acrid indoors because they want easy lighting.

 

The carbon in char starts to change state at about 450C as its bonds change to graphite like structures which are more recalcitrant.

 

Retort char is always likely to be non homogeneous because of the difficulty of transferring heat from the heat source through the wall to evenly heat the interior so it will tend to the lower end of the range.

 

Also bear in mid a steel sheet will stand a temperature of 700C on one side if the other side is in ambient air being cooled but in a retort if you have 700C on the ouside and 450C on the inside...

[steve collins]

temperature in the inner chamber is most critical to producing quality charcoal and keeping that temperature steady is even harder so a qualty gauge is key to the whole operation

[Woodworks]

temperature in the inner chamber is most critical to producing quality charcoal and keeping that temperature steady is even harder so a qualty gauge is key to the whole operation

 

If you don't keep it steady which I probably haven't how is the charcoal different. I clearly have charcoal and it works fine but maybe it could be better. What sort of temp would you aim at for BBQ charcoal. Is the 400C mentioned by openspaceman good enough for this use?

 

Thanks

[steve collins]

I wont say exactly what temp as we were using large retorts and wouldnt want to give you a number and your retort start having problems, reason for steady temp was that we had to be consistant and we found a +/ - drop of 5 degrees meant we either had a lighter char or a few brown ends

[openspaceman]

I wont say exactly what temp as we were using large retorts and wouldnt want to give you a number and your retort start having problems, reason for steady temp was that we had to be consistant and we found a +/ - drop of 5 degrees meant we either had a lighter char or a few brown ends

 

How many temperature probes did the retort have?

[the village idiot]

The Exeter measures the temperature of the flue gasses as they exit the charge chamber. I try to maintain a retorting temperature of between 450 and 500 degrees C for no other reason than this is what was advised by the designers. This produces a very nice, pure, but potentially light charcoal. The Exeter, as opposed to a lot of other retorts heats the charge wood directly from below along its whole length, resulting in an even temperature throughout and no unconverted wood (so far).

I'm surprised Steve that you had to be quite so precise with your temperature control.