Gasification Tests of Pelletized Biomass in a Downdraft Gasifier

Abstract

Downdraft gasifiers are recognized as the most suitable gasification technology on a small scale due to the very low tar content of the syngas and the high fuel conversion. However some technological issues limit the reliability and diffusion of this technology, in particular tight feedstock specifications such as low moisture content and narrow size distribution. These specifications are hardly met by biomass residues from agriculture and agro­industries, which therefore need to be conditioned before being processed in downdraft gasifiers. Pelletization is a suitable option for biomass conditioning, allowing production of stable dry fuels of uniform size from different biomass residues. In this work pelletized residues obtained from sunflower seeds pressing are mixed with wood pellets and tested in a downdraft gasifier. The testing facility is a 200 kWth downdraft gasifier operating with air as a gasifying agent. The paper reports the results of the gasification tests along with samples characterization and plant performance indicators, providing a discussion about the evolution of the operating parameters.