Control device and control method for a gas turbine

Abstract

A gas turbine control device (CL) of the present disclosure includes an air-fuel ratio adjustment unit (52) that adjusts an air-fuel ratio in accordance with a sub-fuel ratio of a mixture, the air-fuel ratio being a volume flow ratio of air with respect to the mixture supplied to a combustor (2), and a fuel control unit (53) that determines a supply amount of at least one of the mixture or the air supplied to the combustor (2) based on the air-fuel ratio adjusted by the air-fuel ratio adjustment unit (52).

Description

Related Applications

[0001] This application claims the priority of Japanese Patent Application No. 2024-014449 filed on February 1, 2024, the entire contents of which are incorporated herein by reference as part of the present application. Technical Field

[0002] The present disclosure relates to a control device and a control method for a gas turbine that uses a mixture of at least two fuels with different combustion velocities as fuel. Background Art

[0003] In gas turbine engines, in consideration of environmental protection, strict environmental standards are set for the composition of exhaust gas discharged by combustion, and reduction of nitrogen oxides (hereinafter referred to as NO x ) and other harmful substances is required. Accordingly, a dry DLE (Dry Low Emissions) combustor is known, which injects a premixed gas generated by mixing fuel and compressed air into a combustion chamber and performs lean premixed combustion at a low temperature.

[0004] In the DLE combustor, for further low NO x operation, there is a method using two burners: a main burner having a premix combustion nozzle and an afterburning burner arranged downstream of the main burner (for example, Patent Document 1). The main burner supplies fuel in a manner that controls the local air-fuel ratio, and the remaining required fuel is supplemented by the afterburning burner to perform control for adjusting electric power. Since the mixture injected from the afterburning burner is supplied into the combustion flame generated by the main burner, that is, the high-temperature combustion gas, even a lean mixture that cannot normally be combusted can be combusted, and the method has a feature that NO generated by the combustion of the afterburning burner is scarcely present within a certain mixture range x emission amount.

[0005] Furthermore, the DLE combustor of Patent Document 1 exclusively combusts natural gas, but with the recent increasing trend of CO2 reduction, efforts are being made to reduce CO2 by mixing hydrogen into natural gas.

[0006] Prior Art Literature Patent Documents Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-141078 Contents of the Invention

[0007] (1) Technical Problems to be Solved However, since hydrogen has a high combustion velocity, the local combustion temperature tends to be high, and there is a problem that NO xThe tendency to increase NO levels means that, while maintaining the combustion adjustment settings for natural gas, the desired NO levels cannot be met. x The issue of discharge volume.

[0008] In addition, when burning fuels with high combustion rates, such as hydrogen, backfire can easily occur, where the flame generated in the combustion chamber returns to the burner side.

[0009] The purpose of this application is to solve the aforementioned technical problems, providing a control device and method for a gas turbine that produces NO emissions at the same level as when burning a mixture of at least two fuels with different combustion rates, even when burning a mixture of these fuels. x Discharge volume.

[0010] (II) Technical Solution One aspect of the gas turbine control device disclosed herein is a gas turbine control device having a combustor for burning a mixture of primary fuel and secondary fuel. The gas turbine control device comprises: an air-fuel ratio adjustment unit that adjusts the air-fuel ratio according to the proportion of secondary fuel in the mixture, the air-fuel ratio being a ratio of air to the volumetric flow rate of the mixture supplied to the combustor; and a fuel control unit that determines the supply amount of at least one of the mixture or air supplied to the combustor based on the air-fuel ratio adjusted by the air-fuel ratio adjustment unit.

[0011] According to one aspect of the control device for a gas turbine disclosed herein, by increasing the air-fuel ratio based on the proportion of auxiliary fuel in the mixture, the fuel consumption can be reduced, thereby reducing NO. x The emission rate is suppressed to the same extent as in the case of dedicated natural gas combustion.

[0012] This disclosure also includes any combination of at least two structures disclosed in the claims and / or description and / or drawings. In particular, any combination of two or more claims is also included in this disclosure. Attached Figure Description

[0013] This disclosure will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of this disclosure. The scope of this disclosure is defined by the appended claims. In the drawings, the same part numbers in the plurality of drawings denote the same or equivalent parts.

[0014] Figure 1 This is a schematic diagram of a gas turbine power generation system using the gas turbine control device disclosed herein.

[0015] Figure 2 This is a longitudinal sectional view showing the burner of this disclosure.

[0016] Figure 3 This is a schematic diagram illustrating the control circuit of this disclosure. Detailed Implementation

[0017] <First Implementation Method> The embodiments of this disclosure will be described with reference to the accompanying drawings.

[0018] Figure 1 This diagram illustrates the schematic structure of a gas turbine power generation system using a control device CL for a gas turbine GT according to an embodiment of this disclosure. In this diagram, the gas turbine GT comprises a compressor 1, a combustor 2, and a turbine 3 as its main structural elements. The combustor 2 includes a fuel supply device 5 and a fuel mixing device 6 for mixing primary fuel F1 and secondary fuel F2 supplied from the fuel supply device 5. Between the combustor 2 and the fuel mixing device 6, a main fuel control valve B1 is provided, adjusting its opening according to the mixing ratio of the primary fuel F1 and secondary fuel F2 supplied from the fuel supply device 5. Compressed air A supplied from the compressor 1 and a mixture F (F1+F2) supplied from the fuel mixing device 6 are combusted in the combustor 2, and the high-temperature, high-pressure combustion gas G generated by combustion is supplied to the turbine 3, driving the turbine 3. Exhaust gas E is discharged from the turbine 3. The compressor 1 is driven by the turbine 3 via a rotating shaft 7, and the turbine 3 also drives a load 9, such as a generator, via a reduction gear 8.

[0019] The primary fuel F1 can be natural gas, city gas, etc. City gas refers to artificially produced gas with natural gas as the main raw material. The primary fuel F1 is not limited to these; any fuel containing 60% or more hydrocarbons is acceptable. Additionally, the secondary fuel F2 can include hydrogen, by-product hydrogen, or natural gas containing or by-product hydrogen. The secondary fuel F2 is not limited to these; any gas with a high combustion temperature and fast combustion rate is acceptable. Ammonia can be an example of such a fuel. Furthermore, the mixture F disclosed herein is described as a mixture of two fuels, primary fuel F1 and secondary fuel F2, with different combustion rates, but it is not limited to this; it can also be a mixture of three or more fuels.

[0020] Furthermore, in the following description, the compressor 1 side in the axial direction of the gas turbine GT is referred to as the "upstream side," and the turbine 3 side is referred to as the "downstream side." Additionally, in the following description, unless otherwise specified, "axial direction," "radial," and "circumferential" refer to the axial direction, radial direction, and circumferential direction of the gas turbine GT, respectively.

[0021] Figure 2 This refers to burner 2. In this embodiment, burner 2 is supplied by compressor 1 ( Figure 1A counter-current canister burner in which the flow direction of the supplied compressed air A is internally opposed to the flow direction of the combustion gas G. The burner can also be an annular type with multiple fuel injection valves on its circumference.

[0022] The burner 2 includes a combustion chamber 34 and a housing 35 arranged concentrically on a central shaft 302. A burner nozzle unit 30 is mounted on the top of the combustion chamber 34, and a combustion chamber 33 is formed inside the combustion chamber 34 to burn fuel injected from the burner nozzle unit 30. The combustion chamber 34 is surrounded by a cylindrical housing 35, and a space is formed between the combustion chamber 34 and the housing 35 for fuel injected from the compressor 1. Figure 1 The supplied compressed air A flows through an annular combustion air path 37. The housing 35 and the combustion chamber 34 support multiple afterburner nozzles 36 on a downstream side compared to the burner unit 30.

[0023] In this embodiment, the burner unit 30 includes: a main burner 31, which is arranged along a central axis 302 and injects a premixed gas generated by mixing the mixture F with compressed air A into the combustion chamber 33; and a diffusion combustion type pilot burner 32, which directly injects the mixture F into the combustion chamber 33. The main burner 31 is arranged concentrically around the pilot burner 32. The main burner 31 and the pilot burner 32 are connected to the fuel mixing device 6 via a piping 304.

[0024] In this embodiment, the main burner 31 has an outer cylinder 310 and an inner cylinder 312 arranged concentrically along the central axis 302. In this embodiment, as shown, the inner cylinder 312 also serves as the combustion air injection tube 322b for the pilot burner 32, which will be described later. The annular space between the outer cylinder 310 and the inner cylinder 312 is used as a premixing flow path 314 for mixing the gas mixture F with compressed air A. One end of the premixing flow path 314 opens into the combustion chamber 33, and the other end opens radially outward into the combustion air flow path 37 via a plurality of air intakes 315. A plurality of main fuel nozzles 316 for injecting the first fuel are arranged radially outward from the air intakes 315. Although not shown, it is preferable that the plurality of air intakes 315 and their corresponding plurality of main fuel nozzles 316 are arranged at equal intervals in the circumferential direction centered on the central axis 302. Although not shown, each main fuel nozzle 316 has multiple fuel injection holes (not shown) formed at the location opposite the air intake 315, which spray the mixture F toward the air intake 315, and is connected to the fuel mixing device 6 via a pipe 304a with a flow regulating valve 201. By keeping the flow regulating valve 201 open during normal operation, the mixture F supplied from the fuel mixing device 6 and the compressed air A supplied from the combustion air flow path 37 are supplied together from the air intake 315 to the premixing flow path 314 and mixed in the premixing flow path 314 to become a premixed gas, which is then injected into the combustion chamber 33. In this embodiment, multiple rotating blades (swirlers) 317 are provided at the air intake 315 to impart rotational force to the combustion air flowing into the premixing flow path 314, thereby promoting premixing with the mixture F.

[0025] The pilot burner 32 includes a fuel injection tube 322a extending along a central axis 302 and a combustion air injection tube 322b concentrically mounted outside the fuel injection tube 322a. A fuel injection passage (not shown) formed within the fuel injection tube 322a is connected to the fuel mixing device 6 via a pipe 304b with a flow regulating valve 202. By opening the flow regulating valve 202 during startup, the mixture F supplied from the fuel mixing device 6 is injected into the combustion chamber 33. An annular air flow path 324 is formed between the fuel injection tube 322a and the combustion air injection tube 322b. One end of the annular air flow path 324 is connected to the combustion air flow path 37, and the other end is connected to the combustion chamber 33, through which compressed air A supplied from the compressor 1 is injected.

[0026] The afterburner nozzle 36 is mounted on the housing 35 along four axes 360, which are contained in a plane orthogonal to the central axis 302 and are arranged at equal intervals in the circumferential direction. The inner front end of the afterburner nozzle 36 passes through a through hole 340 formed in the combustion cylinder 34 and faces into the combustion chamber 33. The afterburner nozzle 36 is configured to be connected to the fuel mixing device 6 via a pipe 306 with a flow regulating valve 203. By setting the flow regulating valve 203 to the open state during high-load operation, the mixture F can be injected into the combustion chamber 33.

[0027] The following is for reference Figure 2 The operation of burner 2, which has the above-described structure, will be explained. For example... Figure 2 As shown, when the gas turbine GT starts, the flow regulating valve 202 is open, and the mixture F supplied from the fuel mixing device 6 to the pilot burner 32 is injected into the combustion chamber 33. Thereby, it diffuses and mixes with the compressed air A injected into the combustion chamber 33 from the annular air flow path 324, and is ignited by an ignition source such as a spark plug (not shown), forming a pilot flame based on diffusion combustion.

[0028] If the gas turbine GT switches to normal operation, the premixed gas injected from the premixed flow path 314 of the main combustor 31 is ignited by the pilot flame in the combustion chamber 33 and combusted in the primary combustion zone S1 on the upstream side of the combustion chamber 33. By burning the lean premixed gas, the combustion flame temperature in the combustion chamber 33 is reduced, and the NO in the combustion exhaust gas from the main combustor is reduced. x The amount was suppressed.

[0029] When high-load combustion is required to increase the output of the gas turbine GT, a mixture F is introduced from the supplementary combustion nozzle 36 into the combustion chamber 33, and is mixed with the combustion exhaust gas from the main combustion nozzle 31 in the secondary combustion zone S2, which is located further downstream than the primary combustion zone S1.

[0030] Next, the control method for the gas turbine GT with the above-described structure will be explained. Here, the main fuel F1 will be natural gas, and the auxiliary fuel F2 will be hydrogen.

[0031] Figure 3 This represents a part of the control circuit in the gas turbine control device CL of this disclosure. The ratio of hydrogen to natural gas (mixing ratio) is measured in advance. The gas turbine control device CL includes: a combustion air flow estimation unit 50, which estimates the air flow rate within the gas turbine GT based on intake temperature, gas turbine speed, etc.; and a main air-fuel ratio setting table 51, which sets the air flow rate based on intake temperature, load 9 (…). Figure 1 The air-fuel ratio (hereinafter referred to as the standard air-fuel ratio) is set as the ratio of the volumetric flow rate of compressed air A to the volumetric flow rate of natural gas when it is specifically burned. Figure 3The air-fuel ratio adjustment unit 52 adjusts the compressed air A relative to the hydrogen ratio (hydrogen mixing ratio) of the natural gas and hydrogen mixture F. Figure 1 The air-fuel ratio is determined by the volumetric flow rate of the mixture F supplied to the burner 2; and the fuel control unit 53 determines the supply amount of at least one of the mixture F or air to the burner 2 based on the air-fuel ratio adjusted by the air-fuel ratio adjustment unit 52. The main air-fuel ratio setting table 51 sets a standard air-fuel ratio corresponding to the dedicated combustion of natural gas. As previously described, the volumetric flow rates of natural gas and hydrogen are measured in advance, and the hydrogen co-firing ratio is determined as the hydrogen ratio.

[0032] The air-fuel ratio parameter uses a setting specific to the known load rate for burning natural gas. During hydrogen-fuel mixture combustion, the air-fuel ratio adjustment unit 52 corrects the air-fuel ratio by adding a correction value corresponding to the hydrogen mixing rate to the air-fuel ratio parameter, which serves as the standard air-fuel ratio, using adder 61, thereby increasing the air-fuel ratio. The air-fuel ratio is the value obtained by dividing the air volume by the amount of mixture F; therefore, the correction value is the sum of the air volume and the amount of mixture F. Then, the amount of mixture F supplied to the burner 2 is calculated by dividing the air volume estimated by the combustion air flow estimation unit 50 by the air-fuel ratio corrected by adder 61 using divider 62. In other words, since an air-fuel ratio larger than the standard air-fuel ratio is used, the air-fuel ratio adjustment unit 52 corrects the air-fuel ratio by reducing the amount of mixture F. The fuel control unit 53 calculates the opening degree of the main fuel control valve B1 based on the amount of fuel F supplied to the burner 2, the gas specific gravity, and the valve area. Taking into account the hydrogen ratio, the gas density calculator 65, and the gas specific gravity 66, it issues a command to the main fuel control valve B1 to achieve that valve opening degree. Figure 1 The main fuel control valve B1 controls the flow of fuel to the fuel. Figure 2 The amount of mixture F supplied by the main burner 31 and the afterburner 36.

[0033] In the above control, the fuel control unit 53 controls the amount of fuel F supplied to the burner 2. However, by keeping the amount of fuel F supplied constant and increasing the amount of air supplied to the burner 2, NO can also be suppressed. x Discharge volume. Therefore, the fuel control unit 53 can also determine the amount of air supplied to the burner 2 instead of the amount of fuel F supplied to the burner 2, or determine both the amount of fuel F and the amount of air simultaneously.

[0034] Based on the above structure, since it has a fuel control unit 53, it is possible to control the gas turbine GT to achieve the desired NO. x The amount of exhaust and the amount of CO2 exhaust, wherein the fuel control unit 53 determines the amount of at least one of the mixture F or air supplied to the burner 2 based on the air-fuel ratio adjusted by the air-fuel ratio adjustment unit 52 according to the proportion of auxiliary fuel in the mixture F.

[0035] The air-fuel ratio adjustment unit 52 may also have an air-fuel ratio correction table, which corrects the standard air-fuel ratio based on the proportion of the secondary fuel F2. By using the air-fuel ratio correction table, the correction process can be performed easily, thus simplifying the correction process circuitry.

[0036] The air-fuel ratio adjustment unit 52 can also make corrections by adding a correction value to the standard air-fuel ratio to reduce the air-fuel mixture fuel (F). Because the correction is made by reducing the air-fuel mixture fuel (F), NO can be reduced. x Emissions are suppressed to the same level as when burning only natural gas. Furthermore, when burning fuels with high combustion rates, such as hydrogen, backfire, where the flame from the combustion chamber returns to the burner side, is prone to occur. However, by reducing the fuel mixture (F), backfire is less likely to occur. In addition, by using hydrogenated fuels, CO2 emissions can be reduced compared to burning only natural gas.

[0037] The air-fuel mixture F, supplied based on an air-fuel ratio corrected according to an air-fuel ratio correction table, can be supplied to the main burner 31 and the afterburner 36 located downstream of the main burner 31. Since the air-fuel mixture F, based on the corrected air-fuel ratio, is supplied not only to the main burner 31 but also to the afterburner 36 located downstream of the main burner 31, NO can be further suppressed. x The same principle applies to CO2 emissions.

[0038] In the control method of a gas turbine GT equipped with a combustor 2 for burning a mixture F of primary fuel F1 and secondary fuel F2, the air-fuel ratio, which is the ratio of air to the volumetric flow rate of the mixture F supplied to the combustor 2, is adjusted according to the proportion of secondary fuel in the mixture F. Based on the adjusted air-fuel ratio, the supply amount of at least one of the mixture F or air supplied to the combustor 2 is determined. Because a fuel control unit 53 is provided, it is possible to achieve the desired NO x The gas turbine is controlled by means of emission and CO2 emission, wherein the fuel control unit 53 determines the supply amount of at least one of the mixture F or air to the burner 2 based on the air-fuel ratio adjusted according to the proportion of auxiliary fuel in the mixture F.

[0039] As described above, preferred embodiments of the present disclosure have been illustrated with reference to the accompanying drawings. However, various additions, modifications, or deletions can be made without departing from the spirit of the present disclosure. Therefore, these additions and modifications are also included within the scope of the present disclosure.

Claims

1. A control device for a gas turbine, the gas turbine comprising a burner for burning a mixture of primary fuel and secondary fuel. The control device for the gas turbine includes: An air-fuel ratio adjustment unit adjusts the air-fuel ratio according to the proportion of auxiliary fuel in the air-fuel mixture, the air-fuel ratio being the ratio of air to the volumetric flow rate of the air-fuel mixture supplied to the burner; and A fuel control unit that determines the supply amount of at least one of the air-fuel mixture or air to the burner based on the air-fuel ratio adjusted by the air-fuel ratio adjustment unit.

2. The control device for a gas turbine according to claim 1, characterized in that, The air-fuel ratio adjustment unit has an air-fuel ratio correction table, which corrects the standard air-fuel ratio according to the proportion of the auxiliary fuel.

3. The control device for a gas turbine according to claim 1 or 2, characterized in that, The air-fuel ratio adjustment unit corrects the mixture by adding a correction value to the standard air-fuel ratio.

4. The control device for a gas turbine according to claim 2, characterized in that, The mixture supplied based on the air-fuel ratio corrected according to the air-fuel ratio correction table is supplied to the main burner and the afterburner disposed downstream of the main burner.

5. A control method for a gas turbine, said gas turbine comprising a burner for burning a mixture of primary fuel and secondary fuel. The control method of the gas turbine adjusts the air-fuel ratio according to the proportion of auxiliary fuel in the mixture, wherein the air-fuel ratio is the ratio of air to the volumetric flow rate of the mixture supplied to the burner. The amount of at least one of the mixture or air supplied to the burner is determined based on the adjusted air-fuel ratio.

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