A method for fuel supply during ignition and starting of a gas turbine

Abstract

This disclosure provides a fuel supply method for ignition and starting a gas turbine, including increasing the swashplate angle by a given inclination to bring the engine to ignition speed; activating the starting solenoid valve and ignition device, and starting a timer; after A seconds, controlling the fuel supply flow rate of the main fuel circuit to increase from a lean value to a rich value within N seconds; acquiring the exhaust temperature and calculating the increase in exhaust temperature within a specified time; when the increase in exhaust temperature is greater than or equal to a set value, the engine is determined to have successfully ignited; when the increase in exhaust temperature is less than the set value, the engine is determined to have failed to ignite. The fuel supply method for ignition and starting a gas turbine provided in this disclosure differs from conventional ignition and starting fuel supply methods with a fixed main fuel quantity within the ignition interval. In this method, the fuel quantity within the ignition interval changes gradually, i.e., from lean to rich, continuously adjusting the fuel-air ratio, which improves the reliability of successful engine ignition and reduces the possibility of engine detonation.

Description

Technical Field

[0001] This disclosure relates to the field of gas turbine technology, and in particular to a gas turbine ignition and starting fuel supply method. Background Technology

[0002] Traditional fuel supply control methods utilize a fixed-speed, fixed-flow high-pressure fuel pump driven by a power frequency motor to supply fuel to the regulating system. The regulating system adjusts the fuel flow to the gas turbine according to the control system's instructions, with excess fuel returning to the pump or fuel tank. However, the ignition zone requires a high fuel-air ratio, and a fixed fuel supply results in a low ignition success rate. This leads to frequent ignition failures during ground starting of a certain type of aero-derivative gas turbine. Furthermore, because the modified aero-derivative gas turbine often fails to ignite with a fixed fuel supply, there is a significant amount of fuel buildup in the combustion chamber, which is difficult to clean during cold engine operation. Therefore, once the engine ignites, detonation is likely to occur. Summary of the Invention

[0003] The main objective of this disclosure is to provide a fuel supply method for ignition and starting of a gas turbine, which aims to solve the technical problems of low ignition and starting success rate and easy combustion and explosion in the prior art.

[0004] To achieve the above objectives, this disclosure provides a gas turbine ignition and starting fuel supply method, comprising the following steps:

[0005] Step S10: Increase the swashplate angle by the given slope to bring the engine to ignition speed, then turn on the start solenoid valve and ignition device, and start timing;

[0006] Step S20: After A seconds, control the oil supply flow rate of the main oil circuit to increase from the lean oil value to the rich oil value within N seconds;

[0007] Step S30: Obtain the exhaust temperature and calculate the increase in the exhaust temperature within a specified time.

[0008] Step S40: When the increase in exhaust temperature is greater than or equal to the set value, the engine ignition is determined to be successful;

[0009] Step S50: If the increase in exhaust temperature is less than the set value, the engine ignition is determined to have failed.

[0010] Optionally, the gas turbine ignition and starting fuel supply method further includes the following steps:

[0011] Step S60: After successful engine ignition, continue to increase the swashplate angle by the given inclination until it reaches 100%;

[0012] Step S70: Control the oil supply flow rate of the main oil circuit to decrease stepwise, and then control the oil supply flow rate of the main oil circuit to increase to the specified value within F seconds.

[0013] Optionally, the gas turbine ignition and starting fuel supply method further includes the following steps:

[0014] Step S80: When the engine speed is greater than or equal to the set speed, reduce the swashplate angle to zero and disconnect the main pump motor of the hydraulic starting system.

[0015] Optionally, the gas turbine ignition and starting fuel supply method further includes the following steps:

[0016] Step S90: Obtain the engine speed. If the engine speed is not less than the closed-loop speed within H seconds, determine whether the exhaust temperature is greater than or equal to the limit value.

[0017] Step S100: If the engine speed is less than the closed-loop speed within H seconds, it is determined that the start-up timeout has occurred and the engine stops.

[0018] Step S110: When the exhaust temperature exceeds the limit value, it is determined that the start-up is overheated and the engine is shut down.

[0019] Optionally, step S50: when the increase in exhaust temperature is less than a set value, the step of determining that the engine ignition has failed includes the following:

[0020] Step S501: Disconnect the starting oil circuit solenoid valve and ignition device, close the main oil circuit shut-off valve, and reduce the fuel regulation opening to the minimum;

[0021] Step S502: Reduce the swashplate angular velocity to zero and disconnect the main pump motor of the hydraulic starting system.

[0022] Optionally, the gas turbine ignition and starting fuel supply method further includes:

[0023] Step S120: Obtain the engine speed. If the engine speed is less than the closed-loop speed within H seconds, determine that the engine ignition and starting has failed.

[0024] Step S130: Disconnect the starting solenoid valve and ignition device, close the main fuel circuit shut-off valve, and reduce the fuel regulation opening to the minimum;

[0025] Step S140: Reduce the swashplate angular velocity to zero and disconnect the main pump motor of the hydraulic starting system.

[0026] Optionally, after step S20: controlling the oil supply flow rate of the main oil circuit to increase from a lean value to a rich value within N seconds after A seconds, the method further includes:

[0027] Step S201: Connect the starting solenoid valve and ignition device;

[0028] Step S202: After C seconds, disconnect the starting solenoid valve and the ignition device.

[0029] The gas turbine ignition and starting fuel supply method disclosed herein includes: increasing the swashplate angle by a given inclination to bring the engine to ignition speed; activating the starting solenoid valve and ignition device, and starting a timer; after A seconds, controlling the fuel supply flow rate of the main fuel circuit to increase from a lean value to a rich value within N seconds; acquiring the exhaust temperature and calculating the increase in exhaust temperature within a specified time; determining that engine ignition is successful when the increase in exhaust temperature is greater than or equal to a set value; and determining that engine ignition fails when the increase in exhaust temperature is less than the set value. Unlike conventional ignition and starting fuel supply methods with a fixed main fuel quantity during the ignition interval, this method involves a gradual increase in fuel quantity during the ignition interval, i.e., from lean to rich, continuously adjusting the fuel-air ratio, thus improving the reliability of successful engine ignition and reducing the possibility of engine detonation. This method has a simple system composition, improves engine ignition reliability through dynamic fuel-air ratio adjustment at ignition time, and reduces the possibility of engine detonation after successful ignition by stepping down the fuel quantity. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0031] Figure 1 A schematic flowchart of an embodiment of the gas turbine ignition and starting fuel supply method provided in this disclosure;

[0032] Figure 2 for Figure 1 A flowchart illustrating the fuel supply method for gas turbine ignition and startup provided in the document;

[0033] Figure 3 for Figure 1 The flowchart of the gas turbine ignition and start-up fuel supply method provided in the document.

[0034] The realization of the purpose, functional features and advantages of this disclosure will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0035] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.

[0036] It should be noted that if the embodiments of this disclosure involve directional indication, the directional indication is only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0037] Furthermore, if the embodiments of this disclosure involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Moreover, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this disclosure.

[0038] A gas turbine is an internal combustion engine that uses a continuously flowing gas as its working fluid to drive a high-speed rotating impeller, converting the energy of fuel into useful work. Like most internal combustion engines, a gas turbine cannot start independently; it requires external force (energy) and a pre-programmed startup process to reach a stable operating state. Therefore, starting a gas turbine is a complex system engineering project, with fuel supply being paramount, directly affecting the reliability of engine ignition.

[0039] In view of this, this disclosure proposes a fuel supply method that differs from the conventional ignition start-up fuel supply pattern and the fixed main fuel quantity in the ignition interval.

[0040] See Figures 1-3In this embodiment, the hydraulic starting system swashplate angle is increased by a given slope to bring the engine to the ignition speed, the starting oil circuit solenoid valve is activated, and the ignition device is activated. Simultaneously, a timer is started, and after a certain period, the starting oil circuit solenoid valve and the ignition device are disconnected. This time period is generally the longest permissible operating time of the ignition device in a single operation; for this gas turbine, the longest permissible operating time of the ignition device in a single operation is 30 seconds. Starting from the activation of the starting oil circuit and the ignition device, the main oil circuit begins supplying fuel after a certain time. After fuel supply, the fuel quantity linearly increases from lean to rich within a fixed time period. This type of gas turbine has a pre-combustion chamber. The pre-combustion chamber is ignited first to form a flare to ignite the main combustion chamber. The fuel quantity in the pre-combustion chamber is a calibrated fixed fuel quantity. A certain time is the pre-combustion chamber flare preparation time, generally taken as 3~10 seconds; in this embodiment, 10 seconds is used. The fixed fuel supply time of the main oil circuit is taken as 20 seconds in this embodiment. The lean fuel rating corresponds to a 15% opening of the fuel control valve, with a fuel quantity of approximately 600 kg / h. The rich fuel rating corresponds to a 30% opening of the fuel control valve, with a fuel quantity of approximately 600 kg / h. In other words, starting from the connection of the starting fuel circuit and ignition device, the main fuel circuit begins supplying fuel after 10 seconds, and the fuel supply rate of the main fuel circuit is linearly increased to 600 kg / h within 20 seconds.

[0041] As can be seen from the above, the fuel supply method for ignition and starting of gas turbines provided in this disclosure involves a process of increasing fuel quantity during the ignition interval, i.e., the fuel quantity changes from low to high, continuously adjusting the fuel-air ratio, thereby greatly improving the reliability of successful engine ignition.

[0042] It should be noted that the given slope is adjustable, generally between 0.5% and 1.5%. In this embodiment, it is set to 1% based on the engine acceleration during engine testing.

[0043] The engine ignition is determined by the increase in exhaust temperature over a certain period of time. This is generally based on the rise in exhaust temperature during a normal engine start-up test, combined with the longest single-operation time of the ignition system. In this embodiment, a 30°C increase in exhaust temperature within 20 seconds is used, but this can be adjusted according to specific test conditions. In other words, the exhaust temperature is acquired, and the increase in exhaust temperature within 20 seconds is calculated. If the increase in exhaust temperature is greater than or equal to 30°C, the engine is considered to have ignited successfully; if the increase in exhaust temperature is less than 30°C, the engine is considered to have failed to ignite.

[0044] In addition, if the fuel supply is fixed and the ignition fails frequently, there will be a lot of oil buildup in the combustion chamber, and it will be difficult to clean the engine when it is cold, which can lead to detonation after the engine is started.

[0045] Therefore, to address the issue of potential detonation, this embodiment involves a step reduction in fuel quantity after successful ignition. The specific steps depend on the engine's test run, ensuring that the step reduction does not cause engine stall. Alternatively, the fuel can be reduced in a step after the engine has been running for 50-100ms. The final fuel quantity should not be less than the minimum fuel quantity atomized by the engine nozzles. In this embodiment, the fuel is reduced directly by approximately 150 kg / h after ignition without a sustained period.

[0046] In this embodiment, after the engine is started, the fuel supply is reduced by a fixed amount in a step from the current amount. At the same time, the swashplate angle opening of the hydraulic starter system is increased by a given slope, and the fixed fuel supply is reduced in a step. In this embodiment, the fuel control valve opening is reduced by 6%, which corresponds to a fuel quantity of approximately 150 kg / h.

[0047] Furthermore, in this disclosure, after successful ignition, the hydraulic starting system is disconnected at a speed of 3200 r / min, the starting timeout is 98 s, and the exhaust temperature exceeds 650°C during starting. During ignition and starting, if ignition fails, starting timeout occurs, or starting temperature exceeds the limit, an emergency shutdown is initiated by disconnecting the starting oil solenoid valve, ignition device, hydraulic starting system, main circuit shut-off valve, and minimizing the fuel trim opening.

[0048] In summary, the gas turbine ignition and starting fuel supply method disclosed in this disclosure does not increase the hardware resources of the control system. Compared with a fixed fuel quantity in the ignition interval, this method dynamically adjusts the fuel-air ratio in the ignition interval, improving the reliability of successful ignition. Furthermore, the step reduction of fuel quantity after successful ignition lowers the possibility of engine knock.

[0049] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and are not intended to limit them. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A method for fuel supply during the ignition and starting of a gas turbine, characterized in that, Includes the following steps: Step S10: Increase the swashplate angle of the hydraulic starting system by the given slope to bring the engine to the ignition speed, then connect the starting oil circuit solenoid valve and the ignition device, and start timing; Step S20: After A seconds, control the oil supply flow rate of the main oil circuit to increase from the lean oil value to the rich oil value within N seconds; Step S30: Obtain the exhaust temperature and calculate the increase in the exhaust temperature within a specified time. Step S40: When the increase in exhaust temperature is greater than or equal to the set value, the engine ignition is determined to be successful; Step S50: When the increase in exhaust temperature is less than the set value, the engine ignition is determined to have failed. The gas turbine ignition and starting fuel supply method further includes the following steps: Step S60: After successful engine ignition, continue to increase the swashplate angle by the given inclination until it reaches 100%; Step S70: Control the oil supply flow rate of the main oil circuit to decrease stepwise, and then control the oil supply flow rate of the main oil circuit to increase to the specified value within F seconds.

2. The gas turbine ignition and starting fuel supply method as described in claim 1, characterized in that, The gas turbine ignition and starting fuel supply method further includes the following steps: Step S80: When the engine speed is greater than or equal to the set speed, reduce the swashplate angle to zero and disconnect the main pump motor of the hydraulic starting system.

3. The gas turbine ignition and starting fuel supply method as described in claim 2, characterized in that, The gas turbine ignition and starting fuel supply method further includes the following steps: Step S90: Obtain the engine speed. If the engine speed is not less than the closed-loop speed within H seconds, determine whether the exhaust temperature is greater than or equal to the limit value. Step S100: If the engine speed is less than the closed-loop speed within a specified time H seconds, it is determined that the start-up timeout has occurred and the engine is stopped. Step S110: When the exhaust temperature exceeds the limit value, it is determined that the start-up is overheated and the engine is shut down.

4. The gas turbine ignition and starting fuel supply method as described in claim 1, characterized in that, Step S50: When the increase in exhaust temperature is less than a set value, the step of determining that the engine ignition has failed includes the following: Step S501: Disconnect the starting oil circuit solenoid valve and ignition device, close the main oil circuit shut-off valve, and reduce the fuel regulation opening to the minimum; Step S502: Reduce the swashplate angle to zero and disconnect the main pump motor of the hydraulic starting system.

5. The gas turbine ignition and starting fuel supply method as described in claim 2, characterized in that, The gas turbine ignition and starting fuel supply method also includes: Step S120: Obtain the engine speed. If the engine speed is less than the closed-loop speed within H seconds, determine that the engine ignition and starting has failed. Step S130: Disconnect the starting oil circuit solenoid valve and ignition device, close the main oil circuit shut-off valve, and reduce the fuel regulation opening to the minimum; Step S140: Reduce the swashplate angle to zero and disconnect the main pump motor of the hydraulic starting system.

6. The gas turbine ignition and starting fuel supply method as described in claim 1, characterized in that, Step S20: After A seconds, the step of controlling the oil supply flow rate of the main oil circuit to increase from the lean value to the rich value within N seconds also includes: The timing starts from the moment the starting oil circuit solenoid valve and ignition device are connected, and after a period of time, the starting oil circuit solenoid valve and ignition device are disconnected.

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