[Stoves] 2 KW Woodgas generator with turbine

[CEDESOL Foundation]

On 3/18/07, andrew <list at sylva.icuklive.co.uk> wrote:
>
> On Sunday 18 March 2007 10:24, Crispin Pemberton-Pigott wrote:
>
> >
> > This guy speaks as if it is normal to generate 2 KW worth of
> > electricity from wood gas using his burner.
>
> Firstly this topic is better at [gasification] rather than [stoves],
> complication, safety and capital expense means the waste heat is
> never likely to be a prime use of the technology, least of all for
> cooking.
>
> He may generate 2kW(e) but what is the cost in input kW(t)? My guess
> is around the 5% mark, probably no better than a modern TEG. I say
> this because we built a pyrolyser with a bit more sophistication
> than this. it ran at 2bar above atmospheric. Now think about this
> the next time you pump up a car tyre, it's a non insignificant
> pressure. So the containment has to be internally insulated and
> pressurised, the "skin" has to withstand this and to do so must leak
> a bit of heat.
>
> Why do I compare it with a pyrolyser? It's because there are
> difficulties with complete gasification such that for this use it is
> actually quite a bit easier just to deal with pyrolysis offgas and
> discard the char. I think even fairly successful gasifiers running
> reciprocating ic engines have tended to leave a lot of char with the
> ash.
>
> Terra Preta enthusiasts will see an opportunity similar to that
> presented by a TLUD stove once carbon trading/offsets work at the
> micro level.
>
> There are a number of means of pushing up the conversion from these
> low pressure "agricultural" gas turbines but they involve
> significant cost. An increase from 11% to 20% was mooted for a 250kW
> output with a pressure ratio of 2.9:1.
>
> > There is quite a lot to see (including a 120,000 RPM turbine) at
>
> Maybe but how safe is a turbine with an inlet temperature of ~1000C
> running continuously, when it was designed to operate at an inlet
> temperature of 500C for a vehicle life of a few thousand running
> hours?
> >
> > My simplest interpretation of it is that he is using a vehicle
> > turbocharger to compress the gasifier...yes?
>
> Most likely the compressor provides compressed air for both the
> combustion and the gasification, the containment all running under
> pressure.
>
> > Or is it burning the
> > gas to drive the turbine and get electric power from the shaft?
>
> He'll be burning the gas in a separate combustion region and then
> expanding the products through the turbine, even with wood the thing
> will need quite a lot of dilution air to get the turbine inlet
> temperature low enough (you might be able to do this with the water
> from green wood but it would likely interfere with the gasification
> part too badly).
>
> > Either way there is a lot of heat to cook with left over.
>
> Definitelyy probably about 600C, but the food would fly and the cook
> would go deaf.
>
> Should anyone in UK want to further the concept I may know a man that
> could find the bits still, unless they're already en route to a
> smelter in China.
>
> Andrew Heggi
>
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-- 
David Whitfield V.
Executive Director
CEDESOL Foundation