[Stoves] Tars

[Frank Shields]

Dear Stovers,

 

Reading the book "Biomass Gasifier "Tars"" explains and illustrates the
complexity of measuring Tars. Many very different collection procedures,
extraction steps and reporting units and it seems it all ends up very
confusing. I don't know how we can use gravimetric units on gas samples when
there is such a wide range of organics. And the distribution and make-up of
the organics change as the gases leave the combustion chamber and cool. It's
a very good book for us on a steep learning curve and those wanting to
compare different systems by showing the complexity of reporting and
extractions.

 

Because we want combustion to convert all organic carbon to CO2 (or CO in
pyrolysis gas) It seems to me the definition of tar should be the 'oxygen
demand' of the gas just as it leaves the gasifier or combustion chamber.
Forget the structure of the organics for other research. We could run a gas
sample mixed with oxygen through a metal tube with heated coil inside and
determine the increase in CO2 from going in to the exit. The tube could be
heated to increasing temperatures to separate the tars into Primary,
Secondary and Tertiary products. Or separate using a hot tube at different
length Or differing flow rate. The reported units would be in [ mg O2 demand
per Nm3 ]. Knowing the CO and CO2 going in we can calculate the Tars in the
sample based on the CO2 increase in the out gas reported  on  oxygen demand.
Sampling at the point just after the exit of the combustion chamber or
gasifier (before any work has been done) means most of the tars are still in
the gas phase.

At least this way we will have a common base we can all start at. Then
additional research is done to quantify the types of organics and the
changes that take place as use and cooling takes place down the 'train'. 

 

Anyways - if I had a lot of money and time this is what I would research.. 

 

Regards

Frank

 

 

 

 

Frank Shields

42 Hangar Way

Watsonville,  CA  95076

(831) 724-5244 tel

(831) 724-3188 fax

frank at bioCharlab.com

 

 

 

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