[Stoves] Trials on TLUD Gas Burners - Counter Current Flow

[Erin Rasmussen]

Hi All,  

The links to the pdfs on the page http://stoves.bioenergylists.org/daviesgasifierstove   have been fixed, and so have the file attachments that may have been broken on many of the older stories.  I'm still in the process of fixing things. 

I'm sorry for the broken links. 

 

Kind regards,

Erin Rasmussen

erin at trmiles.com

 

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Crispin Pemberton-Pigott
Sent: Sunday, August 03, 2014 8:52 AM
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] Trials on TLUD Gas Burners - Counter Current Flow

 

Dear Julien

 

 

The only information I can come up with for a stove by John Davies is at:

http://stoves.bioenergylists.org/daviesgasifierstove

 

That is the stove.

 

There is a link at the bottom of the page to a pdf on components and construction, but the link has some "redirect" problems, so the pdf doesn't download.

 

That I didn’t know. 

 

Perhaps it is the document attached.

 

Questions on my mind are: if John's burner was successful, why is it not common use?  Were there some problems we should know about?  Or was it the stove that was promoted and not its burner, so the burner went unnoticed?

 

John had the idea that it might go into production with assistance from someone and after a while he gave up. The stove community is not full of commerialisers, it is full of inventors, basically.

 

At least on issue is that the stove is specialised for a particular region and fuel, as probably most stoves should be. The fuel is semi-bituminous coal and he did a lot of testing to get it to work well with a particular size of that fuel. Overall, I can say it works well for its intended purposes.  The applicability of the design is perhaps broader that the highveld of South Africa.

 

The problem with dissemination of space heating stoves is that for the large part, this list is concerned with biomass combustion, there being in certain cases a hostility to burning coal at all, even though millions of poor people are dependent on it and will be for the medium term future. There are only two places that I know of working actively on coal stoves which are South Africa and Mongolia. By ‘working on it’ I mean have a programme to produce scientifically advanced designs applying the latest knowledge.  There are lots of coal and wood burning ‘boxes with chimneys’ but that, these days, can’t be considered a ‘combustor’.

 

In China there is a move towards getting a shift in thinking about coal combustion. Recently a tour of 15 people from China visited the SET Lab in Mongolia to see how the application of testing had produced stoves with a 99% or more reduction in emissions of smoke. The whole Chinese stove market is ready for a change in combustion design – there was a lot of enthusiasm to find out how this can be done. 

 

It is possible then, that the Davies burner will find application. I am not sure that any of it is totally new – for example it has been described using words that already exist but the useful bit is the fact it can burn that coal type which has been widely cited as ‘dirty’ and ‘polluting’ and so on (like most coals). When a really efficient combustion system for coal is shown a common reaction is that ‘it is impossible’ and also ‘people shouldn’t burn coal’. That is about like saying ‘commuters shouldn’t drive cars’ or ‘farmers shouldn’t use fertilisers’. Getting people from a dream world to a real world is sometimes impossible. 

 

The main problem faced by promoters of batch loaded stoves is that they cannot normally be refuelled. For space heating in some climates, that is not a problem. For cooking it has proven to be a formidable barrier because cooks want to keep on cooking, sometimes, and sometimes not. Various things have been tried but turning it off and refuelling a TLUD remain a major issues.

 

The Davies stove is a batch loaded device with a means provided to be able to choose in advance how long it should run. I think the limits are about 2-6 kg of coal chips. Maybe 1.5.  At 5 kW it is 1 kg per hour. Perfect for a small home of two or three rooms, or a medium sized yurt (ger).

 

Packed bed gasifiers are dependent on a particular size of fuel. If it is not available, they are very hit-and-miss to operate. So all things considered, the great effectiveness of the solution is because it is local nature. Nothing wrong with that, we should learn the principles involved so as to apply them universally.

 

Regards

Crispin

 

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