THERMOCHEMICAL ANALYSIS OF ACFB-BASED GAS AND POWER COGENERATION

A first- and second-law analysis is presented for a process developed for simultaneous generation of a fuel gas and electric power (gas and power cogeneration) based on atmospheric circulating-fluidized-bed (AC FB) combustion of coal. The mathematical model has a zone structure, m ulti-species equilibrium calculations for applicable zone conditions a t high temperatures (50 gas-phase and seven solid-phase chemical speci es) and the concept of freezing of the gas composition at low temperat ures. Our analysis shows that the process utilizes coal in a simple, e ffective and environmentally clean manner. The first- and second-law e fficiencies of the process are, respectively, 35.0 and 27.6% for gas g eneration, 15.4 and 14.6% for power generation, 50.4 and 42.2% overall . The heating value of the gas is 11 MJ/Nm(3) (medium). Desulphurizati on is achieved by using CaS-based sulphur capture during limestone add ition to the gasifier bed. Results are compared with data from a 150 k g of coal/h experimental plant.