[Stoves] Early Nariphaltan gasification work (formerly Declaration about Woodgas

[Andrew Heggie]

On 21 October 2017 at 16:01, Ronal W. Larson <rongretlarson at comcast.net> wrote:
> Anil, cc list

>
> 3.  I hope we can have more dialog on the “lethality" of wood or producer
> gas - as it applies to small cookstoves.  When a TLUD flame is extinguished
> by wind or near the end of a run, the acrid fumes can be very disturbing
> until either relit or the stove is completely shut down (zero air supply).
> In a normal operation, the acrid smoke is of course not seen nor expected.

Firstly woodgas is not producer gas, you need a much higher
temperature to crack all the vapours and methane to CO and H2,
probably in excess of 1200C. So woodgas contains all the tarry
volatile compounds which make it so acrid and easily sensed. The
danger tends to come later when only glowing char is left. Even in UK
we still have deaths occurring from CO poisoning, often when a
barbecue is used indoors  or taken inside a tent.
>
> My main question is whether anyone has ever experienced an explosion?   When
> relighting a TLUD stove there can be a small scary burst of flame - but I
> wouldn’t call it an explosion.   This is a good reason for instructions on
> relighting, should that be needed.

I think it is better described as a deflagration, we sometimes saw the
effect when a wood boiler flamed out but the  stoking mechanism
continued to pile woodchip onto embers, the boiler would fill with
yellow smoke and vent it up the chimney but as soon as the embers got
hot enough to ignite the gas at its autoignition point the mixture
caught alight, blowing the roof off a boiler room in one case. I have
triggered such an event by deciding to open the fire door on a boiler
that hadn't fired properly, the sudden exposure to air caused  a
deflagration and ejecting the fire door (no hinges just wing nuts)
into me.

The art is to maintain a flame .

> Regarding lethality,  I recall hearing that a favorite method of suicide
> (Singapore or Hong Kong?) is with a stove in a small closed room.  We must
> all be very conscious of adequate ventilation - as Anil has emphasized.
>

Yes and CO alarms are available cheaply also, I keep one and they are
a requirement when fitting solid fuel stoves or renting out properties
with them in UK.

Andrew