Dual fuel gas turbine clean blow system and method

Abstract

The application discloses a dual-fuel gas turbine purging system and method, and relates to the technical field of gas turbines. The system comprises a first main pipeline, a first branch pipeline, a second branch pipeline, a second main pipeline and a valve assembly, wherein the valve assembly is used for controlling the opening and closing of the first main pipeline and the second main pipeline; the valve assembly comprises a first valve arranged on the first main pipeline and a second valve arranged on the second main pipeline. The application introduces the instrument air source of the gas turbine to purging the liquid fuel pipeline. Since the temperature of the instrument air source is low, the liquid fuel in the liquid fuel pipeline will not be coked during the purging process, and the liquid fuel pipeline or the nozzle will not be easily blocked. In addition, the air source used for purging and cooling in the application is from the gas turbine itself, and the use cost is lower compared with the air source introduced from the outside.

Description

Technical Field

[0001] This application relates to the field of gas turbine technology, specifically to a dual-fuel gas turbine purging system and method. Background Technology

[0002] A dual-fuel gas turbine is a gas turbine that can use both gaseous and liquid fuels. The ability to switch between and co-fire the two types of fuel improves the gas turbine's fuel adaptability. During operation, if the fuel changes from gaseous to liquid, any remaining gaseous fuel in the gaseous fuel line must be promptly removed to prevent potential safety hazards from combustible gases in the gaseous fuel line. Conversely, if the fuel changes from liquid to gas, any residual liquid fuel in the liquid fuel line must be purged to prevent coking and blockage of the lines or nozzles, which could lead to uneven combustion chamber temperature and other malfunctions.

[0003] The removal of gaseous fuel from gaseous fuel lines and the purging of liquid fuel from liquid fuel lines primarily rely on the gas turbine's purging system. Currently, various purging systems are available on the market, such as using compressor bleed air or introducing external gas sources. However, the compressor bleed air temperature is generally high. If bleed air is used to purge liquid fuel from liquid fuel lines, it can easily cause coking of the liquid fuel, clogging the lines or nozzles. To address this technical problem, patent publication number CN106988891A, entitled "A Fuel Purging Device for a Dual-Fuel Gas Turbine," uses externally introduced nitrogen for purging. This not only requires a large amount of other equipment, resulting in high costs, but also makes it difficult to control the pressure of the purging gas. When the dual-fuel gas turbine is operating, insufficient purging gas pressure can easily cause high-temperature combustion gas from the combustion chamber to backflow into the non-working fuel lines, damaging the gas turbine. Summary of the Invention

[0004] The purpose of this application is to provide a dual-fuel gas turbine purging system and method to solve the technical problem that using bleed air from the compressor for purging can easily cause coking of the liquid fuel in the liquid fuel pipeline and nozzle, thus clogging the liquid fuel pipeline or nozzle.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] In a first aspect, this application proposes an embodiment of a dual-fuel gas turbine purging system, the system comprising: a first main pipeline, the first end of which is connected to a compressor; a first branch pipeline, the first end of which is connected to the first main pipeline and the second end of which is connected to a gaseous fuel pipeline; a second branch pipeline, the first end of which is connected to the first main pipeline and the second end of which is connected to a liquid fuel pipeline; a second main pipeline, the first end of which is connected to an instrument gas source and the second end of which is connected to the second branch pipeline; and a valve assembly for controlling the opening and closing of the first main pipeline and the second main pipeline; the valve assembly comprising a first valve disposed on the first main pipeline and a second valve disposed on the second main pipeline.

[0007] As one embodiment of this application, the first main pipeline is further provided with a vent pipe, which is located between the first valve and the second end of the first main pipeline; the valve assembly further includes a third valve disposed on the vent pipe.

[0008] As one embodiment of this application, the vent pipe is further provided with a natural gas monitoring device, and the natural gas monitoring device and the third valve are arranged sequentially along the airflow direction in the vent pipe.

[0009] As one embodiment of this application, the valve assembly includes a fourth valve disposed on the first branch pipe.

[0010] As one embodiment of this application, the valve assembly further includes a first check valve disposed on the first main pipeline, and the second valve and the first check valve are arranged sequentially along a first direction, the first direction being from the first end of the second main pipeline to the second end.

[0011] As one embodiment of this application, the valve assembly further includes a fifth valve disposed on the second branch pipe.

[0012] As one embodiment of this application, the valve assembly further includes a second check valve disposed in the second branch pipe, and the fifth valve and the second check valve are arranged sequentially along a second direction, which extends from the first end of the second branch pipe to the second end.

[0013] Secondly, this application proposes an embodiment of a dual-fuel gas turbine having a dual-fuel gas turbine cleaning system as described in any one of the first aspects.

[0014] Thirdly, this application provides an embodiment of a purge method for a dual-fuel gas turbine, the method comprising:

[0015] Purge liquid fuel pipelines using instrument air source;

[0016] Cooling of liquid fuel pipelines is achieved using bleed air from the compressor.

[0017] As one embodiment of this application, the purging of the liquid fuel pipeline based on the instrument gas source includes:

[0018] Obtain a preset opening degree and a first switching command, wherein the first switching command is obtained based on the operating mode of the dual-fuel gas turbine;

[0019] Based on the first switching command, after closing the first valve, the second valve, the fourth valve, and the fifth valve, fuel switching is performed;

[0020] If the fuel switch is complete, open the second valve to the preset opening degree;

[0021] If the opening time of the second valve reaches a preset threshold, then the second valve is closed;

[0022] The cooling of the liquid fuel pipeline based on compressor bleed air includes:

[0023] Open the first valve and the fifth valve.

[0024] As one embodiment of this application, obtaining the preset opening degree includes:

[0025] Obtain the volume of the liquid fuel pipeline, the cross-sectional area of ​​the nozzle, and the liquid fuel flow rate;

[0026] The purging pressure is obtained based on the volume of the liquid fuel pipeline, the cross-sectional area of ​​the nozzle, and the liquid fuel flow rate.

[0027] The preset opening degree is obtained based on the blowing pressure.

[0028] Compared with the prior art, the beneficial effects of this application are:

[0029] This application introduces the instrument air source from the gas turbine itself to purge the liquid fuel pipeline. Because the instrument air source has a low gas temperature, coking of the liquid fuel in the pipeline will not occur during the purging process, and blockage of the liquid fuel pipeline or nozzles is less likely. Furthermore, the air source used for purging and cooling in this application originates from the gas turbine itself. Compared to introducing air from an external source, the gas pressure from the gas turbine's own source is relatively stable, reducing the likelihood of high-temperature combustion chamber gas flowing back into non-working fuel pipelines, and also resulting in lower operating costs. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the dual-fuel gas turbine cleaning system for removing valve assemblies proposed in the embodiments of this application;

[0031] Figure 2 This is a schematic diagram of the structure of the dual-fuel gas turbine cleaning system proposed in the embodiments of this application;

[0032] Figure 3 This is a flowchart of the purging method for a dual-fuel gas turbine proposed in the embodiments of this application;

[0033] Figure 4 This is a flowchart illustrating the process of purging liquid fuel pipelines based on an instrument air source, as proposed in an embodiment of this application.

[0034] Figure 5 This is a flowchart illustrating the process of obtaining a preset opening degree as proposed in an embodiment of this application.

[0035] In the diagram: 1. Compressor; 10. First main pipeline; 11. First valve; 2. Instrument gas source; 20. Second main pipeline; 21. Second valve; 22. First check valve; 3. Gas fuel pipeline; 30. First branch pipeline; 31. Fourth valve; 4. Liquid fuel pipeline; 40. Second branch pipeline; 41. Fifth valve; 42. Second check valve; 5. Natural gas monitoring device; 50. Vent pipe; 51. Third valve; 60. Gas fuel inlet pipe; 70. Liquid fuel inlet pipe. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] It should be noted that in the description of this application, the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0038] Furthermore, it should be understood that, for ease of description, the accompanying drawings are only schematic diagrams, and the dimensions of the various components shown in the drawings are not drawn to actual scale. For example, some pipes are represented by lines, some pipes by circles, and the length and orientation of each pipe may be changed or exaggerated relative to actual needs.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined or described in one figure, it will not need to be discussed or described in detail in the description of the subsequent figures.

[0040] Before understanding this application, it is important to understand that the purging system is one of the important auxiliary systems of a dual-fuel gas turbine. It not only needs to purge the corresponding fuel lines during fuel switching, but also... Figure 1 and Figure 2 The gaseous fuel line 3 and liquid fuel line 4 are used in the dual-fuel gas turbine. Simultaneously, during operation, they also cool the non-working fuel lines to extend nozzle life. Patent CN106988891A uses a method of heating liquid nitrogen to form nitrogen gas to purge either the gaseous fuel passage (equivalent to the gaseous fuel line in this application) or the liquid fuel passage (equivalent to the liquid fuel line in this application). Since the pressure of the formed gas is affected not only by the amount of liquid nitrogen input but also by heating, if the formed nitrogen pressure is lower than the pressure in the combustion chamber, it can easily cause high-temperature combustion gas to backflow into the non-working fuel line, potentially damaging the non-working fuel line or, in severe cases, damaging the gas turbine.

[0041] In existing technologies, there are various methods for purging fuel lines and cooling non-working fuel lines. For example, the purging gas is designed in diverse ways, including using the same gas or two different gases to purge different fuel lines. The choice of gas source is also varied, including using an external gas source for purging or using the gas turbine's own gas source. It is important to understand that using an internal gas source is relatively cheaper than using an external gas source. However, as the background technology shows, the gas source commonly used for purging fuel lines in gas turbines comes from the compressor. The purging gas after the compressor is at a high temperature, which can easily cause coking of the liquid fuel in the liquid fuel lines during purging, clogging the lines or nozzles.

[0042] To address the aforementioned technical problems, this application proposes a technical solution:

[0043] Specifically, an embodiment of this application proposes a dual-fuel gas turbine cleaning system, which, as follows: Figure 1As shown, it includes: a first main pipe 10, a first branch pipe 30, a second branch pipe 40, a second main pipe 20, and a valve assembly. The first end of the first main pipe 10 is connected to the compressor 1; specifically, the first main pipe 10 is mainly used for post-priming gas from the compressor 1. The first end of the first branch pipe 30 is connected to the first main pipe 10, and the second end of the first branch pipe 30 is connected to the gaseous fuel line 3; specifically, the first branch pipe 30 is mainly used to introduce gas from the first main pipe 10 into the gaseous fuel line 3 for subsequent purging and cooling of the gaseous fuel line 3. The first end of the second branch pipe 40 is connected to the first main pipe 10. The second branch pipe 40 is connected to the liquid fuel pipeline 4 at its second end. Specifically, the second branch pipe 40 is mainly used to introduce the gas in the first main pipe 10 into the liquid fuel pipeline 4 for subsequent cooling of the liquid fuel pipeline 4. The first end of the second main pipe 20 is connected to the instrument gas source 2, and the second end of the second main pipe 20 is connected to the second branch pipe 40. Specifically, the second main pipe 20 is mainly used to introduce the gas in the instrument gas source 2 into the liquid fuel pipeline 4 for subsequent purging of the liquid fuel pipeline 4.

[0044] Specifically, in the embodiments of this application, the bleed gas from compressor 1 is used. The gas pressure generated is greater than the working pressure in the combustion chamber, which effectively ensures that the purging gas can be blown into the combustion chamber through the nozzle in a forward direction, effectively preventing the backflow of high-temperature combustion gas into the non-working fuel pipeline. Meanwhile, the use of gas turbines requires the use of instrument air source 2, which is mainly used to control various pneumatic devices in the gas turbine and to purge and release small containers in the gas turbine system. When purging the liquid fuel pipeline 4, firstly, instrument air source 2 is used for purging, and then the bleed gas from compressor 1 is used to cool the liquid fuel pipeline 4. This achieves the purpose of removing residual liquid fuel from the liquid fuel pipeline 4 without requiring additional purging equipment, thus reducing operating costs.

[0045] It is important to understand that each pipe has two ends. In the embodiments of this application, the first end and the second end of the pipe are merely used to functionally define the two ends of the pipe, and do not specifically refer to any one end of the pipe. For example, in one embodiment of this application, such as... Figure 1 As shown, the first end of the second branch pipe 40 is connected to the first main pipe 10, and the second end of the second branch pipe 40 is used to connect to the liquid fuel pipeline 4. If the two ends of the second branch pipe 40 are reversed, the first end of the second branch pipe 40 before the reversal becomes the second end after the reversal, and the second end of the second branch pipe 40 before the reversal becomes the first end after the reversal.

[0046] To control the blowing gas, a valve assembly is also provided in this embodiment. This valve assembly is used to control the opening and closing of at least the first main pipe 10 and the second main pipe 20. That is, valves are required on at least the first main pipe 10 and the second main pipe 20. In a specific embodiment of this application, such as... Figure 2 As shown, the valve assembly includes a first valve 11 disposed on the first main pipeline 10 and a second valve 21 disposed on the second main pipeline 20.

[0047] It should be clear that, as described above, the first valve 11 is mainly used to control the opening and closing of the first main pipeline 10, while the second valve 21 is mainly used to control the opening and closing of the second main pipeline 20. It is easy to understand that, in the embodiments of this application, the first valve 11 and the second valve 21 can be any type of valve. For example, they can be valves that are manually controlled to open and close, valves that are electrically controlled to open and close, or valves that are hydraulically, pneumatically, turbine-driven, pneumatically-hydraulic, spur gear-driven, or bevel gear-driven to open and close; they can be gate valves, globe valves, plug valves, ball valves, or butterfly valves, etc.

[0048] It should be clear that, in order to ensure that the entire cleaning system has good airtightness, in a specific embodiment of this application, the first valve 11 and the second valve 21 are both shut-off valves, and the third valve 51, the fourth valve 31 and the fifth valve 41 mentioned below are also shut-off valves.

[0049] To prevent the inability to remove flammable gases from the first main pipe 10 and the first branch pipe 30, in one embodiment of this application, such as... Figure 1 and Figure 2 As shown, the first main pipe 10 also has a vent pipe 50, which is located between the first valve 11 and the second end of the first main pipe 10. It is easy to understand that the purpose of setting the vent pipe 50 is to remove gas from all pipes between the first valve 11, the fourth valve 31 and the fifth valve 41. In order to facilitate the control of the vent pipe 50, the valve assembly also includes a third valve 51 installed on the vent pipe 50.

[0050] It is important to understand that if some valves in the valve assembly develop gaps due to wear or aging during long-term use, resulting in poor sealing, gaseous fuel can easily seep into the purging system through these gaps. If gaseous fuel is present in the purging system, it can easily lead to a safety accident. Therefore, in another embodiment of this application, the vent pipe 50 is also equipped with a natural gas monitoring device 5. The natural gas monitoring device 5 and the third valve 51 are arranged sequentially along the airflow direction in the vent pipe 50. The natural gas monitoring device 5 is used to monitor whether gaseous fuel has entered the purging system. If gaseous fuel has entered, the third valve 51 is opened to remove the gaseous fuel from the purging system.

[0051] It is easy to understand that the natural gas monitoring device 5 can be any commercially available device capable of monitoring natural gas content. Since this is a mature existing technology, it will not be elaborated upon further. If the third valve 51 is a manually controlled valve, the natural gas monitoring device 5 can be used in conjunction with an alarm device, such as a buzzer, to remind personnel to open the third valve 51. If the third valve 51 is an electrically controlled valve, the natural gas monitoring device 5 and the third valve 51 can be electrically connected. When the natural gas monitoring device 5 detects gaseous fuel in the purging system, it directly opens the third valve 51. Controlling valve opening based on monitoring results is a very mature existing technology, such as programmable logic controller (PLC) technology, and therefore will not be elaborated upon further.

[0052] To prevent gaseous fuel in gaseous fuel pipeline 3 from entering the first branch pipeline 30, in one embodiment of this application, such as Figure 2 As shown, the valve assembly includes a fourth valve 31 disposed on the first branch pipe 30.

[0053] To prevent liquid fuel in liquid fuel line 4 from entering the second branch line 40, in one embodiment of this application, such as... Figure 2 As shown, the valve assembly also includes a fifth valve 41 disposed on the second branch pipe 40.

[0054] It should be clear that, in the embodiments of this application, since the exhaust temperature of the compressor 1 is relatively high, the first valve 11, the fourth valve 31 and the fifth valve 41 can be selected as high-temperature resistant valves so that the first valve 11, the fourth valve 31 and the fifth valve 41 have a longer service life.

[0055] To ensure that liquid fuel in the liquid fuel line 4 does not leak into the second branch line 40 in the event that the gas turbine is using liquid fuel and the fifth valve 41 is damaged, in a specific embodiment of this application, such as... Figure 2 As shown, the valve assembly also includes a second check valve 42 disposed on the second branch pipe 40. The fifth valve 41 and the second check valve 42 are arranged sequentially along a second direction, which points from the first end to the second end of the second branch pipe 40. It should be clear that the function of the second check valve 42 is to allow gas from the compressor 1 to flow from the first end to the second end of the second branch pipe 40, while liquid fuel from the liquid fuel line 4 cannot flow from the second end to the first end of the second branch pipe 40.

[0056] For reasons similar to those described above, in order to ensure that liquid fuel in the liquid fuel pipeline 4 does not leak into the second main pipeline 20 when the gas turbine is using liquid fuel and the second valve 21 is damaged, in a specific embodiment of this application, such as... Figure 2As shown, the valve assembly also includes a first check valve 22 disposed on the first main pipe 10, and a second valve 21 and the first check valve 22 are arranged sequentially along a first direction, which points from the first end of the second main pipe 20 to the second end.

[0057] It should be clear that, in order to avoid the insufficient amount of cleaning gas from the compressor 1 or instrument gas source 2 due to excessive forward opening pressure of the first one-way valve 22 or the second one-way valve 42, which would prevent the liquid fuel pipeline 4 from being cleaned or cooled, in a specific embodiment of this application, the forward opening pressure of both the first one-way valve 22 and the second one-way valve 42 is less than or equal to 10 Pa. Specifically, it can be any pressure value among 1 Pa, 2 Pa, 3 Pa, 4 Pa, 5 Pa, 6 Pa, 7 Pa, 8 Pa, 9 Pa, and 10 Pa, or any pressure value between any two adjacent pressure values ​​mentioned above. Meanwhile, in order to prevent the reverse shut-off pressure of the first check valve 22 and the second check valve 42 from being too low and thus failing to prevent liquid fuel from entering the second branch pipe 40 or the second main pipe 20, in a specific embodiment of this application, the reverse shut-off pressure of the first check valve 22 and the second check valve 42 is greater than or equal to 5 MPa. Specifically, it can be any pressure value among 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa and 10 MPa, or it can be any pressure value between any two adjacent pressure values ​​mentioned above.

[0058] The purging system in this embodiment introduces instrument air source 2 from the gas turbine itself to purge the liquid fuel line 4. Because the gas temperature of instrument air source 2 is low, coking of the liquid fuel in the liquid fuel line 4 will not occur during purging, and blockage of the liquid fuel line 4 or nozzles is less likely. Furthermore, the purging and cooling air sources in this embodiment both originate from the gas turbine itself. Compared to introducing air from an external source, the gas pressure from the gas turbine's own source is relatively stable, reducing the likelihood of high-temperature combustion chamber gas flowing back into non-working fuel lines, and also resulting in lower operating costs.

[0059] After introducing an embodiment of a dual-fuel gas turbine purging system proposed in this application, this application also proposes an embodiment of a dual-fuel gas turbine purging method. It should be understood that the dual-fuel main unit in the gas turbine operates in multiple modes, such as: purging mode, start-up mode, idle mode, load mode, shutdown mode, and switching mode. As is known from the background art, the main technical problem addressed by this application is to purge liquid fuel in liquid fuel pipelines and prevent the liquid fuel from coking and clogging pipelines or nozzles. In other words, the main technical problem addressed by this application is the problem arising during the switching of a gas turbine from liquid fuel to gaseous fuel, a process in which the gas turbine is in switching mode. Therefore, the following description focuses on the operating state of the purging system when the gas turbine is in switching mode, while a brief description is given of the operating state of the purging system in other modes.

[0060] Specifically, such as Figure 3 According to one embodiment of this application, a method for purging a dual-fuel gas turbine includes:

[0061] Step S100: Purge the liquid fuel pipeline 4 based on the instrument air source 2.

[0062] It is important to understand that in this application, when a gas turbine switches from liquid fuel to gaseous fuel, the purging system operates in two separate actions: purging and cooling (see step S200). Specifically, in the embodiments of this application, the purging process involves discharging the remaining liquid fuel in the liquid fuel line 4 into the combustion chamber through the nozzle when the gas turbine switches from liquid fuel to gaseous fuel, thereby emptying the liquid fuel line 4. Unlike existing technologies, this application uses instrument gas source 2 to purge the liquid fuel line 4, effectively preventing the technical problem of coking and clogging of the liquid fuel line or nozzle due to excessively high purging gas temperature.

[0063] Step S200: Cool the liquid fuel pipeline 4 based on the bleed air after compressor 1.

[0064] It is important to understand that after the liquid fuel in liquid fuel line 4 has been purged, the liquid fuel line 4 can be cooled using the higher-temperature bleed air from compressor 1. Since there is no liquid fuel left in liquid fuel line 4, there will be no issues with liquid fuel coking, clogging of the liquid fuel line or nozzles. Furthermore, the lower cost of the bleed air from compressor 1 contributes to cost savings in production.

[0065] It should be clear that dual-fuel gas turbines can be purged and cooled using various purging systems and the purging methods described above. In a specific embodiment of this application, such as... Figure 4 As shown, in an embodiment of the dual-fuel gas turbine purging system proposed in this application, step S100: purging the liquid fuel pipeline 4 based on the instrument air source 2, including:

[0066] Step S110: Obtain the preset opening degree and the first switching command;

[0067] It is important to understand that the purpose of obtaining the first switching instruction is to close or open certain valves in the valve assembly. Therefore, it is easy to understand that if the valves in the valve assembly are manually controlled, the first switching instruction can be a verbal or written notification exchanged between operators; if the valves in the valve assembly are electrically controlled, the first switching instruction can be an electronic signal issued by the programmable logic controller.

[0068] It's easy to understand that during the purging process, it's necessary to avoid both excessively fast and excessively slow purging speeds. If the purging speed is too fast, too much liquid fuel enters the combustion chamber, easily leading to poor combustion and, in severe cases, overload and engine shutdown. If the purging speed is too slow, too little liquid fuel enters the combustion chamber, easily causing insufficient power, and at a low purging speed, the liquid fuel at the nozzle is prone to coking, clogging the nozzle. During the purging process, if... Figure 2 As shown, the larger the opening degree of the second valve 21, the greater the pressure of the purging gas, meaning the faster the liquid fuel is discharged; conversely, the smaller the opening degree of the second valve 21, the lower the pressure of the purging gas, meaning the slower the liquid fuel is discharged. Therefore, during purging, a preset opening degree needs to be obtained in advance to control the overall purging speed.

[0069] Step S120: Based on the first switching command, after closing the first valve 11, the second valve 21, the fourth valve 31 and the fifth valve 41, perform fuel switching.

[0070] It is important to understand that the purpose of closing the first valve 11, the second valve 21, the fourth valve 31, and the fifth valve 41 before the gas turbine switches from liquid fuel to gaseous fuel is to prevent the unstable pressure of the high-temperature gas in the combustion chamber from flowing back into the cleaning system.

[0071] Step S130: If the fuel switching is complete, open the second valve 21 to the preset opening degree.

[0072] It is important to understand that, as mentioned above, the purpose of opening the second valve 21 to the preset opening degree is to ensure that the liquid fuel in the liquid fuel line 4 can flow out of the nozzle at a constant rate during the purging process. It is easy to infer that the flow rate of the liquid fuel is constant during the purging process; that is, this constant flow rate is the flow rate of liquid fuel that the operator expects to flow out.

[0073] In one specific embodiment of this application, such as Figure 5 As shown, in step S110, obtaining the preset opening degree includes:

[0074] Step S111: Obtain the volume of the liquid fuel pipeline 4, the cross-sectional area of ​​the nozzle, and the liquid fuel flow rate.

[0075] It is important to understand that the volume of the liquid fuel line 4 in each gas turbine is constant, the cross-sectional area of ​​the nozzle is also constant, and the liquid fuel flow rate is the flow rate of liquid fuel that the operator expects to flow out. Therefore, all three values ​​mentioned above are constant.

[0076] Step S112: Obtain the purging pressure based on the volume of the liquid fuel pipeline 4, the cross-sectional area of ​​the nozzle, and the liquid fuel flow rate.

[0077] It is important to understand that if the cross-sectional area of ​​the nozzle is constant and the outflow rate of liquid fuel from the nozzle is S, then it is necessary to control the pressure P1 applied to the liquid. At the same time, the high-temperature gas in the combustion chamber will apply a reverse pressure P2 to the liquid fuel. Therefore, the pressure P that the purge gas needs to apply to the liquid fuel is P = P1 + P2.

[0078] Step S113: Obtain the preset opening degree based on the blowing pressure.

[0079] It should be noted that since controlling the opening of the second valve 21 based on the relationship between the gas purging pressure and the opening of the second valve 21 is existing technology, it will not be described in detail.

[0080] Step S400: If the opening time of the second valve 21 reaches the preset threshold, then close the second valve 21.

[0081] If the flow rate S of liquid fuel from the nozzle is constant during purging, and the volume of liquid fuel line 4 is also constant, then the time T for purging liquid fuel line 4 is fixed.

[0082] It should be clear that in the embodiments of this application, the preset threshold can be directly equal to the time T for emptying the liquid fuel pipeline 4. In other embodiments of this application, in order to ensure that the liquid fuel in the liquid fuel pipeline 4 can be completely emptied, the preset threshold can be equal to T+t, where t is any time value greater than 0.

[0083] The purging method in this embodiment uses the gas turbine's own instrument gas source 2 to purge the liquid fuel pipeline 4. Because the gas temperature of the instrument gas source 2 is low, coking of the liquid fuel in the liquid fuel pipeline 4 will not occur during the purging process, and blockage of the liquid fuel pipeline 4 or nozzles is less likely. Furthermore, the gas source used for purging and cooling in this embodiment comes from the gas turbine itself. Compared to introducing gas from an external source, the gas pressure of the gas turbine's own source is relatively stable, reducing the likelihood of high-temperature combustion chamber gas flowing back into the non-working fuel pipeline, and also resulting in lower operating costs.

[0084] It should be clear that the above-described method embodiments describe the workflow when the gas turbine switches from liquid fuel to gaseous fuel in the switching mode of the purging system. The workflows for other operating modes of the purging system proposed in this application embodiment are also described below.

[0085] If the gas turbine switches from gaseous fuel to liquid fuel, the first valve 11, the second valve 21, the fourth valve 31 and the fifth valve 41 are closed before the fuel switch. After the fuel switch, the first valve 11 and the fourth valve 31 are opened to purge and cool the gaseous fuel pipeline 3.

[0086] If the purging system is in purging mode, the dual-fuel main unit is driven by the starter motor and does not inject fuel for ignition, so there is no need to purge the non-working fuel pipeline. At this time, the first valve 11, the second valve 21, the fourth valve 31 and the fifth valve 41 are all in the closed state.

[0087] If the purging system is in start-up mode, the dual-fuel main engine speed is low, the afterpressure of compressor 1 is low, the purging effect is poor, and the running time of this stage is short. Therefore, it is not necessary to purge the non-working fuel pipeline during this stage. At this time, the first valve 11, the second valve 21, the fourth valve 31 and the fifth valve 41 are all in the closed state.

[0088] If the purging system is in slow mode, the dual-fuel main unit is in a warm-up state, which means that the dual-fuel main unit needs to run stably for a certain period of time. During this process, the non-working fuel lines can be purged.

[0089] If the purging system is in load mode, the dual-fuel main unit is in a transitional state of loading or unloading, and the non-working fuel pipeline needs to be continuously purged.

[0090] It is important to understand that the purging system has two shutdown modes: normal shutdown and emergency shutdown. If the purging system is in normal shutdown mode and the dual-fuel main unit is currently under load, the dual-fuel main unit will be unloaded to idle. After running at idle for a period of time, the unit will be allowed to cool down. Throughout this process, and while the dual-fuel main unit is at idle, the non-working fuel lines must be continuously purged. Once the cooling process is complete and a shutdown command is issued, the valves corresponding to the purging lines will be closed, and the third valve 51 will be opened. If the purging system is in emergency shutdown mode, all valves in the purging system will be closed, and the third valve 51 will be opened.

[0091] It is important to understand that when the gas turbine burns liquid fuel, both the second valve 21 and the fifth valve 41 are closed; the first valve 11 and the fourth valve 31 are open. High-pressure gas, after passing through the compressor 1, purifies and cools the gaseous fuel pipeline 3 through the first main pipeline 10 and the first branch pipeline 30. When the gas turbine burns gaseous fuel, the fourth valve 31 is closed; the first valve 11 and the fifth valve 41 are open. High-pressure gas, after passing through the compressor 1, purifies and cools the liquid fuel pipeline 4 through the first main pipeline 10 and the second branch pipeline 40. Of course, in other embodiments, when the gas turbine burns gaseous fuel, the second valve 21 can also be opened. The high-pressure gas in the instrument gas source 2 can then merge with the high-pressure gas from the first main pipeline 10 in the second branch pipeline 40 through the second main pipeline 20 to purify and cool the liquid fuel pipeline 4.

[0092] After describing an embodiment of the dual-fuel gas turbine cleaning method proposed in this application, this application also proposes a dual-fuel gas turbine having the dual-fuel gas turbine cleaning system described in any of the above embodiments.

[0093] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for purging a dual-fuel gas turbine, the dual-fuel gas turbine comprising a dual-fuel gas turbine purging system; characterized in that, The dual-fuel gas turbine cleaning system includes: The first main pipe (10) is used to connect the first end to the compressor (1); The first branch pipe (30) has its first end connected to the first main pipe (10) and its second end connected to the gas fuel pipeline (3). The second branch pipe (40) has its first end connected to the first main pipe (10) and its second end connected to the liquid fuel pipeline (4). The second main pipeline (20) has its first end connected to the instrument air source (2) and its second end connected to the second branch pipeline (40). A valve assembly is used to control the opening and closing of the first main pipe (10) and the second main pipe (20); the valve assembly includes a first valve (11) disposed on the first main pipe (10) and a second valve (21) disposed on the second main pipe (20); The method includes: When cleaning the liquid fuel line (4), firstly, the instrument air source (2) is used for cleaning, and then the back air of the compressor (1) is used to cool the liquid fuel line (4).

2. The purging method for a dual-fuel gas turbine according to claim 1, characterized in that, The first main pipe (10) also has a vent pipe (50) leading out, the vent pipe (50) being located between the first valve (11) and the second end of the first main pipe (10); the valve assembly also includes a third valve (51) disposed on the vent pipe (50).

3. The purging method for a dual-fuel gas turbine according to claim 2, characterized in that, The vent pipe (50) is also equipped with a natural gas monitoring device (5), and the natural gas monitoring device (5) and the third valve (51) are arranged sequentially along the airflow direction in the vent pipe (50).

4. The method for cleaning a dual-fuel gas turbine according to any one of claims 1 to 3, characterized in that, The valve assembly includes a fourth valve (31) disposed on the first branch pipe (30).

5. The method for cleaning a dual-fuel gas turbine according to any one of claims 1 to 3, characterized in that, The valve assembly further includes a first check valve (22) disposed on the first main pipe (10), and the second valve (21) and the first check valve (22) are arranged sequentially along a first direction, the first direction being from the first end of the second main pipe (20) to the second end.

6. The method for purging a dual-fuel gas turbine according to any one of claims 1 to 3, characterized in that, The valve assembly also includes a fifth valve (41) disposed in the second branch pipe (40).

7. The purging method for a dual-fuel gas turbine according to claim 6, characterized in that, The valve assembly also includes a second check valve (42) disposed in the second branch pipe (40), and the fifth valve (41) and the second check valve (42) are arranged sequentially along a second direction, which extends from the first end of the second branch pipe (40) to the second end.

8. The method for cleaning a dual-fuel gas turbine according to any one of claims 1 to 3, characterized in that, The liquid fuel pipeline (4) is purged using the instrument air source (2), including: Obtain a preset opening degree and a first switching command, wherein the first switching command is obtained based on the operating mode of the dual-fuel gas turbine; Based on the first switching command, after closing the first valve (11), the second valve (21), the fourth valve (31) and the fifth valve (41), fuel switching is performed; If the fuel switch is complete, open the second valve (21) to the preset opening degree; If the opening time of the second valve (21) reaches a preset threshold, then the second valve (21) is closed; Cooling the liquid fuel pipeline (4) using the bleed air from the compressor (1) includes: Open the first valve (11) and the fifth valve (41).

Images