A novel two-stage biomass gasification concept: Design and operation of a 1.5 MWth demonstration plant

To gasify the biofuel of low ash melting temperature and overcome the high content of tar in bio-gas, a novel two-stage gasification concept is proposed. This concept enables the tar-free bio-gas generated in the gasification process under thermal cracking. On that basis, a demonstration project is introduced. Rice husk acts as the feedstock for its accessibility on-site in the commissioning period. System reliability has been confirmed for the stable operation of more than 60 days. Tests have been performed under some typical operating conditions. As the results suggest, the bio-gas of 6.7 MJ/Nm(3) LHV is generated with cold gas efficiency and carbon conversion of 67.5% and 87% respectively. Elementary economic evaluation of this concept is also made in accordance with the commissioning results. As a result, the annual net profit of 40.92 K USD is yielded without a subsidized price for biomass materials.