Performance assessment of a demonstration-scale biomass gasification power plant using material and energy flow analyses

Abstract

In this study, biomass gasification was investigated in a 1.5 MWth bubbling fluidized bed demonstration plant using air or an air/steam mixture as gasifying agent, and olivine as bed material. The gasification tests were performed in autothermal conditions and keeping constant the equivalence ratio at 0.30. The gasification products, such as producer gas, elutriated particles, tar, and contaminant gases were comprehensively characterized. Moreover, the performance of the whole gasification plant and that of its specific process units were quantitatively assessed by employing material and energy flow analyses. The results indicated that steam addition improved the producer gas quality by promoting tar and char conversion into permanent gases, thus increasing the producer gas specific yield, even if the lower heating value of the producer gas and cold gas efficiency slightly decreased. Material flow analysis highlighted that the carbon conversion efficiency was mainly affected by the carbon loss due to the solid particles collected by the cyclone, while energy flow analysis revealed that the cold gas efficiency was significantly influenced by the energy the system used to convert the starting biomass into producer gas. The biomass conversion efficiency into electrical energy was about 24 %.