[Gasification] [Stoves] Comments about T-LUDs

[Thomas Reed]

Dear AJH, Paul and Aul:

Good question. 

I differentiate gasifiers many ways, but for this the best is

TAR BURNING, CHAR MAKING = Conventional downdraft gasifiers, inverted 
(more recently called also TLUD) and blowing air into a lit cigar (not 
inhaled).  These are most appropriate for biomass which is 80% volatile, 
only 20% fixed carbon. 

CHAR BURNING, TAR MAKING = Conventional updraft gasifiers (Lurgi for 
coal, Purox for MSW), and an inhaled cigar.  Most appropriate for coal  
which is 80% fixed C and only 20%  valuable volatiles. 

An important distinction is what I began to call "FLAMING PYROLYSIS" (c 
1982).  This is similar to what you observe in the burning match 
(FLAMING COMBUSTION, except that it occurs in the presence of a large 
excess of biomass, so is only a partial combustion. 

AJH wrote:
> On Mon, 02 Oct 2006 11:37:53 -0500, Paul S. Anderson wrote:
>
>   
>> Test question:  Among the different types of gasifiers, in which type(s) does
>> the incoming primary air FIRST create the pyroylis gases and then move to the
>> zone where char-gasification can take place?
>>     
>
> in a kiln or stove I think you are bound always to burn some char
> before you create pyrolysis gases, I think there is a slight
> difference in the way the tlud works compared with the down draught
> and that is to do with how the heat is transferred  because the
> convection currents work differently. So I say that char will always
> burn preferentially to off gas in the pyrolysis zone and that its the
> combustion of a very small amount of char that drives the pyrolysis in
> the tlud.
>
> AJH
>
>
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