[Gasification] Making char vs producer gas

[David Coote]

I'm curious about the effects of trying to achieve the multiple 
objectives of char production and producer gas. One combustion engineer 
I've spoken to who has done a lot of work in gasification stated that 
from his perspective char was a sign of an inefficient gasification 
process. If the inefficiency is just a reduced yield of producer gas 
then this might be OK for a particular application. But if the 
inefficiency results in a gas that needs more filtering/volume this may 
adversely affect the economics.

I haven't found any mixed char and producer gas systems in operation 
that meet Knoef's commercial criteria which makes me wonder if detuning 
the gasification in favour of char does affect the quality of the gas.

Is anyone aware of mixed char and producer gas systems in operation that 
meet Knoef's criteria? Perhaps a good paper that summarises the producer 
gas characteristics over a range of char manufacturing percentage?

Thanks

David