[Stoves] Charcoal burning, secondary flame vs no flame

[Crispin Pemberton-Pigott]

Dear Roberto

 

It is unlikely that you will be able to burn charcoal without any CO2 at
all. In the centre of a charcoal flame, under the middle of the pot, there
is often a very high CO2 level, but it is so hot, excess C is available and
it is  absent of free oxygen so it breaks apart to make 2 CO. 

 

If you can estimate the mass of CO2 and the mass of CO you can calculate the
difference. C to CO2 is 33 MJ/kg (close enough) and C to CO is a bit more
than 8. So you lose ¾ of the available heat energy if you fail to burn the
CO to CO2.

 

For 600m of char, (assuming 85% carbon) the loss would be 32.8 x 0.85 x 0.75
x 0.600 = 12.6 MJ loss

 

Or 29.5 MJ/kg for the char x 0.6 kg to get the available heat  = 17.7 MJ

And

Subtract the CO loss: 0.600 kg x 0.85 carbon x 75% x 32.9 carbon heat =
12.6MJ loss, the same thing. Heat released by burning C to CO = 5.1 MJ. 

 

If you have a portion of the gas as CO2 and another as CO, you can pro-rate
the heat available as ‘yielded’ or ‘lost’ according to CO/(CO2+CO) and
CO2/(CO+CO2) times the carbon mass times 32.9 MJ/kg.

 

The CO loss is closer to 74.5 % of the CO2 energy if you really want to be
picky.

 

Regards

Crispin

 

 

Hi,

I want to know what is the difference in combustion efficiency between
burning charcoal with secondary flame (burning CO) vs burning without
secondary flame (CO escape to the chimney).

 

For example, burning 3 kg in a TLUD produce 600 grs of charcoal. Then if we
decide to burn this charcoal, burning with secondary flame is more efficient
than burning charcoal with no secondary flame.

How can I measure this difference?

 

Greetings

Roberto Poehlmann

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