Hydromethanation of a carbonaceous feedstock with improved carbon utilization

• US 10,344,231 B1
• Filed: 10/26/2018
• Issued: 07/09/2019
• Est. Priority Date: 10/26/2018
• Status: Active Grant

• Current Assignee: Sure Champion Investments Limited
• Original Assignee: GreatPoint Energy, Inc.
• Inventors: Robinson, Earl T., Sirdeshpande, Avinash, Raman, Pattabhi K., Keckler, Kenneth
• Primary Examiner(s): Bahta, Medhanit W
• Application Number:
  US16/171,858
• Time in Patent Office: 256 Days
• Field of Search: None
• CPC Class Codes: C01B 2203/0244 the reforming step being an autothermal reforming step, e.g. secondary reforming processes
• CPC Class Codes: C01B 2203/0255 containing a non-catalytic partial oxidation step
• CPC Class Codes: C01B 2203/0261 containing a catalytic partial oxidation step [CPO]
• CPC Class Codes: C01B 2203/0415 Purification by absorption in liquids
• CPC Class Codes: C01B 2203/0445 Selective methanation
• CPC Class Codes: C01B 2203/0475 the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/0485 the impurity being a sulfur compound
• CPC Class Codes: C01B 2203/049 the impurity being carbon
• CPC Class Codes: C01B 2203/0495 the impurity being water
• CPC Class Codes: C01B 2203/0877 by direct injection of fluid
• CPC Class Codes: C01B 2203/0883 by indirect heat exchange
• CPC Class Codes: C01B 2203/0888 by evaporation of a fluid
• CPC Class Codes: C01B 3/04 by decomposition of inorganic compounds, e.g. ammonia C01B3/0005 takes precedence
• CPC Class Codes: C01B 3/42 using moving solid particles
• CPC Class Codes: C01B 3/48 followed by reaction of water vapour with carbon monoxide
• CPC Class Codes: C07C 1/0485 Set-up of reactors or accessories; Multi-step processes
• CPC Class Codes: C07C 2/84 catalytic
• CPC Class Codes: C07C 2523/04 Alkali metals
• CPC Class Codes: C07C 4/025 Oxidative cracking, autothermal cracking or cracking by partial combustion
• CPC Class Codes: C07C 4/06 Catalytic processes C07C4/025 takes precedence
• 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 2300/0906 : Physical processes, e.g. shredding, comminuting, chopping, sorting
• CPC Class Codes: C10J 2300/0909 : Drying
• CPC Class Codes: C10J 2300/0913 : Carbonaceous raw material
• CPC Class Codes: C10J 2300/093 : Coal
• CPC Class Codes: C10J 2300/0959 : Oxygen
• CPC Class Codes: C10J 2300/0966 : Hydrogen
• CPC Class Codes: C10J 2300/0976 : as steam
• CPC Class Codes: C10J 2300/0986 : Catalysts
• CPC Class Codes: C10J 2300/1653 : integrated in a gasification combined cycle [IGCC] engines driven by heat coming from a gasification or pyrolysis unit F01K23/067
• CPC Class Codes: C10J 2300/1662 : to methane (SNG) production of synthetic natural gas C10L3/08
• CPC Class Codes: C10J 2300/1678 : with air separation separating gases using rectification of air F25J3/04521
• 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 3/16 : simultaneously reacting oxygen and water with the carbonaceous material
• CPC Class Codes: C10J 3/482 : Gasifiers with stationary fluidised bed
• CPC Class Codes: C10J 3/523 : for gasifiers with stationary fluidised bed
• CPC Class Codes: C10L 3/06 : Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04 liquefying by pressure and cold treatment F25J
• CPC Class Codes: C10L 3/08 : Production of synthetic natural gas
• CPC Class Codes: Y02E 20/18 : Integrated gasification combined cycle [IGCC], e.g. combined with carbon capture and storage [CCS]
• CPC Class Codes: Y02E 60/36 : Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Abstract

The present invention relates generally to processes for hydromethanating a carbonaceous feedstock in a hydromethanation reactor to a methane-enriched raw product stream, and more specifically to processing of solid char by-product removed from the hydromethanation reactor to improve the carbon utilization and thermal efficiency of the overall process and thereby lower the net costs of the end-product pipeline quality substitute natural gas.

Claims

1. A process for generating, from a non-gaseous carbonaceous material and a hydromethanation catalyst, (1) fines-cleaned methane-enriched raw product gas stream and (2) an oxidation reactor char product stream, the process comprising the steps of:

a) preparing a carbonaceous feedstock from the non-gaseous carbonaceous material;

b) introducing the carbonaceous feedstock, a hydromethanation catalyst, steam and oxygen into a hydromethanation reactor, the hydromethanation reactor comprising a fluidized bed, an initial disengagement zone above the fluidized bed, and a gas mixing zone below the fluidized bed;

c) reacting the carbonaceous feedstock in the hydromethanation reactor in the presence of carbon monoxide, hydrogen, steam and hydromethanation catalyst, and at an operating temperature from about 400°

F. (about 205°

C.) up to about 1500°

F. (about 816°

C.), and an operating pressure of at least about 250 psig (about 1825 kPa), to produce a methane-enriched raw product gas, heat energy and a by-product char;

d) withdrawing a stream of methane-enriched raw product gas from the hydromethanation reactor as the methane-enriched raw product gas stream, wherein the methane-enriched raw product gas stream comprises methane, carbon monoxide, hydrogen, carbon dioxide, hydrogen sulfide, steam, and entrained solids;

e) removing a substantial portion of the entrained solids from the methane-enriched raw product gas stream to generate a solids-depleted, methane-enriched raw product gas stream and a recovered primary solids stream;

f) removing a substantial portion of any fines from the solids-depleted, methane-enriched raw product gas stream to generate a fines-cleaned methane-enriched raw product gas stream and a recovered secondary fines stream;

g) withdrawing a stream of by-product char from the hydromethanation reactor as the by-product char stream, wherein the by-product char stream comprises a carbon content and entrained hydromethanation catalyst;

h) feeding all or a portion of the by-product char stream, oxygen and steam into an oxidation reactor integrated with the hydromethanation reactor or into a standalone oxidation reactor;

i) reacting at least a portion of the carbon content of the by-product char with oxygen and steam in the oxidation reactor at a temperature of about 1500°

F. (about 816°

C.) or less, to produce (1) an oxidation reactor char product stream comprising entrained hydromethanation catalyst, (2) an oxidation gas comprising steam, carbon monoxide, carbon dioxide, and hydrogen, and (3) heat energy;

j) withdrawing a stream of the oxidation gas from the standalone oxidation reactor, if present, as the oxidation gas stream and;

(1) feeding all or a portion of the oxidation gas stream into the hydromethanation reactor through an oxidation gas distributor plate, or

(2) combining all or a portion of the oxidation gas stream with the methane-enriched raw product gas stream, or

(3) combining all or a portion of the oxidation gas stream with the solids-depleted methane-enriched raw product gas stream, or

(4) combining all or a portion of the oxidation gas stream with the fines-cleaned methane-enriched raw product gas stream, or

(5) a combination thereof; and

k) withdrawing the oxidation reactor char product stream from the oxidation reactor.

2. The process of claim 1, wherein the process has a steam demand and a power demand that are met by internal energy integration such that the process requires no net import of steam or power.

3. The process of claim 1, wherein the operating pressure in the hydromethanation reactor ranges from at least about 250 psig (about 1825 kPa) up to about 1200 psig (about 8375 kPa).

4. The process of claim 1, wherein the oxidation reactor is a fluidized-bed oxidation reactor.

5. The process of claim 1, wherein the hydromethanation catalyst comprises an alkali metal.

6. The process of claim 5, wherein the alkali metal is potassium.

7. The process of claim 5, further comprising the steps of:

(i) treating the oxidation reactor char product stream in a catalyst recovery unit to extract a portion of the entrained catalyst, to generate a washed char product, and to generate liberated hydromethanation catalyst;

(ii) withdrawing a stream of the washed char product from the catalyst recovery unit; and

(iii) withdrawing a stream of the liberated hydromethanation catalyst from the catalyst recovery unit as a recovered hydromethanation catalyst stream.

8. The process of claim 7, further comprising the steps of:

(i) feeding the recovered primary solids stream into the hydromethanation reactor; and

(ii) feeding all or a portion of the recovered secondary fines stream into a catalyst recovery unit or into the oxidation reactor.

9. The process of claim 7, wherein the hydromethanation catalyst comprises at least a portion of the recovered hydromethanation catalyst stream.

10. The process of claim 1, further comprising the steps of:

l) introducing the fines-cleaned methane-enriched raw product gas stream into a heat exchanger unit to remove heat energy and generate a cooled methane-enriched raw product stream;

m) steam shifting a portion of the carbon monoxide in the cooled methane-enriched raw product stream as required in a shift reactor system to generate a hydrogen-enriched raw product gas stream with a molar ratio of hydrogen to carbon monoxide of close to 3;

n) dehydrating the hydrogen-enriched raw product gas stream in a low-temperature gas cooling system, to generate a dry raw gas stream; and

o) removing a substantial portion of the carbon dioxide and a substantial portion of the hydrogen sulfide from the dry raw gas stream in an acid gas removal unit to produce a sweetened gas stream comprising a substantial portion of the hydrogen, carbon monoxide and methane from the dry raw gas stream.

11. The process of claim 10, further comprising the steps of:

p) reacting the carbon monoxide and hydrogen in the sweetened gas stream in a methanation system in the presence of a methanation catalyst to produce heat energy and a pipeline quality substitute natural gas stream;

q) recovering the heat energy from the catalytic methanation; and

r) utilizing at least a portion of the recovered heat energy to generate and superheat a steam stream.

12. The process of claim 11, wherein the process has a steam demand and a power demand that are met by internal energy integration such that the process requires no net import of steam or power.