Clean gas fuel made by the gasification of coal

Abstract

A fuel preparation apparatus in which coal or coal and other carbon containing material is converted to an environmentally acceptable fuel gas by the reaction with air and steam at a pressure of from 20 to 90 pounds per square inch absolute suitable for providing fuel to a gas turbine, or a stoker type or other boiler having a coal delivery system, a coal crusher, coal storage bins, lock hoppers, a gasifier vessel of two stages, liquid and solid separator vessels, heat and steam recovery vessels, equipment to control the flow of steam and air to the gasifier so as to maintain fuel quality, and a gas clean up plant that will remove environmentally unacceptable components of the gas such as hydrogen sulphide and other sulphur containing compounds and tars and light oils.

1 - 15 . (canceled)  
   
   
       16 . A method for converting a coal to a gas, comprising: 
 gasifying the coal at a first temperature in a first vessel; and    gasifying the coal in a second vessel at a second temperature which is lower than the first temperature by flowing the gas from the first vessel into the second vessel.    
   
   
       17 . The method according to  claim 16 , further including passing the coal through a flow area in the second vessel which is smaller than the flow area of the first vessel.  
   
   
       18 . The method according to  claim 16 , further including operating the second vessel and the first vessel at a pressure ranging from about 20 to 90 pounds per square inch absolute.  
   
   
       19 . The method according to  claim 16 , further including operating the second vessel and the first vessel by adding an air mixture having an oxygen concentration up to as much as 45% of the air mixture.  
   
   
       20 . The method according to  claim 16 , further including varying a height of the second vessel by less than twenty-five percent by adjudging the height according to the reactivity of the coal, performed prior to said steps of gasifying the coal.