JP2022175083A - gas turbine - Google Patents

Abstract

To provide a gas turbine in which ignition failure or ignition lag hardly occurs at starting and which is good in startability.SOLUTION: A gas turbine 1 includes a fuel pump 6 for supplying fuel to a combustor 5, nozzles 21, 22 for supplying fuel to the combustor, a fuel shut-off valve 8 provided between the fuel pump and the nozzles, a pressure sensor 18 provided between the fuel shut-off valve and the nozzles, and a control part 20 for confirming that the pressure of the fuel detected by the pressure sensor before ignition rises up to a first threshold value or higher. Since the control part can confirm that a fuel pipe from the fuel pump to the pressure sensor is filled with the fuel before ignition on the basis of a pressure detected by the pressure sensor, the occurrence of ignition failure at starting due to the impossibility of supplying a required amount of fuel can be prevented.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine that is rotated by combustion gas generated in a combustor, and more particularly to a gas turbine that is less prone to ignition failure or ignition delay during start-up.

Patent Literature 1 discloses an invention of a method for checking ignition of a gas turbine. According to the invention, after receiving a permit signal associated with a gas flow control valve, a fuel supply pressure signal, an igniter signal and a compressor pressure release signal, changes in each of said signals satisfying predetermined conditions are Based on this, an ignition status associated with the gas turbine combustor is determined, and an ignition status signal is output based on the determined ignition status. The present invention allows control of a gas turbine system to detect and verify its flame ignition.

Patent Document 2 discloses an invention of a fuel control device for a gas turbine. According to the present invention, the first supply line L1 for fuel control is a line that increases along the ignition limit line LM in the ignition region, and the start of fuel supply is delayed compared to the case where the fuel flow rate is constant, resulting in higher rotation. Start with speed (more air volume). The time at which the first supply line L1 intersects the ignition limit line LM is later than when the fuel flow rate is constant, and the tolerance (T) for the ignition delay of the first supply line L1 is the same as when the fuel flow rate is constant. For this reason, less fuel is supplied when there is less air, the total amount of fuel input until ignition is reduced, and the condition is always lean and ignites. Reduces smoke.

JP 2012-17738 A JP 2013-44263 A

A gas turbine is an internal combustion engine that rotates the turbine with the combustion gas generated in the combustor, rotates the compressor that compresses the air for combustion, and takes out the remaining energy at the output shaft. There was a problem that ignition delay may occur and startability is unstable.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems in the conventional technology, and an object of the present invention is to provide a gas turbine with good startability in which ignition failure or ignition delay is less likely to occur at start-up.

A gas turbine according to claim 1,
A gas turbine that is rotated by combustion gas generated in a combustor,
a fuel pump that supplies fuel to the combustor;
a nozzle that supplies fuel to the interior of the combustor;
a fuel cutoff valve provided between the fuel pump and the nozzle;
a pressure sensor provided between the fuel cutoff valve and the nozzle;
A control unit that confirms that the pressure of the fuel detected by the pressure sensor before ignition has risen to a first threshold or more;
It is characterized by having

The gas turbine according to claim 2 is the gas turbine according to claim 1,
Having a main nozzle and a sub-nozzle as the nozzle,
The pressure sensor is provided between the fuel cutoff valve and the sub nozzle,
A restriction having a predetermined passage area is provided between the pressure sensor and the sub-nozzle or at the sub-nozzle.

The gas turbine according to claim 3 is the gas turbine according to claim 1 or 2,
The gas turbine further comprises a fuel control valve provided between the fuel pump and the fuel cutoff valve,
The control unit operates the fuel pump before ignition, opens the fuel cutoff valve and the fuel control valve, and after confirming that the pressure detected by the pressure sensor has risen to the first threshold value or more, It is characterized by performing control to close either or both of the fuel cutoff valve and the fuel control valve.

The gas turbine according to claim 4 is the gas turbine according to claim 3,
After closing either or both of the fuel cutoff valve and the fuel control valve, the control unit confirms that the rotation speed of the gas turbine has increased to a second threshold value or higher, and then closes the fuel cutoff valve and the fuel control valve. It is characterized by performing control to open the fuel control valve.

According to the gas turbine of claim 1, the pressure sensor detects that the fuel pipe from the fuel pump to the pressure sensor is filled with fuel before main ignition (see FIG. 2, details will be described later). Since the control unit can be checked based on the pressure, it is possible to prevent ignition failure from occurring at the time of starting due to the inability to supply the required amount of fuel.

According to the gas turbine described in claim 2, the following three effects are obtained. First, in addition to the main nozzle that supplies fuel for main combustion into the combustor, it is possible to promote ignition at startup by installing a sub-nozzle that supplies a small amount of fuel for ignition into the combustor. can. Second, by providing a pressure sensor between the sub-nozzle and the fuel cutoff valve, it is possible to detect the pressure of the fuel sent to the sub-nozzle and ensure that there is fuel in the fuel pipe. As a third point, a constriction having a predetermined passage area such as an orifice is provided between the pressure sensor and the sub-nozzle or inside the sub-nozzle, or the exit of the sub-nozzle is used as a constriction, and the exit diameter of the exit is is determined to have a predetermined passage area, the relationship between the fuel pressure and the flow rate can be made constant. That is, by setting the passage area of the throttle through which the fuel passes to a predetermined value, the fuel can be controlled so that a predetermined flow rate can be obtained at a predetermined pressure. This makes it possible to send an optimum amount of fuel to the combustor for ignition, and to ensure that the fuel is atomized and sprayed into the combustor.

According to the gas turbine according to claim 3, by filling the fuel in the pipe in advance before the main ignition, when the next control to open the fuel cutoff valve and the fuel control valve is performed, the fuel in the fuel pipe can be discharged without delay. It becomes possible to increase the pressure. In addition, by sending fuel to the combustor in advance, it is ignited once before main ignition, and immediately after that, either or both of the fuel cutoff valve and the fuel control valve are closed to extinguish the flame, thereby increasing the temperature in the combustion chamber. It is possible to create an environment in the combustor in which vaporized fuel is easily ignited, such as by letting the vaporized fuel float, so that it is possible to reliably ignite at an arbitrary time. In general, gas turbines emit less black smoke as the rotational speed at the ignition timing at startup becomes higher, but ignition at high rotational speeds tends to become unstable, which causes poor starting. According to this gas turbine, such problems are eliminated.

According to the gas turbine according to claim 4, it is confirmed that the fuel pipe from the fuel pump to the pressure sensor is filled with fuel before the main ignition, and the fuel cutoff valve and the fuel control valve are closed at the time of the main ignition. When the valve is controlled to open, the pressure can be immediately increased to the pressure required for ignition, so the timing of ignition can be set arbitrarily, and ignition can be performed after the rotation speed of the gas turbine rises above the second threshold. Thus, black smoke at startup can be reduced.

1 is a schematic configuration diagram of a gas turbine according to an embodiment; FIG. FIG. 2 is a diagram showing, with the horizontal axis as the time axis, the relationship between the rotation speed of the gas turbine, the opening degree of the fuel control valve, the operation status of each part, the timing of the command signal, and the like, in the operation of the gas turbine of the embodiment. FIG. 4 is a diagram showing non-ignitable regions and other ignitable regions in the operation of the gas turbine of the embodiment, by the relationship between the rotational speed of the gas turbine, the fuel oil pressure, and the opening of the fuel control valve. As a comparative example, ignition by a conventional gas turbine (conventional (1) example with fuel in fuel pipe) is shown. (example without), and part (c) shows ignition by the gas turbine of the embodiment. Part (d) is a diagram for confirming the ignition state in the operation of the gas turbine of the embodiment, and is a diagram showing the relationship between the rotation speed of the gas turbine and the exhaust temperature.

The overall configuration of a power generator using the gas turbine of the embodiment will be described with reference to FIG.
This gas turbine 1 includes a compressor 3 and a turbine 4 attached to a rotatable common rotor 2 and a combustor 5 for supplying combustion gas for driving the turbine 4 . The combustor 5 is connected to an air flow path 9 for guiding compressed air compressed by the compressor 3 and a fuel supply system for supplying fuel. The fuel supply system will be detailed later. Further, the combustor 5 is provided with a spark plug 10, which ignites and burns the mixture of compressed air and fuel supplied to the combustor 5 to generate combustion gas. A thermometer 30 is installed at the outlet of the turbine 4, and it can be confirmed that the temperature of the exhaust gas rises due to ignition. The combustor 5 and the turbine 4 are connected by a combustion gas flow path 11, and the combustion gas generated in the combustor 5 is guided to the turbine 4 through the combustion gas flow path 11, which drives the rotor 2. can be rotated. A generator 13 is connected to the rotor 2 via a reduction gear 12 and an output shaft 16 . When the gas turbine 1 is driven, the rotational force of the rotor 2 is converted to an appropriate rotational speed by the speed reducer 12, and the generator 13 is driven to obtain electric power. The speed reducer 12 is connected to a starter 14, which is an electric motor that drives the rotor 2 when the gas turbine 1 is started, and a main pump 23, which will be described later.

Next, the configuration of the fuel supply system connected to the combustor 5 will be described with reference to FIG.
The fuel supply system includes a fuel tank 24 for storing fuel, a fuel pump 6 for sending fuel, a fuel control valve 7 for controlling the flow rate of the fuel sent from the fuel pump 6, a fuel control valve 7 and a combustor 5. It is composed of a fuel cutoff valve 8 that opens and closes a connecting flow path as needed, and a nozzle that supplies fuel to the combustor 5, and these are connected by a fuel pipe. The fuel stored in the fuel tank 24 is pressurized by the fuel pump 6 and sent to the fuel control valve 7 . The fuel pump 6 is driven by a battery (not shown) when the gas turbine 1 is started, and the power supplied from the reduction gear 12 is used to supply fuel while the gas turbine 1 is operating at the rated rotational speed. It is done by the main pump 23 with.

The fuel control valve 7 can freely and continuously adjust the fuel flow rate. The required amount of fuel corresponding to the rotational speed or load of the gas turbine 1 is set based on the test results, and the fuel control valve 7 continuously opens based on a command given to the control unit 20, which will be described later. can be adjusted dynamically to deliver the required amount of fuel to the fuel cutoff valve 8 . The fuel cutoff valve 8 opens and closes at an arbitrary timing to send the fuel sent from the fuel control valve 7 to the nozzle at an arbitrary timing, or cut off the supply of the fuel sent from the fuel control valve 7 to the nozzle. be able to. The nozzle consists of a main nozzle 22 that sends fuel to the combustor 5 after main ignition and a sub nozzle 21 that sends fuel for ignition to the combustor 5 before main ignition. ing. A pressure regulating valve 17 is provided on the upstream side of the main nozzle 22 (on the side of the fuel cutoff valve 8 ) to control the pressure of the fuel sent to the main nozzle 22 . Between the auxiliary nozzle 21 and the fuel cutoff valve 8 , a pressure sensor 18 is installed on the upstream side of the pipeline near the fuel cutoff valve 8 . In addition, an orifice 19 is provided in the sub nozzle 21 or on the upstream side of the pipeline near the sub nozzle 21 as a "restriction" that is an element for controlling the flow of fuel. The outlet of nozzle 21 may be an orifice. The diameter of the orifice 19 is determined so that the pressure of the fuel and the flow rate of the passing fuel have a predetermined correspondence relationship. It becomes a flow rate and is sent to the sub-nozzle 21 .

A power generation device including the gas turbine 1 and the power generator 13 shown in FIG. 1 is controlled as a whole by a control unit 20 having a function as a fuel control device. That is, as shown in FIG. 1, the fuel pump 6, the fuel control valve 7, the fuel cutoff valve 8, the spark plug 10, the starter 14, the rotation speed detection means 15, etc. are connected to the control unit 20, and the control unit A fuel pump 6, fuel control valve 7, Power generation by the gas turbine 1 can be performed by appropriately controlling each part of the device such as the fuel cutoff valve 8, the spark plug 10, the starter 14, and controlling the fuel flow rate.

Next, with reference to FIG. 2, the operating state from start-up to rated operation of the gas turbine 1 in the embodiment will be described.
When an instruction to start starting (starting command) is input, the control unit 20 starts the starter 14 with the battery to start driving the rotor 2, starts the fuel pump 6 for starting with the battery, and ignites with the spark plug 10. to start. At the same time, command 1 is sent to the fuel control valve 7 to set the degree of opening of the fuel control valve 7 to a predetermined value and to open the fuel cutoff valve 8 . It should be noted that the opening degree of the valve indicated by command 1 (and command 2 described later) sent to the fuel control valve 7 varies depending on the type and displacement of the gas turbine 1, the type of the fuel control valve 7, etc., and the test results is appropriately set based on

The control unit 20 confirms that the fuel pressure detected by the pressure sensor 18 has reached or exceeded a predetermined threshold value (hereinafter referred to as a first threshold value) due to the supply of fuel from the fuel pump 6 . As a result, it is confirmed by detecting pressure equal to or higher than the first threshold that the fuel pipe from the fuel pump 6 to the pressure sensor 18 is filled with fuel before the main ignition, and the required amount (or pressure) of fuel is detected. Therefore, it is possible to prevent the occurrence of poor ignition at the time of starting.

Further, the fuel sent from the fuel pump 6 to the orifice 19 via the fuel control valve 7 and the fuel cutoff valve 8 passes through the opening of the orifice 19 and is sent to the auxiliary nozzle 21 . At this time, the pressure regulating valve 17 is closed so that the fuel is not sent to the main nozzle 22 even if the fuel cutoff valve 8 is opened. The first threshold, which is the reference value of the fuel pressure detected by the pressure sensor 18 and confirmed by the control unit 20, and the diameter of the opening of the orifice 19 differ depending on the type of the gas turbine 1, the displacement, and the like. An appropriate value is set in advance based on the result. In this way, fuel having a pressure exceeding the first threshold detected by the pressure sensor 18 and the orifice 19 having a diameter selected so as to achieve a predetermined flow rate according to the pressure of the fuel are supplied to the sub nozzle 21. It is possible to manage the flow rate of fuel and send the optimum amount of fuel to the combustor 5 for ignition.

In the combustor 5 , the ignition plug 10 is continuously operated to ignite the fuel supplied from the secondary nozzle 21 through the orifice 19 . Since this ignition is ignited in advance before the subsequent main ignition, it is called pre-ignition with respect to the subsequent main ignition. In general, the higher the rotation speed at the ignition timing of the gas turbine 1 at the time of start-up, the more the amount of black smoke emitted is reduced. However, ignition at high rotational speeds tends to be unstable, which causes poor start-up. Therefore, in the embodiment, the temperature inside the combustor 5 is raised by pre-ignition to create an environment that facilitates ignition, such as by causing vaporized fuel to float, so that main ignition can be reliably obtained even at high rotational speeds. there is As will be described later, the generation of black smoke is reduced by causing the main ignition after the rotation speed has increased to some extent.

Next, when the control unit 20 confirms that the pressure of the fuel detected by the pressure sensor 18 is equal to or higher than the first threshold value, the control unit 20 sends the command 2 to the fuel control valve 7 to change the opening degree of the fuel control valve 7. The fuel cutoff valve 8 is closed. By closing the fuel cutoff valve 8, the pre-ignition is extinguished. The degree of opening of the fuel control valve 7 according to the command 2 is smaller than the degree of opening of the fuel control valve 7 according to the aforementioned command 1, but since the fuel control valve 7 is already filled with fuel, a relatively small amount of fuel is supplied. The flow path from the fuel control valve 7 to the fuel cutoff valve 8 can be kept filled with fuel only by supplying the fuel. In addition, since the control unit 20 confirms that the detection value of the pressure sensor 18 is equal to or greater than the first threshold value, the flow path downstream of the closed fuel cutoff valve 8 is not filled with fuel. remains filled.

Next, after confirming that the rotation speed of the gas turbine 1 has increased to N% or more by the rotation speed detection means 15, the control unit 20 opens the fuel cutoff valve 8, and Fuel is sent into 5 and ignited. This ignition is called main ignition as opposed to the pre-ignition described above (see FIG. 2). The rotation speed N (%) of the gas turbine at which main ignition is started is referred to as a second threshold. By setting the second threshold as large as necessary or as large as possible, the main ignition is performed after the rotational speed of the gas turbine 1 becomes higher, thereby reducing the black smoke at startup. Obtainable.

Thereafter, the starter 14, the starting fuel pump 6 and the spark plug 10 are stopped at appropriate times, but the main pump 23 interlocked with the speed reducer 12 supplies fuel to the combustor 5 to continue operation. Until the rotation speed reaches 100%, the fuel flow rate is increased by the fuel control valve 7 corresponding to the air amount. to control.

FIG. 3 shows the correspondence relationship between the rotation speed of the gas turbine (horizontal axis) and the fuel oil pressure and the opening of the fuel control valve (vertical axis). In addition, the gas turbine 1 of the embodiment (partial diagram (c)) and the conventional gas turbine (partial diagrams (a) and (b)) of the comparative example are shown in the case of main ignition (partial Fig. 10(a) and (c)) and a graph showing changes in rotational speed and fuel oil pressure when an attempt to cause main ignition fails (Fig. 1(b)) are superimposed. Part (d) is a diagram showing an example of the relationship between the exhaust temperature and the rotation speed in order to confirm the ignition state in the operation of the gas turbine of the embodiment. The configuration of the fuel supply system of the gas turbine of the comparative example is generally the same as that of the embodiment.

In Fig. 3, in the non-ignitable region where the rotation speed is relatively high, it is difficult to ignite due to the strong flow of compressed air. In addition, black smoke is generated less if ignition is performed at a high rotational speed. Conversely, in the ignitable region, ignition is possible at a relatively low rotational speed, but black smoke is likely to occur due to the small amount of air.

In the comparative example shown in FIGS. 3A and 3B, the fuel control valve 7 and the fuel cutoff valve 8 described in the embodiment are opened, and a predetermined pressure is applied to the passage between the fuel pump 6 and the pressure sensor 18. No control for confirming the presence of fuel is performed before main ignition. However, even if confirmation is not performed, there may be cases where fuel with a pressure higher than a predetermined value exists in the flow path between the fuel pump 6 and the pressure sensor 18, or there is almost no fuel, and the pressure sensor 18 In some cases, it may not be possible to detect a pressure equal to or higher than a predetermined value.

FIG. 3(a) shows a case where fuel having a pressure equal to or higher than a predetermined value exists in the flow path between the fuel pump 6 and the pressure sensor 18. FIG. In this case, when the rotational speed of the gas turbine reaches a predetermined value, the control unit 20 gives an "open" command to the fuel control valve 7 and the fuel cutoff valve 8, and the fuel oil pressure and the opening degree of the fuel control valve gradually increase. to reach main ignition. However, in this case, it is not possible to increase the rotation speed to a desired range and then perform the main ignition to reduce the generation of black smoke.

FIG. 3(b) shows a case where there is no fuel with a pressure equal to or higher than a predetermined value in the flow path between the fuel pump 6 and the pressure sensor 18. FIG. In this case, even if the control unit 20 gives an "open" command to the fuel control valve 7 and the fuel cutoff valve 8 at the same timing as in FIG. Since the amount of fuel required for main ignition is not present in the main ignition, it is not possible to immediately ignite the main ignition, and it takes a certain amount of time for the fuel oil pressure to rise as the amount of fuel that can be ignited fills the fuel pipe. However, compared to the case of FIG. 3(a), there is a delay in the time from the "open" command to the ignition timing, and moreover, the main ignition often fails as shown.

On the other hand, in the embodiment shown in FIG. 3(c), the fuel control valve 7 and the fuel cutoff valve 8 are opened before the main ignition, and the fuel flows through the flow path between the fuel pump 6 and the pressure sensor 18. The presence is confirmed by the control unit 20 judging that the pressure detected by the pressure sensor 18 exceeds the first threshold value. Therefore, since the flow path between the fuel pump 6 and the pressure sensor 18 is filled with fuel, the main ignition operation is performed at a desired rotation speed (an "open" command is output to the fuel control valve 7 and the fuel cutoff valve 8). If resupply of fuel by chance is performed, the amount of fuel supplied increases and immediately reaches the required amount, immediately leading to main ignition.

As described above, according to the embodiment shown in FIG. 3(c), it is confirmed that fuel exists in the flow path between the fuel pump 6 and the pressure sensor 18 before main ignition. Since ignition failure or ignition delay is less likely to occur, the timing of main ignition can be arbitrarily changed after the above confirmation is completed. Therefore, as compared with the conventional example of FIG. 3(a), ignition can be delayed until the timing considered necessary by the driver, as indicated by the difference in the timing of the "open" command. The difference between the main ignition of the conventional example shown in FIG. 3A and the main ignition of the embodiment shown in FIG.

In addition, as shown in FIG. 3(d), in the embodiment shown in FIG. 3(c), even after the pre-ignition flame is extinguished, the exhaust gas temperature maintains a predetermined value at which ignition is likely to occur. After the "open" command is output to the fuel control valve 7 and the fuel cutoff valve 8, the main ignition occurs quickly, and the exhaust temperature rises stably as the gas turbine rotation speed rises smoothly. .

As described above, according to the gas turbine 1 of the embodiment, the pressure sensor 18 detects that the fuel pipe from the fuel pump 6 to the pressure sensor 18 is filled with fuel before main ignition. It is possible to prevent the ignition delay and ignition failure seen in the conventional example because there is no fuel, and to improve the startability. In addition, since the ignition is performed at a higher rotational speed than in the conventional example, the generation of black smoke can be reduced.

DESCRIPTION OF SYMBOLS 1... Gas turbine 4... Turbine 5... Combustor 6... Fuel pump 7... Fuel control valve 8... Fuel cutoff valve 18... Pressure sensor 19... Orifice 20... Control part 21... Sub nozzle 22... Main nozzle

Claims (4)

A gas turbine that is rotated by combustion gas generated in a combustor,
a fuel pump that supplies fuel to the combustor;
a nozzle that supplies fuel to the interior of the combustor;
a fuel cutoff valve provided between the fuel pump and the nozzle;
a pressure sensor provided between the fuel cutoff valve and the nozzle;
A control unit that confirms that the pressure of the fuel detected by the pressure sensor before ignition has risen to a first threshold or more;
A gas turbine comprising: Having a main nozzle and a sub-nozzle as the nozzle,
The pressure sensor is provided between the fuel cutoff valve and the sub nozzle,
2. A gas turbine according to claim 1, wherein a restriction having a predetermined passage area is provided between said pressure sensor and said sub-nozzle or at said sub-nozzle. The gas turbine further comprises a fuel control valve provided between the fuel pump and the fuel cutoff valve,
The control unit operates the fuel pump before ignition, opens the fuel cutoff valve and the fuel control valve, and after confirming that the pressure detected by the pressure sensor has risen to the first threshold value or more, 3. The gas turbine according to claim 1, wherein control is performed to close either or both of the fuel cutoff valve and the fuel control valve. After closing either or both of the fuel cutoff valve and the fuel control valve, the control unit confirms that the rotation speed of the gas turbine has increased to a second threshold value or higher, and then closes the fuel cutoff valve and the fuel control valve. 4. The gas turbine according to claim 3, wherein control is performed to open said fuel control valve.

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