Thermodynamic analysis of the gasification of coal water slurry fuels for a circulating fluidized bed gasifier

To validate the concept of coal gasification in the integrated coal gasification combined cycle (IGCC), a novel laboratory gasifier consisting of a circulating fluidized bed and a cyclone combustor has been constructed. This paper reports a thermodynamic analysis conducted to predict the maximum capacity and the condition for best operation of this circulating fluidized bed gasifier, which has an inside diameter of 0.3048 m and a height of 2.5 m. The equilibrium feed rates of materials and the quality of the product gas are described as a function of the reactor temperature, the thermal capacity of the gasifier, and the water concentration in coal water slurry fuel. The results of parametric analysis show that the thermal efficiency decreases, but the efficiency of desulfurization increases as the reactor temperature increases. The thermal capacity of the gasifier has no influence on the quality of the product gas. The thermal efficiency and the efficiency of desulfurization decrease as the water concentration in the coal water slurry increases. The desulfurization in the gasifier at equilibrium conditions is very efficient and meets the EPA regulations of the USA.