Dear Tom The carbon burn out is accomplished by admitting air into the kiln while the temperature is held at about 600. The hole in the case of the flu, 1.8 m3 kilns in Maputo was about 50 mm in diameter, too and bottom. So the oxygen is definitely from outside the material. Is the mechanism CO moving in to b click me CO2 then migrating out, giving up one C to a project passing O2 then going back again? It seems this won't work on char as the heat and O2 would combust the char. On reflection the mechanism must operate in an anoxic environment with the tunneling of the char. That it happens at a much higher temperature would explain the similar chemical path with less O2. Regards Crispin in the snow Crispin, I remember your experiences firing the ceramic POCA stoves. I donât know the answer to your question. In char gasification, or even wood gasification, it is primarily the CO2 reacting with carbon to form CO. If only heat is applied to the ceramic mix I would think that burning out carbon would be primarily through oxidation of the char particles using the entrained oxygen in the mix. Tom From: Crispin Pemberton-Pigott [mailto:[email protected]] Dear Tom I am not subscribed to the Char lists but I appreciate the copy. I have a question: âThey point out that the mass loss with surface gasification occurs within the smaller pores leading to pore widening.â Is this the same process that is used for clearing out the carbon from ceramics in the 300-650 C range using CO? U understand the shuttling back and forth was done primarily by CO at that temperature. The importance is the time to tell people to hold the temperature steady while removing char/carbon that is trapped inside the thicker ceramic parts. You may remember some discussion about this with reference to making the POCA stoves in Maputo. Getting the carbon out is an important step before ramping to the final temperature. We were using crushed charcoal as a source of carbon for the creating of pores, while not creating quasi-pores filled with sand. Thanks |
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