Experimental Studies Of The Biomass Pyrolysis & Char Gasification Reactivity

Biomass is a kind of important renewable energy. Using and developing biomass energy was widely concerned. Study on biomass pyrolysis- biomass char gasification is of great important significance.In this study, the pyrolysis of two biomass samples, wheat stalk and corn stalk and gasification of biomass char were performed by TG-DSC technique. The effects of four pyrolysis conditions such as heating rates, soaking time, residence time and pyrolysis temperature on biomass pyrolysis characteristics, and ones of pyrolysis conditions and gasification conditions on biomass char reactivity were investigated. Experimental results showed that pyrolysis conditions had some effects on biomass char yield. Increasing soaking time and pyrolysis temperature can obviously decrease the biomass char yield, and with increasing residence time the yield increased first and then decreased. The activation energies for pyrolysis of two samples were respectively calculated by FWO, DAEM and Popescu methods.Gasification reactivity of biomass char increased first and then decreased while increasing heating rates. Increasing soaking time and pyrolysis temperature can decrease the biomass char gasification reactivity. And increasing gasification temperature can obviously improve gasification rate. It was also found that two kinds of biomass had the same gasification reaction trend. However, the wheat stalk has higher reactivity than that of corn stalk under the same gasification conditions.The two samples were also pyrolyzed in a fixed bed. The pyrolysis solid products were tested by accelerated surface area and porosimetry and SEM, the gases products were tested by GC. The SEM results showed that biomass char existed porous structure. The amount of micro porous increased with increasing pyrolysis temperature so that the surface area increased. In the mean time, the actual large reacting porous decreased due to the existence of floc-material, the biomass reactivity decreased with rising temperature. The pyrolysis gases consist mainly of H₂, CH₄, CO and CO₂ for Two kinds of biomass.