Method of igniting liquid fuel in a turbine

Abstract

The invention is entitled "Method of igniting liquid fuel in a turbine". The invention provides a method of igniting liquid fuel (58) in a turbine combustor (22). The method includes the step of initiating a flow of gaseous fuel (28) from a gaseous fuel supply (228) to a gaseous fuel nozzle (322). The method also includes the step of initiating a flow of liquid fuel (58) from a liquid fuel supply (158) to a primary liquid fuel cartridge (358). After both the flow of gaseous fuel (28) and the flow of liquid fuel (58) are initiated, the method includes the step of igniting the flow of gaseous fuel (28) and the flow of liquid fuel (58) with an igniter (370). The method also includes the step of terminating the flow of gaseous fuel (28) from the gaseous fuel supply (228) to the gaseous fuel nozzle (322).

Description

Technical Field

[0001] This disclosure relates in its entirety to a method for igniting liquid fuel in a turbine. More specifically, this disclosure relates to a method for igniting liquid fuel within the combustor of a turbine. Background Technology

[0002] Turbines are used in a variety of industries and applications for energy transfer purposes. For example, a gas turbine engine typically includes a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section gradually increases the pressure of the working fluid entering the gas turbine engine and supplies this compressed working fluid to the combustion section. The compressed working fluid and fuel (e.g., natural gas) mix in the combustion section and are burned in the combustion chamber to produce high-pressure, high-temperature combustion gases. The combustion gases flow from the combustion section into the turbine section, where they expand to do work. For example, the expansion of the combustion gases in the turbine section can cause a rotor shaft connected to, for example, a generator to rotate to generate electricity. The combustion gases then exit the gas turbine via the exhaust section.

[0003] In the combustion zone, the fuel nozzles can operate for gaseous fuel only, liquid fuel only, or both simultaneously. In many cases, power plants may experience situations where it is necessary to operate using only liquid fuel for a given period. In these situations, plant operators have found it convenient to transition from gaseous fuel operation to liquid fuel operation. However, situations arise where the primary gaseous fuel supply is unavailable. During these situations, igniting liquid fuel at startup without relying on the primary gaseous fuel supply to complete the transition remains a challenge.

[0004] One challenge in igniting liquid fuel during startup is ensuring the igniter is close enough to the area of ​​the liquid spray capable of igniting. If the igniter is not close enough to the liquid spray, ignition will fail. Some conventional ignition systems rely on spark igniters positioned within the flame zone and then retracting due to the pressure of the igniting combustion gases. Such spark igniters can experience accelerated wear due to their proximity to hot combustion gases, especially if the retraction mechanism malfunctions.

[0005] The challenges associated with igniting liquid fuels occur in combustion systems that use cross-ignition tubes to propagate the flame within a burner array. In these systems, proper cross-ignition of the burner will not occur if the combustible liquid cannot cross the width of the burner (and thus enter the range of the cross-ignition tubes). This problem can be exacerbated when liquid fuel is supplied from a centrally located liquid fuel cartridge.

[0006] Another challenge associated with igniting liquid fuels occurs in combustion systems with non-intersecting liquid fuel jets exiting from a liquid fuel cartridge. In such systems, igniting each of the non-intersecting fuel jets can be difficult or impossible when operating solely with liquid fuel.

[0007] Existing methods for igniting liquid fuels in combustion systems typically rely on the presence of a pre-established flame. For example, liquid fuel is usually ignited by first flowing gaseous fuel through one or more fuel nozzles and igniting it, followed by flowing liquid fuel through one or more liquid fuel containers. The pre-existing flame from the gaseous fuel exiting the fuel nozzles propagates to and ignites the liquid fuel exiting the liquid fuel containers. However, this method for igniting liquid fuels in combustion systems has problems.

[0008] For example, since gaseous fuels are typically burned preferentially over liquid fuels in combustion systems, turbines will usually only switch to liquid fuel combustion when their gaseous fuel supply begins to run out or becomes unusable. Therefore, it is important that the remaining gaseous fuel be managed effectively to ensure that the turbine can perform multiple starts and can be switched to liquid fuel-only operation. Thus, methods relying on a pre-established gaseous flame require a relatively large amount of gaseous fuel, which adversely affects the number of starts that can occur.

[0009] Therefore, there is a need in the art for an improved method for igniting liquid fuels that does not require a pre-established gas combustion flame. Specifically, there is a need in the art for an improved method for igniting liquid fuels in a combustion system that advantageously minimizes the amount of gaseous fuel used during startup. Summary of the Invention

[0010] The aspects and advantages of the methods according to this disclosure will be set forth in part in the following description, or may be apparent from the description, or may be learned by practice of the technique.

[0011] According to one embodiment, a method for igniting liquid fuel in a turbine combustor is provided. The method includes the step of initiating a gaseous fuel flow from a gaseous fuel supply device to a gaseous fuel nozzle. The method also includes the step of initiating a liquid fuel flow from a liquid fuel supply device to a primary liquid fuel box. After initiating both the gaseous and liquid fuel flows, the method includes the step of igniting both the gaseous and liquid fuel flows with an igniter. The method further includes the step of terminating the gaseous fuel flow from the gaseous fuel supply device to the gaseous fuel nozzle.

[0012] According to another embodiment, a method for starting a gas turbine with liquid fuel is provided. The gas turbine includes a rotor shaft mounted to a compressor and a turbine. The gas turbine also includes a plurality of combustors disposed between the turbine and the compressor. The method further includes increasing the rotational speed of the rotor shaft to force air through the gas turbine at a combustion rate. The method includes the step of initiating a gaseous fuel flow from a gaseous fuel supply device to a gaseous fuel nozzle. The method also includes the step of initiating a liquid fuel flow from a liquid fuel supply device to a primary liquid fuel box. After initiating both the gaseous and liquid fuel flows, the method includes the step of igniting the gaseous and liquid fuel flows with an igniter. The method further includes the step of terminating the gaseous fuel flow from the gaseous fuel supply device to the gaseous fuel nozzle.

[0013] These and other features, aspects, and advantages of the method of the invention will become more readily understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the technology and, together with the description, serve to explain the principles of the technology. Attached Figure Description

[0014] This specification sets forth a complete and practicable disclosure of the methods of the invention as understood by one of ordinary skill in the art, with reference to the accompanying drawings, including the best mode for manufacturing and using the systems and methods of the invention, wherein:

[0015] Figure 1 This is a schematic diagram of a turbine according to an embodiment of this disclosure;

[0016] Figure 2 A schematic cross-sectional view of a burner and liquid fuel ignition system according to an embodiment of the present disclosure is shown;

[0017] Figure 3 A side view of a liquid fuel cartridge according to an embodiment of the present disclosure is shown;

[0018] Figure 4 A top view of the top of a liquid fuel cartridge according to an embodiment of the present disclosure is shown;

[0019] Figure 5 A plan view (viewed from back to front) of a first exemplary burner head end according to an embodiment of the present disclosure is shown;

[0020] Figure 6 A plan view (viewed from back to front) of a second exemplary burner head end according to an embodiment of the present disclosure is shown;

[0021] Figure 7 A flowchart illustrating a method for igniting liquid fuel in a turbine combustor according to an embodiment of the present disclosure is shown; and

[0022] Figure 8 A flowchart of a method for starting a gas turbine using liquid fuel according to an embodiment of the present disclosure is shown. Detailed Implementation

[0023] Reference will now be made in detail to embodiments of the method of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the inventive technique and not as a limitation thereof. Indeed, it will be apparent to those skilled in the art that modifications and variations may be made to the inventive technique without departing from the scope or spirit of the technique protected by the claims. For example, features shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, this disclosure is intended to cover such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0024] The detailed description uses numbers and letters to refer to feature structures in the drawings. Similar or analogous names in the drawings and description have been used to refer to similar or analogous parts of the invention. As used herein, the terms "first," "second," and "third" are used interchangeably to distinguish one part from another and are not intended to indicate the location or importance of the various parts.

[0025] As used herein, the terms “upstream” (or “upward”) and “downstream” (or “downward”) refer to the relative directions of fluid flow within a fluid passage. For example, “upstream” refers to the direction from which fluid flows, and “downstream” refers to the direction towards which fluid flows. The term “radial” refers to a relative direction substantially perpendicular to the axial centerline of a particular component, the term “axial” refers to a relative direction substantially parallel and / or coaxially aligned with the axial centerline of a particular component, and the term “circumferential” refers to a relative direction extending around the axial centerline of a particular component.

[0026] Approximate terms, such as “generally” or “about,” include values ​​that are greater than or less than ten percent of the specified value. When used in the context of angles or directions, such terms include values ​​that are greater than or less than ten degrees of the angle or direction. For example, “generally vertical” includes directions that are within ten degrees of vertical in any direction (e.g., clockwise or counterclockwise).

[0027] Now refer to the attached diagram, Figure 1 A schematic diagram of one embodiment of a turbine is shown, which in the illustrated embodiment is a gas turbine 10. Although industrial or land-based gas turbines are shown and described herein, this disclosure is not limited to industrial and / or land-based gas turbines unless otherwise specified in the claims. For example, the methods described herein can be used in any type of turbine, including but not limited to steam turbines, aircraft gas turbines, or marine gas turbines.

[0028] As shown in the figure, the gas turbine 10 is a heavy-duty gas turbine used for power generation. The gas turbine 10 typically includes an inlet section 12, which may include a series of filters, cooling coils, moisture separators, and / or other devices to purify and otherwise regulate the working fluid 24 (e.g., air) entering the gas turbine 10. The working fluid 24 flows to a compressor section, where a compressor 14 gradually imparts kinetic energy to the working fluid 24 to produce a compressed working fluid 26.

[0029] The compressed working fluid 26 is mixed with gaseous fuel 28 or liquid fuel mixture 58 to form a combustible mixture within one or more burners 22 in the combustion section or system 16. Gaseous fuel 28 may originate from a main gaseous fuel supply system 128 (such as a gaseous fuel line) via a main gaseous fuel supply line 170, or from an auxiliary gaseous fuel supply device 228 (such as a storage tank) via an auxiliary gaseous fuel supply line 270. In various embodiments, a gaseous fuel supply valve 135 may be positioned in fluid communication with both the main gaseous fuel supply line 170 and the auxiliary gaseous fuel supply line 270, such that gaseous fuel 28 is delivered from a single source (main gaseous fuel supply system 128 or auxiliary gaseous fuel supply system 228). Liquid fuel mixture 58 originates from a liquid fuel supply system 158 (such as a mixing tank), within which liquid fuel 38 and water 40 are mixed and delivered to the burner 22 via a liquid fuel supply line 160. Liquid fuel supply valve 165 controls the delivery of liquid fuel 58.

[0030] A combustible mixture, including gaseous and / or liquid fuels, may be burned to produce combustion gas 30 with high temperature, high pressure, and high velocity. This combustion gas 30 flows through a turbine 18 in a turbine section to perform work. For example, the turbine 18 may be connected to a shaft 17 such that the rotation of the turbine 18 drives a compressor 14 to produce a compressed working fluid 26. Alternatively or otherwise, the shaft 17 may connect the turbine 18 to a generator 20 for generating electricity.

[0031] Exhaust gas 32 from turbine 18 flows through an exhaust section (not shown) that connects turbine 18 to an exhaust pipe downstream of the turbine. The exhaust section may include, for example, a heat recovery steam generator (not shown) for cleaning the exhaust gas and extracting additional heat from it before it is released into the environment.

[0032] The burner 22 can be any type of burner known in the art, and the method of the invention is not limited to any particular burner design unless specifically stated in the claims. For example, in some embodiments, the burner 22 may form a canister-type or canister-annular combustion section, wherein each burner 22 may have its own single combustion chamber that produces a portion of the combustion gases 30. In other embodiments, the burner 22 may be an annular combustion section, wherein combustion occurs in a common annular band fed by a circumferential array of burners (fuel nozzles).

[0033] Figure 2 This is a schematic diagram of a burner 22, which may be included in a can-ring combustion system 16 of a heavy-duty gas turbine 10. In the can-ring combustion system 16, a plurality of burners 22 (e.g., 8, 10, 12, 14, 16 or more) are positioned in a ring array around a shaft 17 that connects the compressor 14 to the turbine 18. Each of the plurality of burners 22 has its own local combustion chamber, such that combustion gas 30 can flow from each can-ring burner 22 toward the turbine section 18.

[0034] like Figure 2 As shown, the combustor 22 includes a liner 312 that contains and delivers combustion gases 30 to the turbine. The liner 312 may define a combustion chamber in which combustion occurs. The liner 312 may have a cylindrical liner portion and a tapered transition portion separate from the cylindrical liner portion, as is the case in many conventional combustion systems. Alternatively, the liner 312 may have an integrated body (or “one-piece”) construction, in which the cylindrical portion and the tapered portion are integrated with each other. Therefore, any discussion of the liner 312 herein is intended to cover both conventional combustion systems with separate liners and transition portions and those with one-piece liners. Furthermore, this disclosure is equally applicable to those combustion systems in which the turbine transition portion and stage nozzle are integrated into a single unit (sometimes referred to as a “transition nozzle” or “integrated outlet portion”).

[0035] The liner 312 is surrounded by an outer sleeve 314, which is radially spaced outward from the liner 312 to define an annular band 332 between the liner 312 and the outer sleeve 314. The outer sleeve 314 may include a flow sleeve portion at a front end and an impact sleeve portion at a rear end, as is the case in many conventional combustion systems. Alternatively, the outer sleeve 314 may have an integral body (or “integral sleeve”) construction, wherein the flow sleeve portion and the impact sleeve portion are integrated with each other in the axial direction. As previously stated, any discussion herein of the outer sleeve 314 is intended to cover both conventional combustion systems with separate flow sleeves and impact sleeves and combustion systems with an integral sleeve-type outer sleeve.

[0036] The head portion 320 of the burner 22 includes one or more fuel nozzles 322. Each fuel nozzle 322 has a fuel inlet 324 at its upstream (or inlet) end. This fuel inlet 324 can be formed by an end cap 326 at the front end of the burner 22. The downstream (or outlet) end of the fuel nozzle 322 extends to the burner top cap 328 (also located at...). Figure 4 (as shown in the diagram) and / or extending through the burner top cover, or including a rear plate 368 serving as the top cover (as shown in the diagram). Figure 5 (As shown).

[0037] In many embodiments, the head portion 320 of the burner 22 may be at least partially surrounded by a front housing that is physically coupled and fluidly connected to a compressor discharge housing. In various embodiments, the compressor discharge housing may be fluidly connected to the outlet of the compressor 14 and define a pressurized air charge chamber surrounding at least a portion of the burner 22. Compressed air 26 may flow from the compressor discharge housing into the annular belt 332 at the rear end of the burner 22 via an opening defined in an outer sleeve 314. Because the annular belt 332 is fluidly coupled to the head portion 320, the airflow 26 travels upward from the rear end of the burner 22 into the head portion 320, where the airflow 26 reverses direction and enters the fuel nozzle 322. For example, the air 26 may travel through the annular belt 332 in the opposite direction to the combustion gas 30 within the liner 312.

[0038] Fuel 28 and compressed air 26 are introduced into the combustion chamber 350 at the front end of the liner 312 via fuel nozzle 322, where the fuel 28 and air 26 are ignited and burned via igniter 370 to form combustion gas 30. Ignitioner 370 is positioned close to the head end 320 of burner 22. Alternatively, the igniter may be a torch-type igniter 380 positioned within the head end 320 of burner 22 (e.g., via an end cap 326 upstream of one fuel nozzle in fuel nozzle 322). Combustion gas 30 from one burner 22 travels through cross-ignition tubes (not shown) between the liners 312 of adjacent burners 22 to propagate the flame around the array of burners 22.

[0039] In one embodiment, fuel 28 and air 26 are mixed within fuel nozzle 322 (e.g., in a premixed fuel nozzle). In other embodiments, fuel 28 and air 26 may be introduced into combustion chamber 350 separately and mixed within combustion chamber 350 (e.g., as can happen with a diffusion nozzle). The term "fuel / air mixture" as used herein should be interpreted to describe both premixed fuel / air mixtures and diffusion-type fuel / air mixtures, either of which may be generated by fuel nozzle 322.

[0040] In liquid fuel operation, the liquid fuel mixture 58 is delivered to the liquid fuel cartridge 358 via the liquid fuel supply line 160. In an exemplary embodiment, the liquid fuel cartridge 358 is mounted along the axial centerline 310 of the burner 22 and is coaxially disposed within one of the fuel nozzles 322. In many embodiments, the liquid fuel cartridge 358 may extend coaxially with both the burner 22 and the fuel nozzle 322.

[0041] Combustion gas 30, generated by burning gaseous fuel 28 and / or liquid fuel 58 with compressed air 26, travels downward toward the rear frame 318 of the burner 22, which represents the rear end of the burner 22. In many embodiments, the rear frame 318 may be connected to a turbine 18, such that the combustion gas 30 may exit the burner section 16 at the rear frame 318 and enter the turbine 18.

[0042] The control system or controller 400 can be used to control the supply of fuels 28 and 58 to the burner 22. The control system 400 can communicate via signal 435 with a gas fuel supply valve 135, which is located along a main gas fuel supply line 170 and an auxiliary gas fuel supply line 270, such that gas fuel 28 is directed from one or both of these supply lines 170 or 270 through valve 135 and into the gas fuel supply line 70. The control system 400 also communicates via signal 465 with a liquid fuel supply valve 165 located along a liquid fuel supply line 160. In some embodiments, the control system 400 transmits a start signal 470 to the igniter 370 during burner 22 startup. In other embodiments, the control system 400 transmits a start signal 480 to the flare igniter 380 during combustion system startup.

[0043] Flame detector 412 or 414 (in Figure 2 A flame detector 412 (marked with "S" to indicate a sensor) can be used to detect the flame within the combustion chamber 350. The flame detector 412 is disposed within or through the end cap 326 and is positioned to detect the flame in the combustion chamber 350, as observed from the upstream end of the fuel nozzle 322. The flame detector 414 may be disposed along the inner surface of the liner 312 and is positioned to detect the flame in the combustion chamber 350, as observed from the downstream end of the burner 22 upstream toward the head end 320 (i.e., from back to front). The flame detector 412 or 414 communicates with the controller 400 such that the detection of the flame is transmitted to the controller 400 as signals 422, 424. The flame detectors 412 and 414 can be any type of flame detector known in the art, including but not limited to optical detectors, photometers, cameras, ultraviolet flame detectors, infrared flame detectors, thermal detectors, pressure sensors, or combinations thereof.

[0044] Figure 3 It shows that it can be used with Figure 2 A liquid fuel cartridge 358 is used in conjunction with burner 22. The liquid fuel cartridge 358 includes a cylindrical body 360, a liquid fuel cartridge top 362, and a mounting flange 366 that defines an inlet 364 for receiving a liquid fuel mixture 58 from a liquid fuel supply line 160. As shown, in many embodiments, the cartridge top may include a base 361 directly coupled to the cylindrical body 360, such that the base 361 is the axially innermost portion of the cartridge top 362 relative to the axial direction A. Figure 3 As shown, the top of the housing 362 can radiate radially inward from the base 361 to the downstream surface 363, such that the top of the housing 362 has a generally tapered shape. The tapered shape of the top of the housing 362 is preferable to, for example, a cylindrical shape, in order to provide an aerodynamic profile that minimizes the possibility of fuel vortices or hot spots along the top of the housing 362. In various embodiments, such as Figure 2 As best shown, the top of the burner housing 362 can be completely disposed within the combustion chamber 350 and terminate at a downstream surface 363, which is positioned downstream of the burner top cover 328. Figure 3 As shown, the top of the box 362 can be defined by multiple rows of liquid fuel injection holes 364 spaced apart from each other along the circumference on the top of the box 362.

[0045] Figure 4 The top of the box, 362, is shown as viewed from slightly downstream to upstream. (As shown) Figure 3 and Figure 4 As shown, the liquid fuel injection orifice 364 can deliver the liquid fuel mixture 58 in a direction inclined and / or perpendicular to the direction from which the fuel / air mixture is delivered from the fuel nozzle 322. Figure 4 As shown, the liquid fuel injection orifices 364 can converge into a circumferentially offset group such that the streams of liquid fuel mixture 58 exiting the top of the cartridge 362 do not overlap. Therefore, in the absence of gaseous fuel, the flame from one stream of liquid fuel mixture generally will not propagate to another stream of liquid fuel. In some embodiments, the downstream surface 363 may define one or more liquid fuel injection orifices 365 that deliver the liquid fuel mixture 58 in a direction parallel to the direction from which the fuel / air mixture is delivered from the fuel nozzle 322, i.e., parallel to the axial direction A.

[0046] Figure 5 This is a plan view of the first embodiment of the burner head 320a, in which the burner head is installed. Figure 3 and Figure 4The liquid fuel cartridge 358 is shown in the figure. This liquid fuel cartridge 358 can be a primary liquid fuel cartridge 357 installed within a central fuel nozzle 322a, which is a type of vortex fuel nozzle, swirl nozzle, or other suitable fuel nozzle. The central fuel nozzle 322a is surrounded by a plurality of outer fuel nozzles 322b, which can also be vortex fuel nozzles, swirl nozzles, or other suitable fuel nozzles. As shown in the figure, one or more secondary liquid fuel cartridges 359, having a configuration similar to that of the liquid fuel cartridge 358, can be disposed within one or more outer fuel nozzles 322b.

[0047] Each fuel nozzle 322a, 322b may include a vortex blade 323 that directs a vortex direction toward the air flowing through it. In some embodiments, the vortex blade 323 of the outer fuel nozzle 322b is arranged around a central hub 321. In other embodiments, as shown, the vortex blade 323 may be arranged around a secondary liquid fuel cartridge 359. In an exemplary embodiment, each outer fuel nozzle 322b may include a central hub 321 such that only the liquid fuel cartridge 358 is the primary liquid fuel cartridge 359 disposed within the central fuel nozzle 322a. The vortex blade 323 in the central fuel nozzle 322a may be arranged around the primary liquid fuel cartridge 359. Although six outer fuel nozzles 322b are shown, it should be understood that other numbers of fuel nozzles 322b (such as 4, 5, or 8 fuel nozzles 322b) may be used. The fuel nozzles 322a, 322b are mounted within corresponding openings (not individually labeled) in the burner top cover 328.

[0048] Figure 6 This is a plan view of the second embodiment of the burner head 320b, in which the burner head end 320b is installed. Figure 3 and Figure 4 The liquid fuel cartridge 358 is shown. As illustrated, the liquid fuel cartridge 358 may be a primary liquid fuel cartridge 357, such as a bundled fuel nozzle, installed within a central fuel nozzle 322c. The central fuel nozzle 322c is surrounded by a plurality of fuel nozzles 322d, which may also be bundled fuel nozzles. As illustrated, one or more secondary liquid fuel cartridges 359, having a configuration similar to the liquid fuel cartridge 358, may be disposed within one or more fuel nozzles 322d. Each bundled fuel nozzle 322c, 322d includes a plurality of individual premixing tubes 522 in which fuel and air are mixed. The premixing tubes 522 extend through a rear plate 368, which may be unique for each bundled fuel nozzle 322c, 322d, or may extend across all bundled fuel nozzles 322c, 322d.

[0049] The bundled fuel nozzles 322c and 322d may include an upstream fuel filling chamber specific to each fuel nozzle 322c and 322d, and each premixing tube 522 may include one or more fuel injection ports in fluid communication with the fuel filling chamber. Air flowing through the inlet end of each premixing tube 522 mixes with fuel flowing through the fuel injection port, and the fuel and air mixture is delivered through the outlet end of each tube 522.

[0050] Alternatively, each premixing tube 522 may include an inlet end in which a fuel injector is mounted. Multiple air inlet holes are located downstream of the fuel injector, such that air flowing through the air inlet holes mixes with fuel from the fuel injector. The fuel and air mixture is then conveyed through the outlet end of each tube 522.

[0051] Although the bundled fuel nozzle 322d is shown as having a sector shape including two radially extending sides and two opposing arcuate sides, it should be understood that the bundled fuel nozzle 322d may have any shape or size relative to the central bundled fuel nozzle 322c.

[0052] Figure 7 This is a flowchart of a set of sequential steps 710 to 760 according to an embodiment of the present disclosure, which define a method 700 for igniting liquid fuel in a gas turbine combustor. The flowchart includes schematic diagrams to illustrate the process from... Figure 2 The corresponding flow of fuel nozzle 322 and liquid fuel box 358 in burner 22.

[0053] like Figure 7 As shown in the dashed box, method 700 may include optional step 710. This optional step 710 may include detecting the absence of a valid flame within combustion chamber 350 using one or more flame detectors (such as flame detectors 412, 414). As described herein, flame detectors 412, 414 are operable to sense the presence of a flame within combustion chamber 350 and transmit the sensed data to controller 400 via signals 422, 424.

[0054] Step 720 includes initiating a gaseous fuel flow 28 from the gaseous fuel supply device to the gaseous fuel nozzle 322. Step 730 includes initiating a liquid fuel flow 58 from the liquid fuel supply device to the primary liquid fuel container 357. Figure 2As shown, the gaseous fuel supply device can be a main gaseous fuel supply device 128, an auxiliary gaseous fuel supply device 228, or both. Similarly, the liquid fuel supply device can be a liquid fuel supply system 158. Steps 720 and 730 can be performed by transmitting signal 435 to gaseous fuel supply valve 135 and signal 465 to liquid fuel supply valve 165 to open both valves 135 and 165 and supply gaseous and liquid fuel to combustion zone 350 before ignition in the burner.

[0055] In an exemplary embodiment, method 700 advantageously eliminates the need to ignite gaseous fuel 28 prior to initiating the liquid fuel flow 58, allowing for more efficient use of gaseous fuel 28. In this way, gaseous fuel 28 can be utilized efficiently to maximize the number of starts when operating the gas turbine 10 with liquid fuel 58.

[0056] In some embodiments, steps 720 and 730 can be performed simultaneously. In such embodiments, a signal 435 to open the gaseous fuel supply valve 135 and a signal 465 to open the liquid fuel supply valve 165 can be sent simultaneously to supply gaseous fuel 28 and liquid fuel 58 within the burner 22 at the same time. Figure 2 As shown, opening the gas fuel supply valve 135 allows gaseous fuel to flow from the main gas fuel supply device 128, the auxiliary fuel supply device 228, or both, via the fuel supply line 70 to the gas fuel nozzle 322. Similarly, opening the liquid fuel supply valve 165 allows liquid fuel to flow from the liquid fuel supply system 158 to the liquid fuel box 358 via the liquid fuel supply line 160. Thus, a gaseous fuel / air mixture is delivered from the gas fuel nozzle 322 to the combustion zone 350, and liquid fuel 58 is delivered from the primary liquid fuel box 357 to the combustion zone 350 before ignition within the burner 22, as illustrated in schematic diagram 735.

[0057] In step 740, after steps 720 and 730 have been performed, the controller 400 activates the igniter, such as igniter 370 or torch igniter 380, by transmitting signals 470 and / or 480 to igniter 370 and / or torch igniter 380. Performing steps 720 and 730 before step 740 advantageously allows for the simultaneous ignition of gaseous fuel 28 and liquid fuel 58, which allows for gaseous fuel conservation.

[0058] In many embodiments, gaseous fuel 28 and liquid fuel 58 can be ignited via an igniter 370 positioned downstream of the gaseous fuel nozzle 322 and the liquid fuel cartridge 358. The igniter 370 can generate a spark to ignite the gaseous fuel / air mixture within the combustion chamber 350.

[0059] In an exemplary embodiment, gaseous fuel 28 and liquid fuel 58 can be ignited via a torch igniter 380 positioned within the head end 320 of burner 22 (e.g., via an end cap 326 upstream of one of the fuel nozzles in fuel nozzle 322). Since liquid fuel 58 is present within burner 22 when the gaseous fuel is ignited, the flame generated by the gaseous fuel / air mixture will immediately propagate to the liquid fuel 58 exiting the primary liquid fuel cartridge 358.

[0060] Method 700 may also include an optional step 750 of detecting the presence of a flame emanating from both the gaseous fuel nozzle 322 and the liquid fuel cartridge 358 within the combustion zone 350 using one or more flame detectors 412, 414. The controller 400 may receive signals 422, 424 from one or both of the flame detectors 412, 414 indicating that combustion has occurred within the combustion chamber and a flame is emanating from both the gaseous fuel nozzle 322 and the liquid fuel cartridge 358. This step may be performed to confirm that the liquid fuel 58 leaving the liquid fuel cartridge 358 has been ignited.

[0061] In step 760, controller 400 may terminate the supply of gaseous fuel to gaseous fuel nozzle 322 by transmitting a second signal 435 only to gaseous fuel supply valve 135. Gaseous fuel supply valve 135 closes the passage between gaseous fuel supply lines 170 and / or 270 and gaseous fuel supply line 70. The passages from gaseous fuel supply line 170 to gaseous fuel supply line 70 and from gaseous fuel supply line 270 to gaseous fuel supply line 70 remain closed, preventing gaseous fuel 28 from traveling through gaseous fuel supply line 70 to gaseous fuel nozzle 322. Therefore, as shown in schematic diagram 755, only liquid fuel mixture 58 is delivered from liquid fuel cartridge 358, and gaseous fuel nozzle 322 is not fueled (i.e., air may be delivered only). If step 750 is included, controller 400 may initiate step 760 based on a time sequence or based on received signals 422 or 424.

[0062] Figure 8 This is a flowchart of a set of sequential steps 810 to 870 according to another aspect of this disclosure, which defines a method 800 for starting a gas turbine with liquid fuel. As described in detail above, the gas turbine 10 may include a rotor shaft 17 coupled to a compressor 14 and a turbine 18, and a plurality of burners 22 may be disposed between the turbine 18 and the compressor 14. Figure 8 As shown, the flowchart includes schematic diagrams to illustrate the flow from... Figure 2 The corresponding flow of fuel nozzle 322 and liquid fuel box 358 in burner 22.

[0063] Method 800 may include step 810 of accelerating the rotation of rotor shaft 17 toward a combustion speed in order to force air through gas turbine 10. This forcing air through gas turbine 10 includes directing airflow through burner 22, for example, through one or more gaseous fuel nozzles 322, such that air is present in the combustion chamber prior to combustion. Once the rotor shaft reaches the combustion speed, fuel may begin to be directed to the gaseous fuel nozzles 322 and / or liquid fuel cartridge 358.

[0064] like Figure 8 As shown in the dashed box, method 800 may include optional step 820. This optional step 820 may include detecting the absence of a valid flame within combustion chamber 350 using one or more flame detectors (such as flame detectors 412, 414). As described herein, flame detectors 412, 414 are operable to sense the presence of a flame within combustion chamber 350 and transmit the sensing data to controller 400 via signals 422, 424.

[0065] Step 830 includes initiating a gaseous fuel flow from the gaseous fuel supply device to the gaseous fuel nozzle 322. Step 840 includes initiating a liquid fuel flow from the liquid fuel supply device to the primary liquid fuel container 357. Figure 2 As shown, the gaseous fuel supply device can be a main gaseous fuel supply device 128, an auxiliary gaseous fuel supply device 228, or both. Similarly, the liquid fuel supply device can be a liquid fuel supply system 158. Steps 830 and 840 can be performed by transmitting signal 435 to gaseous fuel supply valve 135 and signal 465 to liquid fuel supply valve 165 to open both valves 135 and 165 and supply gaseous fuel 28 and liquid fuel 58 to combustion zone 350 before ignition in burner 22.

[0066] In an exemplary embodiment, method 800 advantageously eliminates the need to ignite gaseous fuel 28 prior to initiating the liquid fuel flow 58, allowing for more efficient use of gaseous fuel 28. In this way, gaseous fuel 28 can be utilized efficiently to maximize the number of starts when operating the gas turbine 10 with liquid fuel 58.

[0067] In some embodiments, steps 830 and 840 can be performed simultaneously. In such embodiments, a signal 435 to open the gaseous fuel supply valve 135 and a signal 465 to open the liquid fuel supply valve 165 can be sent simultaneously to supply gaseous fuel 28 and liquid fuel 58 within the burner 22 at the same time. Figure 2As shown, opening the gas fuel supply valve 135 allows gaseous fuel to flow from the main gas fuel supply device 128, the auxiliary fuel supply device 228, or both, via the fuel supply line 70 to the gas fuel nozzle 322. Similarly, opening the liquid fuel supply valve 165 allows liquid fuel to flow from the liquid fuel supply system 158 to the liquid fuel box 358 via the liquid fuel supply line 160. Thus, a gaseous fuel / air mixture is delivered from the gas fuel nozzle 322 to the combustion zone 350, and liquid fuel 58 is delivered from the primary liquid fuel box 357 to the combustion zone 350 before ignition within the burner 22, as illustrated in schematic diagram 845.

[0068] In step 850, controller 400 activates an igniter, such as igniter 370 or torch igniter 380, by transmitting signals 470 and / or 480 to igniter 370 and / or torch igniter 380. In many embodiments, gaseous fuel 28 and liquid fuel 58 can be ignited via igniter 370, which is positioned downstream of gaseous fuel nozzle 322 and liquid fuel cartridge 358. Igniter 370 can generate a spark to ignite the gaseous fuel / air mixture within combustion chamber 350.

[0069] In an exemplary embodiment, gaseous fuel 28 and liquid fuel 58 can be ignited via a torch igniter 380 positioned within the head end 320 of burner 22 (e.g., via an end cap 326 upstream of one of the fuel nozzles in fuel nozzle 322). Since liquid fuel 58 is present within burner 22 when the gaseous fuel is ignited, the flame generated by the gaseous fuel / air mixture will immediately propagate to the liquid fuel 58 exiting the primary liquid fuel cartridge 357.

[0070] Method 800 may further include an optional step 860 of detecting the presence of a flame emitted from both the gaseous fuel nozzle 322 and the liquid fuel cartridge 358 within the combustion chamber 350 using one or more flame detectors 412, 414. The controller 400 may receive signals 422, 424 from one or both of the flame detectors 412, 414 indicating that combustion has occurred within the combustion chamber 350 and a flame is emitted from both the gaseous fuel nozzle 322 and the liquid fuel cartridge 358. This step may be performed to confirm that the liquid fuel 58 leaving the liquid fuel cartridge 358 has been ignited.

[0071] In step 870, controller 400 may terminate the supply of gaseous fuel to gaseous fuel nozzle 322 by transmitting a second signal 435 only to gaseous fuel supply valve 135. Gaseous fuel supply valve 135 closes the passage between gaseous fuel supply lines 170 and / or 270 and gaseous fuel supply line 70. The passages from gaseous fuel supply line 170 to gaseous fuel supply line 70 and from gaseous fuel supply line 270 to gaseous fuel supply line 70 remain closed, preventing gaseous fuel 28 from traveling through gaseous fuel supply line 70 to gaseous fuel nozzle 322. Therefore, as shown in schematic diagram 875, only the liquid fuel mixture is delivered from liquid fuel cartridge 358, and gaseous fuel cartridge 322 is not fueled (i.e., only air may be delivered). If step 860 is included, controller 400 may initiate step 870 based on a time sequence or based on the received signal 422 or 424.

[0072] In many embodiments, methods 700 and 800 may be performed with only an auxiliary fuel supply device connected, such as the auxiliary fuel supply system 228 described herein. In such embodiments, the main gas fuel supply system 128 may not be available. Therefore, it is very important to effectively manage the gaseous fuel from the auxiliary fuel supply system 228 to ensure that the gas turbine reliably performs multiple starts and operations with liquid fuel.

[0073] Therefore, within tens of seconds (e.g., less than a minute), burner 22 is reliably and successfully started and operated with liquid fuel. The methods 700, 800 described herein advantageously allow the gas turbine 10 to be started without a pre-established flame in burner 22, which advantageously minimizes the amount of gaseous fuel required for start-up, thereby effectively managing the available fuel supply within auxiliary fuel supply system 228 to maximize the number of starts. Specifically, the methods 700, 800 described herein may be superior to methods requiring a pre-established flame, i.e., "fuel delivery methods," because methods 700, 800 require significantly less gaseous fuel than said fuel delivery methods. For example, in fuel delivery methods, gaseous fuel is ignited in the burner even before the introduction of liquid fuel, which requires a large portion of the gaseous fuel from the auxiliary fuel supply. Using the method of the present invention, multiple starts can be accomplished with a single gas fuel tank 228, thus providing greater operational flexibility for plant operators.

[0074] The methods and systems described herein facilitate the ignition of liquid fuels in gas turbine combustors. More specifically, these methods and systems facilitate the ignition of liquid fuels without access to a primary gas fuel supply. Therefore, these methods and systems improve the overall operational flexibility of combustors, such as those in gas turbine assemblies. This can reduce the costs associated with operating combustors, such as those in gas turbine assemblies, and / or increase the combustor's operating time (and output).

[0075] The foregoing has described in detail exemplary embodiments of liquid fuel ignition methods. The methods described herein are not limited to the specific embodiments described herein, but rather components of the methods can be utilized independently and separately from other components described herein. For example, as described herein, the methods described herein can have other applications not limited to the use of turbine components. Conversely, the methods and systems described herein can be implemented and used in conjunction with a variety of other industries.

[0076] This written description uses examples to disclose the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including making and using any device or system and performing any combined methods. The patentable scope of the invention is defined by the claims and may include other examples that would occur to a person skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A method for igniting liquid fuel (58) in a turbine combustor (22), the method comprising: Initiate a flow of gaseous fuel (28) from the gaseous fuel supply device to the gaseous fuel nozzle (322); Initiating a liquid fuel flow (58) from the liquid fuel supply device (158) to the liquid fuel box (358), wherein the step of initiating the liquid fuel flow occurs together with or after the step of initiating the gaseous fuel flow; After initiating both the gaseous fuel stream (28) and the liquid fuel stream (58), the gaseous fuel stream (28) and the liquid fuel stream (58) are simultaneously ignited by an igniter (370); and The gas fuel flow (28) from the gas fuel supply device to the gas fuel nozzle (322) is terminated.

2. The method according to claim 1, wherein the liquid fuel box (358) is positioned along the axial centerline of the turbine combustor (22), and wherein the gas fuel nozzle (322) surrounds the liquid fuel box (358), the liquid fuel box (358) and the gas fuel nozzle (322) are positioned in the head end of the turbine combustor (22).

3. The method according to claim 1, wherein the gas fuel supply device is one of the following: a main gas fuel supply (128) system, an auxiliary gas fuel supply (228) system, or both the main gas fuel supply system and the auxiliary gas fuel supply system.

4. The method of claim 1, further comprising providing a controller (400) that communicates with the igniter (370), the gas fuel supply device and the liquid fuel supply device (158).

5. The method of claim 4, further comprising using flame detectors (412, 414) to detect a flame in the combustion chamber (350) of the turbine combustor, the flame detectors (412, 414) communicating with the controller (400).

6. The method of claim 5, wherein the steps of initiating the gaseous fuel flow (28) and initiating the liquid fuel flow (58) occur before the flame detectors (412, 414) detect a flame in the combustion chamber (350).

7. The method of claim 1, wherein the step of initiating the gas fuel flow (28) from the gas fuel supply device is achieved by controlling a gas fuel valve (135) located in a gas fuel supply (228) line extending from the gas fuel supply device.

8. The method according to claim 7, wherein the step of terminating the gas fuel flow (28) from the gas fuel supply device is achieved by controlling the gas fuel valve (135).

9. The method of claim 1, wherein the step of initiating the liquid fuel flow (58) from the liquid fuel supply device (158) is achieved by controlling a liquid fuel valve (165) located in a liquid fuel supply (158) line extending between the liquid fuel supply device (158) and the liquid fuel cartridge (358).

10. A method for starting a gas turbine using liquid fuel (58), the gas turbine including a rotor shaft coupled to a compressor and the turbine, wherein a plurality of burners (22) are disposed between the turbine and the compressor, the method comprising: The rotational speed of the rotor shaft is increased to force air through the combustion speed of the gas turbine; as well as Within each of the plurality of burners (22): Initiate a flow of gaseous fuel (28) from the gaseous fuel supply device to the gaseous fuel nozzle (322); Initiating a liquid fuel flow (58) from the liquid fuel supply device (158) to the liquid fuel box (358), wherein the step of initiating the liquid fuel flow occurs together with or after the step of initiating the gaseous fuel flow; After initiating both the gaseous fuel stream (28) and the liquid fuel stream (58), the gaseous fuel stream (28) and the liquid fuel stream (58) are simultaneously ignited by an igniter (370); and The gas fuel flow (28) from the gas fuel supply device to the gas fuel nozzle (322) is terminated.

11. The method of claim 10, wherein the liquid fuel cartridge (358) is positioned along the axial centerline of each of the plurality of burners (22), and wherein the gas fuel nozzle (322) surrounds the liquid fuel cartridge (358), the liquid fuel cartridge (358) and the corresponding gas fuel nozzle (322) are positioned at the head end of each of the plurality of burners (22).

12. The method according to claim 10, wherein the gas fuel supply device is one of the following: a main gas fuel supply (128) system, an auxiliary gas fuel supply (228) system, or both the main gas fuel supply system and the auxiliary gas fuel supply system.

13. The method of claim 10, further comprising providing a controller (400) that communicates with the igniter (370), the gas fuel supply device and the liquid fuel supply device (158).

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