Coal enhancement process

Abstract

The present process produces a clean burning coal from low grade coal and has a higher heating value per unit mass, as compared to the feed stock coal. The clean coal may be used in coal-fired power plants, industrial boilers, and homes since it produces fewer or none of the emissions commonly associated with coal burning devices. The process treats coal prior to its combustion and removes about 90 percent of the pollutants. These pollutants are removed within 6 to 18 minutes, many of which may be recycled into products such as roofing tar, chemical feed stocks, and light hydrocarbons that can be used as gaseous fuels. The final product is suitable for use in homes where coal is used for cooking and heating, and significantly improves the health of those who have previously been exposed to toxic fumes from burning uncleaned coal in their homes. The process is fueled by its own by-products, recycles heat, and reduces coal weight to save energy in transporting it to the user.

1 . A coal enhancement process to increase its rank comprising:
 heating coal in a substantially oxygen free atmosphere in at least one zone to remove moisture and drive off by-products to increase coal rank;   cooling coal in a substantially oxygen free atmosphere in another zone;   collecting the enhanced coal; and   recycling some of the by-products as fuel to heat the coal and conserve energy.   
     
     
         2 . The process of  claim 1  which further comprises dividing the heating of the coal into two zones, the first heating to approximately 400° F. to remove surface moisture, and the second heating to approximately 1500° F. to remove more moisture and by-products. 
     
     
         3 . The process of  claim 1  which further comprises separating out by-products not recycled and collecting same for productive use elsewhere. 
     
     
         4 . The process of  claim 2  which further comprises cooling the coal using carbon dioxide cooled using a cooling tower, and recycling the heat removed from the coal to heat incoming coal in the first zone to remove surface moisture. 
     
     
         5 . The process of  claim 1  in which the by products comprise methane and ethane, propane, heavy carbons, pentane and heavier hydrocarbons, and the process further comprises:
 recycling the methane and ethane from a gas separation unit to a heating zone to use as fuel in heating the coal after start-up of the process; and 
 recycling propane produced earlier by the process to use as fuel in starting up the process. 
 
     
     
         6 . The process of  claim 1  which further comprises using carbon dioxide as inert gas to create the substantially oxygen free atmosphere. 
     
     
         7 . The process of  claim 3  in which the carbon dioxide is used as a carrier to entrain moisture and entrain by-products in the heating phase to carry them to a gas separation unit where it is separated from the by-products, dehumidified in a gas cleaning module, passes through a heat exchanger to be cooled using water from a cooling tower, used in the cooling zone to cool coal where it is heated in so doing, and is recycled back to the heating phase to assist in heating incoming coal again. 
     
     
         8 . The process of  claim 1  in which driving off the by-products by heating the coal reduces the weight of the coal while increasing its rank, wherein the reduced weight of the coal reduces energy costs in transporting the enhanced coal to a user thereby conserving energy. 
     
     
         9 . The process of  claim 1  in which driving off the by-products reduces release of pollutants when the coal is burned. 
     
     
         10 . The process of  claim 1  in which driving off the by-products reduces the amount of smoke produced by burning the coal. 
     
     
         11 . A coal enhancement process to increase its rank comprising:
 heating coal in an inert substantially oxygen free atmosphere in a first zone to approximately 400° F. to remove surface moisture;   heating coal in an inert substantially oxygen free atmosphere in a second zone to approximately 1500° F. to drive off more moisture and drive off by-products to increase coal rank;   cooling coal in an inert substantially oxygen free atmosphere in a third zone;   collecting the enhanced coal;   recycling some of the by-products as fuel to heat the coal and conserve energy;   separating out remaining by-products from the coal and from each other;   collecting the separated out by products for productive uses elsewhere; and   recycling heat removed from the coal in the third zone to the first zone to heat the coal to 400° F. and conserve energy.   
     
     
         12 . The process of  claim 11  in which the by products comprise methane and ethane, propane, heavy carbons, pentane and heavier hydrocarbons, and the process further comprises:
 recycling the methane and ethane from a gas separation unit to zone 2 to use as fuel in heating the coal to approximately 1500° F. after start-up of the process; and 
 recycling propane produced earlier by the process to use as fuel in starting up the process. 
 
     
     
         13 . The process of  claim 11  which further comprises using carbon dioxide as the inert substantially oxygen free atmosphere. 
     
     
         14 . The process of  claim 13  in which the carbon dioxide is used as a carrier to entrain moisture in the first zone, passes through a dust collector to remove dust picked up in the first zone, is dehumidified in a gas cleaning module, is cycled into zone 2 to entrain by-products to carry them to a gas separation unit where it is separated from the by-products, passes through a heat exchanger to be cooled using water from a cooling tower, used in the cooling zone to cool coal where it is heated in so doing, and with supplemental heat added is recycled back to zone 1 to heat incoming coal and entrain moisture again. 
     
     
         15 . The process of  claim 11  in which driving off the by-products by heating the coal to approximately 1500° F. in zone 2 reduces the weight of coal while increasing its rank, wherein the reduced weight of the coal reduces energy costs in transporting the enhanced coal to a user thereby conserving energy. 
     
     
         16 . The process of  claim 11  in which driving off the by-products reduces release of pollutants when the coal is burned. 
     
     
         17 . The process of  claim 11  in which driving off the by-products reduces the amount of smoke produced by burning the coal. 
     
     
         18 . The process of  claim 11  in which increasing the rank of the coal is accomplished with a processing time of six to eighteen minutes.