Refining coal-derived liquid from coal gasification, coking, and other coal processing operations

Abstract

A method of treating a coal-derived liquid byproduct from a coal gasification process includes subjecting the coal-derived liquid to a vacuum distillation process, thereby separating the coal-derived liquid into condensed gas and coal-derived liquid bottoms. The coal-derived liquid bottoms are mixed with a bottoms solvent capable of dissolving the coal-derived liquid bottoms. The solvent/bottoms mixture is introduced along with a linear chain hydrocarbon solvent into a liquid extractor. The Raffinate is separated from the solvent for the coal-derived liquid/bottoms mixture, thereby producing a heavy extract. The condensed gas is subjected to atmospheric distillation producing a bottoms fraction and another condensed fraction. The bottoms fraction may be used as fuel or for diesel fuel production. The condensed fraction is extracted with a linear hydrocarbon solvent in an extractor to produce light neutral oil and a Raffinate which is a cresylic acid feed stock.

1 . A method of treating a coal-derived liquid byproduct from a coal gasification process comprising:
 subjecting the coal-derived liquid to a vacuum distillation process, thereby separating the coal-derived liquid into condensed gas and coal-derived liquid bottoms;   mixing the coal-derived liquid bottoms with a bottoms solvent capable of dissolving the coal-derived liquid bottoms; and   introducing the solvent/bottoms mixture along with a linear chain hydrocarbon solvent into a liquid extractor, and separating Raffinate from the solvent for the bottoms mixture, thereby producing a heavy extract.   
   
   
       2 . The method of  claim 1  including removing the linear chain hydrocarbon solvent from the heavy extract, thereby forming a stripped wax feedstock. 
   
   
       3 . The method of  claim 1  including removing the solvent for the coal-derived liquid bottoms from the stripped wax feedstock to form wax. 
   
   
       4 . The method of  claim 1  in which the bottoms solvent for the coal-derived liquid bottoms is N-methylpyrrolidone. 
   
   
       5 . The method of  claim 1  in which the linear chain hydrocarbon solvent is heptane. 
   
   
       6 . The method of  claim 5  in which the step of removing heptane from the heavy extract is carried out with a vacuum distillation step 
   
   
       7 . The method of  claim 1  in which the vacuum distillation process for the coal-derived liquid is conducted at a temperature less than or equal to about 260° C. 
   
   
       8 . The method of  claim 1  in which the bottoms solvent is removed from the Raffinate in a vacuum distillation process to form a pitch product. 
   
   
       9 . The method of  claim 8  in which the linear chain hydrocarbon solvent is removed from the Raffinate in a distillation process prior to removing the bottoms solvent. 
   
   
       10 . A method of treating a coal-derived liquid byproduct from a coal gasification process comprising:
 subjecting the coal-derived liquid to a vacuum distillation process, thereby separating the coal-derived liquid into condensed gas and coal-derived liquid bottoms;   subjecting the condensed gas to an atmospheric distillation process, thereby producing light cut byproducts, middle cut byproducts, and bottoms;   treating the middle cut byproduct by subjecting it, along with a linear chain hydrocarbon solvent, to a liquid extraction process, thereby producing a middle cut extract and Raffinate; and   subjecting the middle cut extract to a distillation process to remove the linear chain hydrocarbon solvent, thereby forming cresylic acid feedstock.   
   
   
       11 . The method of  claim 10  in which the linear chain hydrocarbon solvent is heptane. 
   
   
       12 . The method of  claim 10  including subjecting the Raffinate to a distillation process to remove the linear chain hydrocarbon solvent, thereby forming oil. 
   
   
       13 . The method of  claim 10  including subjecting the light cut byproducts to a decanting process to remove process water, thereby forming decant oil. 
   
   
       14 . The method of  claim 10  whereby the bottoms cut is combined with the light oil and decant oil to form a marketable diesel oil. 
   
   
       15 . The method of  claim 10  including subjecting the bottoms to extraction with a linear chain hydrocarbon solvent to form an extract and a Raffinate, and subsequently recovering the linear chain hydrocarbon solvent from both streams to produce separate middle oil and middle polars product streams. 
   
   
       16 . A method of treating a coal-derived liquid byproduct from a coal gasification process comprising:
 subjecting the coal-derived liquid to a vacuum distillation process, thereby separating the coal-derived liquid into condensed gas and coal-derived liquid bottoms;   subjecting the condensed gas to an atmospheric distillation process, thereby producing light cut byproducts, middle cut byproducts, and bottoms;   treating the middle cut byproduct by subjecting it, along with heptane, to a liquid extraction process, thereby producing a middle cut extract and Raffinate;   subjecting the middle cut extract to a distillation process to remove the heptane, thereby forming cresylic acid feedstock; and   forming cresylic acid from the cresylic acid feedstock.   
   
   
       17 . The method of  claim 16  including subjecting the Raffinate to a distillation process to remove the linear chain hydrocarbon solvent, thereby forming oil. 
   
   
       18 . The method of  claim 16  including subjecting the light cut byproducts to a decanting process to remove process water, thereby forming decant oil. 
   
   
       19 . The method of  claim 16  whereby the bottoms cut is combined with the light neutral oil and decant oil to form a marketable diesel oil. 
   
   
       20 . The method of  claim 16  including subjecting the bottoms to extraction with a linear chain hydrocarbon solvent to form an extract and a Raffinate, and subsequently recovering the linear chain hydrocarbon solvent from both streams to produce separate middle oil and middle polars product streams.