Study of Tar Removal in the Biomass Gasification Process

• Main Authors: Po-Chang Hu, 胡博誠
• Other Authors: 吳耿東
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/25504985963333816548

碩士 === 國立中興大學 === 森林學系所 === 97 === Tar can be defined as all organic contaminants in biomass-derived syngas with a molecular weight larger than that of benzene. The formation of tar in the gasification process is one of the major problems to affect the utilization of syngas in power systems. This study is to investigate tar formation and elimination for gasification of wood-based materials, e.g. Cunninghamia lanceolata, Acacia confuse, Pinus taiwanensis and Trema orientalis. All experiments were carried out in a 30 kWth bubbling fluidized bed gasification system with a diameter of 7.6 cm in the bed region, 19.8 cm in the freeboard region, and a total high of 2.0 m. Oyster shell powder, dolomite, clay brick powder and limestone were employed as gasification tar-cracking catalysts. The results show that the tar content within the syngas decreases with increasing the gasification temperature and the equivalence ratio (ER). Injecting steam and employing catalysts also can eliminate the tar more effectively. Especially tar conversion can reach 69-80% by applying clay brick powder as the catalyst. In addition, tar content increases with increasing the lignin content of woody biomass. For example, the tar content increased 263%, while the lignin content increased from 26.82% to 33.20%. However, the effect of the lignin content was not obvious for the gasification temperature at 900oC. Moreover, the tar content decreases with increasing the CaO/MgO ratio of Ca-based catalysts.