GAS-L: Cheap charcoal gasifiers

["Graeme Williams" <graeme@powerlink.co.nz>]

Dear Andrew and gasification colleagues.

My apologies for replying to earlier postings at this late date, but I am
disappointed that so many good questions and statements are unanswered or
challenged.  Is our knowledge so insecure we fear to present it, or do we
think its too commercially valuable to share?

Andrew, your questions about charcoal gasifiers and their cost compared to
wood gasifiers is you could say, a trick question.  You still need the same
amount of components gasifier (simpler), cyclone, coolers and filter, with
the only real difference being in the lack of condensate.  The more gas you
need, the bigger they become, and they do need to move away from the single
big nozzle to achieve the increase in size.  It would not be necessary to do
this if charcoal quality was consistent, but in the real world, its more
often torrified wood than charcoal.

As to the cost of these charcoal gasifiers, why does anyone expect them to
be cheap, work for 10 years and come complete with commercial warranties
There is also an expectancy that you the owner, can ignore the need for
operational training, servicing, and maintaining safety standards, all
issues that a responsible manufacturer has to resolve, in order to sell you
a gasifier.

The interest in charcoal gasifiers of course comes from the simplistic
pictures you see in historical literature, the Kalle for instance.  Its
actually a very crude example of gas making principles and far less reliable
than a cross draught system.  They all worked of course, but in the end the
reliability and durability of components came back to the individual
manufacturers skill and understanding of the gas making phenomena.

Simple charcoal gasifiers for developing countries were developed at AIT in
Thailand using Ferro cement and chicken wire.  These were further developed
at Bremen University in Germany (1989) and BTG in the Netherlands.  I
participated in the Bremen project supervising "cheap" steel gasifiers.

I'd like to suggest that it be kept in mind, that we cannot impose our
ideals on rural populations in far away places.  Our choice of technologies
is not simple or cheap, but it can be reliable if the gas making phenomena
is understood.

Finally, don't believe all you read in historical literature, for even with
all the dimensions they supply to copy, you will have a hard time making
them work.

Doug Williams
Fluidyne Gasification.


Date: Thu, 30 Mar 2000 22:16:25 +0100
> From: Andrew Heggie <andrew.heggie@dtn.ntl.com>
> Subject: Re: GAS-L: Oh!! -- that small steam power plant ---
>
> On Tue, 28 Mar 2000 08:32:53 EST, Tom wrote:
>
>
> >Most of the early work on gasification (1900-1940) used charcoal for its
> Yup, I understand that.
> >convenience, and hang the cost or inefficiency.  After WWII got going all
the
> >countries realized that throwing away 70% of the wood energy to make the
> But the whole point for this discussion is that nothing is thrown
> away. The wood is pyrolysed to charcoal and the off gas is burned
> cleanly to cook food. Ronal was previously a champion of this
> co-product for export as a cash return, Alex and I were just
> suggesting an alternate market to cooking charcoal.
>
> I have been discussing the relative merits of converted automobile
> engines as prime movers (powered with steam versus producer gas) with
> Vernon Harris. He suggests that some cultures are so poor any
> technology will require continuing support. My viewpoint is parochial,
> I have not travelled anywhere dependant on biomass as a cooking fuel.
> It seems to me that automobile technology is available to many people
> still dependant on biomass for cooking. Fuel for these engines must be
> a drain on currency. My guess was that substituting an imported fuel
> with a home grown one would be beneficial.
> >charcoal was destroying their forests, so they took the extra steps
required
> >for wood gasifiers (tar cleaning etc.)  It's all detailed in the books
below
> >and I have been re-reading them with new insites.  "Those who don't study
> >history are doome dto repeat the mistakes of history." (Lord Acton?)
> >
> >We are developing a "tarfree" gasifier at CPC and expect to throw out all
the
> >wet scrubbing etc. the bedeviled the WWII "Stoves".
> I hope you do bring this device to the market, but will it be cheaper
> than a charcoal gasifier and as simple as the Kalle one appears to be?
> My proposition was that a charcoal gasifier might be cheaper to make,
> easier to operate and more compact than a wood gasifier.
> AJH


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