Method for syngas clean-up of semi-volatile organic compounds with carbonyl sulfide removal

Patent metadata

Field	Value
Publication number	US-10011483-B2
Application number	US-201715430654-A
Country	US
Kind code	B2
Filing date	Feb 13, 2017
Priority date	Sep 27, 2011
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

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.

First claim

What is claimed is:

1. A method for cleaning unconditioned syngas for introduction into a syngas processing technology application, the unconditioned syngas including semi-volatile organic compounds (SVOC), at least one or both of hydrogen chloride and hydrogen sulfide, and having a carbonyl sulfide concentration greater than 0 ppm and less than or equal to 15 ppm, the method comprising:
(a) contacting the unconditioned syngas with 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 and water;
(b) 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 and solids relative to the unconditioned gas, and (ii) a second mixture comprising SVOC, solids and water;
(c) after step (b), removing hydrogen chloride and/or hydrogen sulfide from the first depleted syngas stream with a scrubber;
(d) after step (c), compressing the syngas to a pressure ranging from 100 PSIG to 2,000 PSIG;
(e) after step (d), removing at least a portion of the carbonyl sulfide from the syngas;
(f) after step (e), removing carbon dioxide from the syngas with one or more from the group consisting of a membrane, an adsorber and an absorber;
wherein:
(i) the carbonyl sulfide concentration after step (e) is less than or equal to 30 ppb;
(ii) the hydrogen chloride concentration in unconditioned syngas ranges from greater than 0 ppm to less than or equal to 1000 ppm;
(iii) the hydrogen chloride capture efficiency of the scrubber is greater than 80%;
(iv) the hydrogen sulfide concentration ranges from greater than 0 ppm to less than or equal to 1000 ppm;
(v) the hydrogen sulfide capture efficiency of the scrubber is greater than 80%;
(vi) the carbon dioxide concentration to step (f) ranges from 10% by volume to 40% by volume; and
(vii) the carbon dioxide capture efficiency of step (f) is greater than 20%.

2. The method of claim 1 , comprising, in step (e):
In step (e) injecting water into a packed hydrolysis bed containing alumina media, to hydrolyze the carbonyl sulfide.

3. The method of claim 2 , comprising:
converting the carbonyl sulfide into carbon dioxide and hydrogen sulfide.

4. The method of claim 1 , wherein:
the unconditioned syngas has a metal concentration greater than 0 ppm and less than or equal to 30 ppm, said metal being one or more from the group consisting of mercury, arsenic, lead, and cadmium; and the method further comprises:
after step (d) and before step (e), removing at least a portion of said metal such that the metal concentration is less than or equal to 10 ppb.

5. The method of claim 4 , comprising:
removing said metal with a cylindrical pressure vessel containing one or more from the group consisting of cellulose acetate, cellulose acetate packing, cellulose acetate beads, cellulose acetate spheres, cellulose acetate flake, cellulose acetate pellets, and sorbents.

6. The method of claim 1 , comprising, in step (d):
compressing syngas with a syngas compressor from a first pressure ranging from 15 PSIG to 50 PSIG to a second higher pressure ranging from 100 PSIG to 2,000 PSIG.

7. The method of claim 6 , comprising:
introducing a gaseous hydrocarbon source to the inlet of the syngas compressor, said gaseous hydrocarbon including one or more from the group consisting of natural gas, syngas, refinery offgases, naphtha, methanol, ethanol, petroleum, methane, ethane, propane, butane, hexane, benzene, toluene, xylene, and naphthalene.

8. The method of claim 1 , wherein:
the unconditioned syngas has an ammonia concentration greater than 0 ppm and less than or equal to 1000 ppm; and the method further comprises:
after step (d) and before step (e), removing at least a portion of the ammonia with a capture efficiency greater than 80%.

9. The method of claim 8 , comprising removing ammonia with water in a scrubber.

10. The method of claim 9 , wherein:
after removing ammonia with water in a scrubber, the syngas has a residual ammonia concentration greater than 0 ppm and less than or equal to 15 ppm; and the method further comprises:
polishing ammonia in a fixed bed adsorber such that the ammonia concentration is reduced to less than or equal to 10 ppb.

11. The method of claim 10 , wherein:
the fixed bed adsorber comprises a cylindrical pressure vessel containing one or more from the group consisting of sorbents, molecular sieve type 4A, 5A sorbents, 13× sorbents, dealuminated faujasite, dealuminated pentasil, and clinoptilolite.

12. The method of claim 1 , comprising:
(g) after step (f), removing sulfur with a fixed bed adsorber to reduce sulfur concentration to less than 30 ppb.

13. The method of claim 12 , comprising:
removing at least one sulfur containing compound with a cylindrical pressure vessel containing one or more from the group consisting of sorbent media, zinc oxide sorbent media, zinc oxide beads, zinc oxide pellets, zinc oxide granules, zinc oxide spheres, and zinc oxide packing.

14. The method of claim 1 , comprising:
(g) after step (f), steam methane reforming to form hydrogen and carbon monoxide within a steam methane reformer.

15. The method of claim 14 , wherein:
the steam methane reformer accepts an inlet gaseous hydrocarbon concentration ranges from 1 wt % to 100 wt %; and
the steam methane reformer operates at a conversion efficiency ranging from 50% to 100%.

16. The method of claim 14 , wherein:
the steam methane reformer accepts an inlet SVOC concentration greater than 0 ppm; and
the steam methane reformer operates at a conversion efficiency greater than 50%.

17. The method of claim 14 , wherein:
the steam methane reformer accepts an inlet volatile organic compound (VOC) concentration greater than 0 ppm; and
the steam methane reformer operates at a conversion efficiency greater than 50%.

18. The method of claim 1 , comprising:
in step (c), introducing the first depleted syngas stream into a scrubber; and
removing hydrogen chloride from the first depleted syngas stream, using water as the main scrubbing absorption liquid in said scrubber.

19. The method of claim 18 , comprising:
condensing residual steam contained within the syngas to provide at least a portion of said water as the main scrubbing absorption liquid.

20. The method of claim 18 , wherein:
the scrubber comprises a pressure vessel having a lower section, an upper section, and a central section located between the upper and lower sections, the central section containing packing; and the method comprises:
introducing water into the packing of the central section; and
introducing the first depleted syngas stream into the lower section of the scrubber so that the first depleted syngas stream passes up through the central section and comes into intimate contact with the water traveling countercurrently via gravity flow down through the packing.

21. The method of claim 20 , wherein:
the scrubber is connected to a recirculation pump via recirculation piping; and the method further comprises:
removing water from the scrubber by a level control loop including a level transmitter and a level control valve; and
operating said level transmitter and said level control valve such that water is bled from the recirculation piping, via a waste transfer conduit, to maintain a steady liquid level within the lower section of the scrub

Assignees

• Thermochem Recovery Int Inc

Inventors

• Chandran Ravi
• Leo Daniel Michael
• Freitas Shawn Robert
• Newport Dave G
• Whitney Hamilton Sean Michael
• Burciaga Daniel A

Classifications

• B01D2257/306

  Organic sulfur compounds, e.g. mercaptans · CPC title

• C01B2203/0485

  the impurity being a sulfur compound · CPC title

• C01B2203/0475

  the impurity being carbon dioxide · CPC title

• B01D53/1487

  Removing organic compounds · CPC title

• C01B2203/0465

  Composition of the impurity · CPC title