Very High-Pressure Fuel-Slurry Integrated Gasifier/Gas Turbine (FSIG/GT) Power Generation Applied to Biomass

Abstract

The work contributes to the study of the fuel-slurry integrated gasifier/gas turbine (FSIG/GT) concept for the electric power generation process consuming biomass or, more specifically, sugar cane bagasse (SCB). The FSIG/GT process allows for pumping of the solid fuel as a slurry into pressurized reactors, therefore dispensing the need for complex systems of sequential lock hoppers. The slurry drying is achieved through the application of a residual hot gas stream from the process. Because the dryer and gasifier operate at similar pressures, the transfer of particles can be made using simple rotary valves and Archimedes screws. The produced fuel gas is cleaned and injected into the turbine. Previous studies were limited at operational pressures around 2 MPa, while the present evaluates the process working at the vicinity of 10 MPa. This requires intercooling between compression stages as a result of limits of the temperature imposed by the axial compressor blade materials. Rankine cycles are employed to recover energy from the gas-cleaning and exiting process streams as well from the compression intercooling systems. At the present stage investigation, operations at 10 MPa led to overall efficiencies around 34%. That is significantly higher than that presently practiced at power plants of large sugar and alcohol mills but below that achieved in previous studies of FSIG/GT processes consuming SCB and operating around 2 MPa. The main reason for that is attributed to the impossibility of total energy recover and irreversibilities introduced during intercooling. Future works might improve that value.