"THERMOLYSIS" defined (relative to biomass PGC)

[Reedtb2@cs.com]

Dear All:

I feel somewhat proprietary about the word "Thermolysis", having used it carefully in the field of Pyrolysis/Gasification/Combustion (PGC) since 1978.  I remember proposing it to Tom Milne (at SERI/NREL) during writing of our first "Survey of Biomass Gasification" (soon to be re-issued) in 1978-80.

PYROLYSIS:  Complete Break Down by heat

THERMOLYSIS: Partial rearrangement by heat

So, if you cook your steak medium, well done or rare, that's thermolysis.  If you forget and leave it in the oven overnight and it comes out mummified, that is pyrolysis.  

In the early 1990s we developed a process for making the oil absorbent "SeaSweep" (US Patent 5 110 785) in which we heat sawdust to 350 C and then quench it to PREVENT further breakdown to charcoal.  The patent examiner bought the process and our definition.
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The ENCARTA dictionary gives...
thermolysis

ther·mol·y·sis [thr móllssiss ] noun

1.  PHYSIOLOGY heat loss:  loss of heat from the body, for example, by sweating

2.  CHEMISTRY decomposition by heat:  the breaking down of a substance by heat

This seems inadequate, since the same dictionary says for pyrolysis..

pyrolysis
py·rol·y·sis [p róllssiss ] noun
decomposition of complex molecules by heat:  the use of heat to break down complex chemical substances into simpler substances

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A Google search turns up 4560 uses of the word - here are a few...

Hair Removal Clinic: Electrolysis - Thermolysis
... Thermolysis was developed in the 1940's and works with the type of current we have
these days (AC/DC - I could say, current current).

Hitachi to Develop Kiln-type Waste Thermolysis System
... March 23, 1998. Hitachi to Develop Kiln-type Waste Thermolysis System. - 20 ton/day
pilot waste treatment plant to be built in Hitachinaka City -. ...

So, you can see that context completes the definition.

I hope you find this distinction between THERMOLYSIS and PYROLYSIS useful...

Yours truly,         TOM REED                   


In a message dated 1/7/02 4:16:49 PM Mountain Standard Time, andrew.heggie@dtn.ntl.com writes:

Pyrolysis comes from a classical root (Greek I think) where pyro means
fire and lysis means to split. Hence it means to split the biomass, in
this case into char and offgas, by use of fire. I guess thermolysis is
the same with the heat being derived without a fire, in which case a
retort may involve thermolysis? or perhaps they are both the same.