Power cycle with liquefied natural gas regasification

• US 7,600,396 B2
• Filed: 08/26/2003
• Issued: 10/13/2009
• Est. Priority Date: 06/05/2003
• Status: Expired due to Fees

• Current Assignee: Fluor Technologies Corporation (Fluor Corporation)
• Original Assignee: Fluor Technologies Corporation (Fluor Corporation)
• Inventors: Mak, John
• Primary Examiner(s): Doerrler; William C
• Application Number:
  US10/559,171
• Publication Number:
  US 20070101732A1
• Time in Patent Office: 2,240 Days
• Field of Search: 62/502, 626/20
• US Class Current: 62/620
• CPC Class Codes: F17C 2205/0352 Pipes
• CPC Class Codes: F17C 2221/033 Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
• CPC Class Codes: F17C 2221/035 Propane butane, e.g. LPG, GPL
• CPC Class Codes: F17C 2223/0161 cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2225/0123 gaseous, e.g. CNG, GNC
• CPC Class Codes: F17C 2225/0153 Liquefied gas, e.g. LPG, GPL
• CPC Class Codes: F17C 2225/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2225/035 High pressure, i.e. between 10 and 80 bars
• CPC Class Codes: F17C 2227/0135 Pumps
• CPC Class Codes: F17C 2265/05 Regasification
• CPC Class Codes: F17C 2265/068 Distribution pipeline networks
• CPC Class Codes: F17C 2270/0581 Power plants
• CPC Class Codes: F17C 9/02 with change of state, e.g. vaporisation
• CPC Class Codes: F17C 9/04 Recovery of thermal energy
• CPC Class Codes: F25J 2200/04 in a dual pressure main column system
• CPC Class Codes: F25J 2200/70 Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
• CPC Class Codes: F25J 2200/74 Refluxing the column with at least a part of the partially condensed overhead gas
• CPC Class Codes: F25J 2210/06 Splitting of the feed stream, e.g. for treating or cooling in different ways
• CPC Class Codes: F25J 2215/62 Ethane or ethylene
• CPC Class Codes: F25J 2230/08 Cold compressor, i.e. suction of the gas at cryogenic temperature and generally without afterstage-cooler
• CPC Class Codes: F25J 2230/60 : the fluid being hydrocarbons or a mixture of hydrocarbons
• CPC Class Codes: F25J 2235/60 : the fluid being (a mixture of) hydrocarbons
• CPC Class Codes: F25J 2240/02 : Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 2240/70 : Steam turbine, e.g. used in a Rankine cycle
• CPC Class Codes: F25J 2240/80 : Hot exhaust gas turbine combustion engine
• CPC Class Codes: F25J 2260/02 : Integration in an installation for exchanging heat, e.g. for waste heat recovery
• CPC Class Codes: F25J 2260/60 : Integration in an installation using hydrocarbons, e.g. for fuel purposes
• CPC Class Codes: F25J 2270/02 : Internal refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 3/0214 : Liquefied natural gas
• CPC Class Codes: F25J 3/0233 : separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0238 : separation of CnHm with 2 carbon atoms or more
• CPC Class Codes: F25J 3/0242 : separation of CnHm with 3 carbon atoms or more
• CPC Class Codes: Y02E 20/16 : Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
• CPC Class Codes: Y02E 20/18 : Integrated gasification combined cycle [IGCC], e.g. combined with carbon capture and storage [CCS]

Abstract

Liquefied natural gas (LNG) or components thereof are used as working fluids in power generation cycles in a LNG regasification plant. Especially preferred plant configurations will be able to process LNG of different composition while generating on-spec pipeline gas, CNG, LNG vehicle fuel, and LPG.

Claims

1. A regasification plant for liquefied natural gas comprising:

a liquefied natural gas fractionation unit that forms a process product from the liquefied natural gas;

a cooler and a pump fluidly coupled to the fractionation unit and configured to allow liquefaction and pressurization of the process product to so form a liquefied and pressurized process product;

a heat source fluidly coupled to the pump and configured to heat the liquefied and pressurized process product to thereby produce a heated process product; and

wherein at least one component of the fractionation unit uses refrigeration content of the liquefied natural gas, and wherein an expander expands the heated process product to produce work.

2. The regasification plant of claim 1 wherein the process product comprises a demethanizer overhead vapor.

3. The regasification plant of claim 2 wherein the process product further comprises a recycle vapor.

4. The regasification plant of claim 1 wherein the heated process product is a supercritical process product that is expanded in the expander.

5. The regasification plant of claim 3 wherein the recycle vapor comprises the process product after the process product is expanded in the expander.

6. The regasification plant of claim 1 farther comprising a second expander that expands at least a portion of the liquefied natural gas, wherein the portion of the liquefied gas is compressed and heated in a second heat source before expansion in the second expander.

7. The regasification plant of claim 6 wherein the second heat source is at least one of a demethanizer overhead heat exchanger, a deethanizer reflux condenser, a turbine combustion air intake cooler, a flue gas from a gas turbine, a heat recovery unit, air separation plant, a sea water heat exchanger, and a fired heater.

8. The regasification plant of claim 1 further comprising a conduit that allows removal of a portion of the process product from the plant as compressed natural gas, and further comprising another conduit that allows removal of a portion of the liquefied and pressurized process product from the plant as liquefied fuel gas.

9. A liquid natural gas regasification plant, comprising:

a demethanizer that receives a natural gas and produces an overhead product gas, and a first heat exchanger that cools the product gas to produce a product liquid;

a pump that increases pressure of at least a portion of the product liquid to form a pressurized product liquid;

a second heat exchanger that vaporizes the pressurized product liquid to form a supercritical compressed product gas; and

an expander that expands at least a portion of the supercritical compressed product gas to produce work.

10. The plant of claim 9 further comprising a second expander that extracts work from the supercritical natural gas before the natural gas enters the demethanizer.

11. The plant of claim 10 wherein a portion of the overhead product gas is compressed to a pipeline pressure using a compressor that is operationally coupled to the second expander.

12. The plant of claim 9 wherein the expanded compressed product gas is combined with the overhead product gas.

13. The plant of claim 9 wherein the demethanizer receives heated liquefied natural gas as demethanizer reflux.

14. The plant of claim 13 wherein the first heat exchanger heats liquefied natural gas to form the heated liquefied natural gas.

15. The plant of claim 9 wherein another portion of the compressed product gas is extracted from the plant as compressed natural gas, and wherein another portion of the product liquid is extracted from the plant as liquefied natural gas fuel.

16. A plant for regasification of liquefied natural gas, comprising:

a first expander fluidly coupled to a demethanizer and configured to expand a heated and supercritical liquefied natural gas to thereby form a demethanizer feed;

a second expander fluidly coupled to the demethanizer and configured to expand a heated and compressed demethanizer overhead to a first pressure;

optionally a third expander fluidly coupled to the second expander and configured to further expand the expanded demethanizer overhead to a second pressure below the first pressure; and

wherein the first, second, and optional third expanders are configured to produce work from at least a component of the liquefied natural gas.

17. The plant of claim 16 wherein a first pump increases pressure of at least a portion of the liquefied natural gas, and wherein the portion of the liquefied natural gas is heated by a heat source to form the heated and supercritical liquefied natural gas.

18. The plant of claim 17 wherein the heat source is at least one of a demethanizer overhead heat exchanger, a deethanizer reflux condenser, a turbine combustion air intake cooler, a flue gas from a gas turbine, a heat recovery unit, a sea water heat exchanger, and a flame heater.

19. The plant of claim 16 wherein a first heat exchanger liquefies a demethanizer overhead, a second pump increases pressure of the liquefied demethanizer overhead, and wherein a second heat exchanger heats and vaporizes the pressurized liquefied demethanizer overhead to form the heated and compressed demethanizer overhead.

20. The plant of claim 19 wherein the first heat exchanger cools the demethanizer overhead using a liquefied natural gas feed as refrigerant.

21. The plant of claim 20 wherein the second heat exchanger heats the pressurized liquefied demethanizer overhead using the expanded demethanizer overhead.

22. The plant of claim 16 wherein the first pressure is a pipeline pressure of between about 700 psi and 1500 psi, and wherein the second pressure is a demethanizer operating pressure of between about 300 psi and 750 psi.