[Gasification] Difference between Coal and biomass gasification

[Peter Davies]

Dear Tom Reed,

We have successfully gasified run-of-mine black coal (30% ash, 3%mc) 
crushed to >30mm piece sizes, and both brown coal briquettes and run of 
mine (but dried <10%mc) fine lignite material in our design of down 
draft system.

The brown coal behaves very similar to wood chips in the system, with 
similar gas qualities, the fine lignite was very pleasing as apart from 
a very vigorous clean flare it resulted in a high recovery of carbonised 
material suitable for briquetting as a co product, this was tested in 
Melbourne for this purpose with excellent results and found to need less 
binder than other carbonised product they normally worked with.

The black coal needed more air and had lower H2 content of the gas but 
still worked well, obviously introducing some steam would also improve 
outcomes here. We did not find either coals raised temperatures 
significantly in the gasifier, rather the higher density types simply 
took longer on a volume basis. We found the biggest problem was with the 
high ash black coal the inorganic components are not evenly distributed, 
not every black piece was coal and some of the rock like bits were just 
that, rocks! Hence the need to crush (for our system) to sub 30mm piece 
size so that the stuff that doesn't gasify will still go through our 
active grate and not create blockages.

The only other change of note discovered during earlier testing was 
where some condensate (light tars) was recovered in the built for 
purpose trap, testing showed that the pyridine component normally found 
from wood gasification had been replaced by benzene when the coals were 
gasified. I would be interested in your comments on this.

Cheers,
Peter
Managing Director
ID Gasifiers Pty Ltd
Australia

On 24/05/2015 4:17 AM, Tom Reed wrote:
> Dear Thomas Koch and ALL:
>
> Thomas asks a very interesting question.  Best answer would be for 
> someone (me?) to get a batch of coal and try it.
>
> First, I would expect that it m i g h t  burn up the gasifier.  Coal 
> burns so much hotter than wood.  But I hope the stainless steel can 
> stand it.
>
> Secondly it would burn twice as long due to the high density of the 
> coal and the high volatile content which could keep it from burning up.
>
> I hope someone will try it and give a report.  I'm on the road, but 
> will try it when I get home if no one else does...
>
> TOM REED
>
> Thomas B Reed
> 280 Hardwick Rd
> Barre, MA 01005
> 508 353 7841
>
> On May 22, 2015, at 11:51 AM, Thomas Koch <tk at tke.dk 
> <mailto:tk at tke.dk>> wrote:
>
>> Hi Saiteja
>>
>> That depends very much on which principle of gasifier you are using.
>>
>> If you use an entrained flow gasifier the only real difference is the 
>> pretreatment equipment.
>>
>> Best regards
>>
>> Thomas Koch
>>
>> *Fra:*Gasification 
>> [mailto:gasification-bounces at lists.bioenergylists.org] *På vegne af 
>> *Saiteja Chinta
>> *Sendt:* 22. maj 2015 20:28
>> *Til:* Gasification at bioenergylists.org 
>> <mailto:Gasification at bioenergylists.org>
>> *Emne:* [Gasification] Difference between Coal and biomass gasification
>>
>> Hi,
>>
>> I want to know what would be major design variations while designing 
>> for gasifiers which are coal fed from that of biomass.
>>
>> Thanks
>>
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-- 
Peter Davies
Director
ID Gasifiers Pty Ltd
Delegate River, Victoria
Australia
Ph: 0402 845 295

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