Wood Gasification

Wood starts to gasify at around 750 degrees F. Primary air is delivered to the top loading chamber in a regulated way so as to maintain an oxygen starved region. In the top chamber the wood gas is essentialy baked from the wood. This wood-gas is forced downward through a refractory nozzle where pre-heated secondary air is combined. By combining this pre-heated air with the volitile wood gas, spontaneous combustion ensues. Temperatures exceeding 2000 degrees F are reached in the lower chamber, resulting in nearly complete combustion. These high temperatures in the lower burn chamber heat the refractory material around the nozzle and throughout the boiler providing a sustained high temperature environment, to carry forth complete combustion. After efficient combustion of available gases has occured, the heat produced is exchanged to the boiler water via heat exchanger tubes at the back of the boiler before flue gas is expelled into the chimney.

Above - The Orlan Super Gasification Boiler, Illustrating stages of Wood Gasification.

Combustion Efficiency and Thermal Efficiency

The overall efficiency of a wood fired boiler is the result of the combustion efficiency and of the ability to transfer the resulting heat to the boiler water. With wood gasification, combustion efficiencies of 90% can be realized. This results in a tremendous amount of heat. With efficient heat exchange to the system water, flue gas entering the chimney can be regulated to around 350 degrees F. The boiler controls could be adjusted for even better thermal efficiency, but this could result in costly damage to the chimney as a result of the condensation of flue gases before leaving the chimney. The best indicator of good combustion is the absence of smoke coming from the chimney. Overall operating efficiency is assured by incorporating a Thermal Storage system with your wood gasifier.