Low carbon dioxide footprint process for coal liquefaction

Abstract

A method for producing hydrocarbons is provided, which comprises (a) subjecting a coal feedstock to mechanical activation ( 203 ) in a liquid medium, thereby obtaining a mixture of solubilized asphaltenes; and (b) at least partial cracking ( 207 ) the resulting mixture in a supersonic nozzle reactor, thereby obtaining hydrocarbon products derived from the asphaltenes.

What is claimed is: 
     
         1 . A method for producing hydrocarbons, comprising:
 subjecting a coal feedstock to mechanical activation in a first liquid medium containing covalently bound oxygen, thereby obtaining a mixture of solubilized asphaltenes; and   cracking the asphaltenes in a nozzle reactor, thereby obtaining hydrocarbon products derived from the asphaltenes.   
     
     
         2 . The method of  claim 1 , wherein the liquid medium comprises an alcohol. 
     
     
         3 . The method of  claim 2 , wherein the alcohol is a primary alcohol. 
     
     
         4 . The method of  claim 1 , wherein the liquid medium comprises methanol. 
     
     
         5 . The method of  claim 1 , wherein the liquid medium comprises an ether. 
     
     
         6 . The method of  claim 1 , wherein the liquid medium comprises dimethyl ether. 
     
     
         7 . The method of  claim 1 , wherein the liquid medium comprises a methyl carbonate. 
     
     
         8 . The method of  claim 1 , wherein the liquid medium comprises a di-methyl carbonate 
     
     
         9 . The method of  claim 1 , wherein the liquid medium in an iteration of the method is a portion of the hydrocarbon products generated by a previous iteration of the method. 
     
     
         10 . The method of  claim 1  wherein, prior to mechanical activation, the coal feedstock is subjected to an ash removal process. 
     
     
         11 . The method of  claim 10 , wherein the ash removal process comprises grinding the coal feedstock. 
     
     
         12 . The method of  claim 11 , wherein grinding the coal feedstock produces a ground product having an average particle size within the range of about 1 to about 10 mm. 
     
     
         13 . The method of  claim 11 , wherein the ash removal process further comprises subjecting the ground coal feedstock to mineral flotation. 
     
     
         14 . The method of  claim 1 , wherein mechanical activation of the coal feedstock generates a mixture comprising asphaltenes and inorganic materials, and further comprising subjecting the mixture to a separation procedure which produces an organic phase rich in asphaltene and an inorganic phase rich in ash. 
     
     
         15 . The method of  claim 1 , wherein subjecting the mixture to a separation procedure involves treating the mixture in a centrifuge. 
     
     
         16 . The method of  claim 15 , wherein the supernatant obtained from the centrifuge is rich in asphaltenes. 
     
     
         17 . The method of  claim 1 , wherein cracking the asphaltenes comprises:
 injecting a pressurized stream of cracking material through a cracking material injector and into a reaction chamber of a nozzle reactor; and   injecting a feed material comprising the solubilized asphaltenes into the reaction chamber adjacent to the cracking material injector and transverse to the pressurized stream of cracking material entering the reaction chamber.   
     
     
         18 . The feed material cracking method of  claim 18 , wherein the cracking material injector includes a converging/diverging passage. 
     
     
         19 . The method of  claim 18 , wherein injecting a pressurized stream of cracking material comprises:
 passing the cracking material through the converging/diverging passage; and   accelerating the cracking material to supersonic speed within the cracking material injector.   
     
     
         20 . The method of  claim 17 , wherein the feed material is injected into the reaction chamber annularly around the pressurized stream of cracking material. 
     
     
         21 . The method of  claim 18 , wherein the feed material is injected into the reaction chamber annularly around the pressurized stream of cracking material. 
     
     
         22 . The method of  claim 19 , wherein the feed material is injected into the reaction chamber annularly around the pressurized stream of cracking material. 
     
     
         23 . The method of  claim 17 , wherein the cracking material is a cracking gas. 
     
     
         24 . The method of  claim 22 , wherein the cracking material is a cracking gas. 
     
     
         25 . The feed material cracking method of  claim 17 , wherein the cracking gas comprises steam. 
     
     
         26 . The feed material cracking method of  claim 17 , wherein the cracking gas comprises methane. 
     
     
         27 . The feed material cracking method of  claim 17 , wherein the cracking gas comprises hydrogen. 
     
     
         28 . A method for cracking coal asphaltenes, comprising:
 mechanically activating a coal feedstock in a liquid medium comprising a material which generates hydrogen in situ under a set of cracking conditions; and   cracking the mechanically activated coal feedstock under said cracking conditions.   
     
     
         29 . The method of  claim 28 , wherein the material generates hydrogen radicals under said cracking conditions. 
     
     
         30 . The method of  claim 28 , wherein the cracking conditions involve exposure of the material to steam. 
     
     
         31 . The method of  claim 28 , wherein the cracking conditions involve cracking the asphaltenes in a nozzle reactor. 
     
     
         32 . The method of  claim 31 , wherein the nozzle reactor is a supersonic nozzle reactor. 
     
     
         33 . The method of  claim 28 , wherein the cracking conditions involve accelerating the asphaltenes to a speed within the range of Mach 1 to Mach 10. 
     
     
         34 . The method of  claim 28 , wherein the cracking conditions involve accelerating the asphaltenes to a speed within the range of Mach 2 to Mach 8. 
     
     
         35 . The method of  claim 28 , wherein the cracking conditions involve accelerating the asphaltenes to a speed within the range of Mach 4 to Mach 6. 
     
     
         36 . The method of  claim 28 , wherein the mechanically activated feedstock absorbs a portion of the material. 
     
     
         37 . A method for cracking coal asphaltenes in a nozzle reactor under a set of reactor conditions, comprising:
 providing a nozzle reactor having first and second reactant inlets;   injecting an activated coal feedstock into the first inlet; and   injecting a material into the second inlet which generates hydrogen in situ under said reactor conditions.   
     
     
         38 . The method of  claim 37 , wherein the material generates hydrogen radicals in situ under said reactor conditions. 
     
     
         39 . The method of  claim 37 , wherein the material is methanol. 
     
     
         40 . The method of  claim 39 , wherein the methanol is mixed with steam prior to being injected into the second inlet. 
     
     
         41 . A system for obtaining hydrocarbon liquids from a coal feedstock, comprising:
 a grinding mill which mechanically activates the coal feedstock by grinding it in a liquid medium; and   a supersonic nozzle reactor which cracks the activated coal feedstock to generate hydrocarbon liquids.   
     
     
         42 . The system of  claim 41 , further comprising:
 a separator which separates the ash content from the asphaltene content of the coal feedstock.   
     
     
         43 . The system of  claim 41 , wherein the liquid medium comprises an alcohol. 
     
     
         44 . The system of  claim 41 , wherein the liquid medium comprises methanol.