System and method for syngas clean-up

• US 9,499,404 B2
• Filed: 09/27/2012
• Issued: 11/22/2016
• Est. Priority Date: 09/27/2011
• Status: Active Grant

• Current Assignee: Thermochem Recovery International, Inc.
• Original Assignee: Thermochem Recovery International, Inc.
• Inventors: Chandran, Ravi, Leo, Daniel Michael, Freitas, Shawn Robert, Newport, Dave G., Whitney, Hamilton Sean Michael, Burciaga, Daniel A.
• Primary Examiner(s): WARTALOWICZ, PAUL A
• Application Number:
  US14/347,431
• Publication Number:
  US 20140252276A1
• Time in Patent Office: 1,517 Days
• US Class Current: 1/1
• CPC Class Codes: B01D 17/0208 by sedimentation
• CPC Class Codes: B01D 2252/102 Ammonia
• CPC Class Codes: B01D 2252/103 Water
• CPC Class Codes: B01D 2252/20436 Cyclic amines
• CPC Class Codes: B01D 2252/504 Mixtures of two or more absorbents
• CPC Class Codes: B01D 2252/602 Activators, promoting agents, catalytic agents or enzymes
• CPC Class Codes: B01D 2256/16 Hydrogen
• CPC Class Codes: B01D 2256/20 Carbon monoxide
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/306 Organic sulfur compounds, e.g. mercaptans
• CPC Class Codes: B01D 2257/406 Ammonia
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/60 Heavy metals or heavy metal compounds
• CPC Class Codes: B01D 2257/708 Volatile organic compounds V.O.C.'s
• CPC Class Codes: B01D 2259/402 using two beds
• CPC Class Codes: B01D 29/27 Filter bags
• CPC Class Codes: B01D 29/66 by flushing, e.g. counter-current air-bumps
• CPC Class Codes: B01D 46/0036 by adsorption or absorption
• CPC Class Codes: B01D 47/10 Venturi scrubbers
• CPC Class Codes: B01D 5/0027 by direct contact between vapours or gases and the cooling medium
• CPC Class Codes: B01D 5/006 : with evaporation or distillation
• CPC Class Codes: B01D 5/0072 : with filtration
• CPC Class Codes: B01D 5/0075 : with heat exchanging B01D5/0039 takes precedence
• CPC Class Codes: B01D 5/009 : Collecting, removing and/or treatment of the condensate
• CPC Class Codes: B01D 50/60 : Combinations of devices covered by groups B01D46/00 and B01D47/00
• CPC Class Codes: B01D 53/0423 : Beds in columns
• CPC Class Codes: B01D 53/0462 : Temperature swing adsorption
• CPC Class Codes: B01D 53/047 : Pressure swing adsorption
• CPC Class Codes: B01D 53/0476 : Vacuum pressure swing adsorption
• CPC Class Codes: B01D 53/12 : according to the "fluidised technique"
• CPC Class Codes: B01D 53/1406 : Multiple stage absorption
• CPC Class Codes: B01D 53/1412 : Controlling the absorption process
• CPC Class Codes: B01D 53/1431 : Pretreatment by other processes
• CPC Class Codes: B01D 53/1462 : Removing mixtures of hydrogen sulfide and carbon dioxide
• CPC Class Codes: B01D 53/1468 : Removing hydrogen sulfide
• CPC Class Codes: B01D 53/1487 : Removing organic compounds
• CPC Class Codes: B01D 53/18 : Absorbing units; Liquid distributors therefor B01D3/16, B01D3/26, B01D3/30 take precedence; packing elements B01J19/30, B01J19/32
• CPC Class Codes: B01D 53/265 : by refrigeration (condensation)
• CPC Class Codes: B01D 53/326 : in electrochemical cells
• CPC Class Codes: B01D 53/48 : Sulfur compounds
• CPC Class Codes: B01D 53/76 : Gas phase processes, e.g. by using aerosols
• CPC Class Codes: B01D 61/362 : Pervaporation
• CPC Class Codes: B01D 61/3621 : comprising multiple pervaporation steps
• CPC Class Codes: C01B 2203/0227 : containing a catalytic reforming step
• CPC Class Codes: C01B 2203/0233 : the reforming step being a steam reforming step
• CPC Class Codes: C01B 2203/025 : containing a partial oxidation step
• CPC Class Codes: C01B 2203/0261 : containing a catalytic partial oxidation step [CPO]
• CPC Class Codes: C01B 2203/04 : containing a purification step for the hydrogen or the synthesis gas
• CPC Class Codes: C01B 2203/0415 : Purification by absorption in liquids
• CPC Class Codes: C01B 2203/042 : Purification by adsorption on solids
• CPC Class Codes: C01B 2203/043 : Regenerative adsorption process in two or more beds, one for adsorption, the other for regeneration
• CPC Class Codes: C01B 2203/0435 : Catalytic purification
• CPC Class Codes: C01B 2203/045 : Purification by catalytic desulfurisation
• CPC Class Codes: C01B 2203/0465 : Composition of the impurity
• CPC Class Codes: C01B 2203/0475 : the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/048 : the impurity being an organic compound
• CPC Class Codes: C01B 2203/0485 : the impurity being a sulfur compound
• CPC Class Codes: C01B 2203/061 : Methanol production
• CPC Class Codes: C01B 2203/062 : Hydrocarbon production, e.g. Fischer-Tropsch process
• CPC Class Codes: C01B 2203/068 : Ammonia synthesis
• CPC Class Codes: C01B 2203/0877 : by direct injection of fluid
• CPC Class Codes: C01B 2203/1235 : Hydrocarbons
• CPC Class Codes: C01B 2203/1241 : Natural gas or methane
• CPC Class Codes: C01B 2203/142 : At least two reforming, decomposition or partial oxidation steps in series
• CPC Class Codes: C01B 2203/147 : Three or more purification steps in series
• CPC Class Codes: C01B 2203/84 : Energy production
• CPC Class Codes: C01B 3/24 : of hydrocarbons
• CPC Class Codes: C01B 3/38 : using catalysts
• CPC Class Codes: C01B 3/382 : Multi-step processes
• CPC Class Codes: C01B 3/386 : Catalytic partial combustion
• CPC Class Codes: C01B 3/52 : by contacting with liquids; Regeneration of used liquids C01B3/508 takes precedence
• CPC Class Codes: C01B 3/56 : by contacting with solids; Regeneration of used solids C01B3/508 takes precedence
• CPC Class Codes: C01B 3/58 : including a catalytic reaction
• CPC Class Codes: H05K 999/99 : dummy group
• CPC Class Codes: Y02C 20/40 : of CO2
• CPC Class Codes: Y02P 20/129 : Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
• CPC Class Codes: Y02P 30/00 : Technologies relating to oil refining and petrochemical industry

Abstract

A system and method for processing unconditioned syngas first removes solids and semi-volatile organic compounds (SVOC), then removes volatile organic compounds (VOC), and then removes at least one sulfur containing compound from the syngas. Additional processing may be performed depending on such factors as the source of syngas being processed, the products, byproducts and intermediate products desired to be formed, captured or recycled and environmental considerations.

Claims

1. A method of processing unconditioned syngas, comprising:

(a) removing solids and semi-volatile organic compounds (SVOC) from the unconditioned syngas to form a first depleted syngas stream which has a reduced amount of solids and SVOC relative to the unconditioned syngas;

(b) after step (a), removing volatile organic compounds (VOC) from the first depleted syngas stream to form a second depleted syngas stream which has a reduced amount of VOC relative to the first depleted syngas stream;

(c) after step (b), removing at least one sulfur containing compound from the second depleted syngas stream to produce a sulfur-depleted syngas stream which has a reduced sulfur amount of sulfur relative to the second depleted syngas stream.

2. The method according to claim 1, further comprising compressing the first depleted syngas stream prior to step (b).

3. The method according to claim 2, further comprising filtering fine particulates after step (a) and prior to compressing the first depleted syngas stream.

4. The method according to claim 2, further comprising removing one or more metals after compressing the first depleted syngas stream.

5. The method according to claim 2, further comprising:

removing ammonia without a sorbent bed; and

optionally removing additional ammonia using a sorbent bed.

6. The method according to claim 2, further comprising heating the sulfur-depleted syngas stream to facilitate contaminant removal.

7. The method according to claim 2, further comprising, after step (c), removing carbon dioxide from the sulfur-depleted syngas stream.

8. The method according to claim 2, further comprising, after step (c), an additional sulfur polishing step using a fixed bed adsorption system to reduce total sulfur content to less than 100 part-per billion.

9. The method according to claim 2, further comprising, after step (c), a carbon dioxide electrolysis step to increase carbon monoxide concentration.

10. The method according to claim 1, wherein in step (a), the SVOC is removed by scrubbing the unconditioned syngas with a hydrocarbon liquid created from a downstream catalytic syngas conversion system.

11. The method according to claim 10, wherein the hydrocarbon liquid created from the downstream catalytic syngas conversion system is based on a Fischer-Tropsch process.

12. The method according to claim 1, wherein the VOC removed from the first syngas stream is desorbed by utilizing both pressure swing desorption and temperature swing desorption.

13. The method according to claim 12, wherein the VOC is removed by a microchannel heat exchanger having an adsorption chamber having at least one of a particulate bed, a packing and a coating in contact with the first depleted syngas stream, the adsorption chamber being separated from a thermal transfer chamber.

14. The method according to claim 1, wherein the unconditioned syngas has a first temperature above a SVOC condensation temperature, and said step (a) comprises:

(a1) contacting the unconditioned syngas with a solvent and water to reduce the temperature of the syngas to below the SVOC condensation temperature to thereby form an intermediate SVOC-depleted syngas containing steam, and a first mixture comprising SVOC, solids, solvent and water;

(a2) removing steam from the intermediate SVOC-depleted syngas containing steam to form;

(i) a first depleted syngas stream which has a reduced amount of SVOC relative to the unconditioned gas stream, and (ii) a second mixture comprising SVOC, solids, solvent and water;

(a3) separating the water within the second mixture based upon immiscibility so that the SVOC, solids and solvent collect together to form a third mixture above the water;

(a4) separating the solids from the SVOC and solvent in a vessel having at least one liquid phase candle filter such that the solids agglomerate on a surface of the candle filter and form a filter cake having density greater than that of water within the vessel;

(a5) backflushing the candle filter to loosen the filter cake so that the filter cake sinks into the water within the vessel; and

(a6) removing the filter cake from a bottom of the vessel.

15. The method according to claim 14, comprising:

separating the water within the second mixture based upon immiscibility in a decanter;

transferring the third mixture from the decanter to the vessel having the candle filter therein.

16. The method according to claim 14, comprising using a Fischer-Tropsh liquid product as the solvent.

17. The method according to claim 16, comprising using a mid-distillate or Medium Fraction Fischer-Tropsch Liquid (MFTL) as the solvent.

18. The method according to claim 14, wherein the solvent is a biodegradable solvent suitable for biodiesel residue.

19. The method according to claim 14, comprising:

removing the SVOC and solvent from the vessel through the candle filter; and

backflushing the candle filter using a recirculated portion of the removed SVOC and solvent.

20. The method according to claim 19, comprising:

backflushing the candle filter using a recirculated portion of the removed SVOC and solvent.

21. The method according to claim 19, comprising separating the SVOC from the solvent and recycling the solvent, after the SVOC and solvent have been removed from the vessel.

22. The method according to claim 19, comprising separating the SVOC from the solvent using vacuum flashing, after the SVOC and solvent have been removed from the vessel.

23. The method according to claim 19, comprising separating the SVOC from the solvent using membranes, after the SVOC and solvent have been removed from the vessel.

24. The method according to claim 1, further comprising removing at least one sulfur containing compound after step (a) and before step (b).

25. The method according to claim 24, wherein triazine is employed to scavenge the at least one sulfur containing compound.

26. The method according to claim 1, further comprising cooling the unconditioned syngas prior to step (a).

27. The method according to claim 1, further comprising, prior to step (a):

hydrocarbon reforming and/or cracking at least a portion of the unconditioned syngas to form hydrogen and carbon monoxide; and

cooling the hydrogen and carbon monoxide formed by said hydrocarbon reforming and/or cracking.

28. The method according to claim 1, further comprising hydrocarbon reforming at least a portion of the sulfur-depleted syngas stream to form hydrogen and carbon monoxide, after step (c).

29. The method according claim 1, further comprising removing chlorine from the first depleted syngas stream by scrubbing, prior to step (b).

30. The method according to claim 1, wherein in step (a), the SVOC is removed by scrubbing the unconditioned syngas with a biodegradable solvent suitable for biodiesel residue.

31. The method according to claim 1, wherein:

in step (a), removing solids and SVOC by scrubbing;

in step (b), removing VOC by adsorption; and

in step (c), removing the at least one sulfur-containing compound by adsorption.

32. The method according to claim 1, wherein the SVOC removed from the unconditioned syngas in step (a) include

one or more polyaromatics from the group consisting of indene, indan, napthalene, methylnapthalene, acenapthylene, acenapthalene, anthracene, phenanthrene, (methyl-) anthracenes/phenanthrenes, pyrene/fluoranthene, methylpyrenes/benzofluorenes, chrysene, benz[a]anthracene, methylchrysenes, methylbenz[a]anthracenes, perylene, benzo[a]pyrene, dibenz[a,kl]anthracene, and dibenz[a,h]anthracene.

33. A method of processing unconditioned syngas containing solids, semi-volatile organic compounds (SVOC), volatile organic compounds (VOC) and at least one sulfur containing compound, the method comprising:

(a) removing solids and SVOC from the unconditioned syngas by scrubbing, to form a first depleted syngas stream which has a reduced amount of solids and SVOC relative to the unconditioned syngas;

(b) after step (a), removing VOC from the first depleted syngas stream by adsorption, to form a second depleted syngas stream which has a reduced amount of VOC relative to the first depleted syngas stream;

(c) after step (b), removing at least one sulfur containing compound from the second depleted syngas stream by adsorption, to produce a sulfur-depleted syngas stream which has a reduced sulfur amount of sulfur relative to the second depleted syngas stream.

34. The method according to claim 33, wherein:

the semi-volatile organic compounds in the unconditioned syngas include one or more polyaromatics from the group consisting of indene, indan, napthalene, methylnapthalene, acenapthylene, acenapthalene, anthracene, phenanthrene, (methyl-) anthracenes/phenanthrenes, pyrene/fluoranthene, methylpyrenes/benzofluorenes, chrysene, benz[a]anthracene, methylchrysenes, methylbenz[a]anthracenes, perylene, benzo[a]pyrene, dibenz[a,kl]anthracene, and dibenz[a,h] anthracene.