Process for converting high sulfur coal to low sulfur power plant fuel

Abstract

Pulverized coal having a sulfur content of up to 2.5% is introduced into a gasification vessel together with air preheated to a temperature above 900.degree. F. The pulverized coal and preheated air react in the gasification vessel which is operated at temperatures in excess of 1800.degree. F. with a residence time of less than three seconds therein. The reaction between the concurrent downwardly flowing coal and air produces a product comprising partially gasified char entrained in a product gas comprising methane, hydrogen, hydrogen sulfide and oxides of carbon. The partially gasified low sulfur char entrained in the product gas is withdrawn from the gasifier and conducted to a waste heat boiler to provide steam as a source of energy for power generation. Thereafter, the low sulfur char is separated from the product gas and fed to a char storage hopper which maintains the char at a temperature above 900.degree. F. and preferably above 1100.degree. F. The product gas after being cooled to a temperature of 200.degree. F. in a heat exchanger enters a scrub tower where small amounts of char and hydrogen sulfide are removed from the product gas. The purified product gas is then fed to a gas or steam turbine of a power plant and together with the steam serves to provide energy for power generation during offpeak periods of power demand. During peak power demand periods, the low sulfur char is withdrawn from the storage hopper and burned as foiler fuel to satisfy the increased power needs. Thus, by partially gasifying high sulfur coal, a power plant fuel is produced consisting of char and fuel gas that on a heating value basis of coal has a sulfur content of less than 0.7%.

Dependencies are inferred from the claim text.