INTEGRATED CHP SYSTEM EFFICIENCY ANALYSIS OF AIR, MIXED AIR-STEAM AND STEAM BLOWN BIOMASS GASIFICATION FUELLED SOFC

摘要

A solid oxide fuel cell system (SOFC) integrated with biomass gasifier has been proposed in this article. The integrated combined heat and power (CHP) system consists of gasifier, gas cleaner, an air heater, an anode preheater, internal reforming solid oxide fuel cell (IRSOFC) stack and an afterburner. Biomass gasfier blown with air, steam and mixed air-steam were compared to know the system efficiency performance of overall CHP configuration. The SOFC stack was operated under isothermal conditions. The excess heat generated from the SOFC stack and the afterburner was supplied to the reformer and pre-heaters as well as to the gasification. The effects of heat utilization for gasifier and preheaters on the overall system efficiency were examined. Air gasifier shown least electrical efficiency of 18 % in the gasification range of ER: .20. Steam gasifier showed electrical efficiency about 45 % at low steam to biomass ratio (SBR:.3).Mixed air-steam gasifier shown maximum electrical efficiency of 13 to 33 % in the SBR range of. 1 to 4.2. Thermal efficiency that is excess heat available for air-gasifier shown to be 33% at lower ER ratio of .2, steam gasifier shown peak thermal efficiency of 49 % where as for the mixed air-steam gasifier thermal efficiency was in between the air and steam gasification system. Overall efficiency for steam gasifier showed highest as compared to mixed air steam and air gasifier.