Coal liquefaction using vacuum distillation and an external residuum feed

Claim 2

A process for liquefying coal comprising: (a) heating a slurry comprising a petroleum or petroleum-derived solvent and particulate coal in a dissolution zone to substantially dissolve the coal to produce a first effluent containing undissolved solids; (b) adding petroleum residuum from an external source to at least a portion of the first effluent to produce a second effluent containing said solids; and (c) distilling the second effluent under reduced pressure to produce an overhead fraction and a bottoms fraction containing said solids.

Claim 3

The process of claim 1, wherein the residuum has a solids content less than about 1%.

Claim 4

The process of claim 1, further comprising recycling at least a portion of the overhead fraction to the dissolution zone.

Claim 5

The process of claim 1, wherein conditions in the dissolution zone include a temperature of from about 400° C. to 480° C., a pressure of from about 70 to 700 atmospheres, a hydrogen gas rate of from about 170 to 3500 cubic meters per cubic meter of slurry, and a residence time of from about 0.1 to 3 hours.

Claim 6

The process of claim 1, wherein the dissolution zone contains a dispersed dissolution catalyst.

Claim 7

The process of claim 1, wherein the addition of petroleum residuum in step (b) is controlled so that the bottoms fraction of step (c) contains about 50% solids.

Claim 8

The process of claim 1, wherein the weight ratio of solvent to coal is from about 1:2 to 5:1.

Claim 9

A process for liquefying coal comprising: (a) heating a slurry comprising a petroleum or petroleum-derived solvent and particulate coal in a dissolution zone to substantially dissolve the coal to produce a first effluent containing undissolved solids; (b) contacting at least a portion of the first effluent with hydrogen in a reaction zone under hydrogenation conditions in the presence of an externally-supplied hydrogenation catalyst to produce a second effluent containing undissolved solids; (c) adding petroleum residuum from an external source to at least a portion of the second effluent to produce a third effluent containing said solids; and (d) distilling the third effluent under reduced pressure to produce an overhead fraction and a bottoms fraction containing said solids.

Claim 10

A process for liquefying coal comprising: (a) heating a slurry comprising a petroleum or petroleum-derived solvent and particulate coal in a dissolution zone to substantially dissolve the coal to produce a first effluent containing undissolved solids; (b) contacting at least a portion of the first effluent with hydrogen in a reaction zone under hydrogenation conditions in the presence of an externally-supplied hydrogenation catalyst to produce a second effluent containing undissolved solids; (c) adding petroleum residuum from an external source to at least a portion of the second effluent to produce a third effluent containing said solids; and (d) distilling the third effluent under reduced pressure to produce an overhead fraction and a bottoms fraction containing said solids.

Claim 11

The process of claim 8, wherein the residuum has a solids content of less than about 1%.

Claim 12

The process of claim 8, wherein hydrogenation conditions include a temperature of below 425° C., a pressure of from about 70 to 700 atmospheres, a hydrogen rate of from about 350 to 3500 cubic meters per cubic meter of slurry, and a slurry hourly space velocity of from about 0.1 to 2 hours -1 .

Claim 13

The process of claim 8, further comprising recycling at least a portion of the overhead fraction to the dissolution zone.

Claim 14

The process of claim 8, wherein conditions in the dissolution zone include a temperature of from about 400° C. to 480° C., a pressure of from about 70 to 700 atmospheres, a hydrogen gas rate of from about 170 to 3500 cubic meters per cubic meter of slurry, and a residence time of from about 0.1 to 3 hours.

Claim 15

The process of claim 8, wherein the dissolution zone contains a dispersed dissolution catalyst.

Claim 16

The process of claim 8, wherein the addition of petroleum residuum in step (c) is controlled so that the bottoms fraction of step (d) contains about 50% solids.

Claim 17

The process of claim 8, wherein the weight ratio of solvent to coal is from about 1:2 to 5:1.