Three stages gasifier (Biomass Technology)

Three stages gasifer technology in Thailand is implemented at Thungtrapungclone area, Ladbualuang, Ayuthaya province. Rice husk is used as biomass feedstock. The operation principle of this technology is as follow: 1. Oven drying of rice husk: the exhaust gas will be used to heat up rice husk to about 100 oC in order to decrease its moisture content. The electric blower will then be used to transport the rice husk to pyrolysis reactor. 2. In the pyrolysis reactor, hot sand will be served as a heat source. Together with usingelectric blower, the continuous flow of hot air inside the reactor will circulate rice husk in the form of bubbling bed, and thus enhancing the volatile compound to be separated out of the rice husk. The temperature inside this unit is about 450-600 oC. During starting time of the system, LPG will be used at the mass flow rate of 0.6 kg/h to start up the heating system. 3. Partial oxidation occurs at the throat of reactor. This is the incomplete combustion process of volatile organic compounds and tar (byproduct from pyrolysis) at temperature between 850 oC to 1100 oC. The end product of this process is CO2, water, and ash. 4. The CO2 obtained from partial oxidation is then converted in to synthetic gas (CO, H2, CH4) in the reduction zone by using ash. 5. The synthetic gas produced might still contain some dust and moisture, therefore gas cleaning and cooling need to be done as final steps. Cleaning of fuel gas is operated by using a cyclone, a wet scrubber, and a bag house filter. The fuel gas is cool down to about 45 oC before it can be used in the gas engine.