[Stoves] LPG import in India

[Andrew Heggie]

On 29 December 2017 at 02:03, Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:
> I don't think it's that difficult.
>
> The highest I have heard of is 45% which much be very high in volatiles. 35% yield with 15% volatiles is 30% carbon which is a 40% carbon loss.
>
> That's not so difficult, is it?

It looks impossible to me unless there is a wood with very high lignin
content. we'd need a bomb calorimeter to get empirical data. You can
increase yield by increasing pressure and residence time in larger
lumps as some of the tars will crack and deposit soot in the char
matrix.

I have easily made a char from pine with a char weight of 45% of the
original dry weight, in a bean tin in my wood stove at home, but it
burns with a yellow flame suggestion a high tar content. From Beale
wood science 1974 ( bearing in mind this cites hardwoods and pine is a
conifer) it interpolates as a formation temperature of about 400C[1].
Again interpolating this in a graph by Pohl 1970 suggests there is
stil around 15% oxygen present by weight which will reduce the energy
content by mass. I have an unattributed table which details the energy
yield per unit mass for charcoal  from acacia busei being 29.88 MJ/kg
at 400C with a 28% yield.


[1] this bears a bit of thinking about as Tom Reed suggested this is
in the 330C-440C exothermic region so we might expect the temperature
to rise to 440 with no other intervention

Andrew ( post may be a bit disjointed as I broke off for my cold 50th
anniversary bike motorbike ride, it didn't worry me when I was 16 ;-))