Re "terminology"

["Ron Larson" <ronallarson@qwest.net>]

Hi all:

	This is intended to agree with most everything I hear from Andrew and
mostly from Tom - as a part of the terminology thread started by Paul (and I
have changed the subject heading back to
"terminology".  I am not happy with Paul's use of the word "gasifier".

1.  Tom Reed said today re terminology:  " The distinction is not trivial
since there are often tax credits for
gasification and not for combustion of biomass.  Testifying in court, I
would say that if in principal you can put a septum between the gasification
section and the combustion section and remove samples of combustible gas
requiring more air, it is a gasifier.  If sufficient air is supplied in one
step for "substantially" complete combustion (like the pellet stoves), it is
a combustor.

	(RWL1):  I wish that we had this tax credit problem to contend with.  If we
did, I might change some of the following.  I would say that Tom's remark is
true on the gasification list - where I think they almost never use the term
"pyrolysis".  Gasifying people, as Andrew has emphasized, try for a minimum
amount of charcoal, for continuous operation, - and often are adding steam.
You (Paul) and I (and Andrew a lot) are not doing any of these.  So
everything Tom says about the septum is true - but the septum criterion also
applies to pyrolysis units - which I claim are a different animal from
gasifiers.

	I am pretty sure that when one uses the term "down draft" among the various
"crest" lists, people will think you are talking gasification and
mechanical/electrical power.  We have talked a small amount about down-draft
stoves (especially Piet Verhaart)- but they don't seem to being pushed by
anyone. I have to look again - but I think Piet has a combustor.

	When Tom adds "inverted" to get IDD - he is thinking updraft - and minimum
charcoal and gasification.  I try to avoid IDD as not being very
comprehensible to the average client for one of these stoves. very few of us
can explain even down draft - and get across the concept of pyrolysis
instead of gasification.

	 I even avoid the term "pyrolysis" since that is likely to not be
understood either when reading may not even be possible.  But
"charcoal-making" I have found is pretty understandable.
So on this list, I think "pyrolysis" is much better for what you are doing
that is "gasification". I contend you will lead both technical and lay
people astray with the term "gasification" - which implies to most of us the
diappearance of charcoal (maybe even only starting with charcoal - as is the
case with many gasifiers)- and likely to imply a continuous rather than
batch operation - with minimum charcoal production.

	Now if you are determined to consume the charcoal - which I don't think you
are - then the term "gasifier" is possibly OK - although I still don't like
it - as there is a distinct change part way through the process after you
have converted everything to charcoal and start consuming it.  I say you
have shifted from having a pyrolyzer (not a "gasifier") to a combustor - in
accordance with Tom's definition above (at any "septum" level above the
primary (now both primary and secondary) air supply port, you have already
had the "substantially complete combustion" defined by Tom as the
distinction.

	The same is true for the description given recently by Dean Still of his
experiments with a blower attached to the Rocket - that is a combustor, not
a gasifier.  Dean has no separate secondary air supply.

	The same is true for the blower/fan driven ZZ-stoves - I think.  They have
multiple air holes above and below the fuel supply- and the "septum" concept
may apply somewhat here. Tom Reed's "turbo" (fan driven) is definitely not a
combustor during the early stages - but is at the end, I think we will all
agree. I know of one person on the list who is possibly achieving
gasification during the charcoal combustion stage (ie needs a secondary aire
supply).

	Crispin's Shisa may be more of a combustor when he is bottom lighting and a
pyrolyzer when he is top-lighting. However, Crispin has reported that he
gets charcoal even when bottom lit and (I think) there must be some valid
aspect of Tom's "septum" definition even with the many holes that make it
look rather like a "ZZ-stove" (and not like Tom's).  That is - I am
extending Tom's definition to say that if you can find a place where the
"septum" shows incomplete combustion - then you have by definition either a
pyrolyzer or a gasifier - but the term "pyrolyzer" is more apt if you have
batch operation and are trying for the charcoal.

	Whew.

	I like this last of Andrew's sentence quoting Tom saying " >If you would
like to be more accurate, I would propose the terms
>"Pyrolysis gas" - made from the volatiles of the biomass, but leaving the
>charcoal as a by-product"
 where Andrew added:  ""This is the term I have seen used, I went a step
further to "pyrolysis
offgas".

	We will have to see whether "offgas" catches on.  It has some value - in
implying that something (charcoal) is left behind.

	To Paul - the important point throughout the three of our remarks is the
term - "pyrolysis".  I think you will find greater understanding if you use
that term on this list for what you are doing rather than "gasifier" and
"gasification".

	But as we all know "pyrolysis" can also mean liquid production - even when
used as "pyrolytic gasification".  To the best of my knowledge, no one on
this list is proposing a combined charcoal - liquid retrieval stove - but
this possible source of future confusion is another reason to use the term
"charcoal-making" stove if you are saving the charcoal (and I think you
are).

	As I have tried to emphasize many times on this list, I think saving the
charcoal is a must with natural draft (if not also stoves with blowers)
because so little useful energy for cooking (not so restricted for heating -
but the power out and air controls must be drastically re-configured) can be
captured after the pyrolysis (charcoal-making) phase is over.

	Sorry for taking so much space - but I got carried away.  I hope my
prejudice in favor of the word "pyrolysis" and "charcoal-making" is not
blinding me to some missing attribute of "gasifier" - which I just don't
believe is what you are doing in the standard sense of that word on the
"crest" lists.

	I hope Mike Antal and others emphasizing charcoal can now weigh in on the
terminology they prefer - in answer to the important question that Paul is
asking.


Ron




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