Method and apparatus for vaporizing liquid natural gas in a combined cycle power plant

• US 6,367,258 B1
• Filed: 07/21/2000
• Issued: 04/09/2002
• Est. Priority Date: 07/22/1999
• Status: Active Grant

• Current Assignee: Bechtel Corporation (Bechtel Group Incorporated)
• Original Assignee: Bechtel Corporation (Bechtel Group Incorporated)
• Inventors: Wen, Harvey, Narula, Ram G.
• Primary Examiner(s): NGUYEN, HOANG M
• Application Number:
  US09/620,822
• Time in Patent Office: 627 Days
• Field of Search: 60/390.2, 60/391.82, 60/394.65, 607/28, 606/416, 606/417, 606/411, 606/70
• US Class Current: 60/641.7
• CPC Class Codes: F02C 3/22 the fuel or oxidant being gaseous at standard temperature and pressure F02C3/28 takes precedence
• CPC Class Codes: F02C 7/143 before or between the compressor stages
• CPC Class Codes: F02C 7/224 Heating fuel before feeding to the burner
• CPC Class Codes: F17C 2265/05 Regasification
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

Abstract

A method and apparatus for increasing the efficiency of a combined cycle generation plant by assisting the vaporization of cold liquid including liquefied natural gas (“LNG”) or liquefied petroleum gas (LPG) in a combined cycle power plant. Cold liquid vaporization is assisted by circulating a warm heat transfer fluid to transfer heat to a LNG/LPG vaporizer. The heat transfer fluid is chilled by LNG/LPG cold liquid vaporization and warmed by heat from a gas turbine. The heat transfer fluid absorbs heat from the air intake of a gas turbine and from a secondary heat transfer fluid circulating in a combined cycle power plant. Chilling the gas turbine air intake densifies the air and increases the gas turbine output. Chilling the steam condenser cooling water increases steam turbine output. The effects of chill recovery is higher output and better efficiency of the combined cycle plant.

Claims

1. A LNG/LPG combined cycle power plant comprising:

a cold liquid storage tank for storing LNG/LPG;

a cold liquid vaporizer for receiving LNG/LPG from the cold liquid storage tank and vaporizing LNG/LPG;

a circulating primary heat transfer fluid for supplying heat to the LNG/LPG vaporizer to assist in vaporizing LNG/LPG wherein the heat transfer fluid is chilled;

a gas turbine having a cooling coil wherein the cooling coil receives the chilled primary heat transfer fluid to increase the output and efficiency of the gas turbine; and

a circulating water/heat transfer fluid (HTF) heat exchanger for receiving the primary heat transfer fluid from the gas turbine cooling coil and placing the primary heat transfer fluid in heat exchange relationship with a secondary heat transfer fluid wherein the primary heat transfer fluid is warmed and returns to the vaporizer.

2. The apparatus of claim 1 further comprising:

a secondary heat transfer fluid pump for supplying a secondary heat transfer fluid to the circulating water/heat transfer fluid (HTF) heat exchanger.

3. The apparatus of claim 1 wherein the secondary heat transfer fluid comprises seawater provided from a seawater supply to the circulating water/heat transfer fluid (HTF) heat exchanger where it is chilled and returned from the circulating water/heat transfer fluid (HTF) heat exchanger to a circulating seawater return for at least one of continued circulation or discharge to the sea.

4. The apparatus of claim 1 wherein the secondary heat transfer fluid comprises water from a circulating water supply wherein the secondary heat transfer fluid is chilled and returned from the circulating water/heat transfer fluid (HTF) heat exchanger to a cooling tower to reduce the duty cycle of the cooling tower.

5. The apparatus of claim 1 wherein the secondary heat transfer fluid comprises water from a circulating water supply wherein the secondary heat transfer fluid is chilled and returned from the circulating water/heat transfer fluid (HTF) heat exchanger to cooling tower.

6. The apparatus of claim 1 wherein the secondary heat transfer fluid comprises water provided from a condenser discharge to the circulating water/heat transfer fluid (HTF) heat exchanger and returned to a circulating water return.

7. The apparatus of claim 1 further comprising a primary heat transfer fluid fill tank to replace primary heat transfer fluid lost during circulation within the apparatus.

8. The apparatus of claim 7 further comprising a liquid and gas separator for separating gas and liquid from the primary heat transfer fluid.

9. The apparatus of claim 1 wherein the primary heat transfer fluid comprises a water glycol combination.

19. The apparatus of claim 6 further comprising a set of valves enabling routing of the primary heat transfer fluid so that the primary heat transfer fluid bypasses the gas turbine so that substantially all cold energy in the primary heat transfer fluid is transferred to the condenser discharge in the circulating water/heat transfer fluid (HTF) heat exchanger.

10. A method for producing power in a LNG/LPG combined cycle power plant comprising the steps for:

storing LNG/LPG;

vaporizing LNG/LPG;

circulating a primary heat transfer fluid for supplying heat to the LNG/LPG vaporizer to assist in vaporizing LNG/LPG wherein the primary heat transfer fluid is chilled; and

circulating the primary heat transfer fluid to chill input air to a gas turbine to increase the output and efficiency of the gas turbine;

receiving the primary heat transfer fluid from the gas turbine cooling coil and placing the primary heat transfer fluid in heat exchange relationship with a secondary heat transfer fluid wherein the primary heat transfer fluid is warmed and returns to the vaporizer.

11. The method of claim 10 further comprising the step for:

supplying a secondary heat transfer fluid to the circulating water/heat transfer fluid (HTF) heat exchanger.

12. The method of claim 10 wherein the secondary heat transfer fluid comprises seawater provided from a seawater supply to the circulating water/heat transfer fluid (HTF) heat exchanger where the seawater is chilled and returned from the circulating water/heat transfer fluid (HTF) heat exchanger to a circulating seawater return for at least one of the following:

continued circulation or discharge to the sea.

13. The method of claim 10 wherein the secondary heat transfer fluid comprises water from a circulating water supply further comprising the step for:

chilling the secondary heat transfer fluid and returning the secondary heat transfer fluid to a cooling tower to reduce the duty cycle of the cooling tower.

14. The method of claim 10 further comprising the steps for:

providing the secondary heat transfer fluid from a circulating water supply wherein the secondary heat transfer fluid is chilled and returned to a cooling tower.

15. The method of claim 10 further comprising the steps for:

providing the secondary heat transfer fluid from a condenser discharge to the circulating water/heat transfer fluid (HTF) heat exchanger and returning the secondary heat transfer fluid to a circulating water return.

16. The apparatus of claim 10 further comprising a primary heat transfer fluid fill tank to replace primary heat transfer fluid lost during circulation within the apparatus.

17. The method of claim 16 further the steps for:

separating gas and liquid from the primary heat transfer fluid.

18. The method of claim 10 further wherein the primary heat transfer fluid comprises a water glycol combination.