Gasification process of woody biomass in CFB

Recently, the woody biomass has been attracted attention for the clean energy as the carbon neutral resources. However, it has been just disposed by an incinerator and it has not been utilized as the energy in Japan. Although the biomass power generation process by steam boiler was designed and developed as the effective energy utilizations, a large-scale biomass power generation plant might be required for the sufficient efficiency level. On the other hand, the biomass gasification process is the one of the promising new energy utilization process, and it would be able to increase the efficiency dramatically even in a small-scale facility. In this study, a circulating fluidized bed (CFB) type biomass gasification system was developed for the generation of clean gas fuel. The experimental gasifier unit was composed riser, down comer, pneumatic valve, cyclone and gas cooler. The riser was made of stainless steel with 5100 mm in height and 67.9 mm in diameter. External heater was equipped whole the gasifier unit to keep the temperature around 1073K. Biomass pellets, mostly from thinned wood, was used for the raw material of gasification. In this study pyrolysis experiment and investigation of particle holdup were carried out in various operation-conditions such as gasification atmosphere; temperature, fluidizing gas velocity and gasification materials, and the gasifier unit characteristics and gasification behavior were evaluated. In the results, the gas yields in the CFB gasification system was obtained with as high heating value as 13.2 MJ/m(3) under the riser temperature of 1073 K.