Technical and economic assessment of the pyrolysis and gasification integrated process for biomass conversion

Abstract

The technical and economic prospects for synthesis gas production via an integrated biomass pyrolysis and gasification (IBPG) process are evaluated for the case where rice straw is a considered feedstock. Modeling of the integrated process is performed by using the Aspen Custom Modeler program. The simulation results show that the production rates of synthesis gas and bio-oil derived from an IBPG process increase as pyrolysis temperature increases, due to the increased volatiles. Compared to a conventional biomass gasification, IBPG provides additional bio-oil as a valued by-product, releases less waste heat and offers higher energy efficiency at the same synthesis gas production rate. The IBPG process with a pyrolysis temperature of 700 °C shows the best technical performance. However, pinch analysis indicates that the IBPG process with a pyrolysis temperature of 400 °C or 500 °C and conventional biomass gasification is technically feasible; the optimum heat integration structures are achieved. The economic analysis, which considers only the reaction-related equipment, indicates that the IBPG process with a pyrolysis temperature of 500 °C offers synthesis gas and bio-oil production rates of 1.185 and 0.2044 kmol h−1, respectively, and an energy efficiency of 68.86% is most economically feasible.