[Stoves] Traditonal Charcola Making Process / retort

[Kevin Chisholm]

Dear Crispin

I think we are getting closer. :-)

1 kG of wood at 15% moisture has very close to 1 kw-hr of energy.

1: If you gasified all the wood, and did not stop at the charcoal stage, 
you would probably have about 70% gasification efficiency, suggesting 
that for a 7 kW thermal heat load, you would need about 10 kG wood per hour.

2: If you pyrolized the wood, leaving behind the charcoal, but burned 
only the pyrolysis gases, the "charcoal loss" would be about 30% of the 
energy content, but the gasification efficiency would be greater... say 
only 10% energy loss. You would probably need about 11 kG/hr of wood to 
yield sufficient pyrolysis gases to heat your oven. However, you should 
be left with about 20% charcoal by weight, or 30% of your starting energy.

3: If you wanted to produce charcoal to run a charcoal gasifier, 
charcoal would contain about 1.73 kw-hr/kg, so you would need about 4 kG 
charcoal per hour. At 20% yield, this would require about 20 kG/hr of 
bone dry wood, or about 23 kG/hr wood at 15% moisture.

Does this sound like we are on the right track now?

Best wishes,

Kevin



Crispin Pemberton-Pigott wrote:
> Dear Kevin
> 
>> It appears that I totally misunderstood the problem. 
> 
> In that case I have failed to communicate properly.
> 
> The Maputo Ceramic Stoves (MCS) are electrically fired but that is expensive
> compared with gas.  It turns out the reason gas is cheaper is not because it
> is inherently cheaper, but because gas is sold at an energy discount
> compared with oil, and the electricity price is similarly manipulated.  Thus
> is oil goes up, everyone pays more for energy which makes no sense but those
> are the powers that be.
> 
> Gas is inherently less efficient in a furnace because of the need to have a
> high exit temperature.  The loss is about 50%.  What people do is lower the
> gas price so it is cheaper to accomplish a task, so gas has to be about 5/6
> of 1/2 the price of electric heat.  This means if you have a big oven, you
> can save at most 16.66% of fuel costs.  This is apparently a fixed
> relationship.
> 
> If I turn wood into gas to make charcoal I can fire the stoves using the
> gas, but at an efficiency of only about 50%.  Thus my 3.5 KWH of electric
> power needs 7 KWH of gas power due to the way hot gases leave the furnace.
> 
> That is the origin of the 7KW.
> 
> So I was wondering how much wood I would have to charcoal to fire a stove.
> 
> Regards
> Crispin
> 
> 
> _______________________________________________
> Stoves mailing list
> Stoves at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/stoves_listserv.repp.org
> http://stoves.bioenergylists.org
> http://info.bioenergylists.org
> 
>