chris cromeens wrote:I have seen engines run on an updraft system (smaller engines and not efficiently). It is my understanding (I am no expert) that the Imbert system was developed post ww2 and all the trucks and tractors that used wood gasification during the war were updraft systems. I have seen a retort placed in a barrel of burning wood (w/ intake holes at bottom of barrel), w/ a line coming off the retort to a generator, straight to the carb and it ran the generator.
Oh, you can run an engine on pyrolysis gas and it will run strong. Unfortunately, there will be tar deposited in the intake manifold that will eventually sieze the intake valve. Also, the dirty gas will quickly foul the lubricating oil. Running an engine this way will necessitate a regular engine rebuild. An engine is not likely to go more than 10 hours under these conditions without a tear down. One might extend operation by using a solvent between runs to try and strip off the tar "varnish" that will form in the intake manifold and especially near the intake valve, but it sure makes a lot more sense to design the gasifier properly instead.
The Imbert was developed during WW2... by 1943 the Imbert was being mass produced (Imbert is a brand name), but the basic design was developed pre-WW2. All the trucks and tractors that used wood gasification during the war were downdraft systems.
If you want to run an engine reliably more than a few times, then you will have to use a downdraft system. The tar load in the gas from an updraft system is on the order of 1000 times higher than a downdraft. This assumes wood/biomass is used, and not charcoal. An updraft gasifier using charcoal can fuel an engine fine.