Self-pressurized ammonia fuel supply system and method for gas turbine engine

Abstract

To provide a self-pressurized ammonia fuel supply system and method for a ga turbine engine.SOLUTION: A power generation system (100) includes a rotary machine (102) including a combustor (106), and a fuel supply system (114) configured to supply a liquid ammonia fuel to the combustor (106). The fuel supply system (114) comprises a fuel supply line (116) coupled to the combustor (106), a supply tank (118) disposed on the fuel supply line (116) on the upstream side of the combustor (106), the supply tank (118) being sized to receive the liquid ammonia fuel therein, and a heat exchanger (128) configured to heat the liquid ammonia fuel in the supply tank (118) such that an ammonia vapor pressure in the supply tank (118) is sufficient to drive the liquid ammonia fuel from the supply tank (118) towards the combustor (106).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technical field relates generally to gas turbine engines, and more particularly to systems and methods for supplying ammonia fuel to gas turbine engines. [Background technology]

[0002] Gas turbine engines are widely used in industry and power generation. A conventional gas turbine engine includes a compressor, one or more combustors downstream of the compressor, and a turbine (e.g., an expansion turbine) downstream of the combustor. A working fluid, such as ambient air, enters the compressor where it is compressed before entering the combustor. The compressed working fluid is mixed with fuel and combusted in the combustor to generate combustion gases that expand through a turbine, rotate a shaft, and generate power.

[0003] Combustion gases can contain various combustion by-products, such as nitrogen oxides (NOx), carbon monoxide (CO), and unburned hydrocarbons. Reducing these emissions can be difficult because reducing the operating temperature and amount of oxygen during combustion to reduce NOx production can increase CO and unburned hydrocarbon levels. Recent efforts to further reduce such emissions include using ammonia as a combustion fuel source. Ammonia-based fuels have the advantage of not producing carbon-based emissions when burned.

[0004] The use of ammonia-based fuel in combustion engines, such as gas turbine engines, poses several technical challenges. For example, fuel pumps commonly used to deliver fuel to the combustor section may not be suitable for delivering ammonia fuel to the combustor section. Ammonia has a relatively high vapor pressure, and the mechanical work performed by the fuel pump can generate ammonia bubbles in the liquid ammonia fuel flow. Gaseous ammonia entrained in the liquid ammonia fuel flow can adversely affect flame propagation in the combustor section or cause undesirable combustion dynamics. Ammonia is also a corrosive chemical, and its use as a fuel can significantly increase equipment and material costs, as fuel delivery components (e.g., fuel pumps) must be manufactured from ammonia-compatible, corrosion-resistant materials to maintain component life. Therefore, integrating ammonia fuel into combustion engines remains challenging.

[0005] Therefore, there is a need for systems and methods that facilitate the use of ammonia fuel in gas turbine engines and address the above-mentioned challenges. Summary of the Invention

[0006] In one embodiment, a power generation system is provided. The power generation system includes a rotary machine including a combustor and a fuel supply system configured to supply liquid ammonia fuel to the combustor. The fuel supply system includes a fuel supply line coupled to the combustor and a supply tank disposed in the fuel supply line upstream of the combustor, the supply tank sized to receive the liquid ammonia fuel therein and including a heat exchanger configured to heat the liquid ammonia fuel in the supply tank such that ammonia vapor pressure in the supply tank is sufficient to drive the liquid ammonia fuel from the supply tank toward the combustor.

[0007] In another aspect, a combined cycle power plant is provided. The combined cycle power plant includes a gas turbine engine including a combustor, a heat recovery steam generator (HRSG) coupled to the gas turbine engine, and a fuel supply system configured to supply liquid ammonia fuel to the gas turbine engine. The fuel supply system includes a fuel supply line connected to the gas turbine engine, a supply tank disposed in the fuel supply line upstream from the gas turbine engine, the supply tank sized to contain the liquid ammonia fuel, and a heat exchanger configured to heat the liquid ammonia fuel in the supply tank such that ammonia vapor pressure in the supply tank is sufficient to drive the liquid ammonia fuel from the supply tank toward the gas turbine engine, the thermal efficiency configured to heat the liquid ammonia fuel in the supply tank using steam generated by the HRSG.

[0008] In another aspect, a method of supplying liquid ammonia fuel to a rotary machine is provided, the method including flowing liquid ammonia fuel to a supply tank, heating the liquid ammonia fuel in the supply tank to increase ammonia vapor pressure in the supply tank, and using the ammonia vapor pressure in the supply tank to drive the liquid ammonia fuel from the supply tank toward a combustor of the rotary machine. [Brief explanation of the drawings]

[0009] These and other features, aspects and advantages of the present disclosure will be better understood from the following detailed description when taken in conjunction with the accompanying drawings, in which like characters represent like parts throughout. [Figure 1] 1 is a schematic diagram of a power generation system including an exemplary fuel supply system. [Figure 2] 2 is a schematic diagram of another power generation system including the example fuel supply system of FIG. 1 and an exhaust gas recirculation system coupled to the fuel supply system. [Figure 3] FIG. 2 is a schematic diagram of a combined cycle power plant including the exemplary fuel supply system of FIG. 1. [Figure 4]4 is a schematic diagram of a portion of the power generation system of FIG. 1 showing in greater detail an exemplary starting skid that may be included in the fuel supply system of FIGS. 1-3. [Figure 5] 4 is a flow chart of an exemplary method for supplying liquid ammonia fuel to a rotary machine, such as a gas turbine engine, associated with the power generation systems of FIGS. 1-3.

[0010] Unless otherwise noted, the drawings provided herein are intended to illustrate features of embodiments of the present disclosure. These features are believed to be applicable to a wide variety of systems incorporating one or more embodiments of the present disclosure. As such, the drawings are not intended to include all conventional features known to those skilled in the art that are necessary to practice the embodiments disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0003] Embodiments described herein relate to a system and method for supplying liquid ammonia fuel to a combustor of a rotary machine (e.g., a gas turbine engine). An exemplary fuel supply system configured to supply liquid ammonia fuel to a combustor includes a fuel supply line coupled to the combustor, a supply tank disposed on the fuel supply line upstream of the combustor and sized to contain the liquid ammonia fuel, and a heat exchanger configured to heat the liquid ammonia fuel in the supply tank. Heating the liquid ammonia fuel increases the ammonia vapor pressure in the supply tank, causing the liquid ammonia fuel to partially vaporize and reach equilibrium with a two-phase mixture of liquid and vaporized ammonia in the supply tank. The liquid ammonia fuel is heated in the supply tank, causing the ammonia vapor pressure in the supply tank to increase to a pressure that exceeds the operating pressure in the combustor. A pressure differential between the supply tank and the combustor drives the liquid ammonia fuel from the supply tank toward the combustor. Thus, the liquid ammonia fuel can be supplied to the combustor without using a fuel pump to move the liquid ammonia fuel from the supply tank to the combustor.

[0012] An exemplary fuel supply system may also include a start-up skid disposed on the fuel supply line between the supply tank and the combustor. The start-up skid may include a start-up fuel pump configured to deliver liquid ammonia fuel to the combustor during a start-up operation while the liquid ammonia fuel in the supply tank is heated to sufficient ammonia vapor pressure. A relatively small amount of liquid ammonia fuel may be required for the start-up operation, and therefore, a low-capacity fuel pump may be included on the start-up skid to reduce costs and required maintenance. In the exemplary start-up skid, the start-up fuel pump is disposed on the start-up line, and the liquid ammonia fuel is initially flowed toward the combustor until the ammonia vapor pressure in the supply tank reaches a pressure sufficient to drive the liquid ammonia fuel toward the combustor without using the fuel pump. During this phase, a control valve may be operated to selectively bypass the liquid ammonia fuel through a bypass line on the start-up skid and bypass the start-up fuel pump. A controller may be configured to operate the control valve based on the ammonia vapor pressure in the supply tank. For example, the controller may operate the control valve based on a measured pressure in the supply tank and / or based on a determined pressure differential between the supply tank and the combustor. In some embodiments, the control valve may be metered to gradually increase the flow of liquid ammonia fuel in the bypass line while simultaneously decreasing the flow of liquid ammonia fuel in the start line as ammonia vapor pressure in the supply tank increases.

[0013] In an exemplary embodiment, the heat exchanger is a heating jacket of the supply tank that circulates a heat exchange fluid for heating the liquid ammonia fuel in the supply tank by conductive or convective heating. The heat exchange fluid may be derived from any suitable heat source. In some embodiments, the heat exchange fluid is hot exhaust gas generated by a turbine of a rotary machine and recirculated to the heat exchanger via an exhaust gas recirculation system. In other embodiments, the heat transfer fluid is steam generated by a heat recovery steam generator coupled to the rotary machine. The steam may be drawn immediately downstream from the heat recovery steam generator or may be drawn downstream from a steam turbine coupled to the heat recovery steam generator.

[0014] In an exemplary embodiment, the fuel supply system also includes a storage tank disposed on the fuel supply line upstream of the supply tank. The storage tank is sized to accommodate liquid ammonia fuel therein. The liquid ammonia fuel may be maintained in the storage tank at a temperature and pressure lower than those in the supply tank to substantially prevent vaporization in the storage tank. As the liquid ammonia fuel in the supply tank is driven toward the combustor, the liquid ammonia fuel in the storage tank flows toward the supply tank to replenish the volume of liquid ammonia fuel in the supply tank. The liquid ammonia fuel replenished in the supply tank maintains ammonia vapor pressure equilibrium in the storage tank. Thus, the storage tank utilizes ammonia vapor pressure in the supply tank to facilitate maintaining a continuous flow of liquid ammonia fuel driven toward the combustor. In some embodiments, a check valve may be disposed between the storage tank and the supply tank to facilitate preventing liquid ammonia fuel from flowing back from the supply tank to the storage tank.

[0015] Exemplary embodiments described herein facilitate the use of ammonia as a combustion fuel in rotary machines while overcoming several technical challenges associated with ammonia fuel. Ammonia is an advantageous combustion fuel because it produces no carbon-based emissions upon combustion. Furthermore, ammonia may offer several advantages over other "green" combustion fuels, such as hydrogen fuel. Compared to hydrogen, ammonia has a 45% higher volumetric density, is safer to handle, and is significantly less expensive to store. However, ammonia is a relatively corrosive chemical, making integration into conventional fuel supply systems limited and potentially costly. This is because certain components of the supply system (e.g., fuel pumps) must be equipped with corrosion-resistant materials, which can increase capital and maintenance costs. The systems and methods described herein include the use of a self-pressurized supply tank to supply ammonia fuel to rotary machines, which may eliminate the need for a fuel pump to move the ammonia fuel or significantly reduce the capacity required for such a fuel pump (e.g., a low-capacity fuel pump may be needed only during start-up operations). The self-pressurized supply tank also helps reduce or eliminate the tendency for gaseous ammonia to become entrained in the liquid ammonia fuel supplied to the combustor, which can adversely affect flame propagation and result in undesirable combustion dynamics in the combustor section. In particular, the liquid ammonia fuel in the self-pressurized tank is driven toward the combustor by a pressure differential rather than by mechanical action, which is known to generate gaseous ammonia bubbles in the liquid ammonia fuel stream. Thus, the exemplary systems and methods provide significant technological advantages, promoting the use of ammonia combustion fuel while reducing or eliminating cost and other limitations that may prevent such use.

[0016] In the following specification and claims, reference will be made to a number of terms that shall be defined as set forth below.

[0017] The singular forms "a," "an," "the," and "said" include plural references unless the context clearly dictates otherwise.

[0018] The terms "comprising," "containing," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0019] The term "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes both instances where the event occurs and instances where it does not occur.

[0020] The phrases "one embodiment" or "an embodiment" are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, particular features of the various embodiments described herein may be shown in some drawings and not in others for reasons of convenience. In accordance with the principles of the present disclosure, any feature of any drawing and / or embodiment described herein may be referenced and / or claimed in combination with any feature of any other drawing and / or embodiment described herein. Furthermore, unless expressly stated to the contrary, an embodiment "comprising" or "having" an element or elements having a particular characteristic may also include additional such elements that do not have that characteristic.

[0021] As used herein, the term "real-time" refers to the time of occurrence of relevant events, the time of measurement and collection of given data, the time of processing data, or the time of response of a system to events and circumstances. In the embodiments described herein, these activities and events occur substantially instantaneously.

[0022] As used herein, the terms "processor" and "computer" and related terms, such as "processing device," "computing device," and "controller," alternatively broadly refer to microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits, and / or other programmable circuits, and these terms are used interchangeably herein. In the embodiments described herein, memory includes, but is not limited to, computer-readable media such as random access memory (RAM) and non-volatile computer-readable media such as flash memory. Alternatively, floppy disks, compact disks-read-only memories (CD-ROMs), magneto-optical disks (MODs), and / or digital versatile disks (DVDs) may also be used. Also, in the embodiments described herein, additional input channels may be, but are not limited to, computer peripherals associated with an operator interface, such as a mouse or keyboard. Alternatively, other computer peripherals, such as a scanner, may also be used. Furthermore, in the embodiments described herein, additional output channels may be, but are not limited to, an operator interface monitor.

[0023] Unless otherwise specified, approximate terms such as "generally," "substantially," and "about" used herein indicate that the terms apply only to an approximate degree that would be recognized by a person of ordinary skill in the art, rather than to an absolute or perfect degree. Thus, values modified by terms such as "about," "approximately," and "substantially" are not limited to the exact value specified. In at least some cases, approximate terms may correspond to the precision of the instrument measuring the value. Furthermore, unless otherwise specified, terms such as "first," "second," and "second" are used herein merely as labels and are not intended to impose any order, position, or hierarchical requirements on the items they refer to. Furthermore, a reference to a "second" item does not require or exclude the presence of a "first" or lower-numbered item, or a "third" or higher-numbered item.

[0024] Referring to the drawings, FIG. 1 is a schematic diagram of an exemplary power generation system 100. The power generation system 100 includes a rotary machine 102 operable using liquid ammonia fuel. In an exemplary embodiment, the rotary machine 102 is a gas turbine engine 102 operable using liquid ammonia fuel. The gas turbine engine 102 includes a compressor 104, one or more combustors 106, and a turbine 108 coupled in a serial flow relationship. A shaft 110 extends axially and operably couples the compressor 104 to the turbine 108. The gas turbine engine 102 may be coupled to a generator 112 via the shaft 110 to generate electrical power. It should be noted that while the exemplary power generation system 100 of FIG. 1 includes a gas turbine engine 102, the power generation system 100 is not limited to any particular type of rotary machine. Any suitable rotary machine 102 operable using liquid ammonia fuel may be used in the power generation system 100 in any suitable configuration.

[0025] In an exemplary operation of the power generation system 100, the combustor 106 receives a compressed working fluid including an oxidant (e.g., compressed air) from the compressor 104 and also receives liquid ammonia fuel. The liquid ammonia fuel and compressed working fluid are mixed and combusted in the combustor 106 to generate combustion gases. The combustion gases are channeled to the turbine 108, where they expand and perform work in the turbine 108, rotating a shaft 110, which may enable a generator 112 to generate electrical power. Exhaust gases may exit the turbine 108 through an exhaust duct 132. The exhaust gases may be recirculated back to the compressor 104 or may be used, for example, in a heat recovery steam generator system (see FIG. 3 ) that generates steam from thermal energy extracted from the exhaust gases. Alternatively, the exhaust gases may be subjected to emissions control treatment (e.g., selective catalytic reduction) to remove unwanted combustion by-products (e.g., NOx) from the exhaust stream.

[0026] The power generation system 100 also includes a fuel supply system 114 configured to supply liquid ammonia fuel to the combustor 106. The fuel supply system 114 includes a fuel supply line 116 coupled to the combustor 106. The fuel supply line 116 may include conduits and / or other piping suitable for flowing the liquid ammonia fuel to the combustor 106. In some embodiments, the fuel supply line 116 may be fabricated from steel or other suitable material that is chemically compatible with the liquid ammonia fuel.

[0027] The fuel supply system 114 also includes a supply tank 118 disposed on the fuel supply line 116 upstream of the combustor 106. The supply tank 118 is sized and shaped to accommodate a volume of liquid ammonia fuel. The dimensions of the supply tank 118 may vary depending on the capacity requirements of the power generation system 100. The fuel supply system 114 may include one supply tank 118 or two or more supply tanks 118. In embodiments including multiple supply tanks 118, the supply tanks 118 may be arranged in series, parallel, or a combination thereof on the fuel supply line 116. The supply tank 118 includes an inlet 120 for liquid ammonia fuel to enter the supply tank 118 and an outlet 122 for liquid ammonia fuel to exit the supply tank 118. The supply tank 118 may be vertically oriented and includes a top 124 and a bottom 126. Each of the inlet 120 and outlet 122 may be defined by a fitting (not shown) located near a bottom 126 of the supply tank 118. The fitting couples the inlet 120 and outlet 122 of the supply tank 118 to the fuel supply line 116.

[0028] Fuel supply system 114 also includes a heat exchanger 128 configured to heat the liquid ammonia fuel in supply tank 118. Heat exchanger 128 may be thermally connected to supply tank 118 such that heat exchanger 128 heats the liquid ammonia fuel by conductive heating or convective heating. In an exemplary embodiment, heat exchanger 128 is a heating jacket that surrounds supply tank 118. In other embodiments, heat exchanger 128 may have any suitable configuration that enables heat exchanger 128 to function as described herein (e.g., a thermal fluid-containing tank that surrounds supply tank 118).

[0029] In some embodiments, the heat exchanger 128 is coupled to a heat source 130 that provides a heat transfer fluid (e.g., hot exhaust gas or steam) to the heat exchanger 128. In various embodiments, the heat transfer fluid may include waste heat generated by the power generation system 100. For example, the heat transfer fluid may be exhaust gas generated by the turbine 108 that exits through the exhaust duct 132 and is channeled to the heat exchanger 128 using an exhaust gas recirculation (EGR) system (e.g., EGR system 202 shown in FIG. 2 ). Additionally and / or alternatively, the heat transfer fluid may be steam generated by or downstream of a heat recovery steam generator (HRSG) (e.g., HRSG 304 shown in FIG. 3 ) coupled to the gas turbine engine 102. In other embodiments, the heat transfer fluid may be any suitable heat transfer fluid that enables the heat exchanger 128 to function as described herein.

[0030] One or more heat transfer fluid flow control devices 144 may be disposed between the heat source 130 and the heat exchanger 128. The heat transfer fluid flow control devices 144 may include a control valve that controls the flow rate of the heat transfer fluid supplied from the heat source 130 to the heat exchanger 128. Additional or alternative flow control means may be included as the heat transfer fluid flow control devices 144. For example, the heat transfer fluid flow control devices 144 may include a pump or blower controllable to adjust the flow rate of the heat transfer fluid supplied to the heat exchanger 128. The heat transfer fluid flow control devices 144 may facilitate adjusting the amount of heat transfer fluid supplied to the heat exchanger 128 to heat the liquid ammonia fuel in the supply tank 118 to a desired temperature. The heat transfer fluid flow control devices 144 may be selectively operated using operating condition feedback from sensors (e.g., pressure sensor 138 and / or temperature sensor 142) coupled to the supply tank 118 and / or the heat exchanger 128.

[0031] In the exemplary embodiment, the heat exchanger 128 is operable to heat the liquid ammonia fuel in the supply tank 118 such that the ammonia vapor pressure in the supply tank 118 is sufficient to drive the liquid ammonia fuel from the supply tank 118 towards the combustor 106. In particular, the heat exchanger 128 is operable to heat the liquid ammonia fuel in the supply tank 118 such that the ammonia vapor pressure in the supply tank 118 increases to a pressure that exceeds the operating pressure of the combustor 106. This creates a positive pressure differential between the supply tank 118 and the combustor 106, driving the liquid ammonia fuel from the supply tank 118 towards the combustor 106 (e.g., without the need for a large capacity pump).

[0032] The amount of heat provided by the heat exchanger 128 can vary depending on the desired ammonia vapor pressure in the supply tank 118 and the operating pressure in the combustor 106. The amount of heat provided by the heat exchanger 128 is determined based on the temperature to which the liquid ammonia fuel must be heated to achieve the desired ammonia vapor pressure. The supply tank 118, in some embodiments, may include insulation around the supply tank 118 to insulate heat and help maintain the temperature and ammonia vapor pressure within the supply tank 118.

[0033] The temperature to which liquid ammonia fuel is heated to achieve a desired ammonia vapor pressure may be determined based on the vapor pressure characteristics of ammonia at gas-liquid equilibrium. Table 1 below lists the approximate ammonia vapor pressure (in absolute pressure units) for various temperatures (°C) at gas-liquid equilibrium. Vapor pressure of ammonia in vapor-liquid equilibrium [Table 1]

[0034] As shown in Table 1, at a temperature of about 25°C, the vapor pressure of ammonia is about 10.0 bar absolute (bara). At a temperature of about 40°C, the vapor pressure of ammonia is about 15.5 bar. At a temperature of about 100°C, the vapor pressure of ammonia increases to about 60 bar or greater. At temperatures of about 125°C or greater, the vapor pressure of ammonia increases to about 100 bar or greater.

[0035] In some embodiments, the heat exchanger 128 may heat the liquid ammonia fuel in the supply tank 118 to at least about 20°C, at least about 30°C, at least about 40°C, at least about 50°C, at least about 60°C, at least about 70°C, at least about 80°C, at least about 90°C, at least about 100°C, at least about 110°C, or at least about 120°C. In various embodiments, the heat exchanger 128 is operable to heat the liquid ammonia fuel in the supply tank 118 to a temperature between about 20°C and about 150°C, for example, between about 40°C and about 150°C. In one exemplary embodiment, the heat exchanger 128 is operable to heat the liquid ammonia fuel in the supply tank 118 to a temperature of about 125°C. The temperature to which the liquid ammonia fuel is heated may be any temperature suitable for the fuel supply system 114 to function as described herein.

[0036] In some embodiments, heat exchanger 128 heats the liquid ammonia fuel in supply tank 118 so that the ammonia vapor pressure in supply tank 118 is at least about 15 bar, at least about 20 bar, at least about 30 bar, at least about 40 bar, at least about 50 bar, at least about 60 bar, at least about 70 bar, at least about 80 bar, or at least about 90 bar. In various embodiments, heat exchanger 128 is operable to heat the liquid ammonia fuel in supply tank 118 so that the ammonia vapor pressure in supply tank 118 is from about 15 bar to about 125 bar. In one exemplary embodiment, heat exchanger 128 is operable to heat the liquid ammonia fuel in supply tank 118 so that the ammonia vapor pressure in supply tank 118 is about 100 bar. The heat exchanger 128 may be operable to heat the liquid ammonia fuel in the supply tank 118 to any suitable ammonia vapor pressure for the fuel supply system 114 to function as described herein. For example, the ammonia vapor pressure in the supply tank 118 generated by the heat exchanger 128 may be sufficient to drive the liquid ammonia fuel from the supply tank 118 towards the combustor 106, which may vary depending on, for example, the operating conditions of the power generation system 100 (e.g., the operating pressure of the combustor 106).

[0037] In some embodiments, the heat exchanger 128 is operable to heat the liquid ammonia fuel in the supply tank 118 to an appropriate temperature so that the ammonia vapor pressure in the supply tank 118 is within a range approximately equal to the operating pressure range of the fuel pump. This pressure range may vary depending on the requirements and operating conditions of the power generation system 100. By creating an ammonia vapor pressure in the supply tank 118 approximately equal to the operating pressure range of the fuel pump, it may be possible to eliminate or bypass the fuel pump because the ammonia vapor pressure can drive the liquid ammonia fuel toward the combustor 106 at a rate substantially similar to the fuel pump.

[0038] In the exemplary embodiment, fuel supply system 114 also includes a supply skid 134, also referred to as a start-up skid 134, disposed on fuel supply line 116 between supply tank 118 and combustor 106. Start-up skids are described in more detail below with reference to FIG. 4. Start-up skid 134 may facilitate pumping liquid ammonia fuel from supply tank 118 to combustor 106 during start-up operations while the temperature and ammonia vapor pressure within supply tank 118 increase.

[0039] The start-up skid 134 is communicatively coupled to a controller 136 configured to selectively operate the start-up skid 134 based on the ammonia vapor pressure in the supply tank 118. For example, the controller 136 may selectively operate the start-up skid 134 based on the measured ammonia vapor pressure in the supply tank 118 and / or a determined pressure difference between the ammonia vapor pressure and the operating pressure of the combustor 106. The controller 136 may receive ammonia vapor pressure measurements from one or more supply tank pressure sensors 138 coupled to the supply tank 118. The controller 136 may also receive combustor pressure measurements from one or more combustor pressure sensors 140 coupled to the combustor 106. Other sensors, such as temperature sensors (e.g., sensor 142), may also be coupled to the supply tank 118 and / or the combustor 106 to enable the controller 136 to function as described herein.

[0040] The controller 136 may additionally and / or alternatively be communicatively coupled to the heat exchanger 128, a temperature sensor 142 coupled to the heat exchanger 128 and / or the supply tank 118, and / or one or more heat transfer fluid flow controllers 144 disposed between the supply tank 118, the heat source 130, or the heat source 130 and the heat exchanger 128. The controller 136 may be configured to adjust (e.g., increase or decrease) the heating of the liquid ammonia fuel in the supply tank 118 provided by the heat exchanger 128. For example, the controller 136 may adjust (e.g., increase or decrease) the flow rate of the heat exchange fluid supplied to the heat exchanger 128 by selectively controlling (e.g., metering) the heat transfer fluid flow controllers 144. The controller 136 can selectively control the heat transfer fluid flow control device 144 based on feedback from sensors coupled to the supply tank 118 and / or the heat exchanger 128 (e.g., pressure sensor 138 and / or temperature sensor 142) to achieve a desired heating of the liquid ammonia fuel and / or a desired ammonia vapor pressure within the supply tank 118.

[0041] In the exemplary embodiment, controller 136 is a computer system including at least one processor (not shown) and at least one memory device (not shown). The memory device may include non-transitory computer-readable media and programs accessed by the processor to perform operations for controlling start-up skid 134. Operations performed by controller 136 using the processor may include applying control algorithms to selectively operate start-up skid 134 and / or adjust heating provided by heat exchanger 128 based on, for example, the ammonia vapor pressure in the supply tank and / or a determined pressure differential between the operating pressure of combustor 106 and the ammonia vapor pressure.

[0042] The controller 136 may include a communication interface that communicatively couples the controller 136 to one or more components of the system 100 via one or more connections 162. For example, the one or more connections 162 may communicatively couple the controller 136 to the sensors 138, 140, 142, the starting skid 134, the heat transfer fluid flow control device 144, the heat exchanger 128, and / or other components of the system 100. The communication interface may include, for example, a wired or wireless network adapter and / or a wireless data transceiver for use with a mobile communication network. In this manner, the one or more connections 162 may communicatively couple the controller 136 to one or more components of the system 100 via wired and / or wireless connections.

[0043] In some embodiments, the controller 136 may include and / or generate an operational model of the fuel supply system 114 and the combustor 106. The operational model may define operational boundaries for the combustor 106 based on the liquid ammonia fuel supplied to the combustor 106 by the fuel supply system 114. The controller 136 may identify, for example, that the ammonia vapor pressure in the supply tank 118 is at risk of exceeding the operational boundaries when the ammonia vapor pressure is insufficient to drive the ammonia liquid fuel to the combustor 106, which may adversely affect flame propagation and / or cause unacceptable combustion conditions (e.g., lean burn or engine knock). In this regard, the controller 136 may predict combustion conditions related to the ammonia vapor pressure in the supply tank 118. This allows the controller 136 to determine in real time whether the ammonia vapor pressure should be adjusted (e.g., increased). In response, the controller 136 can generate an output signal that adjusts the heating provided by the heat exchanger 128 .

[0044] For example, the controller 136 may selectively control one or more heat transfer fluid flow control devices 144 to adjust (e.g., increase or decrease) the flow rate of the heat transfer fluid supplied to the heat exchanger 128. Additionally and / or alternatively, in response to determining whether the ammonia vapor pressure in the supply tank 118 should be adjusted (e.g., increased), the controller 136 may selectively operate the start-up skid 134 in a start-up mode to drive liquid ammonia fuel from the supply tank 118 to the combustor 106 while the temperature and ammonia vapor pressure in the supply tank 118 increase to a desired level. When the controller 136 determines that the ammonia vapor pressure in the supply tank 118 is sufficient to drive the liquid ammonia fuel toward the combustor 106, the controller selectively operates the start-up skid 134 to enter an idle mode or a bypass mode, as further described herein.

[0045] In some embodiments, the controller 136 can receive a feedback signal from the combustor 106 (e.g., via the combustor pressure sensor 140 or other sensors) and use the feedback signal in a feedback application to update the operational model. For example, the controller 136 can compare a combustion signal from the combustor 106 to predicted combustion conditions determined by comparing the ammonia vapor pressure in the supply tank 118 to an operational model. The controller 136 can determine whether the predicted combustion conditions match the combustion behavior indicated by the combustion signal. If the predicted combustion conditions do not match the combustion behavior, the controller 136 can update the operational model by correlating the ammonia vapor pressure in the supply tank 118 with the combustion feedback. In this manner, ammonia vapor pressures associated with negative combustion behavior in the combustor 106 can be identified, and the operational model can be updated to better predict these conditions in real time for similar ammonia vapor pressures in the supply tank 118.

[0046] 4 is a schematic diagram of a portion of the example power generation system 100 of FIG. 1 , illustrating in more detail the start-up skid 134 disposed between the supply tank 118 and the combustor 106. In the example embodiment, the start-up skid 134 includes a start-up line 146 and a bypass line 148, which may also be considered part of the fuel supply line 116. The start-up line 146 extends from the supply tank 118 to the combustor 106 and includes a start-up fuel pump 150 configured to drive liquid ammonia fuel to the combustor 106. Because the start-up fuel pump 150 is used only for a relatively short start-up period, the start-up fuel pump 150 may be a low-capacity fuel pump, thereby reducing capital and maintenance costs associated with the fuel pump 150 (e.g., compared to a fuel pump 150 sized for continuous use).

[0047] Suitably, the start-up skid 134 is configured to allow the start-up fuel pump 150 to operate when the ammonia vapor pressure in the supply tank 118 is insufficient to drive the liquid ammonia fuel to the combustor 106. For example, during start-up operations of the power generation system 100, while the heat exchanger 128 begins to heat the liquid ammonia fuel in the supply tank 118, the ammonia vapor pressure in the supply tank 118 may be insufficient to drive the initial flow of liquid ammonia fuel to the combustor 106 during start-up. The start-up fuel pump 150 may be used during this phase.

[0048] The bypass line 148 is positioned to selectively direct the liquid ammonia fuel to bypass the start line 146 and the start pump 150. The bypass line 148 has an inlet end in fluid communication with the start line 146 upstream of the start pump 150 and an outlet end in fluid communication with the start line 146 downstream of the start pump 150, thereby selectively directing the liquid ammonia fuel around (i.e., bypassing) the start pump 150. The start skid 134 also includes a control valve 152 configured to selectively direct the liquid ammonia fuel from the supply tank 118 to one of the start line 146 and the bypass line 148. In particular, control valve 152 may be controlled by controller 136 to direct liquid ammonia fuel to bypass start line 146 through bypass line 148 under certain operating conditions of fuel supply system 114 (e.g., when the ammonia vapor pressure in supply tank 118 is sufficient to drive the liquid ammonia fuel without start fuel pump 150). As shown in FIG. 4 , control valve 152 is located downstream of start fuel pump 150. In this example, control valve 152 is selectively operable to regulate or meter the flow of liquid ammonia fuel through start line 146 and / or bypass line 148, and the position of control valve 152 can be adjusted so that substantially all of the liquid ammonia fuel flows through one of start line 146 or bypass line 148, or so that a portion of the liquid ammonia fuel flows through each of start line 146 and bypass line 148. In other examples, control valve 152 may be located upstream of start fuel pump 150.

[0049] Controller 136 may be communicatively coupled to control valve 152 and configured to operate control valve 152 based on the ammonia vapor pressure in supply tank 118. For example, controller 136 may operate control valve 152 to selectively flow liquid ammonia fuel through start line 146 when there is insufficient ammonia vapor pressure in supply tank 118, such that start fuel pump 150 drives the liquid ammonia fuel toward combustor 106. When there is sufficient ammonia vapor pressure in supply tank 118 to drive the liquid ammonia fuel without using start fuel pump 150, controller 136 may operate control valve 152 to selectively flow liquid ammonia fuel through bypass line 148. Additionally, controller 136 may adjust or meter control valve 152 such that as supply tank 118 heats and the ammonia vapor pressure in supply tank 118 increases, the flow of liquid ammonia fuel in bypass line 148 gradually increases and the flow of liquid ammonia fuel in start line 146 gradually decreases.

[0050] 1 , the fuel supply system 114 may also include a storage tank 154 disposed on the fuel supply line 116 upstream of the supply tank 118. The storage tank 154 is sized and shaped to receive a volume of liquid ammonia fuel (e.g., from a pipeline or other source) and accommodate a volume of liquid ammonia fuel for replenishing the supply tank 118. The dimensions of the storage tank 154 may vary depending on the capacity requirements of the power generation system 100 and the dimensions of the supply tank 118. There may be one or more storage tanks 154. The fuel supply system 114 may include more storage tanks 154 than supply tanks 118, or may include an equal number of storage tanks 154 and supply tanks 118 for each power generation system 100. In embodiments including multiple supply tanks 118, one or more storage tanks 154 may be included and coupled to one of the supply tanks 118. Alternatively, one storage tank 154 may be included and coupled to each supply tank 118. The storage tank 154 includes an inlet 160 that allows liquid ammonia fuel to enter the storage tank 154 and an outlet 158 that allows liquid ammonia fuel to exit the storage tank 154. Each of the inlet 160 and the outlet 158 may be defined by a fitting (not shown) that couples to the fuel supply line 116. A check valve 156 may be disposed between the storage tank 154 and the supply tank 118 to help prevent backflow of liquid ammonia fuel from the supply tank 118 to the storage tank 154.

[0051] The liquid ammonia fuel may be maintained at a temperature and pressure within storage tank 154 that is lower than the temperature and pressure within supply tank 118 to prevent substantial vaporization of the liquid ammonia fuel within storage tank 154. As the liquid ammonia fuel within supply tank 118 is driven toward combustor 106, the liquid ammonia fuel within storage tank 154 flows through check valve 156 toward supply tank 118, replenishing the volume of liquid ammonia fuel within supply tank 118. The liquid ammonia fuel replenished within supply tank 118 maintains equilibrium of the ammonia vapor pressure within storage tank 154 because the relative amounts of vaporized ammonia and liquid ammonia fuel within supply tank 118 remain substantially constant. Additionally, due to the presence of heat exchanger 128 and / or insulation around supply tank 118, and the size of supply tank 118 (relative to the rate at which liquid ammonia fuel enters and leaves supply tank 118), the change in temperature within storage tank 118 due to replenished cold liquid ammonia fuel is negligible and does not substantially affect the ammonia vapor pressure within storage tank 118. Thus, storage tank 154 facilitates utilizing the ammonia vapor pressure within storage tank 118 to maintain a continuous flow of liquid ammonia fuel driven towards combustor 106.

[0052] 2 is a schematic diagram of an alternative power generation system 200 including the gas turbine engine 102 and liquid ammonia fuel supply system 114 of FIG. 1 . The power generation system 200 includes all of the elements and components shown in FIG. 1 and described herein for the power generation system 100. The power generation system 100 also includes an exhaust gas recirculation (EGR) system 202 fluidly coupled downstream from the gas turbine engine 102. The EGR system 202 may be used to recirculate exhaust gases generated by the gas turbine engine 102 toward the compressor 104. The exhaust gases are mixed with the working fluid entering the compressor 104, thereby diluting the working fluid to reduce the amount of oxygen entrained in the compressed working fluid, which may facilitate a reduction in peak combustion temperatures in the combustor 106 and / or a reduction in the formation of NOx. The EGR system 202 is also coupled to the heat exchanger 128 via an exhaust gas line 212, which in this embodiment is used as the heat source 130. In this regard, the waste heat in the exhaust gases may be used to heat the liquid ammonia fuel in the supply tank 118 .

[0053] The EGR system 202 includes an exhaust gas treatment system 204 coupled to the exhaust duct 132 and configured to receive exhaust gases generated by the gas turbine engine 102. The exhaust gases are treated using the exhaust gas treatment system 204 and then recirculated through an EGR loop 214 toward the compressor 104. A portion of the treated exhaust gases is also discharged from the exhaust gas treatment system 204 via an exhaust gas line 212 to the heat exchanger 128. In certain embodiments, the exhaust gas treatment system 204 may include multiple treatment units for use in producing the treated exhaust gases, such as a filter unit 206, a selective catalytic reduction unit 208, an absorption unit 210, and / or any other type of exhaust gas treatment unit. The treated exhaust gases exiting the exhaust gas treatment system 204 may have a lower temperature and / or saturation than the temperature and / or saturation of the exhaust gases exiting the gas turbine engine 102 via the exhaust duct 132.

[0054] In some embodiments, the compressor 104 and / or the heat exchanger 128 may receive treated exhaust gases exiting the exhaust gas treatment system 204, untreated exhaust gases exiting the gas turbine engine 102 via the exhaust duct 132, or other sources of exhaust gases generated within the power generation system 200, with or without passing through various equipment. For example, in some embodiments, the exhaust gases from the gas turbine engine 102 may be recirculated via the exhaust gas line 212 to the compressor 104 via the EGR loop 214 and / or the heat exchanger 128 without passing through the exhaust gas treatment system 202.

[0055] The exhaust gases may be channeled to the respective EGR loop 214 and exhaust gas line 212 using one or more recirculation blowers or compressors (not shown) of the EGR system 202. In some embodiments, the EGR system 202 may include a control valve or other control device (e.g., a splitter, not shown) to facilitate control of the ratio of exhaust gases flowing to the compressor 104 and the heat exchanger 128. For example, the EGR system 202 recirculates between about 0% and about 40% of the exhaust gases exiting the gas turbine engine 102 through the EGR loop 214 to the compressor 104, and channels another portion of the exhaust gases through the exhaust gas line 212 to the heat exchanger 128. In some embodiments, a portion of the exhaust gases flowing through the exhaust gas line 212 to the heat exchanger 128 may be drawn from upstream of the exhaust gas treatment system 204, and a portion of the exhaust gases flowing through the EGR loop 214 to the compressor 104 is drawn from downstream of the exhaust gas treatment system 204.

[0056] One or more heat transfer fluid flow controllers 144 may be disposed on the exhaust gas line 212 upstream of the heat exchanger 128. As described above, the heat transfer fluid flow controllers 144 are selectively operable to facilitate adjusting the amount of exhaust gas (used as a heat transfer fluid in this embodiment) supplied to the heat exchanger 128 to achieve a desired heating state of the liquid ammonia fuel in the supply tank 118. The heat transfer fluid flow controllers 144 may be selectively operated using operating condition feedback from sensors (e.g., pressure sensor 138 and / or temperature sensor 142) coupled to the supply tank 118 and / or the heat exchanger 128. For example, the controller 136 may adjust (e.g., increase or decrease) the flow rate of the exhaust gas in the exhaust gas line 212 based on feedback from sensors (e.g., pressure sensor 138 and / or temperature sensor 142) coupled to the supply tank 118 and / or the heat exchanger 128 to achieve a desired heating of the liquid ammonia fuel and / or a desired ammonia vapor pressure in the supply tank 118. In some embodiments, the exhaust gas line 212 may also include insulation to insulate the exhaust gas as it is routed toward the heat exchanger 128.

[0057] Figure 3 is a schematic diagram of a combined cycle power plant 300 including the gas turbine engine 102 and liquid ammonia fuel supply system 114 of Figure 1. The combined cycle power plant 300 includes all of the elements and components shown in Figure 1 and described herein for the power generation system 100. The combined cycle power plant 300 also includes a heat recovery steam generator 304 downstream of and fluidly coupled to the gas turbine engine 102 via the exhaust duct 132. The combined cycle power plant 300 may also include a steam turbine 306 downstream of and fluidly coupled to the HRSG 304.

[0058] The HRSG 304 is used to generate high-pressure, high-temperature exhaust steam using waste heat available in the exhaust gases exiting the gas turbine engine 102 via the exhaust duct 132. The generated steam may be channeled, at least in part, to the steam turbine 306 to operate it. The HRSG 304 may include various components to facilitate the use of the exhaust gases to generate steam, such as a preheater, an evaporator, an economizer, a reheater, and a superheater. One, two, or more, or all of these components may be incorporated into the HRSG 304. The evaporator is used to evaporate water to generate steam and may include multiple drums to allow the water to interact with the exhaust gases entering the HRSG 304. The economizer may be used to heat feedwater upstream of the evaporator. The steam produced in the evaporator is saturated steam, and the saturated steam exiting the evaporator may be fed to a superheater to produce dry steam. The dry steam exiting the HRSG 304 may be used to operate the steam turbine 306.

[0059] In the exemplary combined cycle power plant 300, a portion of the steam generated using the HRSG 304 is also channeled to the heat exchanger 128. Waste heat from the steam is used as the heat source 130 to heat the liquid ammonia fuel in the supply tank 118. In the illustrated embodiment, the HRSG 304 is coupled to the heat exchanger 128 via a steam line 308. Steam is extracted from the HRSG 304 and routed to the heat exchanger 128 via the steam line 308. The steam routed to the heat exchanger 128 via the steam line 308 may be saturated or dry steam. In other embodiments, the steam used in the heat exchanger 128 may be extracted downstream of the steam turbine 306.

[0060] One or more heat transfer fluid flow controllers 144 may be disposed on the steam line 308 upstream of the heat exchanger 128. As described above, the heat transfer fluid flow controllers 144 are selectively operable to facilitate adjusting the amount of steam (used as a heat transfer fluid in this embodiment) supplied to the heat exchanger 128 to achieve a desired heating state of the liquid ammonia fuel in the supply tank 118. The heat transfer fluid flow controllers 144 may be selectively operated using operating condition feedback from sensors (e.g., pressure sensor 138 and / or temperature sensor 142) coupled to the supply tank 118 and / or the heat exchanger 128. For example, the controller 136 selectively controls (e.g., metering) the heat transfer fluid flow control device 144 based on feedback from sensors (e.g., pressure sensor(s) 142) coupled to the supply tank 118 and / or the heat exchanger 128 to increase or decrease the flow rate of steam in the steam line 308 to achieve a desired heating of the liquid ammonia fuel in the supply tank 118 and / or a desired ammonia vapor pressure in the supply tank 118 coupled to the heat exchanger 128. The steam line 308, in some embodiments, can also include insulation to insulate the steam as it flows toward the heat exchanger 128.

[0061] 5 is a flowchart of an exemplary method 500 for supplying liquid ammonia fuel to a rotary machine (e.g., a rotary machine or gas turbine engine 102). Method 500 may be implemented using fuel supply system 114 in a power generation system (e.g., system 100 of FIG. 1 and / or system 200 of FIG. 2) and / or a combined cycle power plant (e.g., plant 300 of FIG. 3). Method 500 includes a channeling step 502 that flows liquid ammonia fuel to a supply tank 118 located upstream of rotary machine 102. Method 500 also includes a step 504 of heating the liquid ammonia fuel in supply tank 118 to increase the ammonia vapor pressure in supply tank 118. The liquid ammonia fuel may be heated in supply tank 118 using any suitable heat source 130. In some embodiments, the liquid ammonia fuel in supply tank 118 may be heated 504 using exhaust gases generated by rotary machine 102 or steam generated downstream of rotary machine 102 (e.g., by HRSG 304).

[0062] The method 500 also includes utilizing ammonia vapor pressure in the supply tank 118 to drive 506 the liquid ammonia fuel from the supply tank 118 towards the combustor 106 of the rotary machine 102. In this regard, the liquid ammonia fuel in the supply tank 118 is heated to a suitable temperature such that the ammonia vapor pressure in the supply tank 118 can drive 506 the liquid ammonia fuel towards the combustor 106. In some embodiments, the liquid ammonia fuel in the supply tank 118 is heated to at least about 20°C, at least about 30°C, at least about 40°C, at least about 50°C, at least about 60°C, at least about 70°C, at least about 80°C, at least about 90°C, at least about 100°C, at least about 110°C, or at least about 120°C, e.g., between about 20°C and about 150°C, between about 40°C and about 150°C, or about 125°C. In some embodiments, the liquid ammonia fuel in supply tank 118 has an ammonia vapor pressure in supply tank 118 of at least about 15 bar, at least about 20 bar, at least about 30 bar, at least about 40 bar, at least about 50 bar, at least about 60 bar, at least about 70 bar, at least about 80 bar, or at least about 90 bar, for example, between about 15 bar and about 125 bar, or between about 100 bar.

[0063] In some embodiments, the method 500 includes heating 504 the liquid ammonia fuel in the supply tank 118 while operating the start-up skid 134 to drive the liquid ammonia fuel toward the combustor 106. For example, the method 500 includes driving the liquid ammonia fuel to the combustor 106 using the fuel pump 150 when the ammonia vapor pressure in the supply tank 118 is at a first pressure (e.g., a pressure less than or equal to a setpoint ammonia vapor pressure), raising the ammonia vapor pressure in the supply tank from the first pressure to a second pressure (e.g., a pressure at or above the setpoint ammonia vapor pressure), and selectively bypassing the fuel pump 150 and using the ammonia vapor pressure in the supply tank 118 to drive 506 the liquid ammonia fuel from the supply tank 118 toward the combustor 106 of the rotary machine 102 when the ammonia vapor pressure in the supply tank is at the second pressure.

[0064] In some embodiments, liquid ammonia fuel is flowed from storage tank 154 upstream of supply tank 118 and passes through check valve 156, which limits or prevents backflow of liquid ammonia fuel from supply tank 118 to storage tank 154. In some such embodiments, method 500 may include using storage tank 154 to replenish the liquid ammonia fuel in supply tank 118, thereby maintaining ammonia vapor pressure in supply tank 118.

[0065] The above-described systems and methods facilitate the supply of ammonia fuel to the combustors described herein while reducing or eliminating the costs, maintenance, and other limitations associated with the use of ammonia as a combustion fuel. In particular, the systems and methods described herein include the use of a self-pressurizing supply tank to drive the ammonia fuel to the rotary machinery, which may eliminate the need for a fuel pump to move the ammonia fuel or significantly reduce the required capacity of such a fuel pump (e.g., a low-capacity fuel pump may be needed only during startup operations). The self-pressurizing supply tank also helps reduce or eliminate the tendency for gaseous ammonia to become entrained in the liquid ammonia fuel supplied to the combustor. Entrainment of gaseous ammonia could adversely affect flame propagation in the combustor section or cause undesirable combustion dynamics. In particular, the liquid ammonia fuel in the self-pressurizing tank is driven toward the combustor by a pressure differential, rather than mechanical action that could generate gaseous ammonia bubbles in the liquid ammonia fuel stream. The exemplary systems and methods thereby provide significant technological advantages, facilitating the use of ammonia combustion fuel while reducing or eliminating costs and other limitations that may prevent such use.

[0066] Further aspects of the disclosure are provided by the subject matter of the following clauses. [Embodiment 1] 1. A power generation system comprising: a rotary machine comprising a combustor; and a fuel supply system configured to supply a liquid ammonia fuel to the combustor, the fuel supply system including: a fuel supply line coupled to the combustor; a supply tank disposed on the fuel supply line upstream from the combustor, the supply tank being sized to receive the liquid ammonia fuel therein; and a heat exchanger configured to heat the liquid ammonia fuel in the supply tank such that ammonia vapor pressure in the supply tank is sufficient to drive the liquid ammonia fuel from the supply tank toward the combustor. from the supply tank towards the combustor, and a power generation system. [Embodiment 2] 10. The power generation system of any preceding embodiment, wherein the fuel supply system further comprises a start-up skid disposed on the fuel supply line between the supply tank and the combustor, the start-up skid further comprising: a start-up line comprising a fuel pump; a bypass line around the fuel pump; and a control valve configured to selectively route the liquid ammonia fuel from the supply tank through one of the start-up lines and the bypass line based on the ammonia vapor pressure in the supply tank. [Embodiment 3] 10. The power generation system of any preceding embodiment, further comprising a controller configured to operate the control valve based on the ammonia vapor pressure in the supply tank. [Embodiment 4]

[0013] Embodiment 10. The power generation system of any preceding embodiment, wherein the heat exchanger is a heating jacket of the supply tank. [Embodiment 5] 10. The power generation system of any preceding embodiment, wherein the rotary machine is a gas turbine engine comprising the combustor and a turbine coupled to the combustor, and the turbine is configured to generate exhaust gases. [Embodiment 6]

[0023] 3. The power generation system of any preceding embodiment, further comprising an exhaust gas recirculation system configured to recirculate the exhaust gases from the turbine towards the heat exchanger, the heat exchanger being configured to heat the liquid ammonia fuel in the supply tank using the exhaust gases. [Embodiment 7]

[0023] Embodiment 1. The power generation system of any preceding embodiment, wherein the heat exchanger is configured to heat the liquid ammonia fuel in the supply tank to a temperature of at least about 20°C. [Embodiment 8]

[0023] 2. The power generation system of any preceding embodiment, wherein the heat exchanger is configured to heat the liquid ammonia fuel in the supply tank such that the ammonia vapor pressure in the supply tank is at least about 15 bar absolute. [Embodiment 9] 10. The power generation system of any preceding embodiment, wherein the fuel supply system further comprises a storage tank disposed on the fuel supply line upstream from the supply tank, the storage tank being sized to receive the liquid ammonia fuel therein. [Embodiment 10] 10. The power generation system of any preceding embodiment, further comprising a non-return valve disposed on the fuel supply line between the storage tank and the supply tank. [Embodiment 11] A combined cycle power plant comprising: a gas turbine engine comprising a combustor; a heat recovery steam generator (HRSG) coupled to the gas turbine engine; and a fuel supply system configured to supply liquid ammonia fuel to the gas turbine engine.and a fuel supply system configured to supply a liquid ammonia fuel to the gas turbine engine, the fuel supply system including a fuel supply line coupled to the gas turbine engine, a supply tank disposed on the fuel supply line upstream from the gas turbine engine, the supply tank being sized to receive the liquid ammonia fuel therein, and a heat exchanger configured to heat the liquid ammonia fuel in the supply tank such that an ammonia vapor pressure in the supply tank is sufficient to drive the liquid ammonia fuel from the supply tank towards the gas turbine engine. a combined cycle power plant (HRSG) and a heat exchanger (HRSG) configured to use steam generated by the HRSG to heat the liquid ammonia fuel in the supply tank; [Embodiment 12] 10. The combined cycle power plant of any preceding embodiment, further comprising a steam turbine coupled to the HRSG. [Embodiment 13] 10. The combined cycle power plant of claim 1, wherein the fuel supply system further comprises a start-up skid disposed on the fuel supply line between the supply tank and the gas turbine engine, the start-up skid including: a start-up line comprising a fuel pump; a bypass line around the fuel pump; and a control valve configured to selectively route the liquid ammonia fuel from the supply tank through one of the start-up lines and the bypass line based on the ammonia vapor pressure in the supply tank. [Embodiment 14] 10. The combined cycle power plant of any preceding embodiment, further comprising a controller configured to operate the control valve based on the ammonia vapor pressure in the supply tank. [Embodiment 15]

[0023] Embodiment 1. The combined cycle power plant of any preceding embodiment, wherein the heat exchanger is configured to heat the liquid ammonia fuel in the supply tank to a temperature of about 125°C. [Embodiment 16] 10. The combined cycle power plant of any preceding embodiment, wherein the heat exchanger is configured to heat the liquid ammonia fuel in the supply tank such that the ammonia vapor pressure in the supply tank is about 100 bar absolute. [Embodiment 17] 10. The combined cycle power plant of any preceding embodiment, wherein the fuel supply system further comprises a storage tank disposed on the fuel supply line upstream from the supply tank, the storage tank being sized to receive the liquid ammonia fuel therein. [Embodiment 18] 1. A method of supplying a liquid ammonia fuel to a rotary machine, the method comprising: channeling the liquid ammonia fuel into a supply tank; heating the liquid ammonia fuel in the supply tank to thereby increase an ammonia vapor pressure in the supply tank; and driving the liquid ammonia fuel from the supply tank towards a combustor of the rotary machine using the ammonia vapor pressure in the supply tank. [Embodiment 19] driving the liquid ammonia fuel to the combustor using a fuel pump when the ammonia vapor pressure in the supply tank is at a first pressure; heating the liquid ammonia fuel in the supply tank to increase the ammonia vapor pressure in the supply tank from the first pressure to a second pressure; and selectively bypassing the fuel pump when the ammonia vapor pressure in the supply tank is at the second pressure, driving the liquid ammonia fuel from the supply tank towards the combustor of the rotary machine using the ammonia vapor pressure in the supply tank. 10. The method of any preceding embodiment, comprising: [Embodiment 20]

[0023] The method of any preceding embodiment, further comprising heating the liquid ammonia fuel in the supply tank using one of exhaust gases generated by the rotary machine and steam generated downstream from the rotary machine.

[0067] The above description is for illustrative purposes only, and those skilled in the art will recognize that changes can be made to the described embodiments without departing from the scope of the disclosure. Modifications that fall within the scope of the present disclosure will become apparent to those skilled in the art in light of a review of the present disclosure, and such modifications are intended to be included within the scope of the appended claims. The systems and methods described herein are not limited to the specific embodiments described herein; rather, various system components may be utilized independently and separately from other systems and components described herein. For example, an exhaust gas recirculation mixer may be implemented and utilized in connection with any application in which it is desirable to use ammonia as a combustion fuel.

[0068] The methods and systems described herein are not limited to the specific embodiments described herein. For example, each system and / or each method step may be utilized individually, independent of other components and / or steps described herein. For example, the methods and systems may be used in combination with other combustion systems and are not limited to being practiced solely with the gas turbine engines described herein. Rather, the exemplary embodiments may be implemented and utilized in connection with many other rotary machines and combustion applications.

[0069] This specification 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 device or system, and performing the incorporated methods. The patentable scope of the invention is defined by the claims, and may include other embodiments that are apparent to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have 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. The claimed subject matter is as follows: [Explanation of symbols]

[0070] 100: Power generation system 102: Rotating machine / gas turbine engine 104: Compressor 106: Combustor 108: Turbine 110: Shaft 112: Generator 114: Fuel supply system 116: Fuel supply line 118: Supply tank 120: Inlet 122: Outlet 124: Top 126: Bottom 128: Heat exchanger 130: Heat source 132: Exhaust duct 134: Start skid / supply skid 136: Controller 138: Pressure sensor 140: Combustor pressure sensor 142: Temperature sensor 144: Heat transfer fluid flow control device 146: Start line 148: Bypass line 150: Fuel pump 152: Control valve 154: Storage tank 156: Check valve 158: Outlet 160: Inlet 162: Connection 200: Power generation system 202: EGR system 204: Exhaust gas treatment system 206: Filter unit 208: Selective catalytic reduction unit 210: Absorption unit 210: Exhaust gas line 214: EGR loop 300: Combined cycle power plant 304: HRSG 306: Steam turbine 308: Steam line

Claims

1. A power generation system (100), comprising: a rotary machine (102) including a combustor (106); a fuel supply system (114) configured to supply liquid ammonia fuel to the combustor (106); The fuel supply system (114) comprises: a fuel supply line (116) coupled to the combustor (106); a supply tank (118) disposed in the fuel supply line (116) upstream of the combustor (106), the supply tank (118) being sized to contain liquid ammonia fuel therein; a heat exchanger (128) configured to heat the liquid ammonia fuel in the supply tank (118) such that ammonia vapor pressure in the supply tank (118) is sufficient to drive the liquid ammonia fuel from the supply tank (118) toward the combustor (106).

2. The power generation system (100) of any preceding claim, wherein the heat exchanger (128) is a heating jacket of the supply tank (118).

3. 10. The power generation system of claim 1, wherein the rotary machine is a gas turbine engine including a combustor and a turbine coupled to the combustor, the turbine configured to generate exhaust gases.

4. 10. The power generation system of claim 1, further comprising an exhaust gas recirculation system configured to recirculate exhaust gas from the turbine toward a heat exchanger configured to use the exhaust gas to heat the liquid ammonia fuel in the supply tank.

5. A combined cycle power plant (300), comprising: A power generation system (100) according to any one of claims 1 to 4; a heat recovery steam generator (HRSG, 304) coupled to the gas turbine engine; Including, A combined cycle power plant (300) wherein a heat exchanger (128) is configured to heat liquid ammonia fuel in a supply tank (118) using steam produced by the HRSG (304).

6. The combined cycle power plant (300) of claim 5, further comprising a steam turbine (306) coupled to the HRSG (304).

7. the fuel supply system (114) further includes a starting skid (134); The starting skid (134) a start line (146) containing a fuel pump (150); a bypass line (148) around the fuel pump (150); 5. The power generation system of claim 1, further comprising: a control valve configured to selectively flow liquid ammonia fuel from the supply tank to one of the start line and the bypass line based on ammonia vapor pressure within the supply tank.

8. The power generation system (100) of claim 7, further comprising a controller (136) configured to operate the control valve (152) based on ammonia vapor pressure in the supply tank (118).

9. The power generation system (100) of any preceding claim, wherein the heat exchanger (128) is configured to heat the liquid ammonia fuel in the supply tank to a temperature of at least 20°C, optionally 125°C.

10. 2. The power generation system of claim 1, wherein the heat exchanger is configured to heat the liquid ammonia fuel in the supply tank such that the ammonia vapor pressure in the supply tank is at least 15 bar absolute, optionally 100 bar absolute.

11. 10. The power generation system of claim 1, wherein the fuel supply system further comprises a storage tank disposed in the fuel supply line upstream of the supply tank, the storage tank being sized to receive liquid ammonia fuel therein.

12. The power generation system (100) of claim 11, further comprising a check valve (156) disposed in the fuel supply line (116) between the storage tank (118) and the supply tank (118).

13. A method of supplying liquid ammonia fuel to a rotary machine (102), comprising: flowing liquid ammonia fuel into a supply tank (118); heating the liquid ammonia fuel in the supply tank (118) to increase the ammonia vapor pressure in the supply tank (118); utilizing ammonia vapor pressure within the supply tank (118) to drive liquid ammonia fuel from the supply tank (118) toward a combustor (106) of the rotary machine (102).

14. driving liquid ammonia fuel to the combustor (106) using a fuel pump (150) when the ammonia vapor pressure in the supply tank (118) is at a first pressure; heating the liquid ammonia fuel in the supply tank (118) to increase the ammonia vapor pressure in the supply tank (118) from a first pressure to a second pressure; 14. The method of claim 13, further comprising: selectively bypassing the fuel pump (150) when the ammonia vapor pressure in the supply tank (118) is at a second pressure, and utilizing the ammonia vapor pressure in the supply tank (118) to drive the liquid ammonia fuel from the supply tank (118) toward the combustor (106) of the rotary machine (102).

15. 15. The method of claim 13 or 14, further comprising heating the liquid ammonia fuel in the supply tank (118) using exhaust gases generated by the rotary machine (102) or steam generated downstream of the rotary machine (102).

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