Gas treating method and apparatus

• US 20070157806A1
• Filed: 01/10/2006
• Published: 07/12/2007
• Est. Priority Date: 01/10/2006
• Status: Active Grant

• Current Assignee: Valerus Field Solutions, L.P. (Snc-Lavalin Group Incorporated)
• Original Assignee: Edwin W. Cash
• Inventors: Cash, Edwin, Bradley, Thomas
• Granted Patent: US 7,740,691 B2
• Time in Patent Office: Days
• US Class Current: 95/174
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1462 Removing mixtures of hydrogen sulfide and carbon dioxide
• 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: C10L 3/10 Working-up natural gas or synthetic natural gas
• CPC Class Codes: C10L 3/102 of acid contaminants

Abstract

A method and apparatus for treating natural gas comprises a contactor having a manifold for spreading gas in the contactor vessel, a plurality of perforated plates above the manifold, a spray system for spraying a treating liquid into an upwardly rising column of gas and a liquid level controller for maintaining the treating liquid above the perforated plates. Gas and liquid from the contactor pass through a cooler and are then separated. A treating liquid regeneration system receives the treating liquid and flashes the liquid at low pressure to separate hydrocarbon gases, hydrocarbon liquid and treating liquid. The treating liquid is regenerated by heating and flashing off contaminant gases and is ultimately redelivered to the contactor.

Claims

1. A gas treating facility comprising

a contactor for mixing a gas with a treating liquid for absorbing contaminants from the gas;

a heat exchange assembly downstream of the contactor comprising a fan, a motor driving the fan, and a heat exchanger receiving gas and liquid from the contactor and cooling the gas and liquid;

a separator downstream of the heat exchange assembly receiving gas and liquid from the heat exchange assembly and delivering separate streams of gas and liquid; and

a system receiving liquid from the separator for regenerating the liquid and redelivering the regenerated liquid to the contactor.

2. The gas treating facility of claim 1 wherein the contactor comprises a vessel having a gas inlet and a gas outlet;

a manifold connected to the gas inlet for spreading gas throughout the vessel;

at least a pair of vertically spaced flow dispersers above the manifold for spreading gas through the vessel and minimizing gas channeling upwardly;

a liquid level control for maintaining a treating liquid level above an uppermost of the flow dispersers; and

a plurality of individual spray nozzles above the liquid level for spraying treating liquid downwardly and thereby mixing the treating liquid and gas flowing into the vessel.

3. The gas treating facility of claim 1 wherein the contactor is at least partially filled with an amine.

4. The gas treating facility of claim 1 wherein the separator is a high pressure separator and further comprising a pressure reducing valve receiving liquid from the high pressure separator and a low pressure separator receiving liquid from the pressure reducing valve for flashing off hydrocarbon gases at a pressure substantially below the pressure of the high pressure separator and at a temperature of the heat exchange assembly.

5. The gas treating facility of claim 4 wherein the low pressure separator comprises a three phase separator for separating the treating liquid from another liquid and from uncondensed hydrocarbons.

6. The gas treating facility of claim 5 further comprising a burner receiving uncondensed hydrocarbons from the low pressure separator for burning the uncondensed hydrocarbons.

7. A gas treating facility comprising

a contactor for mixing a gas with a liquid for absorbing contaminants from the gas;

a first separator downstream of the contactor for receiving gas and liquid from the contactor and delivering separate streams of gas and liquid; and

a system receiving treating liquid from the first separator for regenerating the treating liquid and delivering the regenerated treating liquid to the contactor including

a second separator receiving liquid from the first separator and reducing the pressure of the liquid and flashing off uncondensed hydrocarbons; and

a burner receiving uncondensed hydrocarbons from the second flash separator for burning the uncondensed hydrocarbons.

8. The gas treating facility of claim 7 wherein the burner comprises part of a heater.

9. The gas treating facility of claim 7 wherein the burner comprises a flare for disposing of the uncondensed hydrocarbons.

10. The gas treating facility of claim 7 wherein the contactor is at least partially filled with an amine treating liquid.

11. A gas treating facility comprising

a contactor for mixing a gas with a liquid for absorbing contaminants from the gas;

a first separator downstream of the contactor for receiving gas and liquid from the contactor and delivering separate streams of gas and liquid; and

a system receiving treating liquid from the first separator for regenerating the treating liquid and delivering the regenerated treating liquid to the contactor including

a second separator receiving liquid from the first separator, reducing the pressure of the liquid, flashing off uncondensed hydrocarbons and delivering a stream of contaminant rich treating liquid;

at least one heater for heating the contaminant rich treating liquid to a temperature sufficient to vaporize water;

a third separator receiving liquid from the heater for flashing off steam and the contaminant and delivering a stream of contaminant lean treating liquid;

a disposal unit receiving and disposing of the contaminant; and

piping including a pump for receiving the contaminant lean treating liquid and delivering it to the contactor.

12. The gas treating facility of claim 11 further comprising a condenser receiving the steam and the contaminant from the third separator and condensing the steam into water and a fourth separator for separating the water from the contaminant and delivering the contaminant to the disposal unit.

13. The gas treating facility of claim 12 further comprising a mixer located between the second separator and the at least one heater and piping including a pump for delivering water from the fourth separator to the mixer for recirculating water.

14. An amine plant having a rated capacity of at least 5,000 MCFD of natural gas at carbon dioxide concentrations of greater than 3% and inlet pressures of less than 1000 psi, the plant being characterized by skid mounted vessels which can be transported in a vertical position by truck over conventional roads having conventional overpasses.

15. A contactor for use in a gas treating facility, comprising

a vessel having a gas inlet and a gas outlet;

a manifold connected to the gas inlet for spreading gas throughout the vessel;

at least a pair of vertically spaced flow dispersers above the manifold for spreading gas through the vessel and minimizing gas channeling upwardly;

a liquid level control for maintaining a treating liquid level above an uppermost of the flow dispersers; and

a plurality of individual spray nozzles above the liquid level for spraying treating liquid downwardly and thereby mixing the treating liquid and gas flowing into the vessel.

16. The contactor of claim 15 wherein the liquid level control comprises a sump having an outlet conduit providing a control valve therein, at least one downcomer having an upper opening in the vessel at a predetermined level above an uppermost of the perforated plates and a lower opening delivering liquid into the sump, and a liquid level sensor for detecting a liquid level adjacent the upper downcomer opening and manipulating the control valve in response to the liquid level thereby creating a liquid seal in the sump and preventing gas from passing through the sump.

17. The contactor of claim 15 wherein the vessel comprises a partition wall adjacent a lower end thereof, the sump being provided in the vessel below the partition wall, the downcomer extending through the partition wall for delivering liquid from the vessel into the sump.

18. The contactor of claim 15 wherein the gas outlet is free of a demister.

19. The contactor of claim 15 wherein the manifold comprises a central branch connected to the gas inlet and a plurality of lateral branches extending away from the central branch, the branches providing a series of gas outlet openings.

20. The contactor of claim 15 wherein the flow dispersers comprise perforated plates.

21. A method of treating natural gas comprising contacting the gas with a liquid for absorbing contaminants from the gas;

separating the gas and liquid and delivering the gas to sales;

regenerating the liquid and delivering the regenerated treating liquid to the contactor including reducing the pressure of the liquid and flashing off uncondensed hydrocarbons and burning the uncondensed hydrocarbons.

22. A method of treating natural gas comprising contacting the gas with a liquid for absorbing contaminants from the gas;

then cooling a commingled stream of the gas and liquid in a powered heat exchanger;

separating the commingled stream and delivering the gas to sales; and

regenerating the liquid and delivering the regenerated treating liquid to the contactor.