Production of liquid and gaseous fuel products from coal or the like

• US 4,097,361 A
• Filed: 08/24/1976
• Issued: 06/27/1978
• Est. Priority Date: 08/24/1976
• Status: Expired due to Term

• Current Assignee: Arthur G Mckee & Company
• Original Assignee: Arthur G Mckee & Company
• Inventors: Ashworth, Robert A.
• Primary Examiner(s): Gantz, Delbert E.
• Assistant Examiner(s): Thierstein, Joan
• Application Number:
  US05/717,102
• Time in Patent Office: 672 Days
• Field of Search: 208/8, 208/10, 208/127, 48/210, 48/197 R
• US Class Current: 208/408
• CPC Class Codes: C10G 1/002 in combination with oil conversion- or refining processes
• CPC Class Codes: C10G 1/083 in the presence of a solvent
• CPC Class Codes: C10G 9/32 according to the "fluidised-bed" technique

Abstract

A continuous deep hydrogenation coal liquefaction process is disclosed wherein a slurry of powdered coal or other carbonaceous material in a recycle solvent is passed with hydrogen through a hydroextraction unit, the heavy coal extract remaining after removal of gas and oil is then fed into a low-temperature fluidized-bed pyrolysis unit, and the char and ash is fed from the pyrolysis unit to a high-temperature fluidized-bed char gasification unit. The gasification unit is specially constructed to provide continuous ash agglomeration and has a funnel-shaped grid plate at the bottom of the fluidized bed and an elutriation leg of reduced diameter at the bottom of the grid plate. Air or oxygen is introduced near the top of the elutriation leg to provide a high temperature such that the ash particles are continuously softened and caused to accrete or agglomerate in a hot spouting zone at the base of the grid plate. Steam is directed upwardly through the elutriation leg so that the smaller lighter agglomerated ash particles are supported in the bed and the larger heavier agglomerated ash particles fall to the bottom for removal. A portion of the hot agglomerated ash from the upper portion of the bed is continually recycled through the pyrolysis unit to function both as a catalyst and as the sole heat source. A portion of the ash may also be recycled with the slurry fed to the hydroextraction unit to serve as a hydrogenation catalyst.

Claims

1. A multistage process for conversion of solid carbonaceous feed material to valuable liquid and gaseous products comprising passing a slurry of the particulate feed in a hydrocarbon oil solvent with hydrogen at high temperature and pressure through a reaction zone of a hydroextraction unit maintained under hydrocracking conditions to provide for coal dissolution, withdrawing liquid and gaseous effluent streams from the reaction zone including unconverted feed material, a fraction comprising a solvent oil being separated from the liquid effluent and continually recycled for mixing with the incoming particulate feed, the amount by weight of recycled solvent oil being greater than the amount of particulate feed and sufficient to dissolve most of the particulate feed, feeding that portion of the effluent stream from said hydroextraction unit containing the heavier oils and unconverted feed material to the reaction zone of a pyrolysis unit containing a fluidized bed of char and agglomerated ash particles to effect thermal cracking, withdrawing oil and gas from the residue of char and ash produced in said pyrolysis unit, feeding the char and agglomerated ash from said pyrolysis unit to the reaction zone of an ash-agglomerating char gasification unit and reacting it with an oxygen-containing gas and steam exothermically to produce fuel gas while generating heat and causing agglomeration of ash particles, and recycling the hot agglomerated ash from said gasification unit to the reaction zone of said pyrolysis unit to transfer heat to said reaction zone and to catalyze the cracking reactions therein.

2. The process of claim 1 in which said char gasification unit comprises a fluidized bed of char and ash particles and in which the ash particles in the bottom portion of the bed are heated and caused to agglomerate.

3. The process of claim 1 in which the hydrogenation and hydrocracking reactions in said hydroextraction unit are catalyzed primarily by addition to the slurry of ash particles corresponding to those which have passed through said gasification unit.

12. The process of claim 1 in which a hot zone is provided at the bottom of the fluidized bed of said gasification unit having a temperature substantially higher than the average temperature of the bed and such that the ash particles are softened and caused to agglomerate in said zone, and in which fine solid particles in the overheads from said pyrolysis unit and said gasification unit are separated out and caused to flow under pressure into the lower portion of said last-named bed toward said hot zone.

4. A coal liquefaction process of the non-catalytic type comprising dissolving dry comminuted coal in a solvent oil to form a slurry, mixing the slurry with hydrogen and subjecting it to hydrogenation and hydrocracking in a high-pressure hydroextractor maintained under conditions suitable for non-catalytic coal dissolution, separating the gas and oil from the residual coal extract, subjecting the extract to flash distillation to recover solvent oil for recycling, at least 90 percent by weight of the moisture-free coal being dissolved, feeding the coal extract to a pyrolysis unit in which it is heated under substantially non-oxidizing conditions to cause thermal cracking and to form a residue of char and ash, said pyrolysis unit containing a fluidizied bed of char and agglomerated ash particles, feeding the char and ash from said pyrolysis unit to a fluidized-bed ash-agglomerating char gasification unit which is maintained at a temperature higher than that of said pyrolysis unit by exothermic reaction of the char with oxygen and steam, whereby fuel gas is produced, causing agglomeration of ash particles in said gasification unit, and recycling hot ash agglomerates from said gasification unit to said pyrolysis unit to transfer heat to the latter and to catalyze the cracking reactions therein.

5. The process of claim 4 in which said char gasification unit contains a fluidized bed of ash and char particles and the fine ash particles are heated and caused to agglomerate at the lower part of the bed.

6. The process of claim 5 in which the bed of said char gasification unit is maintained at a temperature below the ash eutectic fusion temperature and above 1800°

F.

7. The process of claim 4 in which the hydrocracking reactions in said hydroextractor are catalyzed primarily by continual addition to the slurry of ash particles which have passed through said gasification unit.

8. The process of claim 4 in which the hydrogen transfer in said hydroextractor is at least about 4 percent by weight of the moisture- and ash-free coal.

9. A continuous process for converting coal, peat or other carbonaceous material into liquid fuel comprising crushing, drying and classifying the material to provide dry comminuted particles of a predetermined moisture content, mixing the dry particles with a major amount by weight of a naturally-derived solvent oil to form a slurry containing at least 30 percent by weight of said carbonaceous material, preheating the slurry and adding hydrogen thereto to provide a three-phase gas-liquid-solid mixture, pumping said mixture into a hydroextraction unit at a pressure of at least 80 atmospheres and causing it to pass upwardly through the reaction zone of said unit, whereby the more reactive compounds are dissolved and the mixture leaving the unit comprises a first portion containing volatile light oil, gas and water and a second slurry portion containing the heavier extract and the unconverted solids, separating out said first portion and delivering it to a gas-oil recovery system wherein oil and high-energy fuel gas are recovered, delivering said second slurry portion to a flash distillation unit while releasing the high pressure to separate the lower boiling point oil from the remaining heavier extract containing the unconverted solids, delivering said lighter oil to said gas-oil recovery system, fractionating large amounts of oil from said recovery system to produce said naturally-derived solvent oil and recycling the latter for mixing with the aforesaid dry comminuted particles, said solvent oil causing at least 90 percent by weight of the dry particles to be dissolved before they are discharged from said hydroextraction unit, passing said heavier extract from said flash distillation unit to a fluidized bed pyrolysis unit maintained at a temperature of at least 900°

F. and having a fluidized bed of hot ash and char, subjecting said heavier extract to thermal cracking in said pyrolysis unit under substantially non-oxidizing conditions while removing oil and gas from the top of the unit, continually removing ash and char from the bed of said pyrolysis unit and delivering it to a fluidized bed ash-agglomerating char gasification unit having a fluid bed of ash and char, causing air and steam to pass upwardly through the latter bed to fluidize the same and to react exothermically with the char to heat the bed to a temperature in excess of 1800°

F. to convert the char to fuel gas which is removed from the upper portion of the gasification unit, continuously causing fine ash particles from said bed to come together and agglomerate, continually removing a portion of the agglomerated ash from the gasification unit, and continually recycling hot agglomerated ash from the latter unit to said pyrolysis unit to heat the same and to catalyze the reactions therein.

10. The process of claim 9 in which ash from said gasification unit is continually recycled to the slurry being fed to said hydroextraction unit to catalyze the hydrocracking reactions, said ash being the sole catalyst in said hydroextraction unit and being caused to flow with the slurry back to said pyrolysis unit.

11. The process of claim 9 in which the amount of hydrogen supplied to said solvent oil and to the slurry being fed to said hydroextraction unit is sufficient to provide a high yield of oil from the latter unit and such that the Conradson carbon content of the heavy extract entering said pyrolysis unit is not in excess of 40 percent by weight.

13. A multistage process for conversion of solid carbonaceous feed material to valuable liquid and gaseous products comprising passing a slurry of the particulate feed in a hydrocarbon oil solvent with hydrogen at high temperature and pressure through a reaction zone of a hydroextraction unit to effect coal dissolution, withdrawing liquid and gaseous effluent streams from the reaction zone including unconverted feed material, feeding a portion of the effluent stream from said hydroextraction unit containing the heavier oils and unconverted feed material to the reaction zone of a pyrolysis unit in which it is heated under substantially non-oxidizing conditions to effect thermal cracking, said pyrolysis unit comprising a fluidized bed of agglomerated ash and char particles maintained at a temperature of from about 900°

to about 1200°

F., continually removing ash and char from the bed of said pyrolysis unit and delivering it to a char gasification unit having a fluidized bed of ash agglomerates, fine ash and char, causing steam and an oxygen-bearing gas to pass upwardly through the latter bed to generate heat while producing fuel gas, causing a portion of the material in said last-named bed to pass to a high temperature accretion zone at said gasification unit wherein the outer surface portions of the ash particles are heated to a temperature at which such surface portions are softened and capable of adhering or fusing to other ash particles, bringing the ash particles into contact at said accretion zone to form ash agglomerates, cooling the agglomerated ash and recirculating the smaller particles thereof, and continually recycling the agglomerated ash particles from said char gasification unit to said pyrolysis unit to transfer sufficient heat to the latter unit to maintain a temperature of at least 900°

F. therein and to catalyze the cracking reactions therein.

14. The process of claim 13 in which entrained fine solid particles in the overheads from said pyrolysis unit and said gasifier unit are separated out and recirculated through said last-named units, whereby such fine particles are eventually caused to agglomerate.

15. The process of claim 14 in which the gasification unit is maintained at a temperature of at least 1900°

F. and particles at the bottom of the bed are caused to move downwardly and to converge at said accretion zone which is maintained at a temperature higher than the average temperature of said bed by supplying an oxygen-containing gas to said zone, and in which fine solid particles from said overheads are collected and fed toward said accretion zone.

16. The process of claim 14 in which lighter agglomerated ash particles from said accretion zone are raised by the flow of gases through the bed and caused to move toward the top of the bed and such particles are recycled to the bed of said pyrolysis unit, the recycled particles providing the heat required for said pyrolysis unit.

17. A process for treating a heavy residuum obtained by solvent hydrogenation of a slurry of coal particles comprising feeding said residuum to the reaction zone of a pyrolysis unit maintained under substantially non-oxidizing conditions to effect thermal cracking and recovery of oil and gas from said unit, said unit containing a fluidized bed of char and agglomerated ash particles, continually removing ash and char from the bed of said pyrolysis unit and delivering it to a char gasification unit having a fluidized bed of ash and char particles, causing steam and an oxygen-bearing gas to pass upwardly through the latter bed to fluidize the same and to react exothermically with the char to heat the bed to a temperature of from 1800°

to 2400°

F. to convert the char to fuel gas, causing accretion of the fine ash particles of the bed and formation of larger ash agglomerates in a high temperature accretion zone at said gasification unit having a temperature higher than the average temperature of said bed, recirculating a portion of the agglomerated ash particles through said gasification unit, and continually recycling hot agglomerated ash from said gasification unit to said pyrolysis unit to heat the latter unit and to catalyze the reactions therein.

18. The process of claim 17 in which heavier agglomerated ash particles from said accretion zone are cooled and removed and lighter agglomerated ash particles are caused to move upwardly through the bed of said gasification unit.

19. The process of claim 18 in which agglomerated ash particles near the top of the bed of said gasification unit are recycled to the bed of said pyrolysis unit.

20. The process of claim 19 in which fine ash particles entrained with gases leaving the top of said gasification unit are collected and returned to said hot accretion zone, whereby they adhere to larger agglomerated ash particles.

21. The process of claim 17 in which an elutriation zone is provided at the bottom of said gasification unit, the agglomerated ash particles from said accretion zone are cooled by gaseous fluid in said elutriation zone to cause separation of the particles, and larger heavier ash particles are removed while lighter agglomerated ash particles are returned to the bottom portions of the bed and caused to move upwardly through the bed.

22. The process of claim 21 in which the residuum comprises a coal extract with a Conradson carbon content of from about 30 to about 40 percent and a boiling range above 1040°

F., said pyrolysis unit is maintained at a temperature of from about 900°

to about 1200°

F. by the hot recycled ash from said gasification unit, and the gasification unit is operated under conditions such that the larger agglomerated ash particles removed from said accretion zone and from said gasification unit have a carbon content no greater than 10 percent.

23. The process of claim 17 in which said char gasification unit is operated at a temperature of from about 1900°

to about 2200°

F.

24. The process of claim 17 in which said char gasification unit has an elutriation leg of reduced diameter near the bottom of the bed and the downwardly moving particles at the bottom of the bed are caused to converge in a high temperature accretion zone in said elutriation portion which is maintained at a temperature above the average temperature of said bed and sufficient to cause the ash particles to agglomerate, an oxygen-containing gas is supplied to said accretion zone, and steam is supplied to said elutriation leg below said accretion zone to cool the agglomerated particles while causing lighter agglomerated particles to move upwardly through the bed, heavier agglomerated particles being allowed to fall by gravity and being removed from said gasification unit.

25. The process of claim 17 in which said char gasification unit has an elutriation leg of reduced diameter near the bottom of the fluidized bed for receiving ash particles from the bed and means above said elutriation leg for directing steam and an oxygen-containing gas upwardly through the bed to fluidize the bed, and wherein steam is directed upwardly through the lower portion of the elutriation leg to force the lighter agglomerated ash particles upwardly into said bed, and an oxygen-containing gas is fed to the upper portion of said elutriation leg to increase the temperature at the top of said leg and to cause softening and accretion of the ash particles, whereby the larger heavier agglomerated ash particles fall to the bottom of said leg and the smaller lighter ash particles are returned to the bed.

26. A process for treating a residuum obtained by hydrogenation of a slurry of coal particles comprising feeding said residuum to the reaction zone of a pyrolysis unit maintained under substantially non-oxidizing conditions to effect thermal cracking and recovery of oil and gas from said unit, said unit containing a fluidized bed of char and agglomerated ash particles, continually removing ash and char from the bed of said pyrolysis unit and delivering it to a char gasification unit having a fluidized bed of ash and char particles and an elutriation leg of reduced diameter below the bed, causing steam and an oxygen-bearing gas to pass upwardly through the bed above said leg to fluidize the same and to react exothermically with the char to convert the char to fuel gas and ash, feeding air to a high-temperature accretion zone in the upper portion of said leg to cause softening and accretion of the ash particles, causing ash particles in the bed to move downwardly and converge at said accretion zone, whereby the ash particles agglomerate, and feeding steam upwardly through the lower portion of the elutriation leg to cool the ash agglomerates and cause the lighter agglomerates to move upwardly into said bed while permitting the larger heavier agglomerates to fall, cooling and removing the heavier agglomerates, and continually recycling the lighter agglomerates from the bed to said pyrolysis unit to provide the heat required for the latter unit, the entrained fine solid particles in the overheads from said gasification unit being separated out and returned to said high-temperature accretion zone.