[Stoves] Crispin´s kiln

[Crispin Pemberton-Pigott]

Dear Friends

There is certainly a lot of inspiration here.

>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.

The problem with using an arc in combination with a high lithium material
like PK11 (which is 4% lithium) is that it changes colour at just the wrong
moment.  The heat absorbed by the stove body radiated directly from the
elements has to be controlled.  We are taking the material near its melting
point and the arc, unless shielded, would be a very intense source of
infrared radiation.  Just as the material starts to melt, the colour
changes, increasing the absorption of heat which melts it more... and it
collapses in a dark grey-brown heap while the lighter material remains
underfired.

I do like the idea of using elements for topping off.  There is no more heat
in a plasma arc than a coil.  It is just more concentrated to a small
region.  Passing combustion products over very hot elements might eat the
elements at a high rate so I won't jump into that either without first
checking.  I think the elements ought to oxidize less because there is a lot
less oxygen in the gases.


> 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.

The PSA oxygen module sounds like a very interesting device.  The energy
efficiency could easily be calculated and an O2 unit (if it can be
maintained) be used instead of elements.  The gasifier would use the same
amount of air and produce the same amount of gas, but the volume of
secondary air required to burn the gas would be much lower.  For an equal
stack temperature, the losses are proportionally less if the O2 is
concentrated.  Very good. Makes sense.

It still might be cheaper to obtain old engine or cooking oil...

Regards
Crispin