ORC BOTTOMING FOR COMBINED CYCLE SYSTEMS FED BY BIOMASS

asme-orc2015 Tracking Number 111

In the last two decades ORCs have been largely used to convert the heat from biomass combustion into electric energy. The success of the ORC technology for this application is mainly due to its low maintenance requirements, ease of operation and good partial load performance. In quest for higher efficiency systems, biomass gasification , followed by conversion to electric power in a small scale combined cycle, is very promising. Indeed several gasification systems, integrated with gas cleaning and gas engines for power production, have been put into operation in the past, with different results depending on the adopted solution. The paper suggests a different approach featuring an innovative gasification device, a gas turbine prime mover, and an Organic Rankine Cycle as bottoming system, typically for a power of the combined system up to 5 MW. In the paper a preliminary study of the system performance is presented, together with a sensitivity analysis concerning the various components as well as a discussion on the main advantages and shortcomings. A comparison of the proposed system with combustion/ORC systems is , taking also into account expected O&M requirements, load modulation and pollutant emissions.