[Gasification] Gasifiers and kilns

[Mark Loftin]

Paul,
Back in August, we completed 3 months of "beta" testing on one of our 
pressurized downdraft models (industrial) at a continuous tunnel brick 
kiln . The feedstock was hardwood and softwood papermill chip (~560,000 
lbs processed, fed to the unit as received).  The effect on the brick 
was superb.  This beta gasifier was rated for about 12.5% of the total 
kiln heat load and it displaced about 15% of the kiln's natural gas 
usage.  We attributed the extra displacement to improved heat transfer 
in the kiln due to the higher moisture (i.e., heat capacity) of the 
producer gas flue and possibly radiant heat improvement.  Many in the 
brick industry were aware of this beta testing, so most of the 
production units over the next few months are going to various brick 
plants.  These industrial units are rated for about 650 lbs/hr for 
commercial woodchip, which is ~3.5 MMbtu/hr (thermal).  But, they can be 
turned down considerably and run intermittently just fine. The units 
come with a cyclone on the gas outlet line, so they should be good for 
pottery and architectural brick kilns.

By the way, we piped the raw producer gas right into the zone of the 
kiln targeting ~1,540°F (through 2-3" ports spaced about 8 feet apart on 
either side of the kiln).  The producer gas from the unit ran around 
1,250 °F with virtually no tar and only slight periodic char 
carry-over.  The owner said it was the best brick that plant had ever 
made.  I can tell you first-hand that producer gas is excellent for 
commercial brick-making and much better than natural gas for a host of 
reasons other than just price per MMbtu. Rather than make this e-mail 3 
pages long explaining, please send any specific questions about this 
application to me if you wish.

M. Loftin


Paul Stubbs wrote:

>As a potter and kiln builder im intrigued by the idea of using a gasifier to
>generate gas to
>fire pottery kilns. What would be required would be a variable output with a
>maximum delivery of 15,000 Bthu per cu foot of chamber size.The whole cycle
>might run over a period of 8 to 12 hours I would be initially interested in
>trying it out on a test kiln of about 5 cu ft. Is this a do-able project or
>is a gasifier not suitable for a wide, variable-output situation.
> I would envisage using chipped hard wood (oak), a forced air fan for
>secondary air at the burner and presumably a variable blower at the front
>end to provide the draught to the ember bed.
>I guess no worries about tar with this type of application
> I would welcome any comments and suggested reading on this.
> Paul Stubbs Ceramics,Kilns and Potters Tools.pstubbs at uwclub.net
>
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LOFTIN & ASSOCIATES, INC.
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Mobile, Alabama 36695
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