Direct coal liquefaction process

Abstract

A direct coal liquefaction process capable of producing unexpectedly high levels of C5/650° F. product, which process employs a relatively high ratio of solvent plus bottoms product recycle to feed coal.

What is claimed is: 
     
         1 . A process for the direct liquefaction of coal, which process is conducted in the absence of added carbon monoxide, and is performed in a coal liquefaction process plant comprising: a slurry mixing zone, a preheating zone, a liquefaction zone, a separation zone capable of separating a gaseous product stream from a liquid/solids product stream, an atmospheric fractionation zone, and a vacuum fractionation zone, which process comprises:
 a) introducing into said slurry mixing zone:   i) coal having an average particle size of about 75 microns to about 600 microns and a moisture content from about 1 to about 4 wt. %;   ii) effective amount of recycle non-donor solvent from said vacuum fractionation zone and non-donor bottoms from said atmospheric fractionation zone, wherein the ratio of non-donor solvent plus non-donor bottoms to coal is from about 2.5 to 1 to about 4 to 1:   iii) a molybdenum-containing microcatalyst provided at a make-up rate that is equivalent to about 50 wppm to about 2 wt. % molybdenum on a moisture and ash free (MAF) feed coal basis;   b) conducting the resulting slurry from step a) above at a pressure from about 1,500 psig to about 3000 psig and an effective amount of a treat gas containing at least 80 vol. % hydrogen, to said preheating zone wherein it is heated from a temperature from about 200° F. to 600° F. to a temperature of about 650° F.;   c) conducting said heated slurry to said liquefaction zone wherein it is reacted at a temperature from about 700° F. to about 950° F. thereby producing reaction products;   d) conducting said reaction products to a separation zone wherein a gaseous product stream is separated from a liquid/solids product stream;   e) conducting said liquid/solids stream to said atmospheric fractionation zone, wherein it is fractionated to result in a C1 to C4 gaseous fraction, a C5/650° F. fraction, and a 650 F+ bottoms fraction;   f) conducting an effective portion of non-donor 650° F.+ bottoms fraction from said atmospheric fractionation zone to said vacuum fractionation zone thereby resulting in a 1000° F.+ fraction and a non-donor 650° F. to 1000° F. solvent fraction from the vacuum fractionator; and leaving a remaining portion of said non-donor 650° F.+ fraction from said atmospheric fractionator;   g) recycling the remaining portion of said non-donor 650° F.+ fraction from said atmospheric fractionation zone to the slurry mixing zone; and   h) recycling at least a portion of said non-donor 650° F. to 1000° F. solvent fraction from said vacuum fractionation zone to said slurry mixing zone.   
     
     
         2 . The process of  claim 1  wherein the ratio of non-donor solvent plus non-donor bottoms to coal is about 3:1 to 4:1. 
     
     
         3 . The process of  claim 2  wherein the ratio of non-donor solvent plus non-donor bottoms to coal is about 3:1 to about 3.5:1. 
     
     
         4 . The process of  claim 1  wherein the amount of inertinite in said coal is from about 7 to 14 vol. %. 
     
     
         5 . The process of  claim 1  wherein the amount of inertinite in said coal is greater than about 20 vol. %. 
     
     
         6 . The process of  claim 1  wherein said treat gas contains at least about 70 vol. % hydrogen. 
     
     
         7 . The process of  claim 6  wherein said treat gas contains at least about 80 vol. % hydrogen. 
     
     
         8 . The process of  claim 1  wherein the pressure is from about 2000 psig to about 3000 psig. 
     
     
         9 . The process of  claim 1  wherein the liquefaction temperature if from about 800° F. to about 900° F. 
     
     
         10 . The process of  claim 7  wherein the pressure is from about 2000 psig to about 3000 psig and the liquefaction temperature is from about 800° F. to about 900° F.