Floating liquefied natural gas pretreatment system

Patent metadata

Field	Value
Publication number	US-11255486-B2
Application number	US-201715784820-A
Country	US
Kind code	B2
Filing date	Oct 16, 2017
Priority date	Dec 6, 2011
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

A pretreatment system and method for a floating liquid natural gas (“FLNG”) facility are presented. The inlet natural gas stream flows through a membrane system to remove carbon dioxide and a heat exchanger, producing first and second cooled CO2-depleted non-permeate streams. The first cooled CO2-depleted non-permeate stream is routed to additional pretreatment equipment, while the second cooled CO2-depleted non-permeate stream is routed directly to a LNG train. Alternatively, the inlet natural gas stream may flow through a membrane system to produce a single cooled CO2-depleted non-permeate stream that is routed to the LNG train after sweetening and dehydration. Because the pretreatment system delivers the incoming gas stream to the LNG train at a lower temperature than conventional systems, less energy is needed to convert the gas stream to LNG. In addition, the pretreatment system has a smaller footprint than conventional pretreatment systems.

First claim

What is claimed is:

1. A pretreatment system for a floating liquid natural gas (“FLNG”) facility, the pretreatment system comprising:
one or more membranes configured to receive an inlet natural gas stream;
a heat exchanger configured to receive and cross-exchange heat between a cooled permeate stream and a cooled non-permeate stream from the one or more membranes and a water-removed natural gas outlet stream to produce:
a first heated permeate stream,
a first cooled non-permeate stream, and
a second cooled non-permeate stream;
an additional pretreatment process equipment;
means to route the first cooled non-permeate stream to the additional pretreatment process equipment; and
means to route the second cooled non-permeate stream to an LNG train.

2. A pretreatment system according to claim 1 ,
wherein the additional pretreatment process equipment includes a gas dehydrator configured to provide the water-removed natural gas outlet stream to the heat exchanger.

3. A pretreatment system according to claim 1 wherein the one or more membranes includes a CO 2 removal membrane.

4. A pretreatment system according to claim 1 further comprising:
a mercury remover configured to receive the inlet natural gas stream and provide a mercury-removed natural gas stream to the one or more membrances.

5. A pretreatment system according to claim 4 wherein the mercury remover includes a mercury/H 2 S removal bed.

6. A pretreatment system according to claim 4 wherein at least one of the first and second cooled non-permeate streams is used to cool the mercury-removed natural gas stream.

7. A pretreatment system according to claim 1 wherein the additional pretreatment process equipment is chosen from the group consisting of a gas sweetener and a gas dehydrator.

8. A pretreatment system according to claim 7 wherein the gas sweetener includes:
a membrane configured to removing carbon dioxide; and
an amine unit configured to remove hydrogen sulfide.

9. A pretreatment system according to claim 1 wherein the second cooled non-permeate stream has a temperature ranging from about 15° C. to 40° C. (60° F. to 104° F.) when it is delivered to the LNG train.

10. A pretreatment system according to claim 9 wherein the second cooled non-permeate stream has a temperature ranging from about 15° C. to 21° C. (60° F. to 70° F.) when it is delivered to the LNG train.

11. A pretreatment system according to claim 1 wherein at least one of the first and second cooled non-permeate streams is used to cool the inlet natural gas stream.

12. A pretreatment system for a floating liquid natural gas (“FLNG”) facility, the pretreatment system comprising
a mercury remover configured to receive an inlet natural gas stream;
one or more membranes configured to receive a mercury-removed natural gas stream from the mercury removal system;
a heat exchanger configured to receive and cross-exchange heat between a cooled permeate stream and a cooled non-permeate stream from the one or more membranes and water-removed natural gas outlet stream to produce:
a first heated permeate stream,
a first cooled non-permeate stream, and
a second cooled non-permeate stream;

a gas sweetener configured to receive the first cooled non-permeate stream; and
a gas dehydrator configured to receive a sweetened natural gas stream and produce the water-removed natural gas outlet stream.

13. A pretreatment system according to claim 12 wherein the one or more membranes includes a CO 2 removal membrane.

14. A pretreatment system for a floating liquid natural gas (“FLNG”) facility, the pretreatment system comprising
one or more membranes configured to receive an inlet natural gas stream; and
a heat exchanger configured to receive and cross-exchange heat between a cooled permeate stream and a cooled non-permeate stream from the one or more membranes and a water-removed natural gas outlet stream to produce:
a first heated permeate stream,
a first cooled non-permeate stream, and
a second cooled non-permeate stream.

15. A pretreatment system according to claim 14 further comprising:
a mercury remover configured to provide a mercury-removed inlet natural gas stream to the one or more membranes.

16. A pretreatment system according to claim 14 further comprising:
a gas sweetener configured to receive the first cooled non-permeate stream.

17. A pretreatment system according to claim 16 further comprising:
a gas dehydrator configured to receive a sweetened natural gas stream and produce the water-removed natural gas outlet stream.

18. A pretreatment system according to claim 14 wherein the one or more membranes includes a CO 2 removal membrane.

Assignees

• Cameron Int Corp

Inventors

• Jariwala Ankur D
• Peters Richard D

Classifications

• B01D2256/245

  Methane · CPC title

• F25J1/0022

  Hydrocarbons, e.g. natural gas · CPC title

• B01D53/22 Primary

  by diffusion (manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00) · CPC title

• F25J1/0237

  integrating refrigeration provided for liquefaction and purification/treatment of the gas to be liquefied, e.g. heavy hydrocarbon removal from natural gas (details related to rectification F25J3/02; details related to partial condensation F25J3/06; working-up natural gas C10L3/10) · CPC title

• B01D2257/504

  Carbon dioxide · CPC title