[Stoves] Pyrolysis: No Air?

Dean Still deankstill at gmail.com
Sun May 17 08:33:34 MDT 2015


Alex,

Fire must be complicated! Even the words used to describe it seem to be
used for multiple purposes.

I'm writing a book describing the five 'Tier 4' stoves we developed with
DOE funding that includes CAD drawings, etc. It's very interesting to do
more reading/experimenting/thinking and sometimes I get more or less
confused. The book will be available at the Global Alliance Forum in Ghana
November 10 and, of course, on line.

Best,

Dean

On Sun, May 17, 2015 at 5:00 AM, alex english <aenglish444 at gmail.com> wrote:

> Dean,
> Perhaps your right that it is wrong to call a TLUD a pyrolyser, as I have.
> Gasification folks could argue its wrong to call it a gasifier. So
> inefficient! Dirty gas! Perhaps two wrongs can make it right, in the
> middle. Right for its niche, an air starved stove with a difference.
>
>  Viva la difference.
> Alex
>
>
> On Sat, May 16, 2015 at 9:10 PM, Dean Still <deankstill at gmail.com> wrote:
>
>> Hi All,
>>
>> Seems to me that the word gasification might fit the TLUD process better?
>> The primary air controls the amount of oxygen, the rate of reaction?
>> There is no pyrolysis in a Rocket or an open fire?
>>
>> *Gasification* is a process that converts organic or fossil fuel based
>> carbonaceous materials into carbon monoxide, hydrogen and carbon dioxide.
>> This is achieved by reacting the material at high temperatures (>700 °C),
>> without combustion, with a controlled amount of oxygen and/or steam.
>>
>> *Pyrolysis* is a thermochemical decomposition of organic material at
>> elevated temperatures in the absence of oxygen (or any halogen). It
>> involves the simultaneous change of chemical composition and physical
>> phase, and is irreversible. The word is coined from the Greek-derived
>> elements pyro "fire" and lysis "separating".
>>
>> Best,
>>
>> Dean
>>
>> On Sat, May 16, 2015 at 4:58 PM, Crispin Pemberton-Pigott <
>> crispinpigott at outlook.com> wrote:
>>
>>>  Dear Alex, Dean
>>>
>>>  That Reed reference is a good one. As biomass is about 40% oxygen by
>>> mass, there is a real chance one can have some combustion without any air
>>> at all. There is almost enough oxygen to burn all the hydrogen ‎in most
>>> biomass. That is a heat source that could leave all the carbon behind, in
>>> theory. In practise there will always be CO and H2 in the output from a
>>> retort.
>>>
>>>  Regards
>>>  Crispin
>>>
>>>
>>>  Dean,
>>> There being oxygen in the chemical structure of biomass and oxygen in
>>> the spaces and cracks, a strict abstinence is difficult. In one of the
>>> Reed/Das handbooks there is a graph of the
>>> pyrolysis-gasification-combustion continuum, where the x axis goes from say
>>> zero to %200 of stoichiometric oxygen/air. I think ( always roughly)
>>> gasification fit in the %20-%80 range with pyrolysis below and combustion
>>> above. The char and gas yield % was in there too. I'm sure folks could
>>> argue endlessly about where exactly to place the demarcations.
>>> Alex
>>>
>>> On Sat, May 16, 2015 at 6:50 PM, Dean Still <deankstill at gmail.com>
>>> wrote:
>>>
>>>
>>>    1. Hi All,
>>>
>>> When I look up the word pyrolysis I find the following:
>>>
>>>    1. *Pyrolysis* is a thermochemical decomposition of organic material
>>>    at elevated temperatures in the absence of oxygen (or any halogen). It
>>>    involves the simultaneous change of chemical composition and physical
>>>    phase, and is irreversible. The word is coined from the Greek-derived
>>>    elements pyro "fire" and lysis "separating".
>>>    2. However, I think that folks use it to describe what happens in a
>>>    TLUD, etc? Isn't that gasification not pyrolysis because of the presence of
>>>    some air?
>>>
>>> Best,
>>>
>>>  Dean
>>>
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