[Stoves] combustion of char

[ajheggie at gmail.com]

[Default] On Sat, 23 Feb 2013 10:37:42 -0500,Alex English
<english at kingston.net> wrote:

>Frank, Harold,
>
>Interesting discussion, made more so by the fact that I making drums of 
>char yesterday.
>
>Here is a paper that suggests that initial heating of coal has more to 
>do with H20 sorption than oxygen.  Rank and particle size being other 
>factors.
>Where upon oxygen moves to center stage.
>
>http://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/14_1_TORONTO_05-70_0059.pdf


This weight gain being water was my first thought, but Frank said the
oven was at 105C which I thought would militate against sorption of
water, it is possible that as weak bonding forces will play a part in
this hygroscopy  that the water needs a higher temperature to drive it
off and then the converse is true also. Sorption of water in effect
takes vapour and turns it to liquid, giving up its considerable latent
heat as it does so.  Fresh char does seem to have an auto ignition
point below 200C.

Of course moist air ( as considered in the paper Alex cites) is a well
known catalyst, hand warmers using a mixture of steel wool and salt
are  available and char will have mineral salts on the surface.

AJH