[Gasification] Push or pull

[doug.williams]

Hi Luiz,

You ask confirmation:

>  Yes, I understand it applies this way under normal running conditions. 
> But are you confident regarding start-up and shut-down sequences?

If you have change over valves to do the swap of air flows on the gas exit, 
they must be heat proof. This also an expensive option, so we never used 
valves, preferring simple screw caps, and removable flexible hoses for 
start-ups. The shut-down only required the inlet air to be valved or capped, 
and was not only simple, but reliable. Our first three process heat 
gasifiers ran for two years like this (22x7) in a timber drying 
installation, and we had no explosion problems.

> I believe the O2 contents in the producer gas is hard to control in 
> transient conditions.

It is not a problem. Once the suction has ignited the char bed, it remains 
alight for quite a few minutes, so that when the blown air is admitted, the 
nozzle blast just brings the gasifier up to operating temperature.


>  Do you think it is safe anyway?

I think it's safe, and would recommend it to any one, "BUT" because there 
are so many ways to make a gas, you need to first qualify to me what sort of 
system you are thinking of, if you are unable you feel safe with this type 
of air supply.

Regards,
Doug Williams,
Fluidyne Gasification.