Thermal coal upgrading process

Abstract

A process for thermally upgrading coal in a vertical processor wherein the coal is gravity fed and a heated inert gas is introduced into the processor. The temperature of the gas, the size of the coal and the rate of movement of the coal are controlled to efficiently remove moisture from the coal and to not remove volatile organic compound.

1 . A process for thermally upgrading coal comprising the steps of:
 separating the coal into coarse and fine fractions,   providing a vertical processor having a plurality of baffles therein,   introducing the coarse fraction of coal into the top of the processor wherein the coarse coal moves to the bottom of the processor by gravity,   providing moderately high temperature process gas,   introducing the process gas into the bottom of the processor under rows of baffles wherein the gas is uniformly distributed at a low velocity in a cross flow manner throughout the coal in the processor, the coal flows by gravity around the baffles gently agitating the coal while the direct contact with the moderately high temperature process gas heats the coal to remove moisture from the coal altering the combustion and physical characteristics of the coal,   removing the heated, altered coal from the processor, and   mixing the heated altered coal with a controlled amount of the fine fraction coal wherein the coarse fraction of the coal is cooled and the fine fraction of the coal is heated releasing some of the moisture contained in the fine fraction.   
     
     
         2 . The process of  claim 1 , wherein the coarse fraction of the coal does not exceed approximately three inches. 
     
     
         3 . The process of  claim 1 , wherein the baffles are alternating levels of inverted V inlet baffles and outlet baffles extending transversely across the processor wherein the coal is gently mixed as the coal descends by gravity through the processor reducing compressive power requirements. 
     
     
         4 . The process of  claim 1 , wherein the process gas is heated by waste heat from an external source. 
     
     
         5 . The process of  claim 4 , wherein the process gas is exhaust gas from a combustion process. 
     
     
         6 . The process of  claim 4 , wherein the process gas is reheated by indirect exchange with a waste heat source and recycled to the processor. 
     
     
         7 . The process of  claim 1 , wherein the temperature of the process gas ranges from 450° F. to 900° F. 
     
     
         8 . The process of  claim 7 , wherein the temperature of the process gas is approximately 700° F. 
     
     
         9 . The process of  claim 1 , wherein the oxygen content of the process gas is less than 5% by volume. 
     
     
         10 . The process of  claim 1 , wherein the coal in the processor is heated at a rate of less than 10° F. per minute. 
     
     
         11 . The process of  claim 10 , wherein the coal in the processor is heated at a rate of less than 3° F. per minute. 
     
     
         12 . The process of  claim 1 , wherein a minimum amount of volatile organic compounds (VOC) are evolved from the coal. 
     
     
         13 . The process of  claim 1 , wherein the process gas exits the coal at a velocity of less than 5 fps. 
     
     
         14 . The process of  claim 13 , wherein the process gas exits the coal at a velocity of less than 2 fps. 
     
     
         15 . The process of  claim 1 , wherein the product has a temperature of less than 180° F. 
     
     
         16 . The process of  claim 15 , wherein the product has a temperature of less than 140° F. 
     
     
         17 . The process of  claim 1 , wherein the residence time of the coal in the processor is approximately 60 minutes. 
     
     
         18 . A continuous process for thermally upgrading low rank coal comprising the steps of:
 providing a tower means for passing the coal via gravity from the top of the tower, the tower having baffle means with the tower for channeling the coal downwardly within the tower,   providing a source of heated gas, and   introducing the heated gas in outlet means within the tower wherein the heated gas mixes within the tower heating the downwardly descending coal to remove moisture from the coal, the heated gas passing through outlets in the tower.   
     
     
         19 . The process of  claim 18 , wherein the temperature of the heated gas ranges from 450° F. to 900° F. 
     
     
         20 . The process of  claim 18 , wherein the coal in the processor is heated at a rate of less than 3° F. per minute. 
     
     
         21 . The process of  claim 18 , wherein the residence time of the coal in the processor is approximately 60 minutes.