Fluidized Bed Steam Gasification of Solid Biomass: Analysis and Optimization of Plant Operation Using Process Simulation

Fluidized bed steam gasification of solid biomass yields a high quality producer gas, which can be used for efficient combined heat and power production (CHP) and as an intermediate product for chemical syntheses. In order to study the behavior of an 8 MW (fuel power) CHP plant, which has been in successful operation since 2001, a comprehensive model library has been developed for the equation-oriented process simulation software IPSEpro. The models are validated with measured data from the commercial scale plant. Because every model is based on the conservation of mass and energy, the simulation also allows the validation of measured data. By solution of a system describing the entire process, which uses measured data as input, a reference case for actual plant operation can be defined. In a next step, the behavior of the plant is studied during variations of selected parameters. Therefore, a model of the gasification reactor, which is able to describe the behavior during parameter variation, is necessary. It can be shown that fuel water content and gasification temperature significantly influence the global plant performance. The simulation predicts the efficiency of the existing power plant in optimized operation. Finally, part load behavior is investigated and a performance map of the CHP plant is presented. The results show that CHP-concepts based on fluidized bed steam gasification can reach high electric efficiencies and high overall fuel utilization rates even at small plant capacities of 10 MW fuel power.