Combined cycle power plant with reduced parasitic pumping loss

Abstract

A combined cycle power plant (CCPP) is provided. The CCPP includes a gas turbine having a compressor section, a combustion section, and a turbine section. The CCPP also includes a heat recovery steam generator (HRSG) having a first economizer. The HRSG receives an exhaust gas flow from the turbine section. The HRSG also includes a fuel heating system having a fuel supply line and a high temperature heat exchanger disposed on the fuel supply line in thermal communication. The fuel supply line is fluidly coupled to the combustion section. The high temperature heat exchanger is fluidly coupled to the first economizer such that the high temperature heat exchanger receives water from the first economizer. The CCPP also includes a feed pump fluidly coupled to the high temperature heat exchanger.

Description

Technical Field

[0001] The present disclosure generally relates to a combined cycle power plant system. In particular, the present disclosure relates to a combined cycle power plant system having a fuel heating system with reduced parasitic pump losses. Background Art

[0002] A gas turbine power plant, such as a combined cycle power plant (CCPP), typically includes a gas turbine having a compressor section, a combustion section, a turbine section, a heat recovery steam generator (HRSG) disposed downstream of the turbine, and at least one steam turbine in fluid communication with the HRSG. During operation, air enters the compressor via an inlet system and is progressively compressed as the air is directed toward a compressor discharge or diffuser housing of a combustor that at least partially surrounds the combustion section. At least a portion of the compressed air is mixed with fuel and combusted within a combustion chamber defined within the combustor, thereby producing high temperature and high pressure combustion gases.

[0003] The combustion gases are directed from the combustor through the turbine along a hot gas path, where the gases gradually expand as they flow through alternating fixed blade stages and rotatable turbine blade stages coupled to the rotor shaft. Energy is transferred from the combustion gases to the turbine blades, causing the rotor shaft to rotate. The rotational energy of the rotor shaft can be converted into electrical energy via a generator. The combustion gases leave the turbine as exhaust gas, and the exhaust gas enters the HRSG. The heat energy from the exhaust gas is transferred to water flowing through one or more heat exchangers of the HRSG, thereby producing superheated steam. The superheated steam is then directed to a steam turbine, which can be used to generate additional electricity, thereby increasing the efficiency of the entire power plant.

[0004] In many HRSG systems, water from one or more sections of the HRSG can be diverted and used in a fuel heating circuit to preheat the fuel (e.g., via a heat exchanger). The preheated fuel can then be supplied to the combustion section of the gas turbine. The water pressure of the fuel heating circuit must be high enough to ensure that the water remains in the liquid phase under the hottest operating conditions.

[0005] Thus, known fuel heating systems are configured to supply water to the fuel heater at a pressure sufficient to avoid flashing. Wastewater leaving the fuel heater is returned to the feedwater loop either at the condensate line that feeds the low pressure economizer or at the condenser hot well. The power required to re-pressurize this water for heating in the HRSG and return the reheated water to the fuel heater represents a parasitic loss relative to the performance advantage of capturing low-stage exhaust energy into the fuel. As the target temperature for heating the fuel increases, the water pressure must increase exponentially. Thus, the parasitic power loss of re-pressurizing and circulating the water for fuel heating becomes a more significant impediment to CCPP performance.

[0006] Therefore, there is a need for an improved HRSG system including a fuel heating circuit having reduced parasitic pumping losses compared to prior designs and the HRSG system would be appreciated in the art. Summary of the invention

[0007] Various aspects and advantages of a combined cycle power plant and a feedwater pump control system according to the present disclosure will be set forth in part in the following detailed description, or may be obvious from the detailed description, or may be learned through practice of the technology.

[0008] According to one embodiment, a combined cycle power plant (CCPP) is provided. The CCPP includes a gas turbine having a compressor section, a combustion section, and a turbine section. The CCPP also includes a heat recovery steam generator (HRSG) having a first economizer. The HRSG receives an exhaust gas flow from the turbine section. The HRSG also includes a fuel heating system having a fuel supply line and a high-temperature heat exchanger disposed on the fuel supply line in a thermally connected manner. The fuel supply line is fluidly coupled to the combustion section. The high-temperature heat exchanger is fluidly coupled to the first economizer so that the high-temperature heat exchanger receives water from the first economizer. The CCPP also includes a feedwater pump fluidly coupled to the high-temperature heat exchanger.

[0009] According to another embodiment, a combined cycle power plant (CCPP) is provided. The CCPP includes a gas turbine having a compressor section, a combustion section, and a turbine section. The CCPP also includes a heat recovery steam generator (HRSG) that receives an exhaust gas flow from the turbine section. The HRSG includes a high-pressure economizer and a low-pressure economizer. The CCPP also includes a fuel heating system having a fuel supply line, a high-temperature heat exchanger, and a low-temperature heat exchanger. The fuel supply line is fluidly coupled to the combustion section. The high-temperature heat exchanger and the low-temperature heat exchanger are disposed on the fuel supply line in a thermally connected manner. The high-temperature heat exchanger is fluidly coupled to the high-pressure economizer, and the low-temperature heat exchanger is fluidly coupled to the low-pressure economizer. The CCPP also includes a feedwater pump fluidly coupled to the high-temperature heat exchanger.

[0010] According to another embodiment, a feedwater pump control system is provided. The feedwater pump control system includes a heat recovery steam generator (HRSG) having a low-pressure economizer and at least one high-pressure economizer. The feedwater pump control system also includes a fuel heating system having a fuel supply pipeline fluidly connected to the combustion section. The fuel heating system also includes a high-temperature heat exchanger and a low-temperature heat exchanger disposed on the fuel supply pipeline in a thermally connected manner. The feedwater pump control system also includes a feedwater pump having multiple stages. The first pump supply line extends between one of the low-pressure economizer, the low-pressure drum or the deaerator and the initial stage of the multiple stages. The second pump supply line extends between the high-temperature heat exchanger and the intermediate stage of the multiple stages. The feedwater supply line extends between the last stage of the multiple stages and the at least one high-pressure economizer. The feedwater pump control system also includes a sensor disposed on one or more of the first pump supply line, the second pump supply line and the feedwater supply line. One or more sensors are configured to provide data indicating at least one of the pressure, temperature or flow rate of water. One or more valves are disposed on one or more of the second pump supply line and the first feedwater supply line. The feedwater pump control system also includes a controller that is communicatively coupled to the one or more sensors and operably coupled to the one or more valves. The controller includes a memory and one or more processors. The memory stores instructions that, when executed by the one or more processors, cause the feedwater pump control system to perform operations. The operations include monitoring data indicating a temperature difference between water entering the feedwater pump and water leaving the feedwater pump via the one or more sensors. The operations also include determining when the temperature difference exceeds a predetermined temperature range. The operations also include regulating the flow of water to the feedwater pump by actuating the one or more valves to restore the temperature difference to within a predetermined temperature range.

[0011] These and other features, aspects and advantages of the combined cycle power plant and feedwater pump control system of the present invention will be better understood with reference to the following detailed description and the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] This specification sets forth a complete and enabling disclosure of the combined cycle power plant and feedwater pump control system of the present invention, including the best mode of making and using the system and method of the present invention, which will be of interest to one of ordinary skill in the art, with reference to the accompanying drawings, wherein:

[0013] Figure 1 is a schematic diagram of a combined cycle power plant (CCPP) according to an embodiment of the present disclosure;

[0014] Figure 2 is a schematic diagram of a combined cycle power plant (CCPP) according to an embodiment of the present disclosure;

[0015] Figure 3 A schematic diagram of a feedwater pump control system according to an embodiment of the present disclosure is shown;

[0016] Figure 4 is a schematic diagram of a combined cycle power plant (CCPP) according to an embodiment of the present disclosure;

[0017] Figure 5 is a schematic diagram of a combined cycle power plant (CCPP) according to an embodiment of the present disclosure; and

[0018] Figure 6 is a schematic diagram of a combined cycle power plant (CCPP) according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0019] Reference will now be made in detail to embodiments of the combined cycle power plant and feedwater pump control system of the present invention, one or more examples of which are shown in the accompanying drawings. Each example is provided by way of explanation of the technology of the present invention, rather than limitation of the technology of the present invention. In fact, it will be apparent to those skilled in the art that modifications and variations may be made in the technology of the present invention without departing from the scope or spirit of the technology of the present invention protected by the claims. For example, a feature illustrated or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, the present disclosure is intended to cover these modifications and variations that fall within the scope of the appended claims and their equivalents.

[0020] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. In addition, unless otherwise specifically stated, all embodiments described herein should be considered exemplary.

[0021] The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar components of the present invention. As used herein, the terms "first," "second," and "third" are used interchangeably to distinguish one component from another and are not intended to indicate the position or importance of the various components.

[0022] The term "fluid" may be a gas or a liquid. The term "fluid communication" means that a fluid is able to connect between designated areas.

[0023] As used herein, the terms "upstream" and "downstream" refer to the relative directions of the flow of a fluid in a fluid passage. For example, "upstream" refers to the direction from which the fluid is flowing, and "downstream" refers to the direction to which the fluid is flowing. However, the terms "upstream" and "downstream" as used herein may also refer to currents. The terms "front" and "rear" refer to the positions relative to the inlet and outlet of a system (e.g., a turbine or a heat recovery steam generator), respectively, where components closer to the inlet are considered "front" and components closer to the outlet are considered "rear".

[0024] The term "radially" refers to a relative direction that is substantially perpendicular to an axial centerline of a particular component, the term "axially" refers to a relative direction that is substantially parallel and / or coaxially aligned with an axial centerline of a particular component, and the term "circumferentially" refers to a relative direction that extends around an axial centerline of a particular component.

[0025] Terms with approximate meanings (such as "about", "approximately", "substantially" and "substantially") are not limited to the exact values ​​specified. In at least some cases, approximate language may correspond to the accuracy of an instrument used to measure a value, or the accuracy of a method or machine used to construct or manufacture a component and / or system. In at least some cases, approximate language may correspond to the accuracy of an instrument used to measure a value, or the accuracy of a method or machine used to construct or manufacture a component and / or system. For example, approximate language may refer to a tolerance of 1%, 2%, 4%, 5%, 10%, 15% or 20% in an individual value, a range of values, and / or an end value of a range of defined values. When used in the context of an angle or direction, such terms are included within ten degrees greater than or less than the angle or direction. For example, "substantially vertical" includes directions within ten degrees of vertical in any direction (e.g., clockwise or counterclockwise).

[0026] Unless otherwise stated herein, the terms "coupled," "fixed," "attached to," and the like refer to direct coupling, fixing, or attachment, as well as indirect coupling, fixing, or attachment through one or more intermediate components or features. As used herein, the terms "include," "comprises," "includes," "has," or any other variation thereof, are intended to cover non-exclusive inclusions. For example, a process, method, article, or device that includes a list of features is not necessarily limited to only those features, but may include other features that are not expressly listed or inherent to such process, method, article, or device. In addition, unless expressly stated to the contrary, "and / or" refers to an inclusive or rather than an exclusive or. For example, conditions A and / or B are satisfied by any of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); and both A and B are true (or exist).

[0027] Here and throughout the specification and claims, where range limitations can be combined and interchanged, such ranges are identified and include all sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0028] As used herein, "line" may refer to a pipe, a hose, or any other suitable fluid conduit or fluid carrying piping system.

[0029] As used herein, when used in the context of system components, the terms "high," "medium," and "low," or their corresponding comparatives (e.g., "more . . . ," where applicable), may refer to parameters associated with a particular system component in comparison to other system components. For example, a low-pressure economizer, an intermediate-pressure economizer, and a high-pressure economizer may be defined relative to one another (i.e., a low-pressure economizer delivers fluid at a lower pressure relative to an intermediate-pressure / high-pressure economizer, etc.).

[0030] Figure 1 , Figure 2 as well as Figures 4 to 6 Each is a schematic flow diagram of an embodiment of a combined cycle power generation system or combined cycle power plant (CCPP) 10 according to an embodiment of the present disclosure. The CCPP 10 may include a gas turbine 12 for driving a first load 14. For example, the first load 14 may be a generator for generating electricity. The gas turbine 12 may include a turbine section 16, a combustor or combustion section 18, and a compressor section 20. The turbine section 16 and the compressor section 20 may be connected by one or more shafts 21.

[0031] During operation of the gas turbine 12, a working fluid such as air flows into the compressor section 20, where the air is gradually compressed, thereby providing the compressed air to the combustors of the combustion section 18. The compressed air is mixed with fuel and burned in each combustor to produce combustion gases. The combustion gases flow from the combustion section 18 through the hot gas path and enter the turbine section 16, where energy (kinetic energy and / or thermal energy) is transferred from the combustion gases to the rotor blades, thereby causing one or more shafts 21 to rotate. The mechanical rotational energy can then be used to power the compressor section 20 and / or generate electricity. The heated exhaust gas 34 leaving the turbine section 16 can then be discharged from the gas turbine 12 and enter the heat recovery steam generator (HRSG) 32, where heat transfer occurs between the heated exhaust gas 34 and the various components of the HRSG. In this way, the HRSG 32 can receive the exhaust gas flow 34 from the turbine section 16 at the inlet 31, which can be transmitted to the outlet 33 through the HRSG 32 via the various components contained therein. Exhaust gas 34 may exit HRSG 32 and be exhausted to the atmosphere via an exhaust stack 105 .

[0032] The CCPP 10 may also include a steam turbine system 22 for driving a second load 24. The second load 24 may also be a generator for generating electricity. However, both the first load 14 and the second load 24 may be other types of loads that can be driven by the gas turbine 12 and the steam turbine system 22. In addition, although the gas turbine 12 and the steam turbine system 22 may drive separate loads 14 and 24 as shown in the illustrated embodiment, the gas turbine 12 and the steam turbine system 22 may also be used in series to drive a single load via a single shaft.

[0033] In the illustrated embodiment, the steam turbine system 22 may include a low pressure (LP) steam turbine 26, an intermediate pressure (IP) steam turbine 28, and a high pressure (HP) steam turbine 30. The low pressure (LP) steam turbine 26, the intermediate pressure (IP) steam turbine 28, the high pressure (HP) steam turbine 30, and the load 24 may each be disposed on one or more shafts 23 (in some embodiments, such as a common shaft). In other embodiments, the LP steam turbine 26, the IP steam turbine 28, and the HP steam turbine 30 may be disposed on separate shafts (which may be coupled to each other). In some embodiments, the LP steam turbine 26 and the IP steam turbine 28 may be disposed on a common shaft in one or more shafts to form an LP / IP steam turbine, while the HP steam turbine 30 may be located on a separate shaft or not included in the system.

[0034] The CCPP 10 may also include a HRSG 32 having multiple stages. The components of the HRSG 32 in the illustrated embodiment are a simplified depiction of the HRSG 32 and are not intended to be limiting. Rather, the illustrated HRSG 32 is shown to convey the general operation of such HRSG systems. Heated exhaust gas 34 from the gas turbine 12 may be delivered to the HRSG 32 and used to heat steam for powering the steam turbine system 22.

[0035] Exhaust from the low-pressure steam turbine 26 of the steam turbine system 22 may be directed into the condenser 36. Condensate from the condenser 36 may then be directed into the low-pressure section of the HRSG 32 with the assistance of a condensate pump 38. The condensate may then flow through a low-pressure economizer 40 (LPECON), which may be used to heat the condensate. For example, a condensate supply line 80 may extend between the condenser 36 and the LPECON 40 and fluidly couple them. The condensate pump 38 may be disposed on the condensate supply line 80 in a fluid communication manner.

[0036] Condensate (eg, water) may be directed from the low pressure economizer 40 to the low pressure evaporator 42 (LPEVAP), to the feedwater pump 45, and / or to the low temperature fuel heating heat exchanger 208 ( Figure 1 and Figure 2 ). Feedwater may flow from the feedwater pump 45 into the IPECON 44 or the rear high pressure economizer 49 (HPECON), for example, via two separate pipes, tubes, or fluid conduits. For example, a first feedwater supply line 126 may extend from the feedwater pump 45 to the rear HPECON 49, and a second feedwater line 128 may extend from the feedwater pump 45 to the IPECON 44. Feedwater may be directed from the intermediate pressure economizer 44 to the intermediate pressure evaporator 46 (IPEVAP). In addition, condensate may flow from the rear HPECON 49 into the front high pressure economizer 48 (HPECON). Figures 1 to 5 The embodiment shown in FIG. 4 may include multiple economizers, and it should be understood that the term “economizer” may refer to any one of the multiple economizers, such as the LPECON 40 , the IPECON 44 , the rear HPECON 49 , or the front HPECON 48 .

[0037] In many embodiments, the CCPP 10 may also include a low pressure superheater 130 disposed within the HRSG 32. The low pressure superheater 130 may be a heat exchanger that transfers heat between steam flowing therethrough and the exhaust gas 34 flowing through the HRSG 32. The low pressure superheater 130 may receive steam from the LPEVAP 42 (and subsequently superheat the steam). Steam from the low pressure superheater 130 and steam from the exhaust gas of the intermediate pressure steam turbine 28 may be mixed together and supplied to the low pressure steam turbine 26. For example, a connecting line 132 may fluidly couple the outlet of the intermediate pressure steam turbine 28 to the inlet of the low pressure steam turbine 26. An outlet line 134 extends from the low pressure superheater 130 to the connecting line 132, thereby fluidly coupling the low pressure superheater 130 to the connecting line 132. It should be noted that although Figures 1 to 5 Each depicts a steam turbine system 22 having separate IP and LP turbine casings connected by cross-ducting, but it should be understood that the steam turbine system may incorporate a single IP / LP turbine casing (providing interstage inlet for LP steam) without departing from the scope and / or spirit of the present disclosure.

[0038] Similarly, the CCPP 10 may also include an intermediate pressure superheater 70 disposed within the HRSG 32. The intermediate pressure superheater 70 may be a heat exchanger that transfers heat between steam flowing therethrough and the exhaust gas 34 flowing through the HRSG 32. The intermediate pressure superheater 70 may receive steam from the IPEVAP 46 (and subsequently superheat the steam). In some embodiments, the intermediate pressure superheater 70 may be disposed within the HRSG 32 upstream (e.g., immediately upstream or directly upstream) of the low pressure superheater 130 relative to the flow of heated exhaust gas 34 through the HRSG 32. Steam from the intermediate pressure superheater 70 and steam from the exhaust gas of the high pressure steam turbine 30 may be mixed together and supplied to the primary reheater 58. For example, the outlet line 118 may extend from the intermediate pressure superheater 70 to a junction with the outlet line 124 of the high pressure steam turbine 30.

[0039] Each of the economizers described herein (e.g., LPECON 40, IPECON 44, rear HPECON 49, and front HPECON 48) may be a device configured to heat feedwater or condensate using heated exhaust gas 34. In this manner, LPECON 40, IPECON 44, rear HPECON 49, and front HPECON 48 may be heat exchangers that transfer heat between heated exhaust gas 34 produced by gas turbine 12 and water for steam turbine system 22. HRSG 32 may include a plurality of economizers arranged in a serial flow order (from upstream to downstream with respect to the flow of exhaust gas 34 through HRSG 32): front HPECON 48, IPECON 44, rear HPECON 49, and LPECON 40. In this arrangement, front HPECON 48 may be disposed within HRSG 32, upstream of IPECON 44. The IPECON 44 may be disposed within the HRSG 32 upstream of the aft HPECON 49. The aft HPECON 49 may be disposed within the HRSG 32 upstream of the LPECON 40. Generally speaking, the operating temperature of the economizers may decrease from the forward end to the aft end of the HRSG 32 (e.g., economizers closer to the forward end of the HRSG 32 will operate at a higher temperature than economizers closer to the aft end of the HRSG 32).

[0040] Ultimately, the feedwater from the forward high pressure economizer 48 may be directed to the high pressure evaporator 50 (HPEVAP) and / or the high temperature fuel heating heat exchanger 206. The steam exiting the high pressure evaporator 50 may be directed to the primary high pressure superheater 52 and the final high pressure superheater 54 where the steam is superheated and ultimately sent to the high pressure steam turbine 30 of the steam turbine system 22. The superheaters 52, 54 may each be a heat exchanger that transfers heat from the heated exhaust gas 34 flowing through the HRSG 32 from the gas turbine 12 to steam for the steam turbine system 22.

[0041] The interstage thermostat 56 may be positioned in fluid communication between the primary high pressure superheater 52 and the final high pressure superheater 54. The interstage thermostat 56 may allow for more robust control of the discharge temperature of the steam from the final high pressure superheater 54. Specifically, the interstage thermostat 56 may be configured to control the temperature of the steam exiting the final high pressure superheater 54 by injecting a cooler feedwater spray into the superheated steam upstream from the final high pressure superheater 54 whenever the discharge temperature of the steam exiting the final high pressure superheater 54 exceeds a predetermined value. For example, the cooler feedwater spray may be water from the forward HPECON 48. Specifically, the interstage thermostat 56 may be in fluid communication with the HPECON via a first thermostat cooling line 160.

[0042] In addition, the exhaust gas from the high pressure steam turbine 30 of the steam turbine system 22 may be mixed with the intermediate pressure steam exiting the intermediate pressure superheater 70 and directed together to the primary reheater 58 and the final reheater 60, where the exhaust gas may be reheated before being directed to the intermediate pressure steam turbine 28 of the steam turbine system 22. The primary reheater 58 may be fluidly coupled to the final reheater 60 via a reheater connection line. The reheater connection line may extend between the primary reheater 58 and the final reheater 60 and fluidly couple them.

[0043] In various embodiments, the primary reheater 58 and the final reheater 60 may also be associated with an interstage attemperator 62 for controlling the exhaust steam temperature of the final reheater 60. Specifically, the interstage attemperator 62 may be configured to control the temperature of the steam leaving the final reheater 60 by injecting a cooler feedwater spray into the superheated steam upstream from the final reheater 60 whenever the exhaust temperature of the steam leaving the final reheater 60 exceeds a predetermined value. For example, the interstage attemperator 62 may be disposed in a fluid communication manner on a reheater connecting line (e.g., between the primary reheater 58 and the final reheater 60). The interstage attemperator 62 may be fluidly coupled to the feedwater pump 45. Specifically, the interstage attemperator 62 may receive a portion of the water or condensate leaving the feedwater pump 45. For example, as shown, the interstage attemperator 62 may receive a flow of water or condensate from the second feedwater line 128. Specifically, the interstage attemperator 62 may be in fluid communication with the second feedwater supply line 128 via the second attemperator cooling line 162. It should be appreciated that the water used for reheat steam temperature control (i.e., water received by the interstage attemperator 62) may come from anywhere in the intermediate pressure or high pressure feedwater circuit, including but not limited to an IPECON discharged into the intermediate pressure drum or HP feedwater for reheat attemperation.

[0044] Figures 1 to 6 A plurality of valves 150 are shown, each of which is not individually numbered but rather is shown in Figures 1 to 6 150 are represented by common symbols. Each of these valves 150 can be selectively actuated between an open position and a closed position. In the open position, fluid flowing through the pipeline to which the valve 150 is attached may not be restricted. Conversely, in the closed position, fluid flowing through the pipeline to which the valve 150 is attached may be restricted. Each valve can also be selectively actuated to a partially closed (or partially open) position, which can allow the valve 150 to control the flow rate of the fluid flowing through the pipeline to which the valve 150 is attached.

[0045] The gas turbine 12 power generation cycle is often referred to as the "topping cycle," while the HRSG 32 and steam turbine system 22 power generation cycle is often referred to as the "bottoming cycle." Figures 1 to 6 By combining the two cycles as shown, the combined cycle power plant 10 can achieve higher combined power plant efficiency. Specifically, waste heat from the topping cycle can be captured and used to generate steam for the bottoming cycle.

[0046] CCPP 10 advantageously recovers heat from heated exhaust gas 34 by using HRSG 32. Figure 1As shown, the components of the gas turbine 12 and the HRSG 32 can be separated into discrete functional units. In other words, the gas turbine 12 can generate heated exhaust gas 34 and direct the heated exhaust gas 34 to the HRSG 32, which can be primarily responsible for recovering heat from the heated exhaust gas 34 by generating superheated steam. In turn, the steam turbine system 22 can use the superheated steam as an energy source. The heated exhaust gas 34 can be transferred to the HRSG 32 through a series of piping networks, which can vary based on the specific design of the CCPP 10.

[0047] In many embodiments, the CCPP 10 may also include a fuel heating system 200 for preheating fuel supplied to the combustion section 18. For example, the fuel heating system 200 may include a fuel supply line 202 fluidly coupled to the combustion section 18. In many embodiments, the fuel supply line 202 may extend between a fuel supply 204 (e.g., a tank, a reservoir, or other fuel source) and the combustion section 18. In an exemplary embodiment, as shown in FIG. Figure 1 , Figure 2 and Figures 4 to 6 As shown, the fuel heating system 200 may include a high temperature heat exchanger 206 disposed in thermal communication with the fuel supply line 202. For example, the high temperature heat exchanger 206 may exchange heat between the fuel flowing through the fuel supply line 202 and the hot fluid. The high temperature heat exchanger 206 may be fluidly coupled to the economizer so that the high temperature heat exchanger 206 receives water from the economizer. Specifically, as shown in FIG. Figure 1 and Figure 2 As shown in , the high temperature heat exchanger 206 may be in fluid communication with the forward high pressure economizer 48 via a high temperature input line 210 .

[0048] Specific reference Figure 1 and Figure 2 In an exemplary embodiment of the present invention, the feedwater pump 45 can be fluidly coupled to one or more economizers so that the feedwater pump 45 receives water from one of the one or more economizers and provides water to another economizer in the one or more economizers. For example, the feedwater pump 45 can be fluidly coupled (e.g., individually fluidly coupled) to the high temperature heat exchanger 206, the low pressure economizer 40, the intermediate pressure economizer 44, and the rear high pressure economizer 49. Specifically, the feedwater pump 45 can receive water from the outlet of the high temperature heat exchanger 206 and from the outlet of the LPECON 40 (e.g., via one or more fluid conduits 211, 212).

[0049] Alternatively or additionally, such as Figure 1As shown by the dashed lines in FIG. 3 , the feedwater pump 45 may receive water from the low-pressure evaporator 42 (such as a low-pressure drum of the low-pressure evaporator) and / or the deaerator 41. In this manner, the feedwater pump 45 may be fluidly coupled to one of the economizer 40, the low-pressure evaporator 42, or the deaerator 41 so that the feedwater pump 45 receives water from one or more of the economizer 40, the low-pressure evaporator 42, or the deaerator 41. The deaerator 41 may be fluidly coupled to one or more water / steam transport components of the HRSG 32 and may be operable to remove dissolved gases from the water / steam.

[0050] The low pressure economizer 40 may be fluidly coupled to the feedwater pump 45 via a first pump supply line 211, and the high temperature heat exchanger may be fluidly coupled to the feedwater pump 45 via a second pump supply line 212. The first pump supply line 211 may extend (e.g., directly) between the LPECON 40 and the feedwater pump 45. Similarly, the second pump supply line 212 may extend (e.g., directly) between the high temperature heat exchanger 206 and the feedwater pump 45 so that the feedwater pump 45 may receive used hot fluid from the high temperature heat exchanger 206 (e.g., water that has undergone energy transfer from the high temperature heat exchanger 206).

[0051] In such an embodiment, the feedwater pump 45 may receive a first water flow (via supply line 211) from the outlet of the LPECON 40 and a second water flow (via supply line 212) from the high temperature heat exchanger 206. By returning water from the high temperature heat exchanger 206 to the feedwater pump 45, parasitic pumping losses are significantly reduced compared to existing designs. For example, the pressure required and the power consumed to circulate water to (and through) the high temperature heat exchanger 206 may be closely matched (e.g., equal) to the actual friction losses of the circuit through which the high temperature heat exchanger 206 is located.

[0052] Water may flow from the feedwater pump 45 to the IPECON 44, the aft high pressure economizer 49, and / or the interstage thermostats 56 and 62, for example, via separate pipes, tubes, or fluid conduits. For example, a first feedwater supply line 126 may extend from the feedwater pump 45 to the aft high pressure economizer 49, and a second feedwater line 128 may extend from the feedwater pump 45 to the IPECON 44. Additionally, the interstage thermostat 62 may be in fluid communication with the second feedwater supply line 128 via a second thermostat cooling line 162. Alternatively or additionally, the interstage thermostat 56 may receive water from the feedwater pump 45 (e.g., from the first feedwater supply line 126).

[0053] Still reference Figure 1 and Figure 2The fuel heating system 200 may also include a low temperature heat exchanger 208 disposed in thermal communication with the fuel supply line 202 and upstream of the high temperature heat exchanger 206 relative to the flow of fuel through the fuel supply line 202. The low temperature heat exchanger 208 may operate at a lower temperature than the high temperature heat exchanger 206. In many embodiments, a low temperature input line 216 may fluidly connect the LPECON 40 and the low temperature heat exchanger 208 and extend between the two. Additionally, a low temperature output line 218 may fluidly connect the low temperature heat exchanger 208 and the condensate supply line 80 and extend between the two. In some embodiments, as Figure 1 As shown, the cryogenic output line 218 can be fluidly coupled to the condensate supply line 80, downstream of the condensate pump 38 relative to the flow of water through the condensate supply line 80. In other embodiments, such as Figure 2 As shown, the cryogenic output line 218 may be fluidly coupled to the condensate supply line 80 upstream of the condensate pump 38 relative to the flow of water through the condensate supply line 80 .

[0054] In some embodiments, such as Figure 1 As shown, the cryogenic bypass line 220 can fluidly couple the cryogenic input line 216 to the condensate supply line 80. One or more valves 150 can be disposed in fluid communication with the cryogenic bypass line 220 so that the amount (and / or flow rate) of water entering the cryogenic heat exchanger 208 can be regulated by the one or more valves 150 disposed on the cryogenic bypass line 220. In addition, in many embodiments, a cryogenic pump 222 can be disposed in fluid communication with the cryogenic input line 216.

[0055] Reference now Figure 3 , shows a feed water pump control system 600 according to an embodiment of the present disclosure. For example, the feed water pump control system 600 can be used in the above reference Figure 1 to Figure 2 The CCPP 10 shown and described.

[0056] like Figure 3 As shown, the feedwater pump control system 600 may include a heat recovery steam generator 32, which includes a low-pressure economizer 40, an intermediate-pressure economizer 44, a rear high-pressure economizer 49, and a front high-pressure economizer 48 (shown in reverse positions for simplicity). The feedwater pump control system 600 may also include a fuel heating system 200, which includes a fuel supply line 202 that is fluidly coupled to the combustion section 18 of the gas turbine 12. The fuel heating system 200 also includes a high-temperature heat exchanger 206 and a low-temperature heat exchanger 208 disposed on the fuel supply line 202 in a thermally connected manner.

[0057] In an exemplary embodiment, the feedwater pump control system 600 may be described in detail above with reference to Figure 1 and Figure 2 It is implemented in CCPP10. It is worth noting that Figure 3 The heat recovery steam generator 32 shown in FIG. 1 is intended to illustrate which components may be included in the system regardless of the gas flow. In contrast, Figure 1 , Figure 2 and Figures 4 to 6 The arrangement of the various components of the HRSG 32 is shown as it relates to the exhaust gas 34 flowing through the HRSG 32 (where the exhaust gas 34 flows from left to right).

[0058] In an exemplary embodiment, the feedwater pump control system 600 may include a feedwater pump 45 having a plurality of stages 602. For example, the feedwater pump 45 may be a multi-stage pump having a plurality of stages 602. The feedwater pump 45 may include a motor 610 coupled to a shaft 612. The shaft 612 may be coupled to one or more impellers (e.g., one impeller per stage) so that the water moving through the multi-stage feedwater pump 45 gradually increases in pressure as it moves from one stage to another. The plurality of stages 602 may include one or more early stages including an initial stage 604 (or suction side stage), two or more intermediate stages 606, and one or more later stages including a last or final stage 608. The pressure of the water in each of the plurality of stages 602 of the feedwater pump 45 may gradually increase from the initial stage 604 between each intermediate stage 606 to the final stage 608. Although Figure 3 The illustrated embodiment shows a feedwater pump 45 having eleven stages, but it should be understood that the feedwater pump 45 may have any number of stages and that the present disclosure should not be limited to any particular number of stages unless specifically recited in the claims.

[0059] In many embodiments, the first pump supply line 211 may extend between the LPECON 40 and the initial stage 604 of the plurality of stages 602 and fluidly couple them. That is, water from the outlet of the LPECON 40 may be provided to the initial stage 604 of the plurality of stages 602 (e.g., via the first inlet). The second pump supply line 212 may extend between the high temperature heat exchanger 206 and the first intermediate stage 606 and fluidly couple them. In many embodiments, the first feedwater supply line 126 may extend between the last stage 608 of the plurality of stages 602 and the rear high pressure economizer 49 and fluidly couple them. In this way, at least a portion of the water from the last stage 608 of the feedwater pump 45 may be provided to the rear high pressure economizer 49. In addition, the second feedwater supply line 128 may extend between the second intermediate stage 606 of the plurality of stages 602 and the intermediate pressure economizer 44 and fluidly couple them.

[0060] By way of example only, the feedwater pump 45 may include early stages, including the initial stage 604 and the first 25% of the stages; middle stages, which follow the early stages and extend from 25% to 75% of the stages; and late stages, which follow the middle stages and extend to the last 25% of the stages and include the final stage 608. Figure 3 In the illustrated embodiment, the LPECON 40 may be fluidly coupled to an initial stage 604 , the IPECON 44 may be fluidly coupled to an intermediate stage 606 (such as an intermediate stage or a sixth stage), the high temperature heat exchanger 206 may be fluidly coupled to a later stage 606 (such as a penultimate stage or a tenth stage), and the rear high pressure economizer 49 may be fluidly coupled to a final stage 608 .

[0061] In an exemplary embodiment, sensor 614 (at Figure 3 The sensor 614 (denoted by the symbol "S" in the figure) may be disposed in one or more of the first pump supply line 211, the second pump supply line 212, the first feed water supply line 126, and the second feed water supply line 128. The sensor 614 may be configured to provide data indicating at least one of the pressure, temperature, or flow rate of the water. The sensor 614 may provide data indicating such parameters of the water flowing through the line to which the sensor is attached. For example, the sensor 614 disposed on the first pump supply line 211 may be configured to provide data indicating at least one of the pressure, temperature, or flow rate of the water within the first pump supply line 211 (e.g., provided to the controller 106).

[0062] In addition, in many embodiments, valve 150 may be disposed on one or more of the second pump supply line 212, the first feed water supply line 126, and the second feed water supply line 128. Each of these valves 150 may be selectively and independently actuated between an open position and a closed position (e.g., by the controller 106). In the open position, the fluid flowing through the pipeline to which the valve 150 is attached may not be restricted. Conversely, in the closed position, the fluid flowing through the pipeline to which the valve 150 is attached may be restricted. Each valve may also be selectively actuated to a partially closed (or partially open) position by a command from the controller 106, thereby allowing the valve 150 to control the flow rate of the fluid flowing through the pipeline to which the valve 150 is attached.

[0063] In an exemplary embodiment, the feedwater pump control system 600 may also include a controller 106 that is communicatively coupled to the sensor 614 and operably coupled to the valves 150. For example, the controller 106 may independently actuate each valve 150. Figure 3As shown, the controller 106 is shown as a block diagram to illustrate suitable components that may be included within the controller 106. For example, the controller 106 may include: one or more processors 114 and associated memory devices 116, which are configured to perform various computer-implemented functions (e.g., perform methods, steps, calculations, etc. and store related data as disclosed herein). In addition, the controller 106 may also include a communication module 119 to facilitate communication between the controller 106 and various components of the system 600. For example, the communication module 119 can communicate with the sensor 614 and the valve 150.

[0064] In addition, the communication module 119 may include a sensor interface (e.g., one or more analog-to-digital converters) to allow signals transmitted from one or more sensors 614 to be converted into signals that can be understood and processed by the processor 114. It should be understood that the sensors 614 can be communicatively coupled to the communication module 119 using any suitable means. For example, the sensors 614 can be coupled to the communication module 119 via a wired connection. However, in other embodiments, the sensors can be coupled to the communication module 119 via a wireless connection (such as by using any suitable wireless communication protocol known in the art).

[0065] As used herein, the term "processor" refers not only to what is known in the art as an integrated circuit included in a computer, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application specific integrated circuits, and other programmable circuits. In addition, the memory device 116 may generally include memory elements, including but not limited to computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, compact disk-read only memory (CD-ROM), magneto-optical disks (MOD), digital versatile disks (DVD), and / or other suitable memory elements.

[0066] Such a memory device 116 may generally be configured to store suitable computer-readable instructions that, when implemented by one or more processors 114, configure the controller 106 to perform various functions and / or operations, including but not limited to monitoring data indicating a temperature difference between water entering the feedwater pump 45 and water leaving the feedwater pump 45 via one or more sensors 614. These operations may also include determining when the temperature difference is outside a predetermined temperature range (or predetermined temperature difference range). For example, the controller 106 may determine when the temperature difference exceeds a maximum threshold of a predetermined temperature range or falls below a minimum threshold of a predetermined temperature range. In response to determining that the temperature difference is outside the predetermined temperature range, the controller 106 may adjust the flow of water to the feedwater pump 45 by actuating one or more valves 150 to restore the temperature difference to within the predetermined temperature range. The predetermined temperature range (i.e., the predetermined temperature difference between water entering the feedwater pump 45 and water leaving the feedwater pump 45) may be approximately ±30°F, or such as ±20°F, or such as approximately ±10°F, or such as approximately ±5°F.

[0067] For example, when the water entering the feedwater pump 45 via the second pump supply line 212 is overheated (e.g., the temperature difference between the water entering the feedwater pump 45 and the water leaving the feedwater pump 45 exceeds the maximum threshold of the predetermined temperature range of the feedwater pump 45), the controller 106 may actuate the valve 150 on the second pump supply line 212 to restrict the water flowing therethrough (or slow its flow rate), thereby reducing the temperature in the line 212 to be closer to the temperature of the fuel entering the high temperature fuel heater 206. This serves to restore the temperature difference of the water entering / leaving the feedwater pump 45 to within the predetermined temperature range. Conversely, when the water entering the water feed pump 45 via the second pump supply line 212 is supercooled (for example, the temperature difference between the water entering the water feed pump 45 and the water leaving the water feed pump 45 drops below a minimum threshold of a predetermined temperature range for the water feed pump 45), the controller 106 may actuate the valve 150 on the second pump supply line 212 to remove restrictions on (or increase the flow rate of) the water flowing therethrough, thereby causing the high-temperature heat exchanger 206 to increase the temperature of the water flowing through the second pump supply line 212 to restore the temperature difference of the water entering / leaving the water feed pump 45 to within the predetermined temperature range.

[0068] In various embodiments, such as Figure 2 and Figure 4As shown, the CCPP 10 may also include a bridge line 224 that fluidly connects and extends between the first pump supply line 211 and the condensate supply line 80. In such an embodiment, a bridge pump 226 and a bridge valve 228 may be disposed in fluid communication on the bridge line 224. The bridge line 224, the bridge pump 226, and the bridge valve 228 may allow for more robust control of the temperature at the feedwater pump 45 by allowing water from the first pump supply line 211 to selectively move back into the condensate supply line 80. This also allows for more robust temperature control of the fuel heating system 200, for example, and in particular, more robust temperature control of the low temperature heat exchanger 208.

[0069] Reference now Figure 4 , the fuel heating system 200 of the CCPP 10 is configured without the low temperature heat exchanger 208. In this embodiment, the high temperature heat exchanger 206 may be fluidly coupled to the front high pressure economizer 48. The high temperature input line 210 may fluidly couple the front high pressure economizer 48 to the high temperature heat exchanger 206. For example, the high temperature input line 210 may extend between the front high pressure economizer 48 and the high temperature heat exchanger 206 to supply high temperature water to the high temperature heat exchanger 206.

[0070] In such embodiments, a recirculation line 214 may extend (e.g., directly) from the high temperature heat exchanger 206 to the condensate supply line 80. The recirculation line 214 may at least partially fluidly couple the high temperature heat exchanger 206 to the HRSG 32, downstream of an economizer (e.g., forward high pressure economizer 48) relative to the flow of the exhaust gas 34 through the HRSG 32. For example, the high temperature heat exchanger 206 may be fluidly coupled to the condensate supply line 80 via the recirculation line 214. Specifically, the recirculation line 214 may fluidly couple the high temperature heat exchanger 206 to the condensate supply line 80.

[0071] In such an embodiment, a water turbine 230 (or water turbine) may be disposed in fluid communication on the recirculation line 214 (outside the HRSG 32). The water turbine 230 may be a rotary turbine that converts the high-pressure water energy flowing through the recirculation line 214 into rotational / electrical energy, and at the same time, the water turbine 230 may advantageously throttle the high-pressure water from the high-temperature heat exchanger 206 (which is initially supplied from the front HPECON 48) to the condensing pressure so as to enter the condensate supply line 80 without any problems.

[0072] Additionally, the electrical energy generated by the hydro turbine 230 may be used to power one or more components of the CCPP 10. For example, the hydro turbine 230 may compensate for at least a portion of the parasitic losses experienced by the feedwater pump 45. In some embodiments, the electrical energy generated by the hydro turbine 230 may be stored in a battery, which in turn may be used to power one or more components of the CCPP 10. For example, Figure 4 As shown by the phantom lines in FIG. 1 , the hydro turbine 230 may be electrically coupled to one or more electrical components 235 (such as a battery or other energy storage device, a power converter, other components in the HRSG 32 or CCPP 10, or other electrical components). In this manner, the electrical power generated by the hydro turbine 230 may be transmitted as power output to the one or more electrical components 235. It should be understood that in some embodiments, the hydro turbine 230 may be disposed in the above referenced Figure 1 and Figure 2 The second pump supply line 212 is described. In such an embodiment, water leaving the hydro turbine 230 can be added to the first pump supply line 211 and the second pump supply entry can be eliminated.

[0073] Reference now Figure 5 , the fuel heating system 200 may include a high temperature heat exchanger 306 disposed in a fluid communication manner on a dedicated loop 308. Specifically, the high temperature heat exchanger 306 may be disposed in a thermal communication manner on the fuel supply line 202 and on a dedicated loop 308, a portion of which is outside the HRSG 32. The dedicated loop 308 may extend at least partially through the HRSG 32 and may have a dedicated heat exchanger 314 disposed within the HRSG 32. In many embodiments, the dedicated loop 308 may be formed by one or more fluid conduits extending from the outlet of the high temperature heat exchanger 306 to the inlet of the high temperature heat exchanger 306. For example, in such embodiments, the dedicated loop 308 may be fluidly isolated from various components of the HRSG 32 (e.g., not in fluid communication with water / steam circulating through various HRSG 32 components). In this way, the dedicated loop 308 may circulate a non-aqueous thermal fluid (i.e., a thermal fluid other than water). In an exemplary embodiment, the thermal fluid in the dedicated loop 308 may be a synthetic organic thermal fluid (e.g., synthetic oil). In particular, the thermal fluid in the dedicated loop may be DowTherm TM Heat transfer fluid or from Eastman Chemical Company, Kingsport, Tennessee One of the heat transfer fluids.

[0074] like Figure 5As shown, the dedicated loop 308 may include an expansion tank 310, a recirculation pump 312, and a dedicated heat exchanger 314. In an exemplary embodiment, the expansion tank 310, the recirculation pump 312, and the dedicated heat exchanger 314 may each be in fluid communication with the dedicated loop 308 so that the hot fluid flows through each component on the dedicated loop 308. The expansion tank 310 and the recirculation pump 312 may be disposed outside the HRSG 32 (so that these components are not exposed to the high temperature exhaust gas flowing through the HRSG 32). The expansion tank 310 may be a container, reservoir, or vessel for protecting the dedicated loop 308 from excessive pressure. For example, in some embodiments, the expansion tank 310 may be at least partially filled with air, which may absorb (e.g., via the compressibility of the air) some of the shock caused by the excessive pressure from the thermal expansion of the hot fluid in the dedicated loop 308.

[0075] The dedicated heat exchanger 314 may be disposed in the HRSG 32 so that the exhaust gas 34 flowing through the HRSG 32 may transfer thermal energy to the hot fluid in the dedicated loop 308 for use in the high temperature heat exchanger 306. In many embodiments, the dedicated heat exchanger 314 may extend within the HRSG 32 from the outlet 33 of the HRSG 32 to upstream of the high pressure economizer 48 ahead of the exhaust gas flow through the HRSG 32.

[0076] Reference now Figure 6 , the fuel heating system 200 may include a high temperature heat exchanger 406 disposed in thermal communication with the fuel supply line 202. In such embodiments, the high temperature heat exchanger 406 may exchange heat between a portion of the extracted exhaust gas 34 from the HRSG 32 and the fuel flowing through the fuel supply line 202. For example, the CCPP 10 may also include an exhaust gas extraction system 400 that removes a portion of the exhaust gas 34 from the HRSG 32 for use in heating one or more components external to the HRSG 32, such as the high temperature heat exchanger 406. The exhaust gas extraction system 400 may thermally couple the HRSG 32 and the high temperature heat exchanger 406.

[0077] In an exemplary embodiment, the exhaust extraction system 400 may include an exhaust extraction conduit 408 extending from inside the HRSG 32 to outside the HRSG 32 and an exhaust return conduit 412 extending from outside the HRSG 32 to inside the HRSG 32. The exhaust extraction conduit 408 may extend from the HRSG 32 and fluidly couple it to the high temperature heat exchanger 406. Specifically, as shown in FIG. Figure 6As shown, an exhaust extraction conduit 408 may extend from an inlet 410 within the HRSG 32 to the high temperature heat exchanger 406. The inlet 410 may be disposed upstream of the forward high pressure economizer 48 relative to the flow of exhaust gas through the HRSG 32. Additionally, an exhaust return conduit 412 may extend from the high temperature heat exchanger 406 to an outlet 414 within the HRSG 32. The outlet 414 may be disposed within the HRSG 32, immediately downstream of the LPECON 40 relative to the flow of exhaust gas through the HRSG 32 (and / or immediately upstream of the outlet 33 of the HRSG 32). Alternatively, the outlet 414 may be defined in or directly coupled to the exhaust stack 105 without being directed through the HRSG 32. Furthermore, in other embodiments, the outlet 414 may be disposed within the HRSG 32, upstream of the LPECON 40.

[0078] In various embodiments, a fan 411 may be disposed on the exhaust return conduit 412 and may be used to pull a portion of the exhaust gas 34 from the HRSG 32 toward the high temperature heat exchanger 406. In an exemplary embodiment, the fan 411 may be disposed downstream (e.g., immediately downstream) of the high temperature heat exchanger 406 relative to the flow of the exhaust gas 34 through the exhaust return conduit 412. The fan 411 may be used to create a pressure differential within the exhaust extraction system 400 that moves the exhaust gas from the inlet 410 through the exhaust extraction conduit 408 and the exhaust return conduit 412 to the outlet 414.

[0079] References Figure 1 , Figure 2 and Figures 4 to 6 The CCPP 10 and the above references Figure 3 The feedwater pump control systems 600 described above may each be capable of achieving a fuel temperature of greater than about 480° F. (about 250° C.) at the inlet of the combustion section 18 with reduced pumping power compared to prior designs. For example, returning water from the high temperature heat exchanger 206 to the feedwater pump 45 may advantageously reduce the overall parasitic pumping losses experienced by the CCPP 10 system while maintaining a desired fuel temperature at the inlet of the combustion section 18.

[0080] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any combined methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. If these other examples include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ substantially from the literal language of the claims, these other examples are intended to be included within the scope of the claims.

[0081] Further aspects of the invention are provided by the subject matter of the following clauses:

[0082] A combined cycle power plant (CCPP), the combined cycle power plant comprising: a gas turbine having a compressor section, a combustion section and a turbine section; a heat recovery steam generator (HRSG), the heat recovery steam generator having a first economizer, the HRSG receiving an exhaust gas flow from the turbine section; a fuel heating system, the fuel heating system comprising a fuel supply pipeline and a high-temperature heat exchanger disposed in a thermally connected manner on the fuel supply pipeline, the fuel supply pipeline being fluidly connected to the combustion section, the high-temperature heat exchanger being fluidly connected to the first economizer so that the high-temperature heat exchanger receives water from the first economizer; and a feed water pump, the feed water pump being fluidly connected to the high-temperature heat exchanger.

[0083] The CCPP of one or more of these clauses, further comprising at least one of an evaporator or a deaerator, and wherein the feedwater pump is fluidly coupled to one of the first economizer, the evaporator, or the deaerator.

[0084] A CCPP according to one or more of these clauses, wherein the feedwater pump is a multistage pump.

[0085] A CCPP according to one or more of these clauses, wherein the fuel heating system further comprises a low temperature heat exchanger disposed in thermal communication on the fuel supply line upstream of the high temperature heat exchanger with respect to fuel flow through the fuel supply line.

[0086] The CCPP of one or more of these clauses further comprising a steam turbine system fluidly coupled to a second economizer within the HRSG at least in part via a condensate supply line.

[0087] A CCPP according to one or more of these clauses, wherein the first economizer is a high pressure economizer, wherein the second economizer is a low pressure economizer located upstream of the high pressure economizer relative to the exhaust gas flow through the HRSG, wherein a high temperature input line connects the high pressure economizer fluid to the high temperature heat exchanger, and wherein a low temperature input line connects the low pressure economizer fluid to the low temperature heat exchanger.

[0088] A CCPP according to one or more of these clauses, wherein a cryogenic output line fluidly couples the cryogenic heat exchanger to the condensate supply line.

[0089] A CCPP according to one or more of these clauses, wherein a cryogenic bypass line fluidly couples the cryogenic input line to the condensate supply line.

[0090] A CCPP according to one or more of these clauses, wherein a cryogenic pump is disposed in fluid communication with the cryogenic input line.

[0091] A CCPP according to one or more of these clauses, wherein the low pressure economizer is fluidly coupled to the feedwater pump via a first pump supply line, and wherein the high temperature heat exchanger is fluidly coupled to the feedwater pump via a second pump supply line.

[0092] A CCPP according to one or more of these clauses, wherein a bridge line fluidly couples the first pump supply line to the condensate supply line, and wherein a bridge pump and a bridge valve are disposed in fluid communication on the bridge line.

[0093] A combined cycle power plant (CCPP), comprising: a gas turbine having a compressor section, a combustion section and a turbine section; a heat recovery steam generator (HRSG), the heat recovery steam generator receiving an exhaust gas flow from the turbine section, the HRSG having a high-pressure economizer and a low-pressure economizer; a fuel heating system, the fuel heating system comprising a fuel supply pipeline, a high-temperature heat exchanger and a low-temperature heat exchanger, the fuel supply pipeline being fluidly connected to the combustion section, the high-temperature heat exchanger and the low-temperature heat exchanger being arranged on the fuel supply pipeline in a thermally connected manner, the high-temperature heat exchanger being fluidly connected to the high-pressure economizer, and the low-temperature heat exchanger being fluidly connected to the low-pressure economizer; and a feedwater pump, the feedwater pump being fluidly connected to the high-temperature heat exchanger.

[0094] A CCPP according to one or more of these clauses, wherein the feedwater pump is a multistage pump.

[0095] A CCPP according to one or more of these clauses, wherein the low temperature heat exchanger is disposed on the fuel supply line upstream of the high temperature heat exchanger with respect to the flow of fuel through the fuel supply line.

[0096] The CCPP according to one or more of these clauses, further comprising a steam turbine system fluidly coupled to the low pressure economizer at least in part via a condensate supply line.

[0097] A CCPP according to one or more of these clauses, wherein the low pressure economizer is located downstream of the high pressure economizer relative to the exhaust gas flow through the HRSG, wherein a high temperature input line connects the high pressure economizer fluid to the high temperature heat exchanger, and wherein a low temperature input line connects the low pressure economizer fluid to the low temperature heat exchanger.

[0098] A CCPP according to one or more of these clauses, wherein a cryogenic output line fluidly couples the cryogenic heat exchanger to the condensate supply line.

[0099] A CCPP according to one or more of these clauses, wherein the low pressure economizer is fluidly coupled to the feedwater pump via a first pump supply line, and wherein the high temperature heat exchanger is fluidly coupled to the feedwater pump via a second pump supply line.

[0100] A CCPP according to one or more of these clauses, wherein a bridge line fluidly couples the first pump supply line to a condensate supply line, and wherein a bridge pump and a bridge valve are disposed in fluid communication on the bridge line.

[0101] A feedwater pump control system, the feedwater pump control system comprising: a heat recovery steam generator (HRSG), the heat recovery steam generator having a low-pressure economizer and at least one high-pressure economizer; a fuel heating system, the fuel heating system having a fuel supply pipeline fluidly connected to a combustion section, a high-temperature heat exchanger and a low-temperature heat exchanger disposed on the fuel supply pipeline in a thermally connected manner; a feedwater pump, the feedwater pump having a plurality of stages; a first pump supply pipeline, the first pump supply pipeline extending between one of the low-pressure economizer, the low-pressure drum or the deaerator and an initial stage of the plurality of stages; a second pump supply pipeline, the second pump supply pipeline extending between the high-temperature heat exchanger and an intermediate stage of the plurality of stages; a feedwater supply pipeline, the feedwater supply pipeline extending between the last stage of the plurality of stages and the at least one high-pressure economizer; one or more sensors, the one or more sensors being disposed in the first pump supply pipeline, the A sensor on one or more of the second pump supply line and the feed water supply line is configured to provide data indicating at least one of the pressure, temperature or flow rate of water; one or more valves, the one or more valves are arranged on the second pump supply line and one or more of the feed water supply line; and a controller, the controller is communicatively connected to the sensor and operably connected to the valve, the controller includes a memory and one or more processors, the memory stores instructions, and the instructions, when executed by the one or more processors, cause the feed water pump control system to perform operations, the operations including: monitoring data indicating the temperature difference between water entering the feed water pump and water leaving the feed water pump via the one or more sensors; determining when the temperature difference exceeds a predetermined temperature range; and regulating the flow of water to the feed water pump by actuating the one or more valves to restore the temperature difference to within the predetermined temperature range.

Claims

1. A combined cycle power plant (CCPP), comprising: a gas turbine having a compressor section, a combustion section, and a turbine section; a heat recovery steam generator (HRSG) having a first economizer, the HRSG receiving an exhaust gas flow from the turbine section; a fuel heating system comprising a fuel supply line and a high temperature heat exchanger disposed in thermal communication on the fuel supply line, the fuel supply line being fluidly coupled to the combustion section, the high temperature heat exchanger being fluidly coupled to the first economizer so that the high temperature heat exchanger receives water from the first economizer; and A feedwater pump is fluidly coupled to the high temperature heat exchanger.

2. The CCPP of claim 1, further comprising at least one of an evaporator or a deaerator, and wherein the feedwater pump is fluidly coupled to one of the first economizer, the evaporator, or the deaerator.

3. The CCPP of claim 2, wherein the feedwater pump is a multistage pump.

4. The CCPP of claim 1 , wherein the fuel heating system further comprises a low temperature heat exchanger disposed in thermal communication with the fuel supply line upstream of the high temperature heat exchanger with respect to fuel flow through the fuel supply line.

5. The CCPP of claim 1, further comprising a steam turbine system fluidly coupled to a second economizer within the HRSG at least in part via a condensate supply line.

6. The CCPP of claim 5, wherein the first economizer is a high pressure economizer, wherein the second economizer is a low pressure economizer located downstream of the high pressure economizer relative to the flow of exhaust gas through the HRSG, wherein a high temperature input line couples the high pressure economizer fluid to the high temperature heat exchanger, and wherein a low temperature input line couples the low pressure economizer fluid to a low temperature heat exchanger.

7. The CCPP of claim 6, wherein a cryogenic export line fluidly couples the cryogenic heat exchanger to the condensate supply line.

8. The CCPP of claim 6, wherein a cryogenic bypass line fluidly couples the cryogenic input line to the condensate supply line.

9. The CCPP of claim 6, wherein a cryogenic pump is disposed in fluid communication with the cryogenic input line.

10. The CCPP of claim 6, wherein the low pressure economizer is fluidly coupled to the feedwater pump via a first pump supply line, and wherein the high temperature heat exchanger is fluidly coupled to the feedwater pump via a second pump supply line.

11. The CCPP of claim 10, wherein a bridge line fluidly couples the first pump supply line to the condensate supply line, and wherein a bridge pump and a bridge valve are disposed in fluid communication on the bridge line.

12. A combined cycle power plant (CCPP), comprising: a gas turbine having a compressor section, a combustion section, and a turbine section; a heat recovery steam generator (HRSG) receiving the exhaust gas flow from the turbine section, the HRSG having a high pressure economizer and a low pressure economizer; a fuel heating system, the fuel heating system comprising a fuel supply line, a high temperature heat exchanger and a low temperature heat exchanger, the fuel supply line being fluidly coupled to the combustion section, the high temperature heat exchanger and the low temperature heat exchanger being disposed in thermal communication on the fuel supply line, the high temperature heat exchanger being fluidly coupled to the high pressure economizer, and the low temperature heat exchanger being fluidly coupled to the low pressure economizer; and A feedwater pump is fluidly coupled to the high temperature heat exchanger.

13. The CCPP of claim 12, wherein the feedwater pump is a multistage pump.

14. The CCPP of claim 12, wherein the low temperature heat exchanger is disposed on the fuel supply line upstream of the high temperature heat exchanger with respect to the flow of fuel through the fuel supply line.

15. The CCPP of claim 12, further comprising a steam turbine system fluidly coupled to the low pressure economizer at least in part via a condensate supply line.

16. The CCPP of claim 15, wherein the low pressure economizer is located downstream of the high pressure economizer relative to the flow of exhaust gas through the HRSG, wherein a high temperature input line couples the high pressure economizer fluid to the high temperature heat exchanger, and wherein a low temperature input line couples the low pressure economizer fluid to a low temperature heat exchanger.

17. The CCPP of claim 15, wherein a cryogenic export line fluidly couples the cryogenic heat exchanger to the condensate supply line.

18. The CCPP of claim 12, wherein the low pressure economizer is fluidly coupled to the feedwater pump via a first pump supply line, and wherein the high temperature heat exchanger is fluidly coupled to the feedwater pump via a second pump supply line.

19. The CCPP of claim 18, wherein a bridge line fluidly couples the first pump supply line to a condensate supply line, and wherein a bridge pump and a bridge valve are disposed in fluid communication on the bridge line.

20. A water supply pump control system, the water supply pump control system comprising: a heat recovery steam generator (HRSG) having a low pressure economizer and at least one high pressure economizer; a fuel heating system having a fuel supply line fluidly coupled to the combustion section, a high temperature heat exchanger and a low temperature heat exchanger disposed in thermal communication on the fuel supply line; a feed water pump, the feed water pump having a plurality of stages; a first pump supply line extending between one of the low pressure economizer, low pressure drum, or deaerator and an initial stage of the plurality of stages; a second pump supply line extending between the high temperature heat exchanger and an intermediate stage of the plurality of stages; a feedwater supply line extending between a last stage of the plurality of stages and the at least one high pressure economizer; one or more sensors disposed on one or more of the first pump supply line, the second pump supply line, and the feed water supply line, the sensors configured to provide data indicative of at least one of a pressure, a temperature, or a flow rate of the water; one or more valves disposed on one or more of the second pump supply line and the feedwater supply line; and a controller communicatively coupled to the sensor and operably coupled to the valve, the controller comprising a memory and one or more processors, the memory storing instructions that, when executed by the one or more processors, cause the feedwater pump control system to perform operations including: monitoring, via the one or more sensors, data indicative of a temperature difference between water entering the feedwater pump and water exiting the feedwater pump; determining when the temperature difference is outside a predetermined temperature range; and The temperature difference is restored to within the predetermined temperature range by actuating the one or more valves to regulate water flow to the feedwater pump.

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