[Gasification] Charcoal Gasifier No 2.

[Ken Calvert]

Well Doug I have a photo of it too, but only the Good Lord knows where at 
this stage.   ATB. KenC.


----- Original Message ----- 
From: "doug.williams" <Doug.Williams at orcon.net.nz>
To: "Discussion of biomass pyrolysis and gasification" 
<gasification at listserv.repp.org>
Sent: Wednesday, July 25, 2007 9:53 PM
Subject: Re: [Gasification] Charcoal Gasifier No 2.


> Hi Ken and Colleagues,
>
> Really good description of how adaptable people became to using these
> charcoal gasifiers,but remember that Australian hardwoods make really
> superior charcoals.
> ..
>>   Because one could control the temperature  there were no meltdowns and
>> slagged up hearths.
>
> Meltdowns were a problem of those gasifiers that were not cleaned out of 
> the
> sintered ash around the nozzle, causing the oxidation lobe to move to the
> available char against the walls. Then you could  have nozzles too small 
> for
> the job, creating a blast velocity in excess of the temperature needs. The
> nozzle bore size is set at the maximum flow to produce an bed colour of 
> not
> quite white hot. You are aiming for about 1,000-1,200C at the top end, and
> at the lower end there will still be plenty of blast to maintain the bed
> above the 850C at which point reduction almost stops.
>
> Cliff's one tuyere was  a  slab of 1/2"  steel plate
>> accross the side of the hearth with a 1" hole in it. That made it a cross
>> draft model.  The thick mild steel plate conducted heat away from the
>> tuyure
>> and  spread it out accross the bottom of the fuel hopper.
>
> You can see this plate in the photos of the Australian Kent Charcoal
> gasifier on the Fluidyne Archive. www.fluidynenz.250x.com
> It is not welded to the bottom , because an ash door was fitted under the
> nozzle
>
>>     There was no grate or need to remove ash. After a days work the fire
>> was allowed to die out and  part of the start up next morning was to dig
>> into the charcoal fuel, and if you were smart you ran the hopper down at
>> the
>> end of the day so that you reached down and removed a birds nest shape of
>> ash charcoal sinter which sat just opposite the tuyure
>
> You cannot have it both ways. If you run the fuel down to the oxidation
> lobe, combustion and high temperature results in burning of the casing, 
> and
> you can see this on the Kent gasifier where patches have been welded on 
> the
> sides. Clearly there is a need to remove the ash if you dig it out each
> morning, but if you get lazy it soon creates the problems. The Kent
> instructions say to clean out the ash every 10 bags of charcoal.
>
>>    The model that Cliff sent over to us in the Islands was made out of a
>> couple of  44 gallon drums, plus about  2ft of  6"x 1/2" steel bar  and 
>> we
>> ran a  Toyota landcruiser engine  that powered our workshop for over a
>> year
>> before we had to do anything much to it.
>
> The diameter of the drum kept the oxidation lobe away from the walls, and
> the internal inactive char protected the walls from heat stress.
> I might have a photo of this in the files Ken, and will post it with 
> others
> at the end of these charcoal postings.
>
> Doug Williams
> Fluidyne Gasification.
>
>
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