Efficiency of a power generation alternative regarding the composition of feeding biomass-glycerol slurry; theoretical assessment

Abstract

Following studies on Fuel Glycerol Slurry Integrated Gasification/Gas Turbine (FGSIG/GT) power generation processes, the present investigates the efficiency of a FGSIG/GT alternative regarding the composition of the slurry pumped into the process. Such slurry is prepared by mixing sugar-cane bagasse (SCB) and raw glycerol—a residue of biodiesel production. Differently from previous investigations, the current one considers the alternative where the wet solid fuel is dried before mixing with raw glycerol to form the slurry to be pumped into the gasifier. Such feeding alternative circumvents the use of cumbersome multiple lock-hoppers, usually applied in feeding of particulate solid into pressurized vessels. The stream leaving the gasifier goes through cleaning before being injected into commercial turbines. Energy recovering drives two Rankine cycles. Despite biomass fuel enhancement provided by the glycerol, it has been shown that the highest power generation efficiency can be achieved for slurries with relatively small glycerol content. The 1st and 2nd thermodynamic law efficiencies reached maxima nearing 47% and 36%, respectively. Those values are much higher than the 20% 1st law efficiency currently achieved at sugar mill units as well as the 33% predicted by theoretical studies on Biomass Integrated Gasification/Gas Turbine process consuming only sugar cane bagasse.