[Stoves] big TLUD

[ajheggie at gmail.com]

[Default] On Thu, 14 May 2015 15:44:58 -0400,Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:

>A related question for Tom Miles: 
>What do you think of the possibility of running a steam stream into a TLUD
>with the primary air to pass water vapour into the pyrolysis zone to create,
>at a lower temperature, H2 and CO. This will have the effect of decreasing
>the heat available in the fuel bed and increase the CV of the gas produced.

If I may butt in; this water gas reaction depends on the steam meeting
with hot char at above 800C to convert most of the water, it is highly
endothermic, so I doubt the descending pyrolysis front is hot enough
and even if it were the endothermy and small mass of hot char would
very quickly quench the reaction.

>This effect was accomplished by spraying water onto the hot coals in a coal
>gas plant. It reduced the temperature of the working environment and
>increased the CV of the "town gas".

Yes but the mass of hot coke (and probably the brick lining plus the
fact the steam was superheated made the reaction possible for a while,
then the coals cooled and the  steam was shut off whilst the coals
were blasted with air to give a CO and N2 mix, this being endothermic
took the mass back up to above 1100C., The CO+N" at 1100C was then
burned separately to raise steam and repeat the process. This way the
output was H2 and CO nearly free of N2.

AJH