Energy & Fuels, Vol.29, No.6, 3879-3889, 2015
New Developments on Fuel-Slurry Integrated Gasifier/Gas Turbine (FSIG/GT) Alternative for Power Generation Applied to Biomass; Configuration Requiring No Steam for Gasification
The work presents additional improvements on the strategy of the Fuel-Slurry Integrated Gasifier/Gas Turbine (FSIG/GT) concept for electric power generation applied to the case of Sugar Cane Bagasse (SCB). The process allows feeding solid fuel particles into pressurized reactors without the need for complex systems of sequential lock-hoppers. For that, the particulate fuel is mixed with water to produce a high dry solid content slurry that is pumped into a pressurized dryer. Since both the bubbling fluidized bed dryer and gasifier operate at similar pressures, the transference of dried particles to the gasifier can be accomplished with simple Archimedes screws. As the particles are dried before gasification, the process also circumvents the difficulties of fuel slurry ignition, which usually require pure oxygen combined with hydrocarbons. The gas stream leaving the gasifier is cleaned and injected into a gas turbine combustor or combustors. Heat recovering is accomplished by Rankine cycles. The present phase follows preliminary studies where the rates of air and steam injections were variables on the optimization of the dryer and gasifier. Now, the studies include the dryer and gasifier diameters as additional variables for optimizations. The work considers exergetic and cold efficiencies as objective functions. The investigation demonstrates the possibility of achieving higher overall power generation efficiency, which surpasses that achieved by other strategies such as high-pressure Rankine, Biomass Integrated Gasification/Gas Turbines, and combined cycles using pressurized-chamber boilers. The present work concentrates on a possible configuration for the FSIG/GT process that does not require steam for fuel gasification; thus just compressed air is injected into that equipment. Future works will explore other alternatives.