[Gasification] 5 Years Experience with 2 MW CHP Wood Gasification

[Zietsman, Rex]

If one looks at the chart on page 5 of the below report (40% H2) could
it be possible that they figured out how? Or am I reading the chart
wrong? CO2 looks a little high.
http://gasifiers.bioenergylists.org/?q=repoteciea06
(IEA Task 33 Gasification: 5 Years Experience with 2 MW CHP Wood
Gasification 
in G?issing, Austria)
Jeff

Jeff,
If you look carefully at their gasifier, you will see that they did a
small but fundamental change: instead of adding air to the gasifier to
burn the biomass to provide heat (and burn tars), they have a separate
airlift combustion chamber heating sand. The heated sand plus any
entrained biomass is separated from the combustion gas by cyclone and
returned to the gasifier. The combustion gas is post combusted to
consume all the fuel before heat recovery, gas clean up and stack. In
the gasifier, they only use steam for gasification hence the very high
H2 and no N2. I suspect that the reason CO2 is so high is because the
reactions C + H20 = CO + H2 and CO + H2O = CO2 + H2 combine to generate
the 40+% H2 resulting in a higher CO2 content. 
The neat thing about their scrubbing system is that they use biodiesel
as the scrubbing medium. This will absorb the tars from the gas that are
generated due to the method of gasification. I dare say that they add an
emulsifier in the scrubbing circuit to trap the water in the gas to
prevent it causing corrosion. As the solution travels through the
scrubber pump, the high shear caused by the high impeller tip speed
causes the emulsification to occur. Maybe biodiesel already has an
emulsification chemical in it in which case it does not have to be added
specifically. 
I am also impressed that they have a secondary ORC power generation
circuit to milk out as much power as they can with the final low level
energy going to district heating.
Rex