[Gasification] Wood heating in the UK - whole log gasification

Mark Ludlow mark at ludlow.com
Sat Dec 28 01:33:58 CST 2013


Hi Jason,

 

Using a vitreous shield (Dick Gallien's solution) seems functionally
sensible but it confuses the heat-transfer analysis a bit. If this is a
stove (rather than a char producer or gasifier) where we idealize a clean
exhaust, robbed of all of it sensible heat. Hmmm. Are heat recovery coils or
perhaps plate heat-exchangers on the exhaust the only way to go? Naturally,
all of this deviates a bit from pyrolysis and gasification.

I like your targeting of retrofits!

 

Best, Mark

 

From: Gasification [mailto:gasification-bounces at lists.bioenergylists.org] On
Behalf Of Jason
Sent: Friday, December 27, 2013 10:48 PM
To: Discussion of biomass pyrolysis and gasification
Subject: Re: [Gasification] Wood heating in the UK - whole log gasification

 

To all,

my experience with top feeding systems is keeping the upper ends of the fuel
from pyrolysing too early. A water jacket is a logical solution so the link
to the jetstream is interesting for me as I have not come across that
before.

When taking a look at some of the alternate designs at the bottom of that
wikipedia page I am reminded of one discussion with a judge at the wood
stove decathlon. He advised of the terrible pollution problem from poorly
designed boilers, something I had seen discussed but had not explored in
depth. The Alliance For Green Heat is in the thick of combating the problem.
When the problem of combustion chambers surrounded by water jackets was
explained the problem was immediately apparent, the combustion just doesn't
get hot enough or for long enough to be complete. So yes a water jacket but
its integration into the design has to be carefully considered. The plans
for an ultra clean design are in my head now as a consequence of that
discussion :-) 

Jason

 

 

 

On Sat, Dec 28, 2013 at 2:10 PM, Tom Miles <tmiles at trmiles.com
<mailto:tmiles at trmiles.com> > wrote:

Alex,

 

I was thinking of Dick's Jetstream. He employed a lot of good combustion
principles to stick wood burning at a time when we were just migrating from
the "tin wonder" wood stoves.    

 

I didn't realize that there was a Wikipedia page on it.

 

Thanks

 

Tom  

 

From: Gasification [mailto:gasification-bounces at lists.bioenergylists.org
<mailto:gasification-bounces at lists.bioenergylists.org> ] On Behalf Of Alex
English
Sent: Friday, December 27, 2013 4:41 PM
To: Discussion of biomass pyrolysis and gasification


Subject: Re: [Gasification] Wood heating in the UK - whole log gasification

 

Ken,



If you haven't already heard of the Jetstream
The wood was loaded into a vertical tube which passed through the water
jacket into a refractory lined combustion chamber. In this chamber the
burning took place and was limited to the ends of the logs. The water jacket
prevented the upper parts of the logs from burning so they would gravity
feed as the log was consumed.

http://en.wikipedia.org/wiki/Jetstream_furnace

Not a chimney powered stove.

Alex


On 27/12/2013 6:47 PM, Jeff Davis wrote:

Hi Ken, 



Thanks for the interest! 




This is my main unknown as yet,  how would a split log combust and pyrolise,
if presented to the ember bed, cut end first.  I suspect that there would be
little penetration of heat axially, directly through the end, because the
ring structure presents a tough barrier. Therefore, most burning would have
to come radially, and so air nozzles would have to be positioned to act
radially on the sides of the log. 


OK, I should try cutting the wood at 45 deg instead of 90. Interesting! 




In your design, it looks similar to a Rocket, but with the fuel container
near vertical.  However, the top loading hatch looks fairly airtight?  - so
unlike a rocket, there is no air drawn through fuel. 


The next test run will be at almost vertical and more distance between the
tube and grate. 

This has only run for short periods of time but once it's burning OK I have
been leaving it up. In the middle of the door is an adjustable air inlet.
It's rusted open because of the nasty acidic coal that was burned in it for
a few years. 




Nevertheless it appears to burn well and produces a healthy amount of good
sized charcoal.  I would be very interested to know how it copes with a
larger log. Perhaps by way of experiment, one could be loaded, instead of
the 2" material, to see how it fairs - this would be very useful
information. 



In due time. 




Best wishes, 
Jeff 

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