[Gasification] Coke and Char
Doug.Williams at orcon.net.nz
Sun Dec 25 12:49:12 CST 2011
You ask some interesting questions:
> What is difference between coke and char?
I believe the problem of identification caused by the English language. Coke is made in a retort from coal, and char is made in a retort from biomass.
Coke from coal and char from biomass?
Others will give you a more academic answer.
And what's about soot?
I have only worked with soot made in high temperature gasification systems 12-1500>C, and these were studied in 1978 here in New Zealand by Dr J. Cousins. I wrote about these soot in 2008 for our Fluidyne Archive www.fluidynenz.250x.com Scroll down the file list and you will find it 14 from the top.
> According to Franklin's research in 1950s, she mentioned that while the cokes could be graphitized by heat treatments above about 2200 deg-C, the chars could not be transformed into crystalline graphite, even at 3000 deg-C.
If I offer a comment it will be conjecture, because the current work being done on our soot and chars is new research, and not published at this time. Having said that, it was these comments that opened up the research, so may offer you a clue to follow your interest.
The soot of interest to me are those that form from volatiles in the unstable chemistry of the sealed retort, which then pass down through the upper boundary reduction zone,
then the high temperature oxidation, before passing through the reduction at 12-1500C. These are probably those seen in Dr Cousins photos. The remaining char has none of these original volatile carbons present, so no amount of heating will create a crystalline graphite.
Others can provide a qualified answer about coke from coal.
I have a couple of photos that I used for the presentation of the "Enigma of Gasification" at the Workshop following the IEA Gasification Task Force Meeting in Christchurch in April 2011, that show one of these soot (C57 O ) for the first time. I will try to get these up on the Fluidyne Archive as soon as possible, and advise accordingly
Hope this may help.
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