[Gasification] Bisschop Engine - rough & ready

[Doug Williams]

Andrew and Jeff,

A couple of points about this discussion catches my attention, so hope you 
don't mind a comment or two.

1: It appears that these engines ran on producer gas, but I have not seen 
you mention the type of gasifier or fuel to make the gas.

2: In the most likely case scenario, the gasifiers would have been updraft 
coal, and the gas very dirty and tar laden. The coal quality had a big 
influence of the tar levels, but the gas would have had a lot of CH4, making 
it easily ignited.

3: Many of these early coal gasifiers had wet bottoms under the grate, so 
that steam was produced by the radiant heat coming of the grates onto the 
water surface, providing first a cooling of the grate iron work, and then 
making H2 in the incandecent oxidation char, before joining the CO and CH4 
in the updraft gas stream. With the char right on the grates, and air 
passing up through the grates, these gasifiers had a hard time stopping the 
grates melting.

4: I doubt if tar was used as a lubricating factor, as it would require the 
output gas from the gasifier to be kept hot, possibly above 400C to stop the 
tar from condensing. In that situation, the volumetric efficiency would be 
seriously comprimised, and power output useless, compared to colder gas 
being used.  From experience of tar in a conventional engine, and in the 
gasifier system, I doubt if you want to seriously go down that track. The 
engine might run, but you will spend days cleaning out the siezed components 
each time you want to use it. Of course the tar might not be there, and were 
in fact pyrolysis oils, which are not quite the same as tar.

5: I get nervous when producer gas is stated to be cut and dried to some 
sort of specification, without refering to the type of gasification process. 
Few appreciate this point, and a very quick misunderstanding develops, 
particuarly if the reader is a bit stary eyed about gasification. Simulated 
testing of producer gas should take this fact into consideration, especially 
if you are going to concoct it using a reciepe of prepared gases.

Hope this adds to your considerations.

Regards,
Doug Williams,
Fluidyne Gasification.