Gas turbines that can use hydrogen as fuel

Abstract

To reduce NOx emissions in a gas turbine that can use hydrogen as fuel.SOLUTION: A gas turbine 1 is configured so that when rotational frequency of a turbine shaft 2 is predetermined rotational frequency, if a magnitude of a load is set to a predetermined load, an amount of compressed air to be supplied to a primary combustion field in a combustor 6 and an amount of fuel to be supplied to the combustor are set to amounts that enable an equivalence ratio preventing misfire, and so that when the magnitude of the load is set to no-load, the amount of the compressed air to be supplied to the primary combustion field in the combustor and the amount of the fuel to be supplied to the combustor are reduced while maintaining the equivalence ratio enabling prevention of misfire, compared to the case where the magnitude of the load is set to the predetermined load.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a gas turbine engine (hereinafter referred to as a "gas turbine"), and more particularly to the control of a gas turbine (hydrogen gas turbine) that can use hydrogen as fuel.

Background Art

[0002] From the perspective of preventing global warming and decarbonization, research and development of heat engines such as gas turbines that use hydrogen as fuel are progressing. When using hydrogen as fuel, if there are regions with high fuel concentration in the combustion field, the combustion temperature will rise and NOx generation will tend to increase. Therefore, various configurations are being considered for the combustor of a hydrogen-fueled gas turbine to prevent the formation of regions with high fuel concentration in the combustion field as much as possible. For example, Patent Document 1 proposes a configuration for a gas turbine combustor that employs a premixed combustion method, in which the temperature of the flame formed in the combustion chamber is made uniform by supplying a mixture of fuel and air in advance to the combustion chamber, thereby suppressing NOx emissions. This configuration aims to achieve stable combustion throughout the entire operating process from gas turbine ignition to rated load by precisely controlling the fuel-air ratio of the premixed mixture, thereby improving efficiency, reducing NOx emissions, and reducing the number of parts. Specifically, the document discloses a configuration in which a burner that supplies fuel and air to the combustion chamber has an annular fuel nozzle having an annular pipe with multiple fuel injection holes and multiple supply pipes connected thereto, and an air hole plate that is spaced apart downstream of the annular fuel nozzle and has multiple air holes facing the multiple fuel injection holes. Patent Document 2 proposes a configuration in which, in order to achieve stable combustion and low NOx emissions across the entire load range of a gas turbine, the gas turbine combustor has multiple stages of combustion sections spaced apart in the axial direction, multiple fuel supply systems independently connected to each of these combustion sections, a premixed fuel supply section and a diffusion combustion fuel supply section provided in each of these fuel supply systems, and a control device that switches each of these fuel supply sections to supply only either premixed fuel or diffusion combustion fuel, and after starting combustion in a diffusion combustion method that enables stable combustion over a wide fuel-air ratio range, it switches to a premixed combustion method.Patent Document 3 proposes an operating method for a gas turbine engine combustor using a highly reactive fuel such as hydrogen, in which multiple fuel injection units are arranged in a ring to achieve low NOx combustion and prevent the generation of unburned gas during startup and shutdown. This method involves injecting a highly reactive main fuel from one part of the ring, and switching between injecting a less reactive auxiliary fuel and the main fuel from another part. During startup, the auxiliary fuel is injected and ignited, then switched to the main fuel to perform rated rotational speed operation, and during shutdown, the rotation is reduced by switching from the main fuel to the auxiliary fuel. Patent Document 4 describes a combustor for a gas turbine engine with a multi-stage burner configuration, which includes a main burner that supplies fuel or a premix to a primary combustion region upstream of the combustion chamber and a follow-up burner that supplies fuel or a premix to a secondary combustion region downstream of the primary combustion region of the combustion chamber. In order to promote the premixing of hydrogen-containing gas ejected from the follow-up burner with compressed air, it is proposed that after ejecting fuel and air from the nozzle of the follow-up burner, the mixture is passed through a duct of a certain length before being sent into the combustion chamber, thereby thoroughly mixing the fuel and air before combustion. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-23916 [Patent Document 2] Japanese Patent Publication No. 7-233945 [Patent Document 3] Japanese Patent Publication No. 2018-194210 [Patent Document 4] Japanese Patent Publication No. 2018-4138 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In conventional hydrogen gas turbine combustors, as described above, improvements are typically made to the combustion and compressed air supply structure, such as the combustion nozzle that supplies combustion and compressed air to the combustion field, in order to suppress NOx generation and prevent the formation of regions with high fuel concentrations. However, the structure of the conventional technology described above is somewhat complex, with a large number of parts. While this is feasible for combustors of medium to large gas turbines, it becomes difficult to manufacture combustors for small gas turbines because it is difficult to process and form many fine holes with small parts. Furthermore, a large number of parts negates the advantage of the lightweight nature of small gas turbines. Therefore, if there is a method to prevent the formation of regions with high fuel concentrations in the combustion field without complicating the combustion and compressed air supply structure, it would be advantageous as it would allow for the use of a configuration that suppresses NOx generation in various hydrogen gas turbines, regardless of size.

[0005] Incidentally, in the operation of a gas turbine, generally, at startup, the starter rotates the turbine shaft while fuel is supplied to the combustor to ignite it. Then, under no-load conditions, the amount of fuel is increased to raise the rotational speed of the turbine shaft to a predetermined speed, for example, the rated speed. After establishing the predetermined speed and no-load operating state, the amount of fuel is increased to increase the load (power generation in the case of a generator) to a predetermined load, for example, the rated load, while the predetermined speed is maintained. In this operating method, the equivalence ratio (amount of fuel / amount of compressed air) near the fuel supply point in the combustion field (primary combustion field) is adjusted so as not to misfire under the predetermined speed and no-load operating state. Consequently, when increasing the fuel supply to raise the load from no load to a predetermined load while maintaining the rotational speed at a predetermined speed, the equivalence ratio of the primary combustion field increases locally, leading to an increase in NOx generation (in the conventional technology described above, the combustion and compressed air supply structure is designed to suppress such a localized increase in the equivalence ratio of the primary combustion field).

[0006] As described above, when increasing the amount of fuel to raise the load from no load to a predetermined load, one method to reduce the equivalence ratio of the primary combustion field in order to suppress NOx generation is to increase the amount of compressed air supplied to the primary combustion field. In this regard, in research conducted by the inventor of the present invention, it was possible to increase the amount of compressed air supplied to the primary combustion field so that the equivalence ratio of the primary combustion field could be suppressed in the operating state of a predetermined rotational speed and predetermined load. However, when the amount of fuel was reduced with the same amount of compressed air to bring the operating state to the predetermined rotational speed and no load state, the equivalence ratio became too low and misfires occurred. In actual gas turbines, they are usually operated in the operating state of a predetermined rotational speed and predetermined load (for example, the operating state of rated rotational speed and rated load), so it is desirable that the equivalence ratio of the primary combustion field can be suppressed in the operating state of a predetermined rotational speed and predetermined load, and it is also desirable that the operating state of a predetermined rotational speed and no load can be achieved without misfires depending on the operating conditions. In other words, in a gas turbine, in order to suppress NOx generation as much as possible, it is advantageous to reduce the equivalence ratio during long-running operation at a predetermined rotational speed and load, while simultaneously reducing the amount of compressed air during operation at a predetermined rotational speed and no load to prevent misfires. With such a configuration, because the localized rise in the equivalence ratio of the primary combustion field is suppressed, it becomes possible to suppress NOx generation without using the complex combustion and compressed air supply structure of the conventional technology described above.

[0007] Thus, one of the objectives of the present invention is to reduce NOx emissions in a gas turbine that can use hydrogen as fuel.

[0008] Furthermore, a further object of the present invention is to provide a gas turbine, as described above, that has a configuration in which the amount of compressed air supplied to the primary combustion field is increased so that the equivalent ratio of the primary combustion field of the combustor is kept lower when operating at a predetermined rotational speed and a predetermined load, and that can also achieve an operating state at a predetermined rotational speed and no load. [Means for solving the problem]

[0009] According to the present invention, the above problem is solved by a gas turbine, A combustor supplied with fuel to be burned and compressed air, A fuel supply control means for controlling the amount of fuel supplied to the combustor. Load control means for controlling the magnitude of the load acting on the turbine shaft Air supply amount control means for controlling the amount of compressed air supplied to the primary combustion field of the combustor, Includes, This is achieved by a gas turbine configured such that when the rotational speed of the turbine shaft is at a predetermined rotational speed and the load control means is set to a predetermined load, the air supply amount control means and the load control means each supply an amount of compressed air supplied to the primary combustion field in the combustor and an amount of fuel supplied to the combustor in such an amount that the equivalent ratio does not cause misfires, and when the load control means is set to no load, the air supply amount control means and the load control means each supply an amount of compressed air supplied to the primary combustion field in the combustor and an amount of fuel supplied to the combustor in such an amount that the equivalent ratio does not cause misfires, while reducing the load compared to when the load is set to a predetermined load.

[0010] In the above configuration, the "gas turbine" may be any type of gas turbine in which a compressor, a turbine, and load equipment such as a generator on which a load acts are connected to the turbine shaft. The "combustor" may be any type of combustor, such as a can type or annular type. The "fuel supply control means" may be a means for adjusting the amount of fuel supplied to the combustion chamber in any form. The "load control means" may be a means for controlling the magnitude of the load (work or power) acting on the turbine shaft in any form. When the gas turbine is used as a power source for a generator, the load is the amount of power output to the generator or the generated electricity, and the load control means may be a means for adjusting the amount of power output or generated electricity of the generator. The "air supply amount control means" may be a means for controlling the amount of compressed air supplied to the primary combustion field of the combustor in any form. Here, the "primary combustion field," as already mentioned, refers to the combustion field on the upstream side of the combustion chamber of the combustor, specifically the area near fuel supply points such as fuel injection holes. Its specific range varies depending on the shape of the combustion chamber, but it can generally be the range from the upstream edge of the flame resulting from the combustion of fuel and compressed air on the upstream side along the direction of gas flow in the combustion chamber to the downstream point where additional compressed air is supplied along the direction of gas flow (compressed air is usually supplied into the combustion chamber in multiple stages along the direction of gas flow in the combustion chamber). Specifically, the air supply amount control means may include, for example, a valve structure provided in the flow path that delivers compressed air from the compressor of a gas turbine to the primary combustion field. When the air supply amount control means reduces the amount of compressed air supplied to the primary combustion field of the combustor, it is configured to release a portion of the compressed air from the valve structure out of the flow path, thereby allowing a portion of the compressed air flowing through the flow path that delivers compressed air from the compressor to the primary combustion field to be released to the outside or elsewhere without flowing into the primary combustion field. Furthermore, as such a valve structure, a valve installed in the flow path from the compressor to the combustor in a conventional gas turbine may be used as appropriate. In addition, the amount of compressed air supplied to the primary combustion field when compressed air is not leaking from the valve structure can be adjusted by appropriately adjusting the diameter of the supply port that delivers compressed air to the primary combustion field.The "prescribed rotational speed" may be the rotational speed at which the gas turbine rotates stably or efficiently, which can be appropriately set based on experiments, etc., and may be the "rated rotational speed" (rated value of rotational speed), which is the rotational speed during normal operation of the gas turbine. The "prescribed load" may be the magnitude of the load at which the gas turbine outputs stably or efficiently, which can be appropriately set based on experiments, etc., and may be the "rated load" (rated value of load), which is the load during normal operation of the gas turbine.

[0011] Furthermore, in the configuration of the present invention, as described above, when the rotational speed of the turbine shaft is a predetermined rotational speed, first, when the load control means sets the load magnitude to a predetermined load, the air supply amount control means and the load control means each supply the amount of compressed air supplied to the primary combustion field in the combustor and the amount of fuel supplied to the combustor to an amount that maintains an equivalence ratio that prevents misfires. When the load control means sets the load magnitude to no load, the air supply amount control means and the load control means each reduce the amount of compressed air supplied to the primary combustion field in the combustor and the amount of fuel supplied to the combustor to a level that maintains an equivalence ratio that prevents misfires, compared to when the load magnitude is set to a predetermined load. In other words, in the configuration of the present invention, when operating at a predetermined rotational speed and no load, not only the amount of fuel but also the amount of compressed air supplied to the primary combustion field is reduced compared to when operating at a predetermined rotational speed and a predetermined load, in order to maintain an equivalence ratio that prevents misfires.

[0012] According to the configuration of the present invention described above, the amount of compressed air supplied to the primary combustion field during operation at a predetermined rotational speed and no load can be adjusted separately from the operation at a predetermined rotational speed and load to prevent misfires. Therefore, it is no longer necessary to raise the equivalent ratio during operation at a predetermined rotational speed and load in order to ensure a high equivalent ratio to prevent misfires during operation at a predetermined rotational speed and no load. As a result, the equivalent ratio during operation at a predetermined rotational speed and load can be further reduced within a range that does not cause misfires, and thus the amount of NOx generated can be suppressed. Furthermore, it should be understood that in the case of the present invention, such suppression of NOx generation can be achieved without using the complex combustion and compressed air supply structure proposed in the prior art.

[0013] In the above configuration, as already mentioned, the amount of compressed air at a predetermined rotational speed and under no-load conditions is appropriately controlled, so that the equivalence ratio of the primary combustion field when the turbine shaft rotational speed is at a predetermined rotational speed and under a predetermined load can be reduced within a range that does not cause misfires, thereby suppressing the amount of NOx generated as much as possible. Accordingly, in the above configuration of the present invention, when the rotational speed of the turbine shaft is at the predetermined rotational speed and the magnitude of the load is the predetermined load, the amount of compressed air supplied to the primary combustion field in the combustor may be an amount that brings the equivalence ratio in the primary combustion field to the usable lower limit of the equivalence ratio that does not cause misfires under the operating conditions of the predetermined rotational speed and predetermined load. That is, the amount of compressed air supplied to the primary combustion field may be maximized within a usable range that does not cause misfires under the operating conditions of the predetermined rotational speed and predetermined load.

[0014] Furthermore, in the above configuration of the present invention, when the rotational speed of the turbine shaft is at a predetermined rotational speed, the air supply amount control means may be configured to reduce the amount of compressed air supplied to the primary combustion field in the combustor as the load size decreases. This makes it possible to reduce the equivalent ratio so as to suppress NOx generation within a range that does not cause misfires, even when the load size changes.

[0015] Since the configuration of the present invention described above is preferably applicable when hydrogen is used as the fuel of the gas turbine, the fuel may be hydrogen, but is not limited thereto.

Advantages of the Invention

[0016] In a gas turbine, usually, the amount of compressed air input into the primary combustion chamber is uniquely determined by the rotational speed. In the gas turbine of the present invention described above, to put it simply, the amount of compressed air input into the primary combustion chamber is controlled to be different in the state of a predetermined rotational speed and a predetermined load and the state of a predetermined rotational speed and no load. With this configuration, as already mentioned, the equivalence ratio in the state of a predetermined rotational speed and a predetermined load can be reduced without causing misfire in the state of a predetermined rotational speed and no load, and the reduction of the NOx generation amount can be achieved. Importantly, the configuration of the present invention is expected to reduce the NOx generation amount by improving the operation process of the gas turbine, and does not require complicated improvements in the supply parts of the fuel and the compressed air. Therefore, it should be understood that the present invention can be applied to small gas turbines that are difficult to realize a complicated structure regardless of the size of the gas turbine. The gas turbine of the present invention can be used for a gas turbine that is miniaturized to be mounted on vehicles such as automobiles and uses hydrogen as the fuel, and thereby, a wider spread of the hydrogen gas turbine is expected.

[0017] Other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments of the present invention.

Brief Description of the Drawings

[0018] [Figure 1] Figs. 1(A) and (B) are a schematic diagram of a gas turbine according to the present embodiment and a diagram showing the configuration of its control device in the form of a block diagram, respectively. [Figure 2] Fig. 2 is a diagram schematically showing the change in the combustion temperature T with respect to the equivalence ratio (fuel amount / compressed air amount) F / A. [Figure 3]FIG. 3(A) is a diagram schematically showing the change in the equivalence ratio F / A with respect to the increase in the rotational speed Rpm of the turbine shaft in a conventional general operation method at the start of the gas turbine. FIG. 3(B) is a diagram schematically showing a state where the equivalence ratio is changed while the rotational speed of the turbine shaft is maintained at a predetermined rotational speed RT. [Figure 4] FIG. 4 is a diagram showing the change in the amount of compressed air A supplied to the primary combustion field with respect to the load Ld in the gas turbine according to the present embodiment.

Explanation of Signs

[0019] 1... Gas turbine, 2... Turbine shaft, 3... Turbine, 4... Compressor, 5... Load device (generator), 6... Combustor, 7... Compressed air flow path, 7a... Compressed air supply port to the primary combustion field, 7b... Compressed air flow path to the primary combustion field, 7c... Compressed air supply port to the secondary combustion field, 8... Combustion chamber, 8a... Primary combustion field, 8b... Secondary combustion field, 9... Fuel supply device, 10... Combustion gas flow path, 11... Flow control valve, 50... Turbine operation command unit, 51... Load demand unit, 52... Rotational speed control unit, 53... Rotational speed detection unit, 54... Load control unit, 55... Fuel amount control unit, 56... Primary combustion field air supply amount control unit, 60... Starter, 61... Igniter, f... Fuel flow, a... Compressed air flow

Best Mode for Carrying Out the Invention

[0020] Basic configuration of a gas turbine The configuration of this embodiment is applicable to various gas turbines. As shown in Figure 1(A), the gas turbine 1 may, in its basic configuration, have a turbine 3 connected to the turbine shaft 2, a compressor 4, load equipment 5 such as a generator, and a combustor 6. In basic operation, compressed air a, compressed by the rotation of the turbine shaft 2 in the compressor 4, is sent through the passage 7 to the combustion chamber 8 of the combustor 6, where it is mixed with fuel f from the fuel supply device 9 and burned. The resulting combustion gas is sent to the turbine 3 through the combustion gas passage 10, rotating the turbine shaft 2. This performs the compression of air in the compressor 4 and the operation of the load equipment 5, for example, generating electricity by rotating the rotor of a generator. More specifically regarding the combustor 6, typically, compressed air a is sent to the combustion chamber 8 in multiple stages so that the fuel and air are burned more efficiently. Specifically, compressed air a is partially injected from a supply port 7a near the fuel f supply port of the fuel device 9 (the right-hand region of the combustion chamber in the figure, primary combustion field 8a), mixed with fuel f in various ways, and another portion is discharged from a supply port 7c to a region downstream of the primary combustion field 8a (secondary combustion field 8b). The fuel supplied to the combustor 6 may be hydrogen (but is not limited to hydrogen). In this regard, in the gas turbine to which this embodiment is applied, even when the fuel is hydrogen, the specific structure of the combustor 6 may be any, for example, a structure that has conventionally used fossil fuels as fuel, and a special configuration as described in the aforementioned patent document is not essential.

[0021] In this embodiment, the gas turbine 1 is provided with an air supply amount control means for adjusting the amount of compressed air supplied from the supply port 7a to the primary combustion field 8a. As an example of such means, a flow control valve 11 is provided in the middle of the flow path 7b leading to the supply port 7a, as shown in the figure, which releases the compressed air flow to the outside or elsewhere. By controlling the flow rate through the flow control valve 11, the amount of compressed air supplied from the supply port 7a to the primary combustion field 8a can be adjusted. As the flow control valve 11, a valve provided in the flow path from the compressor to the combustor in a conventional gas turbine may be used as appropriate.

[0022] gas turbine control system configuration The control of the gas turbine in Figure 1(A) may be performed by a control device as generally shown in Figure 1(B). The control device may be a computer device having a CPU, ROM, RAM, and input / output port devices interconnected by a bidirectional common bus, and the configuration and operation of each part of this embodiment, which will be described later, may be realized by the operation of the computer device according to a program.

[0023] In the control device, specifically, as shown in Figure 1(B), it may consist of a turbine operation command unit 50, a load request unit 51, a rotational speed control unit 52, a rotational speed detection unit 53, a load control unit 54, a fuel quantity control unit 55, an air supply amount control unit 56 to the primary combustion field, etc. More specifically, the turbine operation command unit 50 may be configured to give control commands to the load request unit 51 and the rotational speed control unit 52 to instruct the operation of the gas turbine based on instructions from the user or requests from any machinery or equipment. The requests or instructions given to the turbine operation command unit 50 may be requests or instructions to operate the gas turbine at a predetermined rotational speed and predetermined load, which may be set as appropriate. The predetermined rotational speed may be, but is not limited to, the "rated rotational speed" set so that the gas turbine rotates stably or efficiently. "Load" is the work given to the load equipment 5 through the turbine shaft 2 of the gas turbine 1, and when the load equipment 5 is a generator, it may be expressed in power units. The "specified load" may be, but is not limited to, the "rated load" set to allow the gas turbine to output power stably or efficiently.

[0024] The load request unit 51 may be configured to receive a control command from the turbine operation command unit 50, set a target value for the magnitude of the load to be generated by the gas turbine (load target value), and transmit that target value to the load control unit 54. The load target value may be a predetermined load instructed by the turbine operation command unit 50. The rotational speed detection unit 53 may be configured to detect the rotational speed of the turbine shaft 2 using any type of sensor and transmit the detected value to each unit.

[0025] The load control unit 54 may be configured to refer to the load target value from the load request unit 51 and the rotational speed detection value from the rotational speed detection unit 53, determine a requested value (load request value) for the magnitude of the load to be applied to the load equipment at the current turbine rotational speed (rotational speed detection value), within a range that does not exceed the load target value, and send a control command to the load equipment 5 to absorb the work of the load request value.

[0026] In general terms, the rotational speed control unit 52 is configured to refer to control commands from the turbine operation command unit 50, rotational speed detection values ​​from the rotational speed detection unit 53, and load request values ​​from the load control unit 54, and to set a target rotational speed (target rotational speed value) to be reached by the gas turbine based on the control commands from the turbine operation command unit 50, start and stop the starter 60, instruct the fuel quantity control unit 55 to supply fuel, and instruct the igniter 61 to ignite. Here, the target rotational speed value may be a predetermined rotational speed instructed by the turbine operation command unit 50. Furthermore, the starter 60 may be controlled to start upon receiving an instruction from the turbine operation command unit 50 to start operation and to stop when the igniter is ignited. Specifically, the instruction to supply fuel to the fuel quantity control unit 55 is first determined based on the detected rotational speed of the turbine shaft 2 and the load request value, and this rotational speed request value is then given to the fuel quantity control unit 55 as a control command for fuel supply.

[0027] The fuel quantity control unit 55 may be configured to compare the rotational speed detection value with the rotational speed request value and control the amount of fuel supplied from the fuel supply device 9 so that the rotational speed detection value matches the rotational speed request value.

[0028] The air supply amount control unit 56 may be configured to control the state of the flow control valve 11 in order to adjust the amount of compressed air introduced from the supply port 7a to the primary combustion field 8a in order to suppress NOx generation without misfires, by referring to the load request value (or load target value) from the load control unit 54 and the amount of fuel supplied from the fuel supply device 9.

[0029] Relationship between combustion temperature and NOx production As is understood by those skilled in the art, as the combustion temperature of fuel and compressed air in the combustion chamber increases, the amount of NOx produced increases. As shown in Figure 2, the combustion temperature T is highest when the equivalence ratio F / A is the stoichiometric air-fuel ratio (ST), and as the equivalence ratio F / A is lower than the stoichiometric air-fuel ratio (lean: L) or higher than the stoichiometric air-fuel ratio (rich: R), the combustion temperature T decreases and the amount of NOx produced decreases. Therefore, in the operation of a gas turbine, it is desirable to use as little fuel as possible, and in order to suppress NOx production, it is preferable to burn the fuel and compressed air in a lean state with a lower equivalence ratio. In particular, when the fuel is hydrogen, the combustion temperature is high, so in order to suppress NOx production, it is desirable to keep the equivalence ratio as low as possible without misfires.

[0030] Gas turbine operating methods (1) Conventional gas turbine operating methods As described in the section on the summary of the invention, in the operation method when starting up the gas turbine 1, conventionally, the turbine speed is generally increased to the rated speed (a predetermined speed normally used when operating a gas turbine) under no-load conditions, and then, when the load is increased, the fuel supply amount is increased while maintaining the rated speed. Specifically, when starting up the gas turbine 1, as illustrated in Figure 3(A), first, the rotation of the turbine shaft 2 is started by the starter 60, and the supply of compressed air a into the combustion chamber 8 begins. The amount of compressed air supplied increases in accordance with the increase in the rotation speed of the turbine shaft 2, provided that the flow control valve 11, which releases the flow midway through the flow path 7b, is not activated. When the rotation speed Rpm reaches RS, fuel supply begins, and when the rotation speed Rpm further reaches RF, the igniter 61 is activated, and combustion of fuel and air begins. Subsequently, as shown in the figure, the fuel supply is gradually increased so that the rotational speed Rpm increases until it reaches the rated rotational speed RT, under no-load conditions (when the load equipment 5 is not performing any work). Note that in the figure, the equivalence ratio F / A decreases as the rotational speed Rpm goes from RS to RT because the increase ratio of compressed air is greater than the increase ratio of fuel. After that, when the load equipment 5 is put to work, the fuel supply is increased while maintaining the rated rotational speed RT (P1), and the load is increased until it reaches the rated load (a predetermined load normally used when operating a gas turbine) (P2).

[0031] In the conventional operating method as shown in Figure 3(A) above, the operating state is first brought to the rated speed, no-load state P1, and then transitioned to the rated speed, rated load state P2. Therefore, it is necessary to ensure a sufficient equivalence ratio F / A so that misfires do not occur in the primary combustion field 8a in the rated speed, no-load state P1. That is, the amount of compressed air supplied to the primary combustion field 8a (the amount of compressed air supplied from the supply port 7a) must be kept within a range that does not cause misfires even in the rated speed, no-load state P1. Consequently, when the fuel supply is increased in order to increase the load to the rated load in that state, the equivalence ratio F / A of the primary combustion field 8a increases accordingly, the combustion temperature rises, and the amount of NOx produced increases.

[0032] (2) Operation method of the gas turbine of this embodiment In the conventional operation method of the gas turbine described above, the amount of compressed air supplied to the primary combustion field 8a was adjusted to ensure an equivalence ratio that prevents misfires even at rated speed and no load, while the fuel supply was increased to increase the load, and the equivalence ratio increased accordingly. In this regard, according to the inventor's research of this embodiment, it has been found that the rated speed and rated load conditions can be achieved even with an equivalence ratio lower than that obtained by increasing the fuel supply while maintaining the amount of compressed air supplied to the primary combustion field 8a to ensure an equivalence ratio that prevents misfires even at rated speed and no load. That is, if the gas turbine is operated with a lower equivalence ratio by increasing the proportion of compressed air compared to before, at a predetermined speed and predetermined load condition or the rated speed and rated load condition that is normally used when operating a gas turbine, the combustion temperature will decrease, and NOx generation will be suppressed. However, if the compressed air volume is increased to keep the equivalence ratio low under rated speed and rated load conditions, or under specified speed and specified load conditions, the fuel volume will be even lower under rated speed and no load conditions, resulting in an equivalence ratio that is too low and can cause misfires (if a misfire occurs, the gas turbine will need to be restarted).

[0033] Therefore, in the gas turbine of this embodiment, in order to suppress NOx generation at a predetermined rotational speed and load that is normally used during operation, the amount of compressed air supplied to the primary combustion teeth is increased to lower the equivalent ratio. At the same time, in order to prevent misfires even at a predetermined rotational speed and no load, the amount of compressed air supplied to the primary combustion field 8a is reduced at a predetermined rotational speed and no load. Such reduction in the amount of compressed air can be achieved with any configuration, but for example, as explained in relation to Figure 1(A), it can be achieved by releasing a portion of the compressed air flow to the outside or elsewhere using a flow control valve 11 provided in the middle of the flow path 7b leading to the supply port 7a. With this configuration, as shown in Figure 3(B), when the load is a predetermined load at a predetermined rotational speed RT, the equivalent ratio is reduced from the previous P2 to P3, thereby suppressing NOx generation. On the other hand, when there is no load, the fuel supply is reduced (P4), and at the same time, the amount of compressed air supplied to the primary combustion field 8a is reduced, thus preventing misfires.

[0034] In the configuration of this embodiment described above, an increase in the amount of compressed air supplied to the primary combustion field 8a at a predetermined rotational speed and load can be achieved, for example, by enlarging the diameter of the compressed air supply port opening to the primary combustion field 8a. In the actual configuration, the amount of compressed air supplied to the primary combustion field 8a at a predetermined rotational speed and load can be set according to suitability. Preferably, the amount of compressed air supplied to the primary combustion field 8a at a predetermined rotational speed and load can be set to an amount that provides the lower limit of the equivalence ratio that does not misfire at a predetermined rotational speed and load (it may be somewhat higher than the lower limit of the equivalence ratio that does not misfire, taking into consideration the stability of the control), so as to suppress the amount of NOx generation as much as possible. Also, as schematically depicted in Figure 4, the amount of compressed air A supplied to the primary combustion field 8a at a predetermined rotational speed can be adjusted to decrease as the magnitude of the load Ld decreases. In that case, if the amount of compressed air supplied to the primary combustion field 8a at a predetermined rotational speed RT and predetermined load LT is provided in such a way that the equivalence ratio is kept as low as possible without misfiring, then, along with a reduction in load Ld, the amount of compressed air supplied to the primary combustion field 8a may be set to an amount that gives the usable lower limit of the equivalence ratio that does not misfire under the load conditions at that time.

[0035] Thus, in the gas turbine of this embodiment described above, the amount of compressed air supplied to the primary combustion field 8a is changed according to the magnitude of the load, so that the equivalence ratio at a predetermined rotational speed and load can be sufficiently reduced, thereby reducing the amount of NOx generated while preventing misfires at a predetermined rotational speed and no load. In other words, it becomes unnecessary to limit the amount of compressed air supplied at a predetermined rotational speed and load to satisfy the equivalence ratio that must be ensured to prevent misfires at a predetermined rotational speed and no load, and the amount of compressed air supplied can be increased to prevent misfires at a predetermined rotational speed and load, thereby suppressing the amount of NOx generated. This embodiment can be used in any type of gas turbine, and it should be understood that a complex structure to prevent combustion concentration unevenness in the primary combustion field is not essential.

[0036] While the above description is made in relation to embodiments of the present invention, many modifications and changes are readily possible for those skilled in the art, and it will be clear that the present invention is not limited to the embodiments illustrated above, but can be applied to various devices without departing from the concept of the present invention.

Claims

1. It is a gas turbine, A combustor supplied with fuel to be burned and compressed air, A fuel supply control means for controlling the amount of fuel supplied to the combustor. Load control means for controlling the magnitude of the load acting on the turbine shaft Air supply amount control means for controlling the amount of compressed air supplied to the primary combustion field of the combustor, Includes, The turbine shaft is operated in a predetermined speed / predetermined load operating state, where the rotational speed of the turbine shaft is a predetermined speed and the magnitude of the load acting on the turbine shaft is a predetermined load, and in a predetermined speed / no load operating state, where the rotational speed of the turbine shaft is the predetermined speed and the magnitude of the load acting on the turbine shaft is no load. The air supply amount control means and the fuel supply control means are configured to supply the compressed air amount and the fuel amount, respectively, such that the equivalent ratio at the predetermined rotational speed and predetermined load operating state is lower than the equivalent ratio at the predetermined rotational speed and predetermined load operating state when the amount of compressed air is the same amount that provides an equivalent ratio that prevents misfires at both the predetermined rotational speed and predetermined load operating state and the predetermined rotational speed and predetermined load operating state. A gas turbine in which, when the operating state of the gas turbine transitions from a predetermined rotational speed / predetermined load operating state to a predetermined rotational speed / no-load operating state, the air supply amount control means and the fuel supply control means are configured to reduce the compressed air amount and the fuel amount, respectively, so as to maintain an equivalence ratio that does not cause misfires.

2. A gas turbine according to claim 1, wherein when the rotational speed of the turbine shaft is the predetermined rotational speed and the magnitude of the load is the predetermined load, the amount of compressed air supplied to the primary combustion field in the combustor is such that the equivalent ratio in the primary combustion field is the usable lower limit of the equivalent ratio that does not misfire in the operating state of the predetermined rotational speed and predetermined load.

3. A gas turbine according to claim 1, wherein when the rotational speed of the turbine shaft is at a predetermined rotational speed, the air supply amount control means is configured to reduce the amount of compressed air supplied to the primary combustion field in the combustor as the magnitude of the load decreases.

4. A gas turbine according to any one of claims 1 to 3, wherein the air supply amount control means includes a valve structure provided in a flow path that delivers compressed air from the compressor of the gas turbine to the primary combustion field, and the air supply amount control means is configured to release a portion of the compressed air from the flow path through the valve structure when reducing the amount of air supplied to the primary combustion field of the combustor.

5. A gas turbine according to claim 1, wherein the fuel is hydrogen.

Images