Variable Pressure Inventory Control of Closed Cycle System with a High Pressure Tank and an Intermediate Pressure Tank

• US 20180179917A1
• Filed: 12/28/2016
• Published: 06/28/2018
• Est. Priority Date: 12/28/2016
• Status: Active Grant

• Current Assignee: Malta, Inc.
• Original Assignee: X Development LLC (Alphabet Inc.)
• Inventors: Apte, Raj, Larochelle, Philippe
• Granted Patent: US 10,458,284 B2
• Time in Patent Office: Days
• CPC Class Codes: F01D 15/10 Adaptations for driving, or combinations with, electric generators
• CPC Class Codes: F01K 13/02 Controlling, e.g. stopping or starting
• CPC Class Codes: F01K 25/06 using mixtures of different fluids plants using mixtures of steam and gas F01K21/04
• CPC Class Codes: F01K 25/103 Carbon dioxide F01K25/065 takes precedence
• CPC Class Codes: F01K 3/02 Use of accumulators and specific engine types; Control thereof
• CPC Class Codes: F01K 3/06 the engine being of extraction or non-condensing type F01K3/004 takes precedence
• CPC Class Codes: F01K 3/12 having two or more accumulators
• CPC Class Codes: F01K 3/18 having heaters having both steam accumulator and heater F01K3/14; steam heaters per se F22
• CPC Class Codes: F01K 7/38 the engines being of turbine type
• CPC Class Codes: F02C 1/04 the working fluid being heated indirectly in a fluidised-bed combustor F02C3/205
• CPC Class Codes: F02C 1/10 Closed cycles
• CPC Class Codes: F02C 1/105 construction; details
• CPC Class Codes: F02C 9/16 Control of working fluid flow F02C9/48 takes precedence; control of air-intake flow F02C7/057
• CPC Class Codes: F02C 9/24 Control of the pressure level in closed cycles
• CPC Class Codes: F22B 1/006 using solar heat solar heat collectors per se F24S; devices for producing mechanical power from solar energy F03G6/00
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

Abstract

Systems and methods for variable pressure inventory control of a closed thermodynamic cycle power generation system or energy storage system, such as a reversible Brayton cycle system, with at least a high pressure tank and an intermediate pressure tank are disclosed. Operational parameters of the system such as working fluid pressure, turbine torque, turbine RPM, generator torque, generator RPM, and current, voltage, phase, frequency, and/or quantity of electrical power generated and/or distributed by the generator may be the basis for controlling a quantity of working fluid that circulates through a closed cycle fluid path of the system.

Claims

1. A method comprising:

in a closed cycle system, circulating a working fluid through a closed cycle fluid path including, in sequence, a compressor, a hot side heat exchanger, a turbine, and a cold side heat exchanger, wherein the closed cycle fluid path comprises a high pressure leg and a low pressure leg;

removing a first quantity of working fluid from the closed cycle fluid path by opening a first fluid connection between the high pressure leg and a high pressure tank, such that pressure of the working fluid in the high pressure leg decreases and pressure of the working fluid in the high pressure tank increases;

closing the first fluid connection when pressure of the working fluid in the high pressure tank reaches a first threshold pressure value; and

removing a second quantity of working fluid from the closed cycle fluid path by opening a second fluid connection between the high pressure leg and an intermediate pressure tank, such that pressure of the working fluid in the high pressure leg decreases and pressure of the working fluid in the intermediate pressure tank increases.

2. The method of claim 1, wherein the closed cycle system comprises a closed Brayton cycle system.

3. The method of claim 1, wherein the first threshold pressure value is defined as an equilibrium pressure between pressure of the working fluid in the high pressure leg and pressure of the working fluid in the high pressure tank.

4. The method of claim 1, wherein the first threshold pressure value is defined as a pressure less than an equilibrium pressure between pressure of the working fluid in the high pressure leg and pressure of the working fluid in the high pressure tank.

5. The method of claim 1, further comprising:

operating the closed cycle system in a power generation mode, wherein a generator coupled to the turbine produces electrical power;

determining an operating condition of the power generation system; and

defining the first threshold pressure value based on the determination of the operating condition of the power generation system.

6. The method of claim 1, further comprising closing the second fluid connection when pressure of the working fluid in the intermediate pressure tank reaches a second threshold pressure value.

7. The method of claim 6, wherein the second threshold pressure value is defined as an equilibrium pressure between pressure of the working fluid in the high pressure leg and pressure of the working fluid in the intermediate pressure tank.

8. The method of claim 6, wherein the second threshold pressure value is defined as a pressure less than an equilibrium pressure between pressure of the working fluid in the high pressure leg and pressure of the working fluid in the intermediate pressure tank.

9. The method of claim 6, further comprising:

operating the closed cycle system in a power generation mode, wherein a generator coupled to the turbine produces electrical power;

determining an operating condition of the power generation system; and

defining the second threshold pressure value based on the determination of the operating condition of the power generation system.

10. A method comprising:

in a closed cycle system, circulating a working fluid through a closed cycle fluid path including, in sequence, a compressor, a hot side heat exchanger, a turbine, and a cold side heat exchanger, wherein the closed cycle fluid path comprises a high pressure leg and a low pressure leg;

removing a first quantity of working fluid from the closed cycle fluid path by opening a first fluid connection between the high pressure leg and a high pressure tank, such that pressure of the working fluid in the high pressure leg decreases and pressure of the working fluid in the high pressure tank increases;

closing the first fluid connection when pressure of the working fluid reaches a first threshold pressure value; and

removing a second quantity of working fluid from the closed cycle fluid path by opening a second fluid connection between the high pressure leg and an intermediate pressure tank, such that pressure of the working fluid in the high pressure leg decreases and pressure of the working fluid in the intermediate pressure tank increases.

11. The method of claim 10, wherein closing the first fluid connection comprises closing the first fluid connection when pressure of the working fluid in the high pressure leg reaches the first threshold pressure value.

12. The method of claim 10, wherein closing the first fluid connection comprises closing the first fluid connection when pressure of the working fluid in the low pressure leg reaches the first threshold pressure value.

13. A method comprising:

in a closed cycle system, circulating a working fluid through a closed cycle fluid path including, in sequence, a compressor, a hot side heat exchanger, a turbine, and a cold side heat exchanger, wherein the closed cycle fluid path comprises a high pressure leg and a low pressure leg;

adding a first quantity of working fluid to the closed cycle fluid path by opening a first fluid connection between the low pressure leg and an intermediate pressure tank, wherein the intermediate pressure tank contains working fluid at a first storage pressure greater than pressure of the working fluid in the low pressure leg, such that pressure of the working fluid in the low pressure leg increases and pressure of the working fluid in the intermediate pressure tank decreases;

closing the first fluid connection when pressure of the working fluid in the intermediate pressure tank reaches a first threshold pressure value; and

adding a second quantity of working fluid to the closed cycle fluid path by opening a second fluid connection between the low pressure leg and a high pressure tank, wherein the high pressure tank contains working fluid at a second storage pressure greater than the first storage pressure and greater than pressure of the working fluid in the low pressure leg, such that pressure of the working fluid in the low pressure leg increases and pressure of the working fluid in the high pressure tank decreases.

14. The method of claim 13, wherein the first threshold pressure value is defined as an equilibrium pressure between pressure of the working fluid in the low pressure leg and pressure of the working fluid in the intermediate pressure tank.

15. The method of claim 13, wherein the first threshold pressure value is defined as a pressure higher than an equilibrium pressure between pressure of the working fluid in the low pressure leg and pressure of the working fluid in the intermediate pressure tank.

16. The method of claim 13, further comprising:

operating the closed cycle system in a power generation mode, wherein a generator coupled to the turbine produces electrical power;

determining an operating condition of the power generation system; and

defining the first threshold pressure value based on the determination of the operating condition of the power generation system.

17. The method of claim 13, further comprising closing the second fluid connection when pressure of the working fluid in the high pressure tank reaches a second threshold pressure value.

18. The method of claim 17, wherein the second threshold pressure value is defined as an equilibrium pressure between pressure of the working fluid in the low pressure leg and pressure of the working fluid in the high pressure tank.

19. The method of claim 17, wherein the second threshold pressure value is defined as a pressure higher than an equilibrium pressure between pressure of the working fluid in the low pressure leg and pressure of the working fluid in the high pressure tank.

20. The method of claim 17, further comprising:

operating the closed cycle system in a power generation mode, wherein a generator coupled to the turbine produces electrical power;

determining an operating condition of the power generation system; and

defining the second threshold pressure value based on the determination of the operating condition of the power generation system.

21. A method comprising:

in a closed cycle system, circulating a working fluid through a closed cycle fluid path including, in sequence, a compressor, a hot side heat exchanger, a turbine, and a cold side heat exchanger, wherein the closed cycle fluid path comprises a high pressure leg and a low pressure leg;

adding a first quantity of working fluid to the closed cycle fluid path by opening a first fluid connection between the low pressure leg and an intermediate pressure tank, wherein the intermediate pressure tank contains working fluid at a first storage pressure greater than pressure of the working fluid in the low pressure leg, such that pressure of the working fluid in the low pressure leg increases and pressure of the working fluid in the intermediate pressure tank decreases;

closing the first fluid connection when pressure of the working fluid reaches a first threshold pressure value; and

adding a second quantity of working fluid to the closed cycle fluid path by opening a second fluid connection between the low pressure leg and a high pressure tank, wherein the high pressure tank contains working fluid at a second storage pressure greater than the first storage pressure and greater than pressure of the working fluid in the low pressure leg, such that pressure of the working fluid in the low pressure leg increases and pressure of the working fluid in the high pressure tank decreases.

22. The method of claim 21, wherein closing the first fluid connection comprises closing the first fluid connection when pressure of the working fluid in the high pressure leg reaches the first threshold pressure value.

23. The method of claim 21, wherein closing the first fluid connection comprises closing the first fluid connection when pressure of the working fluid in the low pressure leg reaches the first threshold pressure value.