Biomass Gasification Combined Cycle Thermodynamic Optimisation Using Integrated Drying

Abstract

The conversion of solid fuels such as biomass into a combustible gas provides the opportunity to enhance the efficiency of biomass based power systems. It allows solid fuels to be used in high efficiency power generation processes such as Integrated Gasification Combined Cycle (IGCC). Using woody biomass with high water content without drying has negative effects on the overall efficiency of the process. The option of using dryer biomass is limited by the higher fuel costs. Drying with low temperature heat is the link between the usage of wet low price fuel and optimum process conditions. In this paper, the possibilities of integrating fuel drying into a pressurized IGCC process and the effects on the efficiencies are discussed. For this purpose, an equation oriented process simulation environment with a modular structure is used. Different dryer types are integrated into this tool. Several solutions for the implementation of a drying into an IGCC process are investigated using steam and exhaust gas as heat sources. The obtained results are analyzed by the means of an exergetic analysis. Finally an optimum concept with a high electrical efficiency was obtained which will also meet the environmental regulations. Integrating drying into a biomass based IGGC concept can be an essential step for the economic operation of a plant.