[Gasification] Very interesting auto engine powered char maker

Tue Feb 20 14:19:58 CST 2007

>From one Ken to another, yes what you say is easily do-able.
We did this 30 years ago on a remote Pacific Island
in what is now called Vanuatu.  We ran a Mission High School on woodgas, 
producer gas
or call it what you will.   During OPEC2, a small roster of pupils for their 
daily work duty went out onto an old abandoned airfield
(From the War in the Pacific) and each child had to cut 5 poles of Leucaena 
scrub  up to 2" and 12-15ft long. The polesof dgreen timber were pushed 
through an automatic docking saw and came out as 2" blocks which were 
wheelbarrowed  up an inclined ramp and into an old rusted out water tank up 
on posted which had a new conical base with a  slide hatch at the bottom, 
just highenough to get the said wheel barrow under it for transporting the 
torrified blocks into the gasifier itself. The engine concerned was an old 
Holden 6 cylinder converted from out of a car and it drove a 25kw alternator 
through its gearbox, permanently in second gear.  It took three days for the 
green wet blocks in the top to come out the bottom as absolutely beautiful 
gasifier fuel. They were so shrunken and split, in fact almost shattered, 
that you could almost light them with a single match. So, the exhaust heat 
from the engine dried the wood, and the cooling water from the engine heated 
the schools hot water supply. We did consider bleeding off some of the gas 
to cook the food in the kitchen, but  the logistics beat us.   However, do 
be warned that you need a very good flame trap on the exhaust pipe before it 
goes into the bottom of the fuel hopper.  We learned the hard way!  Maybe if 
the old tank did not have so many holes in it we could have made char  that 
would not have set fire to the fresh wood coming in.  Tell us how you get 
on?  .
Ken Calvert.

 ---- Original Message ----- 
From: "Ken Boak" <kenboak at stirlingservice.freeserve.co.uk>
To: <gasification at listserv.repp.org>
Sent: Wednesday, February 21, 2007 1:55 AM
Subject: Re: [Gasification] Very interesting auto engine powered char maker


> Tom, Andrew, Drew & List,
>
> For some reason I failed to receive Tom's first reply email about my
> charcoal making this weekend.  I later found it on the archive.
>
> Whilst the method I described produces a fairly low volumetric yield 
> (25%),
> and a lot of smoke,  it does serve to illustrate to the newcomer the 
> various
> stages of the burn and is a good way of learning a little about the
> practical aspects of charcoal making and the process of gasification.  The
> wood was alder, cut from 6" diameter cordwood which was felled last year,
> but left stacked outside - so still fairly high moisture content.
>
> My own aims are to use the waste heat from my Lister exhaust to at least 
> dry
> then torrefy the woodchip fuel.  I have successfully recovered and 
> measured
> 4.2kW heat from the 6hp Lister exhaust when running at rated output.
>
> My next step will be to construct a downdraught gasifier, onto which a
> torrifier stage may be added.
>
> There is also the "pneumatic" power contained in the exhaust of the slow
> speed diesel, which could also be utilised for fuel-handling, 
> grate-shaking,
> de-bridging etc. I like the idea of the metal bellows in the top of the
> Kalle gasifier, that responds to engine demand and is used to provide the
> self cleaning action of the air nozzle.  With the Lister running as slowly
> as 300 rpm, the exhaust beat will be as low as 2.5Hz and could be utilised
> for mechanical agitation of the fuel or reactants in the reaction zone.
>
> The interesting part will be to determine whether there is sufficient
> temperature and excess oxygen in the diesel exhaust to provide an 
> effective
> charcoal initiator.
>
> I have been running the engine very much derated, on waste vegetable oil,
> and this gives rise to much greater quantities of carbon and unburnt fuel
> residues in the exhaust.  When I move to dual fueling on WVO and wood gas,
> my intention is to use the woodchips in the fuel hopper, not only to 
> capture
> these particulates and deliver them to the reaction zone, but to use the
> woodchips as an effective silencer/muffler for the pulsating engine 
> exhaust.
>
> Additionally, with the Lister runnig at 300 rpm,  the powerstroke has a
> duration of  0.1 seconds.  This gives the burning woodgas plenty of time 
> for
> flame propagation. I would be interested in correlating the flame speed of
> the gas mixture to the performance within the slow speed engine - however 
> in
> dual fuel mode, the injected oil will continue to burn well towards the 
> end
> of the powerstroke.
>
> This paper discusses effects of compression ratio on a producer gas 
> fuelled
> engine
>
> http://cgpl.iisc.ernet.in/Biomass%20derived%20producer%20gas%20as%20a%20reciprocating.pdf
>
> It suggests (quite contrary to popular belief) that compression ratios up 
> to
> 17:1 can be retained with producer gas fuel, and that the derating is not 
> as
> severe as often thought - conclusions that require further investigation.
>
>
> regards,
>
>
> Ken
>
>
>
>
>
>
>
>
>
> Dear Ken and All:
>
> I never wanted to be a charcoal maker (Kohlbrenner).  From 100-1900 AD
> they lived in the forest, piled up a dozen chords of  wood, covered it
> with turf, lit it at the bottom, watched the steam phase, the smoke
> phase and finally the blue haze phase, then plugged up the inlet and
> outlet holes and let the pile cool for a week or two.  Total time, a
> month;  I presume they played cards, drank, etc. as they burned down the
> forests of Europe to make the guns and cannon that kept the population
> in check.  The resulting desert and the replanting of the forests is
> described for those who care in the book "The Man who Planted Trees" by
> Jean Giono (available BEF Press, Chelsea Green Press with woodcuts, or
> many other publishers, see
> http://en.wikipedia.org/wiki/The_Man_Who_Planted_Trees).
> ------------------------------------------------------------------------
> Charcoal is the secret to all good biomass gasification, both in the
> production of charcoal (in pyrolytic gasifiers) or the simultaneous
> production and consumption of the charcoal in WWII gasifiers.  Depending
> on the direction of air through biomass, first or last, the resulting
> gasifier will be a "tar-burning, char making" (TBCM) biomass gasifier
> (also known as a downdraft, toplit updraft, crossdraft, flaming
> pyrolysis etc. gasifier) or a "charburning, tar making" (CBTM) gasifier
> (also known as (bottom lit) updraft).  These are all easily illustrated
> in the burning cigarette/cigar gasifier discussed here last week.
>
> Thanks for describing the CBTM production method. If you ever run this
> experiment again, I hope you will report the moisture content and mass
> of the fuel and the final weight of charcoal produced.  I would guess
> between 15 and 25 %, depending on the moisture content.  I presume it
> would work in a 5 gallon can, and I know it works in a tomato soup can.
> However, I hope you didn't have anyone around to object first to the
> white smoke, then yellow, then green, mostly incombustible.
>
> Let me describe three more ways of making a drum of charcoal.
> ------------------------------------------------------------------------
> About 1998 Danny Day at a family party connected the tailpipe of his
> truck to the bottom of a 55 gallon drum full of peanut pellets.  He ran
> the truck (fast idle?) for a while and soon had a combustible gas flare
> 30 feet tall that entertained the guests.  The charcoal was very dense
> and this simple experiment started Danny on making activated charcoal, a
> good idea then, not now that the Chinese do it cheaper....
>
> This method relies on using the dephlogisticated (deoxygenated) hot
> exhaust (>500C?) produced by consuming the oxygen in the input air with
> gasoline.  It differs from the classical method in using higher heat
> transfer heating that is fast enough so that the (dry) pellets pyrolyze
> and dry simultaneously, so that the flare is combustible from the getgo.
> ------------------------------------------------------------------------
> If you repeat your experiment by packing the fuel tight and lighting the
> *top* layer (alcohol or kerosene) of wood or preferably charcoal, air
> will be drawn through the mass of fuel to the burning charcoal.  A
> combustible gas is formed which can be used for cooking (in the TLUD ND
> gasifier) or many other processes.  The charcoal will successively light
> lower and lower layers until the flame turns blue when all the biomass
> is converted to charcoal and it becomes an updraft charcoal gasifier.
> ------------------------------------------------------------------------
> Finally, if you are brave, you can get a vessel that can maintain a
> pressure of 10-20 atmospheres and apply heat (electric or biomass)
> around it.  Since the increased pressure keeps the volatiles from
> vaporizing at the lower temperature, you can achieve a yield of 35-45%.
> This method has been pioneered and patented by Prof. Mike Antal, Coral
> Professor at the U. of Hawaii and is nearing commercialization.  His
> latest paper on the subject is: M. J. Antal et Al,  "Biocarbon
> Production from Hungarian Sunflower Shells", available online at
> ScienceDirect (7 references).  It is on my pile to write Mike with 
> comments.
>
> So, charcoal is the key to biomass gasification in many ways, and is
> also produced by various processes from gasification.  I've learned to
> love it.
>
> Onward, Kohlenbrenners!
>
> TOM REED                          BEF/BEC
> ------------------------------------------------------------------------ 
>
>
>
>
> _______________________________________________
> Gasification mailing list
> Gasification at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org
> http://gasifiers.bioenergylists.org