Pump Control of Closed Cycle Power Generation System

• US 20190162116A1
• Filed: 01/29/2019
• Published: 05/30/2019
• Est. Priority Date: 12/28/2016
• Status: Active Grant

• Current Assignee: Malta, Inc.
• Original Assignee: Malta, Inc.
• Inventors: Apte, Raj, Larochelle, Philippe
• Granted Patent: US 10,920,667 B2
• Time in Patent Office: Days
• 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 6/14 Gas-turbine plants having means for storing energy, e.g. for meeting peak loads
• CPC Class Codes: F03G 6/04 gaseous F03G6/064, F03G6/068 take precedence
• CPC Class Codes: F03G 6/064 having a gas turbine cycle, i.e. compressor and gas turbine combination
• CPC Class Codes: H02P 9/04 Control effected upon non-electric prime mover and dependent upon electric output value of the generator
• CPC Class Codes: Y02E 10/46 Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]

Abstract

Disclosed are systems and methods for pump control of a closed thermodynamic cycle system, such as a Brayton cycle. Operational parameters such as working fluid temperature, thermal fluid temperature, stream pressure, and power generation may be the basis for controlling a thermal fluid pump rate.

Claims

1-20. -20. (canceled)

21. A system comprising:

a closed cycle system comprising a working fluid flowing through, in sequence, a compressor, a recuperative heat exchanger, a first heat exchanger, a turbine, the recuperative heat exchanger, and a second heat exchanger in both a charge mode and a discharge mode;

a first pump configured to pump a first thermal fluid, at a variable flow rate based on a speed of the first pump, through the first heat exchanger and in thermal contact with the working fluid; and

a controller configured to adjust the speed of the first pump based on at least one reported operating condition.

22. The system of claim 21, wherein the working fluid flows through the closed cycle system in the same direction in both the charge mode and the discharge mode.

23. The system of claim 21,

wherein the first heat exchanger comprises a working fluid inlet, a working fluid outlet, a thermal fluid inlet, and a thermal fluid outlet,

wherein the controller is operable to determine an approach temperature of the first heat exchanger, and

wherein the controller is configured to, based on the determined approach temperature, adjust the speed of the first pump.

24. The system of claim 23, wherein the controller is configured to increase the speed of the first pump when the determined approach temperature is above a first value and to decrease the speed of the first pump when the determined approach temperature is below a second value.

25. The system of claim 21, further comprising a generator configured to generate a quantity of electrical power and deliver the quantity of electrical power to an energy grid,

wherein the controller is operable to determine a phase difference between a phase value of the energy grid and a phase value of the generated electrical power, and

wherein the controller is configured to, based on the phase difference, adjust the speed of the first pump.

26. The system of claim 21, further comprising a generator configured to generate a quantity of electrical power and deliver the quantity of electrical power to an energy grid,

wherein the generator comprises an alternator,

wherein the controller is operable to determine a phase difference between a current phase value at the alternator and a voltage phase value at the alternator, and

wherein the controller is configured to, based on the phase difference, adjust the speed of the first pump.

27. The system of claim 21, further comprising a generator configured to generate a quantity of electrical power and deliver the quantity of electrical power to an energy grid,

wherein the generator comprises an alternator and power electronics,

wherein the controller is operable to determine a phase difference between a phase value of the alternator and a phase value of the power electronics, and

wherein the controller is configured to, based on the phase difference, adjust the speed of the first pump.

28. The system of claim 21, wherein the first heat exchanger is a hot-side heat exchanger disposed downstream of the compressor and upstream of the turbine.

29. The system of claim 21, wherein the second heat exchanger is a cold-side heat exchanger disposed downstream of the turbine and upstream of the compressor.

30. The system of claim 21, further comprising a first control device operatively connected to the first pump and configured to control the speed of the first pump,

wherein adjusting the speed of the first pump comprises directing the first control device to adjust the speed of the first pump.

31. The system of claim 21, further comprising a second pump, wherein the second pump pumps a second thermal fluid, at a variable flow rate based on a speed of the second pump, through the second heat exchanger and in thermal contact with the working fluid,

wherein the controller is further configured to adjust the speed of the second pump based on at least one reported operating condition.

32. The system of claim 21, wherein the at least one operating condition is selected from the group consisting of first heat exchanger working fluid inlet temperature, first heat exchanger working fluid outlet temperature, first heat exchanger thermal fluid inlet temperature, first heat exchanger thermal fluid outlet temperature, first heat exchanger approach temperature, second heat exchanger working fluid inlet temperature, second heat exchanger working fluid outlet temperature, second heat exchanger thermal fluid inlet temperature, second heat exchanger thermal fluid outlet temperature, second heat exchanger approach temperature, recuperative heat exchanger inlet temperature, recuperative heat exchanger outlet temperature, recuperative heat exchanger approach temperature, working fluid pressure downstream of the compressor and upstream of the turbine, working fluid pressure downstream of the turbine and upstream of the compressor, compressor torque, turbine torque, generator torque, compressor RPM, turbine RPM, generator RPM, quantity of electrical power, and generated electrical power phase, or a combination thereof.

33. A system comprising:

a closed cycle system comprising a working fluid circulating through, in sequence, a compressor, a recuperative heat exchanger, a hot-side heat exchanger, a turbine, the recuperative heat exchanger, and a cold-side heat exchanger in both a charge mode and a discharge mode;

a hot-side pump, wherein the hot-side pump pumps a first thermal fluid, at a first variable flow rate based on a speed of the hot-side pump, through the hot-side heat exchanger and in thermal contact with the working fluid;

a cold-side pump, wherein the cold-side pump pumps a second thermal fluid, at a second variable flow rate based on a speed of the cold-side pump, through the cold-side heat exchanger and in thermal contact with the working fluid; and

a controller operable to (i) determine an approach temperature of the hot-side heat exchanger, (ii) determine an approach temperature of the cold-side heat exchanger, (iii) adjust the first variable flow rate of the hot-side pump in response to determining a change in the approach temperature of the hot-side heat exchanger, and (iv) adjust the second variable flow rate of the cold-side pump in response to determining a change in the approach temperature of the cold-side heat exchanger.

34. The system of claim 33, wherein the controller determines the approach temperature of the hot-side heat exchanger as a difference between a temperature at a thermal fluid inlet of the hot-side heat exchanger and a temperature at a working fluid outlet of the hot-side heat exchanger, and

wherein the controller determines the approach temperature of the cold-side heat exchanger as a difference between a temperature at a thermal fluid inlet of the cold-side heat exchanger and a temperature at a working fluid outlet of the cold-side heat exchanger.

35. The system of claim 33, wherein the working fluid circulates through the closed cycle system in the same direction in both the charge mode and the discharge mode.

36. A method comprising:

circulating a working fluid through a closed cycle system comprising a first heat exchanger, a turbine, a second heat exchanger, a recuperative heat exchanger, and a compressor, wherein the working fluid circulates through, in sequence, the compressor, the recuperative heat exchanger, the first heat exchanger, the turbine, the recuperative heat exchanger, and the second heat exchanger in both a charge mode and a discharge mode;

pumping a variable flow rate of a first thermal fluid through the first heat exchanger, wherein the first thermal fluid is in thermal contact with the working fluid;

determining an operating condition of the closed cycle system; and

adjusting the variable flow rate of the first thermal fluid based on the operating condition.

37. The system of claim 36, wherein circulating the working fluid through a closed cycle system comprises circulating the working fluid in the same direction in both the charge mode and the discharge mode.

38. The method of claim 36,

wherein determining an operating condition of the closed cycle system comprises determining an approach temperature of the first heat exchanger, and

wherein adjusting the variable flow rate of the first thermal fluid based on the operating condition comprises increasing the variable flow rate of the first thermal fluid when the determined approach temperature of the first heat exchanger is above a first value.

39. The method of claim 36, further comprising:

pumping a variable flow rate of a second thermal fluid through the second heat exchanger, wherein the second thermal fluid is in thermal contact with the working fluid.

40. The method of claim 39, further comprising:

determining an approach temperature of the second heat exchanger; and

adjusting the variable flow rate of the second thermal fluid based on the determined approach temperature of the second heat exchanger.