[Stoves] Fw: Clogged chimney

Fri Sep 2 14:38:55 CDT 2016

Dear Tom

My assessment, listening to the designers, is that this is common. The entire stove and heat exchanger has to be cleaned weekly. Looking into the access doors I see they are coated with a thick fuzzy layer of black carbon and condensed tars. 

The main cause is the way in which they work: bottom lit updraft, refueled by adding coal on top of the fire. 

When using bituminous coal in that design, the result is inevitable. I am introducing two new methods of burning coal and using the worst coal available, we will be able to get a combustion efficiency above 99.5%.  One is a TLUD and the result was about 99.7% in a test run with undersized fuel. In Tajikistan we peaked at 99.99% with coal from here (Kyrgyzstan). The other stove we light tomorrow. It has a cross-draft combustor. It will probably be even better.

Regards

Crispin

Further comment:

It’s fine to show the “ultimate” example but how frequent is chimney clogging in improved stoves? I would hope that clogging is easily recognized and correctable at this time. It is probably more due to stove use (fuel mc, etc.) than design.   

Tom

No further comment?  How about adding “polyaromatic” before “hydrocarbons”?

Philip

Dear Photo Collectors

Attached is the ultimate example of a chimney clogged by long chain hydrocarbons‎.

No further comment needed.

Crispin 

Dear Kirk, Paul and all,

Kirk: thanks for circulating your hypothesis. This seems well-founded.
Paul: measuring long-chain hydrocarbons / tars is part of the planned project of PhD student Thomas Kirch.

The intention is to measure the tars fairly soon. The catch is that our existing micro-GC isn't suitable for this, and finding someone who is willing to put our tars in their GC-MS is proving difficult. Until we get funds to buy our own, any suggestions for other ways of characterising the tars?

Cheers,
Paul

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