Coal upgrading utilizing carbon dioxide

Abstract

Coal is upgraded through use of carbon dioxide and/or nitrogen and optionally integrated with a combustion process.

1 . A process of upgrading coal with carbon dioxide, comprising the steps of: 
 providing a carbon dioxide-containing fluid having a carbon dioxide concentration greater than that of air;    allowing the carbon dioxide-containing fluid to contact coal in a coal upgrading apparatus for a period of time, wherein the coal is not in a water slurry; and    allowing the carbon dioxide-containing fluid to be vented from the coal upgrading apparatus thereby removing at least some non-polar constituents from the coal.    
   
   
       2 . The process of  claim 1 , wherein the coal upgrading apparatus is at a pressure greater than ambient and is sealed during contact of the carbon dioxide-containing fluid and coal.  
   
   
       3 . The process of  claim 1 , wherein the coal is not in a slurry with water.  
   
   
       4 . The process of  claim 1 , further comprising the steps of: 
 separating air into streams of oxygen-enriched air and nitrogen-enriched air;    introducing the stream of oxygen-enriched air and the coal from the coal upgrading apparatus to a combustion chamber;    combusting the coal and oxygen-enriched air in the combustion chamber thereby producing flue gas; and    drying, purifying, and compressing the flue gas to produce the carbon dioxide-containing fluid.    
   
   
       5 . The process of  claim 1 , further comprising the steps of: 
 collecting some of the flue gas from the combustion chamber before said drying, purifying, and compressing step is performed; and    combining the collected flue gas with the stream oxygen-enriched gas being introduced to the combustion chamber.    
   
   
       6 . The process of  claim 5 , further comprising the steps of: 
 allowing the carbon dioxide-containing fluid to exit the coal upgrading apparatus and into a first cleaning unit, wherein contact between the carbon dioxide-containing fluid and the coal in the coal upgrading apparatus results in dissolution of some non-polar constituents of the coal into the carbon dioxide-containing fluid;    separating out some of the carbon dioxide from the combined carbon dioxide-containing fluid and the non-polar constituents at the first cleaning unit;    introducing the separated out carbon dioxide back into the coal upgrading apparatus;    removing at least some of a volatile component content of the non-polar constituents from non-polar constituents; and    introducing the separated volatile content into the combustion chamber.    
   
   
       7 . The process of  claim 1 , wherein the carbon dioxide-containing fluid is a liquid.  
   
   
       8 . The process of  claim 1 , wherein the carbon dioxide-containing fluid is a gas.  
   
   
       9 . The process of  claim 1 , wherein the carbon dioxide-containing fluid has a pressure of no less than 1,000 psia.  
   
   
       10 . The process of  claim 1 , further comprising the steps of: 
 heating a nitrogen-enriched air stream;    introducing the heated nitrogen-enriched air stream into a coal upgrading apparatus containing coal; and    allowing the heated nitrogen-enriched air to contact the coal in the coal upgrading apparatus for a selected period of time.    
   
   
       11 . The process of  claim 10 , further comprising the steps of: 
 allowing the nitrogen-enriched air to exit the coal upgrading apparatus and into a second cleaning unit, wherein contact between the nitrogen-enriched air and the coal in the coal upgrading apparatus results in removal of some of the moisture in the coal;    separating out moisture from the nitrogen-enriched air at the second cleaning unit to produce dried nitrogen-enriched air; and    introducing the dried nitrogen-enriched air into the coal upgrading apparatus.    
   
   
       12 . The process of  claim 1 , wherein, during said step of allowing the heated nitrogen-enriched air to contact, the coal upgrading apparatus is vented.  
   
   
       13 . The process of  claim 10 , further comprising the steps of: 
 separating air into streams of oxygen-enriched air and nitrogen-enriched air;    introducing the stream of oxygen-enriched air and the coal from the coal upgrading apparatus to a combustion chamber; and    combusting the coal and oxygen-enriched air in the combustion, wherein the stream of nitrogen-enriched air is heated with heat produced by said combusting step.    
   
   
       14 . The process of  claim 4 , wherein the oxygen-enriched gas has an oxygen concentration in a range of from 21% to 99.5%.  
   
   
       15 . The process of  claim 4 , wherein the combustion chamber is part of a boiler.