Charcoal quality

[judastreefairy]

40 minutes ago, GarethM said:

Jesus probably doesn't even know if Judas stabbed him in the back

My mate , who overcooks wood 

[Bolt]

7 hours ago, GarethM said:

 

Well as reading obviously isn't your strong point,

 

… and possibly not so gifted with the writing either.

[judastreefairy]

50 minutes ago, Bolt said:

… and possibly not so gifted with the writing either.

Can you learn me marra 

[Stubby]

9 hours ago, judastreefairy said:

Can you learn me marra 

Its can you learn I FFS !

[Vigen Tigen]

On 06/02/2025 at 18:31, judastreefairy said:

My mate , who overcooks wood 

I understand the optimal temperature for turning wood into charcoal within a retort set up is around 500° but my question is how long should I cook the wood to burn off the VOCs and turn into charcoal? Would like to do 2 - 3 cooks a day if possible. I guess from my experiments so far with timings is that you can't overcook as the charcoal within the retort never touches a flame so can't be burnt out but I may be wrong here?

Edited February 8 by Vigen Tigen
typo

[openspaceman]

I thought I had answered that question but I note no answer to my Thursday question.

 

The rate of charring is very dependent on initial mc.

[Vigen Tigen]

On 06/02/2025 at 11:02, openspaceman said:

So the thermocouple measures the temperature at the top outside of the retort?

To clarify, the thermometer on the outside of the retort has a long probe, the end of which hangs in the void containing the fire, and measures the ambient temperature within the main chamber (inside the main chamber is a separate sealed oil drum (with small holes to release the VOCs) which contains the wood to turn into charcoal. Hope I'm painting a clear picture?

[openspaceman]

So the 500°C is separated from the char by the wall of the retort. Thus it's unlikely you will achieve equilibrium  with the same temperature inside the char, as I said once the char exceeds the ~450° temperature after the exothermic stage  more energy is needed as some of the carbon changes from a chain like structure to more graphite like ring structure.

 

I wouldn't worry about cooking it longer, keep an eye on the flames of the offgas and when they die down it's good enough.

 

One thing is that the pyrolysis is much faster than drying wood, so it is better the drier the wood is to start. Else the energy for drying has to be supplied through the retort wall.

[Vigen Tigen]

On 06/02/2025 at 13:47, openspaceman said:

I prefer the term pyrolysis offgas for what evolves from slow pyrolysis. To me syngas is specifically a mixture of carbon monoxide and hydrogen that is produced by the gasification ( 0.2 stoichiometric air) of carbon (coke). I am not a chemist and I was too stupid to learn chemistry at school, my brother was though and top of his field in carbon.

 

As to extended cooking; I expect once a retort has reached 450°C no matter how long you kept at that temperature not much would change. It's complicated by the feedstock but if the temperature uniformly ramps up to ~300°C the endothermy of drying and torrefying is over, then there is a short exothermic stage when the pyrolysis continues up to 440°C. After this the carbon matrix begins to change, whilst pyrolysis and cracking witin the matrix continues,  and this is likely endothermic.

Feeling a bit of a numpty! I've been talking about temperature in Fahrenheit so from the sounds of it, I haven't been getting the temperature high enough, even though I am getting charcoal?

[judastreefairy]

20 hours ago, Vigen Tigen said:

Feeling a bit of a numpty! I've been talking about temperature in Fahrenheit so from the sounds of it, I haven't been getting the temperature high enough, even though I am getting charcoal?

Not another one who can’t cook wood🤦‍♂️