Re: GAS-L: Small Scale Gasifiers Defined

["Paul S. Anderson" <psanders@ilstu.edu>]

Patrick and all,

Your explanation is excellent.  Because your message did not make it
through to the "Stoves list serve", I am including it
below.

However, I must disagree with your conclusion.  You wrote: 
Most lay people do not consider this close coupled system a
gasifier. Therefore while we could call it "Staged
Gasification" or a "Close Coupled Gasifier", we have
elected to call it staged combustion.

Except for one year on the Stoves list serve, I am about as much
of a "lay person" as can be found.  I definitely want the
word "Gasifier" or "Gasification" into the title
because the word "Combustion" is where the confusion takes
place.  The word "combustion" is a lot like the word
"burn".  Neither "combustion" nor
"burn" assists the lay person to appreciate what is happening
when the process of gasification becomes identifiably distinct from
simple "burning."  

Yes, I like your explanation and I like the use of the word
"staged" or the words "close-coupled", (or perhaps
"closely staged").  But we do need to be sure that anyone
reading about these small "combustion chambers" (the name I use
to avoid calling them "stoves" that implies cooking) realizes
that gasification occurs, and that is "closely coupled" or
"staged" with whatever happens next.

And herein lies the problem.  What would you call the "whatever
happens next" when the gases are mixed with air and
"consumed."???   We cannot use the word
"combustion" because it is too vague.  Patrick's full
message (below) has a definition for "combustion" that 
somehow is not the same as what happens to the gases after they are
produced.

I am just the interested lay person, so my next suggestion might be
useless:   Could we call that "consuming of the
gases" to be considered as "flaring" (or perhaps
"flaming")????

If so, does that lead to the name of "combustion chamber for
gasification followed by close-coupled flaring"???   Or it
could be a "gasifier with close-coupled
flaring"    I think that captures what we have been
calling "small scale gasifiers".   I suspect that
there are some large gasifiers what have close-coupled
flaring.   

Whatever happens about the final terminology, this discussion has been
helpful to me.  It has also helped clarify the fairly wide gap
between those who do "big gasifiers" and those who do
"small gasifiers" (meaning the REALLY small ones.)  

I look forward to future sharing of gasifier knowledge with you 
all.

Paul

At 10:24 AM 6/26/02 -0700, Pat Travis wrote:
> Dear Tom and GAS-L
> subscribers,
>  
> When defining or putting a "label" onto a process
> such as gasification there are two distinct audiences that must be
> considered from a commercial standpoint. The first is the regulatory and
> technical community and the second is the general public.
>  
> EPI uses 3 terms for our energy systems. The first,
> "Combustion", is very straight forward and covers projects
> utilizing standard fluidized bed combustors which generate heat for
> process or power applications. 
>  
> The second, "Gasification",  is used when we
> produce a low Btu gas (LBG) in an oxygen deficient atmosphere and burn
> the LBG in a second piece of equipment utilizing a specially designed LBG
> burner, such as a gas boiler, or by injecting it directly into an
> existing coal fired boiler as a reburn gas. In either case, the LBG is
> transferred to a separate piece of equipment for combustion. This is done
> without cooling the LBG, therefore radiant losses from transporting the
> LBG between the gasifier and the end use device is the only energy loss.
> This type of two part process is easy for the public to understand and
> the one I typically find associated with gasification. The same
> definition applies to processes where the LBG or MBG is cooled prior to
> use, such as in an engine or turbine.
>  
> The third, "Staged Combustion", is used to
> describe what some people may consider a close coupled gasifier. In this
> process we combine a fluidized bed gasifier bottom with the upper section
> from a combustor. We generate LBG in the lower portion of the vessel and
> when it reaches a specific elevation above the gasifier section,
> combustion air (including dirty process exhaust gases with a high VOC
> content) is injected and the LBG is ignited. This provides energy for
> process applications and/or for power production. Most lay people do not
> consider this close coupled system a gasifier. Therefore while we could
> call it "Staged Gasification" or a "Close Coupled
> Gasifier", we have elected to call it staged 
> combustion.
>  
> I leave it to those better qualified than myself to set the
> legal definitions.
>  
> Patrick Travis     Energy Products of
> Idaho (EPI)

Paul S. Anderson, Ph.D.,  Fulbright Prof. to Mozambique 8/99 - 7/00

Rotary University Teacher Grantee to Mozambique >10 mo of 2001-2003

Dept of Geography - Geology (Box 4400), Illinois State University

Normal, IL  61790-4400   Voice:  309-438-7360;  FAX:  309-438-5310

E-mail: psanders@ilstu.edu - Internet items:
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