A MULTIPRODUCT COGENERATION SYSTEM USING COMBINED COAL-GASIFICATION AND COMBUSTION

A new system has been developed for clean and highly efficient utiliza tion of coal. The coal is first gasified and the fuel gas is then used for industrial purposes in town gas or as a fuel for gas turbines. Th e char residue from the gasifier is burned in a circulating fluidized- bed combustor to generate steam for power generation, process heating, refrigeration, air conditioning, etc. The ash is used to produce cons truction materials. Metals such as vanadium and uranium can be extract ed if the metal contents of coal are sufficiently high. An important s ystem component is the combined gasifier-combustor. Experiments show t hat the system can produce gas and steam simultaneously. The gas heati ng value is 10-14 MJ/Nm(3) and the fuel conversion is over 90%. The sy stem has low emissions and low cost. A demonstration system has been c onstructed at the Yangzhong Thermal Power Plant in Jiangshu Province o f China. It produces 3,500 Nm(3)/h of dry gas and 75 mt/h steam. The C FB boiler has been in commercial operation since April 1995. It has hi gh efficiency, good fuel adaptability, and a high load turndown ratio. (C) 1998 Elsevier Science Ltd. All rights reserved.