Study On The Characteristics OF Biomass Two-step Pyrolysis

Biomass is a good substitute for fossil energy due to its renewable, abundantly distributed characteristics. Pyrolysis is an important technology among the biomass utilizations. It can offer various products for different applications. A stainless steel reaction boat and a tube furnace are employed to reveal the influences of material types, bed heights and moisture contents on biomass drying and devolatilization in regular conditions. The process is inhibited with the increasing of bed height and moisture content. In comparison to the rice husk, the corn stalks is decomposed more rapidly and harder to dry. TG/DTG experiment is performed, and the result indicate that high temperature makes less contributions on accelerating drying than thermal decomposition. Poplar wood is a good material for the study of biomass pyrolysis and gasification, for its low ash content."Two-step pyrolysis" is proposed to resolve the trouble of tar. The feasibility of the new technology is tested by PY-GC/MS. The first-step pyrolysis temperatures range from250℃to500℃, and the reaction times are10s,30s and60s. The second-step is operated at900℃with reaction timelO s. The result shows that the two-step pyrolysis could enhance the decomposition of lignin compounds in biomass, and significantly reduce the tar formation in high temperature. The high quality liquid products (bio-oil) is obtained at500℃.