[Stoves] Crispin´s kiln - was Re: Traditioal Charcoal Making Process-retort

[Kevin Chisholm]

Dear Peter

Peter Singfield wrote:
> At 02:38 PM 7/7/2007 +0100, AJH wrote:
>> On Sat, 07 Jul 2007 10:23:21 -0300, Kevin Chisholm wrote:
>>> An arc has an intense energy emission characteristic.... say 10,000 
>>> degrees C, while the resistance heating surface temperature is perhaps 
>>> down to the 800 to 1200 C range. Thought would probably have to be given 
>>> to diffusing the intensity so that some stoves near the arc are not 
>>> melted to a puddle of slag, while others are still raw. t2^4 - t1^4 
>>> considerations can be of great significance.
> 
> The point I am trying to make has already been mentioned by AJH --
> 
> Use the arc heating as a "topper" only.

This is an excellent way to go... only provide high grade heat when it 
is needed.

This extra energy could be added as an arc within the kiln space, or as 
an arc external to the kiln, used to preheat the fuel gas and/or 
combustion air and/or products of combustion.

What would you feel is the best way to go?

Best wishes,

Kevin
> 
> A high power ARC would not be required -- probably a rather small -- say
> even but 6 kw -- should be sufficient to boost the temperature of
> combustion products of producer gas to suffici8ently high temps for a cone
> 10 to be achieved.
> 
> The problem -- as I see it -- is not to introduce to much flow of gas
> through the kiln to achieve such high temps -- as that means great wastes
> in the flue stream.
> 
> A gasifier -- then producer gas combustion -- is minimal "air" -- the
> adding -- boosting -- of temps by using a small plasma arc "torch"  -- adds
> no "air" --
> 
> The Kiln would have two firing modes -- a large flow of already hot
> producer gas being combusted to heat the kiln to that maximum flame
> temperature -- plus the intensive curing period at elevated -- but way
> lower than cone 10 temps.
> 
> Then -- a switching over to a less intensive mode where the combusted
> products of the hot producer gas is super heated using a plasma arc torch
> to reach final cone 10 temps.
> 
> One balances flow of producer gas Vs arc amperage -- intensity -- to
> maintain proper temps for the minimum of electric energy expenditure.
> 
>>From past foundry experience -- propane does not burn hot enough to melt
> even brass!! Doubt you could even get a cone 1!!
> 
> Has anyone on this list every used a propane/02 cutting torch?? Even
> burning in pure 02 -- propane takes a long time to reach high temps --
> especially compared to acetylene!
> 
> Natural gas -- maybe ---
> 
> Of course -- the other solution might be to use a PSA unit to supply 90% or
> better 02 for combusting the producer gas -- this to would result in higher
> flame temps.
> 
> Or -- 02 enriched gasification (thus much reduced N2) followed by 02
> enriched combustion of syngas product -- probably also would easily reach
> high temps with very minimal flue traffic.
> 
> The cost of such a PSA unit might be reasonable when compared with all the
> alternatives!!
> 
> Again -- to sweeten this energy flow diagram -- run the gasifier in 02 mode
> only when doing the final cone 10 temps.
> 
> Very little electrical power would be then required -- very little!!
> 
> Plus -- this would revolutionize the gasifier industry somewhat -- as such
> high temps are of immediate application to all foundries.
> 
> And this can be achieved economically at small scale.
> 
> Further -- one could divide up the gasifier operation -- saving the char
> rather than burning it -- first "run" -- then burning just the char for the
> final run -- in an O2 enriched atmosphere -- that would result in more than
> sufficient high temps.
> 
> Further -- one probably would not need enrich the O2 so high.
> 
> This can all be prototyped at very small scale -- again:
> 
> http://www.bodycareozone.com/ProductClass.asp?ClassID=18&NClassID=21
> 
> See their rough description appended -- but these are small units -- 
> 
> Still -- on can run a small unit building up sufficient reserves between
> kiln firings.
> 
> Though this is about gasification -- kilns and foundry is basically hot
> stoves -- or ovens.
> 
> The reason electric resistance or plasma torche heating is so efficient is
> due to no flow of flue gasses is involved.
> 
> Peter/Belize
> 
> ************************appended**********************
> 
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> 
> 
> 
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