Alex English, Sept 27, 2000
Bigtop Gasifier
What we have here is a demonstration of gasification in one of its simplest, yet most effect, forms. This is an old water heater fitted with an air distribution manifold base and a partial premix burner on top.
The cylinder holds 100kg of wood pellets containing 1860 MJoules of energy. The column of pellets is lit on top.
Air flow up through the pellets feeds the pyrolysis process, which creeps down at a rate of aproximately 20cm per hour.
The tar rich gas is continuously burned with a stable orange flame. 7.5 hours later the flame turns to blue as the pyrolysis front reaches the bottom and the volatile component of the fuel is used up. At this point the cylinder can be sealed and the 20 kg of charcoal, containing about 560 MJoules of energy, are allow to cool. The heat output for those seven hours was about 50kWatts. Fan energy consumption is about 120 watts. A few modifications would eliminate the need for any fans.
Green wood chips, bark waste and hay have also been tried with less consistent results so far.
Charcoal by product from dry wood pellets and dry hay.
