Catalytic steam gasification of petroleum coke to methane

• US 20070083072A1
• Filed: 10/12/2005
• Published: 04/12/2007
• Est. Priority Date: 10/12/2005
• Status: Active Grant

• Current Assignee: Sure Champion Investments Limited
• Original Assignee: Great Point Energy Incorporated
• Inventors: Nahas, Nicholas
• Granted Patent: US 8,114,176 B2
• Time in Patent Office: Days
• US Class Current: 585/733
• CPC Class Codes: C07C 1/00 Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
• CPC Class Codes: C07C 2523/04 Alkali metals
• CPC Class Codes: C07C 2527/232 Carbonates
• CPC Class Codes: C07C 9/04 Methane production by treatment of sewage C02F11/04; natural gas, synthetic natural gas C10L3/06
• CPC Class Codes: C10J 2300/0903 Feed preparation
• CPC Class Codes: C10J 2300/0943 Coke
• CPC Class Codes: C10J 2300/0973 Water
• CPC Class Codes: C10J 2300/0983 Additives
• CPC Class Codes: C10J 2300/1807 Recycle loops, e.g. gas, solids, heating medium, water
• CPC Class Codes: C10J 2300/1823 for synthesis gas
• CPC Class Codes: C10J 3/482 Gasifiers with stationary fluidised bed
• CPC Class Codes: C10J 3/84 with means for removing dust or tar from the gas
• CPC Class Codes: Y02P 20/584 Recycling of catalysts

Abstract

The present invention provides a catalytic steam gasification process for gasifying petroleum coke. The solids composition within the gasification reactor of the disclosed invention is maintained by controlling the catalyst composition of the feed. The process utilizes sour water from the raw gasification product gases to recover and recycle catalyst. Fine particles generated in the handling of coke are advantageously utilized to increase the efficiency of the process.

Claims

1. A process for converting petroleum coke to methane, comprising

combining petroleum coke and a catalyst having steam gasification activity in an aqueous medium to form a feed slurry;

introducing said feed slurry and superheated steam into a slurry drier to produce net steam and substantially dry solid particles of petroleum coke impregnated with catalyst;

reacting said dry solid particles with said net steam in a gasification reactor to form a raw product gas comprised of unreacted steam, methane, carbon dioxide, hydrogen, and carbon monoxide;

recovering methane from said raw product gas; and

controlling the concentration of catalyst in said aqueous medium based on the amount of ash in said petroleum coke.

2. The process of claim 1 wherein said catalyst having steam gasification activity comprises one or more from the group consisting of alkali metals and alkali metal compounds.

3. The process of claim 2 wherein said alkali metal compounds are selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, alkali metal formates, alkali metal oxalates, alkali metal amides, alkali metal hydroxides, alkali metal acetates, and alkali metal sulfides.

4. The process of claim 2 wherein said catalyst comprises one or more alkali metal compounds selected from the group consisting of Na₂CO₃, K₂CO₃, Rb₂CO₃, Li₂CO₃, Cs₂CO₃, NaOH, KOH, RbOH and CsOH.

5. The process of claim 2 wherein said catalyst comprises potassium carbonate or potassium hydroxide.

6. The process of claim 5 wherein said potassium carbonate concentration in said aqueous medium is in the range of about 0.9 to 10 wt %.

7. A process for converting petroleum coke to methane, comprising:

combining petroleum coke and a catalyst having steam gasification activity in an aqueous medium to form a feed slurry;

introducing said feed slurry and superheated steam into a slurry drier to produce net steam and substantially dry solid particles of petroleum coke impregnated with catalyst;

reacting said dry solid particles and said net steam in a gasification reactor to form a raw product gas comprised of unreacted steam, methane, carbon dioxide, hydrogen, and carbon monoxide;

withdrawing a solid purge from said reactor, said solid purge comprising coke material and having catalyst incorporated therewith;

cooling said raw product stream to condense unreacted steam to form sour water and a stream of cooled raw product gas;

recovering methane from said raw product gas;

contacting said solid purge with said sour water to dissolve said incorporated catalyst to form a dilute aqueous catalyst solution, and

returning said dilute aqueous catalyst solution to said feed slurry.

8. The process of claim 7 wherein the solid purge from the gasification reactor is contacted with said sour water in a slurry vessel, and ammonia vapor is recovered from said slurry vessel.

9. The process of claim 7 wherein said dilute catalyst solution is contacted with a gas containing CO₂ before returning to said feed slurry.

10. The process of claim 7 wherein said dilute catalyst solution is stripped with said cooled raw product gas before returning to said feed slurry.

11. A process for gasifying petroleum coke comprising:

crushing petroleum coke to produce petroleum coke particles having a mesh size larger than about 325 mesh on the U.S. Standard Sieve Scale and a stream of petroleum coke fines;

combining said petroleum coke particles and at least part of said petroleum coke fines with a catalyst having steam gasification activity in an aqueous medium to form a feed slurry;

introducing said feed slurry and superheated steam into a slurry drier to produce net steam and substantially dry solid particles of petroleum coke impregnated with catalyst;

reacting said dry solid particles and said net steam in a gasification reactor.

12. The process of claim 11 wherein said petroleum coke particles range in size from 33 to 100 mesh.

13. The process of claim 11 wherein said reactor comprises a fluidized bed.

14. The process of claim 13 wherein said reactor has an upper fluidized bed and a lower fluidized bed.

15. A process for converting petroleum coke to methane, comprising:

introducing dry petroleum coke, catalyst having steam gasification activity, and superheated steam to a gasification reactor;

reacting said coke, catalyst, and steam to form a raw product gas comprised of unreacted steam, methane, carbon dioxide, hydrogen, and carbon monoxide;

withdrawing a solid purge from said reactor, said solid purge comprising coke material and having catalyst incorporated therewith;

cooling said raw product stream to condense unreacted steam to form sour water and a stream of cooled raw product gas;

contacting said solid purge with said sour water in a slurry vessel;

recovering ammonia vapor from said slurry vessel; and

recovering methane from said raw product gas.