[Stoves] Is there a role for combining torrefaction and char-making stoves?

[Frank Shields]

Stovers,

So we have 'Wood and Biomass and we have biochar. Isn't everything in
between torrefied biomass?
And the definition of it starts when wood gasses start leaving the biomass
and ends when the weight loss becomes stable (to a point)? If not we need
more terms for fractions not filled in by torrefied biomass. I prefer having
several degrees of torrefaction. That because the curve is steep for weight
loss and structural changes between 250c and 450c. Stable below 250 and
above 450c. 

Not sure how to group the lower, middle and upper values of torrefied
biomass. Lower could be up to when the biomass snaps meaning structure is
broken, Upper is when the volume is 25% reduced to biochar.  

The TD sticks start at 0.69 cm wide and 15 cm long ( 10.35 cm sq)and end up
at 650c to be 0.42 wide and 13 cm long (5.46 cm sq).

Just suggestions

Controlling the process of making the torrefied material we want to be sent
for char making seems real tricky IMO. So much happens in such a small
temperature-time change in this range. 


Frank


Frank Shields
42 Hangar Way
Watsonville,  CA  95076
(831) 724-5244 tel
(831) 724-3188 fax
frank at bioCharlab.com







  
-----Original Message-----
From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
ajheggie at gmail.com
Sent: Tuesday, February 28, 2012 1:29 PM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Is there a role for combining torrefaction and
char-making stoves?

I' not sure about the attribution of the bit below but anyway:

On Tue, 28 Feb 2012 00:32:13 +0000 (UTC), rongretlarson at comcast.net
wrote:

>I don't think that 450 is the right upper limit for the term "torrefaction"
- I think even 280 oC might be too high an upper limit. Saying this because
I think we want to keep as much energy gas in the product as possible. Some
of the first useful gases coming out are not exothermic - and so we don't
mind losing them. We certainly shouldn't ever mind the big water weight
loss. 

450C is definitely the realms of charcoal, over half the dry matter has gone
by this stage.

Just because it has been given off by an endothermic process doesn't mean
the offgas species are non combustible. I think anhydrous acetic acid will
burn but not in combination with the other early species of pyrolysis,
mostly water.

AJH


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