Wood to Char Pictures

1: These are about as big as you can go for pine block fuel, the easiest way for rural people to convert trees into gasifier fuel.

2: Above the air nozzles (about 5") the descending wood blocks are carbonising in the heat radiating upwards from the oxidation zone, releasing the products of distillation or pyrolysis gas. To many, the pyrolysis gas is the only end product gas and then goon to invent ways to clean and filter it for use in engines.

3: By the time the block reaches the incoming air at the nozzle level, the pyrolysis is complete and the block has begun to disintegrate into small pieces about quarter size. As the air begins to contact the char, combustion causes it to break down into smaller pieces as it moves with the oxidising gas stream towards the throat. In the presence of free oxygen the reactions of C+O2 = CO revert back to CO2 with an increase in temperature each time until the free oxygen is consumed, which prevents the formation of CO and result in only incandescent CO2 gas entering the reduction zone under the throat. In the absence of free oxygen, reduction of the CO2 into CO consumes the reduction char which is shrinking in size continuously. All fuel and char is in continuous motion and in this case, goes from block to reduction char in about 6-8 minutes. The highest temperature is at the throat orifice where the temperature should stabilise around 1200 degrees C.