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

[Peter Singfield]

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.

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

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