ALKALI CATALYZED GASIFICATION OF SOLID BIOMASS – INFLUENCE ON FUEL CONVERSION AND TAR/SOOT REDUCTION

摘要

Based on char gasification experiments in an isothermal thermogravimetric analyzer, a suitable concentration of alkali salt (K_2CO_3) was chosen for impregnation due to almost five-fold increase in gasification reactivity and relatively low amount of carbon leaching during impregnation. Furthermore, an optimum method for wet alkali impregnation was proposed based on the several tests performed by varying temperature and time. To study the catalytic effect on tar and soot yield, untreated and impregnated woody biomass were gasified under entrained flow condition between 900 °C and 1200 °C. Impregnation leads to 70% lower tar yield from gasification around 1000 Oc and 1100 °C. The lowest amount of soot was detected for the same temperature range whereas the soot yield was one order of magnitude higher for untreated biomass. For tar, this influence became insignificant at a higher temperature (1200 °C). This defines the suitable temperature range for alkali catalyzed gasification without the loss of catalytic activity.