[Gasification] Heat to enable full H20 Gasification, Digest, Vol 2, Issue 17
tombreed2010 at gmail.com
Mon Oct 18 08:15:37 CDT 2010
Dear Geoff and all
You are definitely on to something, the benefits of moderate amounts of water in combustion, pyrolysis and gasification of wood.
Conventional wisdom CW, says that for running vehicles the moisture content of the wood (wet basis) should be less than 20%. (But CW doesn't specify a lower limit, since everywhere except Colorado wood will have >7% MC).
I wondered how much moisture would prevent our TLUD stoves from burning. I first dried wood chips to 0% moisture, then added water to make samples with 5,10, ...30% moisture. I was delighted to find that I could burn all of them in the TLUD stove, BUT the charcoal yield was 20% for bone dry wood and only 3% for 30% MC WOOD. ObvIously, the charcoal was drying each subsequent layer in the reaction and being proportionally consumed. Also the 30% MC stove had a very blue flame.
More generally, I believe in both pyrolysis and combustion a small amount of water vapor localizes the reaction and keeps hot hot and cold cold. A bone dry log in a. box stove heats uo all over and can't get enough air to keep the flame localized.
I hope there will be more comments on the utility of some water in biomass combustion and pyrolysis.
Tom Reed - Pyrologist
Sent from Tom Reed's Ipad
On Oct 18, 2010, at 6:23 AM, Geoff Thomas IMAP <wind at iig.com.au> wrote:
> Hi Guys, I have long been fascinated with the extra output from those gasifiers with water added or high water content fuel, - mind you I am not an expert nor an engineer, but a renewable energy systems designer, and I demonstrate a Tom Reed camp stove at some of my market stalls, (got to be careful with the down wind pregnant woman who hates any smoke) yeah, market stalls, I am not big time, although quite creative in my own area, but it has always seemed to me how interesting the possibility of using H2O plus carbon, another oxygen lover, to free the hydrogen and then express the energy, - and of course there is (probably) no free lunch, if it is a higher energy density that we require to enable this then what if we contain the whole process in insulation, - then use Solar mirrors to heat all incoming substances, (certainly would only work in full sunshine, but wood gas is storable), - already Solar Thermal is being used to increase the efficiency of Coal fired power stations and Solar thermal power stations would work very well with Geothermal Hot Rocks as they use the same sort of Heat Exchange system as the hot rock Geothermal, (as does Nuclear), - with Geothermal the Sun could provide the heat in the day the buried heat at night, - the hot rock storage, built up over millennium would be extended by the Solar thermal during the day using the same generator, but not depleting the heat storage deep in the earth as much, - similiarly, (sort of) are you suggesting the pre-heating of incoming air and fuel may allow a much higher series of transformation reactions, possibly more energy productive, and solving some of the gasification problems as for instance tars, it sounds like they could be better managed in that environment, and increased water penetration, leading to higher quantities of re-actable gas with more energy within, perhaps an ideal carbon CO or carbon CO2 to H2O ratio, (given whatever required temperature) might be interesting?
> The gas could like wise be used at night to generate peak power, or whatever usage - sort of like replacing batteries.
> Doesn't sound like easily do-able with transport, hard to get that conserving of all heat, but certainly could be very interesting with replacing embedded power, - grid or stand-alone.
> Of course I understand in the meantime the almost infinite varieties of biomass to fuel gasifiers is also relevant, (and fascinating in my own experiments).
> Think you are on to a good thing here,
> Geoff Thomas,
> Advanced Wind Technologies.
> On 18/10/2010, at 5:52 PM, gasification-request at lists.bioenergylists.org wrote:
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