Dynamic simulation of a combined-cycle coal gasification facility

Simulation of this facility, which is being built by Fluor for Commonwealth Edison Co., the Electric Power Research Institute, the state of Illinois, and ERDA, was carried out by Fluor's modification of the DYSCO (Dynamic Process Simulation for Process Control). The combined-cycle plant will use low-Btu gas from coal for baseload electric power generation and an oil-fired gas turbine for daily-load-following (peak shaving), and the simulation is intended to minimize oil use and to determine conditions which could result in compressor surge. The simulation uses a lumped-parameter system of adiabatic or isothermal capacitance, representing heat exchange elements such as the reboiler, waste heat boiler, and thermosyphon loop, and flow-determining elements, e.g., control valves. Control instabilities resulting from shutoff of compressed air to the Lurgi gasifier and from the coal lock cycle when using backpressure control are discussed and illustrated graphically.