Gas turbine combustor operation method

Abstract

To provide an operation method of a gas turbine combustor which can perform stable combustion at a turbine activation operation initial time.SOLUTION: In an operation method of a combustor 10 of this embodiment, a mixture gas containing oxygen circulates in the combustor 10 as a circulation gas before the ignition of the combustor 10. Then, up until stable combustion reaches a stable combustion condition after ignition during an operation time over a turbine rated load time after the ignition of the combustor 10, a control device 100 controls a flow rate of fuel supplied from a fuel supply part 40 and a flow rate of an oxidizer supplied from an oxidizer supply part 50, and makes a combustion gas whose oxygen concentration is maintained at the same as an oxygen concentration of the mixture gas circulate as the circulation gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a method of operating a gas turbine combustor. [Background technology]

[0002] In recent years, power plants equipped with gas turbine combustors have been striving to improve their efficiency in response to demands for reducing carbon dioxide emissions and saving resources. Under these circumstances, gas turbine facilities that recycle a portion of the carbon dioxide emitted from the turbine back into the combustor are being considered.

[0003] 8 is a diagram schematically illustrating a vertical cross section of a combustor 310 provided in a conventional gas turbine facility 300. As shown in FIG. 8, the combustor 310 includes a combustor casing 320, a combustor liner 330, a fuel-oxidizer supply section 340, and a carbon dioxide supply pipe 350.

[0004] A combustor liner 330 and a fuel-oxidizer supply section 340 are provided inside the combustor casing 320. The combustor liner 330 is made up of a tubular member that combusts fuel and oxidizer.

[0005] The fuel-oxidizer supply section 340 is provided at one end (upstream end) of the combustor liner 330. The other end (downstream end) of the combustor liner 330 is provided with a transition piece 360 that guides the combustion gas discharged from the combustor liner 330 to the turbine.

[0006] The fuel-oxidizer supply section 340 includes a fuel supply pipe 341 and an oxidizer supply pipe 342. The fuel supply pipe 341 supplies fuel into the combustor liner. The oxidizer supply pipe 342 is provided on the outer periphery of the fuel supply pipe 341 and supplies oxidizer into the combustor liner. The fuel supply pipe 341 and the oxidizer supply pipe 342 form a double pipe structure.

[0007] The carbon dioxide supply line 350 is connected to the combustor casing 320. The carbon dioxide supply line 350 supplies carbon dioxide to be circulated to the combustor 310 between the combustor casing 320 and the fuel-oxidant supply section 340 and combustor liner 330.

[0008] The flow rates of fuel and oxidizer supplied to the combustor liner 330 are adjusted to a stoichiometric mixture ratio (equivalence ratio of 1). The equivalence ratio is calculated based on the fuel flow rate and the oxygen flow rate. The equivalence ratio is calculated by dividing the fuel-air ratio by the stoichiometric fuel-air ratio.

[0009] In the gas turbine facility 300, water vapor is separated from the combustion gas discharged from the turbine and circulated to the combustor 310. The combustion gas from which the water vapor has been removed is mostly composed of carbon dioxide. Therefore, the combustion gas circulated from the carbon dioxide supply pipe 350 to the combustor 310 is carbon dioxide.

[0010] The carbon dioxide circulated to the combustor 310 functions as a cooling medium and a diluting medium. The circulated carbon dioxide is heated by heat exchange with combustion gas discharged from the turbine, for example, via a regenerative heat exchanger. In the gas turbine facility 300, for example, carbon dioxide pressurized to a pressure equal to or higher than its critical pressure is circulated to the combustor 310.

[0011] Carbon dioxide flowing between the combustor casing 320 and the combustor liner 330 is introduced into the combustor liner 330 through, for example, cooling holes 331 and dilution holes 332 formed in the combustor liner 330 .

[0012] In the above-described gas turbine facility 300, before combustion starts in the combustor 310, the filled carbon dioxide is circulated to the combustor 310. Then, with the carbon dioxide circulated to the combustor 310, the operation of the combustor 310 is started. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-337107 Summary of the Invention [Problem to be solved by the invention]

[0014] During turbine startup operation from the start of combustion (ignition) in the combustor 310 to the initial turbine load, the pressure inside the combustor liner 330 is low during the initial stage of turbine startup operation from ignition to a predetermined time. When the pressure inside the combustor liner 330 is low, the turbulent combustion velocity is low. As a result, stable combustion cannot be achieved and the flame may go out.

[0015] Furthermore, since the flow rates of the fuel and oxidizer supplied to the combustor liner 330 are set to a stoichiometric mixture ratio, the flow rate of oxygen is the minimum flow rate required for complete combustion. Furthermore, carbon dioxide, an inert gas, is introduced into the periphery of the flame through the cooling holes 331 and dilution holes 332. Therefore, carbon dioxide flows into the flame, making it unstable.

[0016] As described above, at the initial stage of turbine startup operation, the turbulent combustion velocity is low in the combustor liner 330, and combustion occurs in a state where there is no excess oxygen and inert gas is mixed in. Therefore, stable combustion cannot be achieved, and the flame may go out.

[0017] An object of the present invention is to provide a method for operating a gas turbine combustor that enables stable combustion during the initial stage of turbine startup operation. [Means for solving the problem]

[0018] In one embodiment, a gas turbine combustor operation method includes: a casing; a combustor liner disposed within the casing and configured to combust fuel and oxidizer; a fuel supply unit configured to supply fuel to the combustor liner; an oxidizer supply unit configured to supply oxidizer to the combustor liner; and a control device configured to control a flow rate of the fuel supplied from the fuel supply unit and a flow rate of the oxidizer supplied from the oxidizer supply unit, wherein exhaust gas discharged from the turbine is circulated into the casing as circulated gas through a circulation system connecting an outlet of the turbine and the casing, and the circulated gas is introduced into the combustor liner through a through-hole provided in the combustor liner. Introduced do.

[0019] In this gas turbine combustor operation method, before ignition in the gas turbine combustor, a mixed gas containing oxygen at a predetermined concentration is circulated as the circulation gas. Then, during an operation time from ignition in the gas turbine combustor to a rated load of the turbine, from the time of ignition until a stable combustion condition is reached where stable combustion is possible and a flame can be maintained, the control device controls the flow rate of the fuel supplied from the fuel supply unit and the flow rate of the oxidizer supplied from the oxidizer supply unit, and circulates, as the circulation gas, combustion gas whose oxygen concentration is maintained the same as the oxygen concentration in the mixed gas in order to prevent flame quenching. The control device, at a first time point when the ignition occurs, burns the fuel at a first equivalence ratio, which is a local equivalence ratio calculated from the flow rate of the fuel supplied from the fuel supply unit and the flow rate of the oxidizer supplied from the oxidizer supply unit; from the first time point to a second time point after the first time point, burns the fuel at a first equivalence ratio, while gradually decreasing the local equivalence ratio from the first equivalence ratio to a second equivalence ratio that is smaller than the first equivalence ratio, while increasing the flow rates of the fuel and the oxidizer; circulates the combustion gas in which the oxygen concentration is maintained the same as the oxygen concentration in the mixed gas as the circulating gas; and from the second time point, until a third time, which is the time when the stable combustion condition is reached, the flow rates of the fuel and the oxidizer are increased while combustion is performed while maintaining the local equivalence ratio at the second equivalence ratio, and the combustion gas in which the same oxygen concentration as that of the mixed gas is maintained is circulated as the circulation gas, and from the third time until a later time of rated operation of the turbine, the flow rates of the fuel and the oxidizer are controlled to increase the local equivalence ratio from the second equivalence ratio, and the oxygen concentration in the circulation gas, which is the combustion gas, is made zero during rated operation of the turbine. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a system diagram of a gas turbine facility in which a combustor operation method according to an embodiment is executed. [Figure 2] 1 is a block diagram showing a configuration of a control device that executes a method of operating a combustor according to an embodiment; [Figure 3] 1 is a diagram schematically illustrating a vertical cross section of a combustor in which a method of operating a combustor according to an embodiment is performed; [Figure 4] 3 is a time chart for explaining a method of operating the combustor according to the embodiment. [Figure 5]3 is a flowchart for explaining a method of operating the combustor according to the embodiment. [Figure 6] FIG. 4 is a diagram showing a flame-holding range at the beginning of turbine startup operation of the combustor according to the embodiment. [Figure 7] FIG. 2 is a diagram for explaining a stable combustion region in the combustor according to the embodiment. [Figure 8] FIG. 1 is a diagram schematically illustrating a vertical cross section of a combustor provided in a conventional gas turbine facility. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] Fig. 1 is a system diagram of a gas turbine facility 1 in which a combustor operation method according to an embodiment is performed. As shown in Fig. 1, the gas turbine facility 1 includes a combustor 10, a fuel supply unit 40, an oxidant supply unit 50, a gas circulation system 60, a turbine 70, a generator 75, a regenerative heat exchanger 80, and a control device 100. The combustor 10 functions as a gas turbine combustor.

[0023] The fuel supply unit 40 supplies fuel to the combustor 10. The fuel supply unit 40 includes a pipe 41. The pipe 41 is provided between a fuel supply source (not shown) and the combustor 10. The pipe 41 also includes a flow rate control valve 42 that adjusts the flow rate of the fuel.

[0024] Here, as the fuel, for example, hydrocarbons such as methane, natural gas, etc. Alternatively, as the fuel, for example, coal gasification gas fuel containing carbon monoxide and hydrogen, etc. may be used.

[0025] The oxidant supply unit 50 supplies an oxidant to the combustor 10. The oxidant supply unit 50 includes a pipe 51. This pipe 51 is provided, for example, between the combustor 10 and an air separation unit (not shown) that separates oxygen from the atmosphere. The pipe 51 includes a flow rate control valve 52 that adjusts the flow rate of the oxidant.

[0026] Here, examples of the oxidizing agent include oxygen, a mixed gas in which oxygen is mixed with carbon dioxide, etc. As the carbon dioxide contained in the mixed gas, for example, a part of the carbon dioxide flowing through the gas circulation system 60 is used.

[0027] Although not shown, a compressor for pressurizing the oxidizer is provided in the pipe 51. For example, even when the circulating gas pressurized to a critical pressure or higher due to operating conditions flows through the gas circulation system 60, this compressor can pressurize the oxidizer to a pressure that allows it to be supplied to the combustor 10.

[0028] Alternatively, the piping 51 may be passed through the regenerative heat exchanger 80 to heat the oxidant and supply it to the combustor 10. In this case, the flow rate adjustment valve 52 is provided upstream of the regenerative heat exchanger 80.

[0029] The gas circulation system 60 includes a pipe 61 that circulates the circulation gas discharged from the turbine 70 to the combustor 10. The pipe 61 is provided between the outlet of the turbine 70 and the combustor 10.

[0030] When the fuel and oxidizer are combusting in the combustor 10, the combustion gas circulates as a circulation gas. This combustion gas is a mixture of the combustion gas generated by the combustion of the fuel and oxidizer and the circulation gas introduced into the combustor liner 20, which will be described later.

[0031] Furthermore, before the turbine is started (before the fuel and oxidizer are combusted in the combustor 10), a mixed gas containing a predetermined concentration of oxygen in carbon dioxide, which is pre-filled in the gas circulation system 60, is circulated as a circulation gas.

[0032] The piping 61 is equipped with a condenser 62 that removes water vapor contained in the combustion gas. The water vapor in the combustion gas condenses into water as it passes through the condenser 62. The water is discharged to the outside, for example, through a piping (not shown).

[0033] The piping 61 also includes a compressor 63 that pressurizes the circulating gas. The compressor 63, for example, pressurizes the combustion gas from which water vapor has been removed in the condenser 62. Depending on the operating conditions, the compressor 63 can pressurize the combustion gas from which water vapor has been removed, for example, to a pressure equal to or higher than the critical pressure. The condenser 62 and the compressor 63 are provided in the piping 61 in a region through which the circulating gas cooled in the regenerative heat exchanger 80 flows.

[0034] The piping 61 is provided so as to pass through the regenerative heat exchanger 80 twice. That is, the piping 61 passes through the regenerative heat exchanger 80 once between the turbine 70 and the condenser 62. Then, the piping 61 passes through the regenerative heat exchanger 80 again between the compressor 63 and the combustor 10.

[0035] Here, the combustion gas (circulation gas) discharged from the turbine 70 is cooled by passing through the regenerative heat exchanger 80. At this time, the heat released from the combustion gas heats the circulation gas that circulates through the pipe 61 to the combustor 10.

[0036] Although not shown, the pipe 61 between the compressor 63 and the regenerative heat exchanger 80 is provided with a pipe branching from the pipe 61. A portion of the circulating gas is discharged to the outside via the branch pipe.

[0037] The turbine 70 is rotated by the combustion gas discharged from the combustor 10. The turbine 70 is connected to, for example, a generator 75 that generates electricity using the rotation of the turbine 70.

[0038] The control device 100 controls the flow rate adjustment valve 42, the flow rate adjustment valve 52, etc. to adjust the fuel flow rate, the oxidizer flow rate, etc. supplied to the combustor 10.

[0039] 2 is a block diagram showing the configuration of a control device 100 that executes the method for operating the combustor 10 according to the embodiment. The control device 100 includes an input unit 110, a storage unit 120, a calculation unit 130, and an output unit 140.

[0040] The input unit 110 receives, for example, an ignition request signal or a load request signal from an input device or the like, a timer signal from a timer device or the like, and detection signals from various detection units.

[0041] The storage unit 120 is configured with a storage medium such as a read-only memory (ROM) or a random access memory (RAM). The storage unit 120 stores, for example, turbine startup operation data 121 indicating the relationship between the operation time during turbine startup operation from the start of combustion (ignition) in the combustor 10 to the turbine initial load, and the fuel flow rate and the oxidizer flow rate. That is, the turbine startup operation data 121 stores, for example, data on the fuel flow rate and the oxidizer flow rate supplied to the combustor 10 at predetermined time intervals from the time of ignition to the time of the turbine initial load.

[0042] The storage unit 120 also stores, for example, turbine load operation data 122 that indicates the relationship between the fuel flow rate and the oxidizer flow rate depending on the turbine load during turbine load operation from the turbine initial load to the rated load.

[0043] Each of the above data also stores information such as the valve opening of the flow rate adjusting valve corresponding to each flow rate.

[0044] Here, the turbine startup operation refers to the operating period from the start of combustion (ignition) in the combustor 10 to the initial load on the turbine. Also, within the turbine startup operation, the period from ignition to a predetermined time when the stable combustion region is entered is referred to as the initial stage of turbine startup operation. The stable combustion region is a range in which combustion conditions satisfy stable combustion conditions that enable stable combustion, and the stable combustion region will be described later.

[0045] The turbine startup operation data 121 is data obtained in a turbine startup operation test using an actual machine. The turbine load operation data 122 is data obtained in a turbine load operation test using an actual machine.

[0046] The calculation unit 130 executes various calculation processes using, for example, an input signal from the input unit 110, and programs and data stored in the storage unit 120. The calculation unit 130 includes an elapsed time determination unit 131, a fuel-oxidizer flow rate determination unit 132, and the like.

[0047] The elapsed time determination unit 131 determines the elapsed time from the time of ignition, etc., based on the timer signal from the input unit 110.

[0048] The fuel-oxidizer flow rate determining unit 132 determines the fuel flow rate and oxidizer flow rate to be supplied to the combustor 10 during the turbine startup operation based on the determination result of the elapsed time determining unit 131 and the turbine startup operation data 121 .

[0049] Furthermore, the fuel-oxidizer flow rate determining unit 132 calculates the fuel flow rate and oxidizer flow rate to be supplied to the combustor 10 during turbine load operation based on the load request signal during turbine load operation and the turbine load operation data 122 .

[0050] The output unit 140 outputs the control signal from the calculation unit 130 to, for example, the flow rate adjustment valves 42, 52. The output unit 140 is connected to the flow rate adjustment valves 42, 52, etc. so as to be able to communicate with them.

[0051] Here, the processing executed by the control device 100 described above is realized by, for example, a computer device.

[0052] Next, the configuration of the combustor 10 will be described.

[0053] 3 is a diagram schematically illustrating a longitudinal cross section of a combustor 10 in which a method of operating a combustor according to an embodiment is performed. As shown in FIG. 3, the combustor 10 includes a combustor casing 15, a combustor liner 20, and a fuel-oxidizer supply unit 30.

[0054] The combustor casing 15 is comprised of a cylindrical body that houses the combustor liner 20 and the fuel-oxidizer supply section 30 .

[0055] The combustor liner 20 is composed of a tubular member that combusts fuel and oxidizer. One end (upstream end) of the combustor liner 20 is closed by an upstream end wall 21, and the other end (downstream end) is open. The other end (downstream end) of the combustor liner 20 is provided with a transition piece 90 that guides combustion gas discharged from the combustor liner 20 to the turbine 70.

[0056] The combustor liner 20 is configured, for example, as a cylindrical body that extends linearly. Note that the combustor liner 20 may also be configured, for example, as a cylindrical body that is partially curved.

[0057] The combustor liner 20 has cooling holes 22 and dilution holes 23 formed in its side to introduce the circulating gas introduced from the piping 61 into the combustor casing 15 into the combustor liner 20. The cooling holes 22 and dilution holes 23 function as through holes.

[0058] The cooling holes 22 are, for example, cooling holes for film cooling, etc. The dilution holes 23 are, for example, through holes formed in a direction perpendicular to the central axis of the combustor liner 20.

[0059] The fuel-oxidizer supply section 30 penetrates the combustor casing 15, and the downstream end of the fuel-oxidizer supply section 30 is disposed at one end (upstream end) of the combustor liner 20. Specifically, for example, the downstream end of the fuel-oxidizer supply section 30 is fitted into a through-hole 21a formed in the upstream end wall 21 so as not to protrude into the inside of the combustor liner 20.

[0060] The fuel-oxidizing agent supply unit 30 includes a fuel supply pipe 31 and an oxidizing agent supply pipe 32 .

[0061] The fuel supply pipe 31 supplies fuel into the combustor liner 20. The fuel supply pipe 31 is configured as, for example, a circular pipe. The fuel supply pipe 31 is connected to a pipe 41 that supplies fuel. An outlet 31a of the fuel supply pipe 31 functions as, for example, a fuel nozzle. The outlet 31a is configured as, for example, a single fuel injection hole or multiple fuel ejection holes. Fuel is ejected from the outlet 31a of the fuel supply pipe 31 into the combustor liner 20.

[0062] The oxidizer supply pipe 32 supplies oxidizer into the combustor liner 20. The outer periphery of the downstream end of the oxidizer supply pipe 32 is fitted into the through-hole 21a of the upstream end wall 21. The oxidizer supply pipe 32 is formed, for example, of a circular pipe having an inner diameter larger than the outer diameter of the fuel supply pipe 31.

[0063] The oxidant supply pipe 32 may be, for example, Figure 3 As shown in Fig. 1, the oxidizer supply pipe 32 is provided on the outer periphery of the fuel supply pipe 31. For example, the central axis of the oxidizer supply pipe 32 is coaxial with the central axis of the fuel supply pipe 31. This forms an annular passage on the outer periphery of the fuel supply pipe 31.

[0064] In this way, for example, the fuel supply pipe 31 and the oxidizer supply pipe 32 are configured with a double pipe structure. The fuel is ejected from a central fuel ejection hole, and the oxidizer is ejected from an annular flow path formed around the central fuel ejection hole. In other words, the combustor 10 employs a diffusion combustion method.

[0065] For example, a swirler 33 that forms a swirling flow of oxidizer is provided at the outlet 32a of the annular passage between the fuel supply pipe 31 and the oxidizer supply pipe 32. The swirler 33 has a plurality of blades arranged in the circumferential direction of the annular passage. The blades are arranged at a predetermined angle with respect to the axial direction of the annular passage.

[0066] As the oxidizer passes through this swirler 33, a swirling flow having a circumferential velocity component is injected into the combustor liner 20. By making the oxidizer a swirling flow in this way, mixing of the fuel and the oxidizer is promoted in the combustor liner 20, and a stable flame is formed.

[0067] The piping 61 for circulating the circulation gas is connected to the combustor casing 15. The piping 61 is connected to, for example, the side of the combustor casing 15 through which the fuel-oxidizer supply section 30 passes.

[0068] The piping 61 supplies circulation gas between the combustor casing 15 and the fuel-oxidizer supply section 30 and the combustor liner 20. The circulation gas is introduced into the combustor liner 20 as a cooling medium or a dilution medium through the cooling holes 22 and the dilution holes 23 of the combustor liner 20 described above.

[0069] The circulating gas introduced into the combustor liner 20 is introduced around or downstream of the flame formed inside the combustor liner 20. The flame burns while entraining the introduced circulating gas. In other words, the combustion reaction progresses while the circulating gas is mixed in the combustion region that forms the flame.

[0070] Next, a method of operating the combustor 10 will be described.

[0071] Fig. 4 is a time chart for explaining the method of operating the combustor 10 according to the embodiment. Fig. 5 is a flowchart for explaining the method of operating the combustor 10 according to the embodiment.

[0072] Here, the horizontal axis of Fig. 4 represents time, and the vertical axis of Fig. 4 represents the pressure ratio, fuel flow rate ratio, oxidizer flow rate ratio, equivalence ratio, and oxygen concentration (wt%) of the circulation gas inside the combustor 10. In Fig. 4, the part showing the pressure ratio inside the combustor 10 is shaded to indicate the range of a stable combustion region, which will be described later.

[0073] Here, the pressure ratio inside the combustor 10 is the pressure ratio inside the combustor liner 20. The pressure ratio inside the combustor 10 indicates the ratio of the pressure inside the combustor liner 20 at each time when the pressure inside the combustor liner 20 at the rated load of the turbine is set to 1. The fuel flow rate ratio indicates the ratio of the fuel flow rate at each time when the fuel flow rate at the rated load of the turbine is set to 1. The oxidizer flow rate ratio indicates the ratio of the oxidizer flow rate at each time when the oxidizer flow rate at the rated load of the turbine is set to 1.

[0074] The oxygen concentration is the oxygen concentration of the circulation gas introduced into the combustor 10. That is, it is the oxygen concentration of the circulation gas introduced into the combustor casing 15 from the pipe 61.

[0075] As equivalence ratios, a local equivalence ratio φl in the fuel-oxidizer supply section 30 and a total equivalence ratio φt in the combustor 10 (combustor liner 20) are shown.

[0076] The local equivalence ratio φl is an equivalence ratio calculated based on the fuel flow rate and oxygen flow rate supplied to the fuel-oxidizer supply section 30. In other words, the local equivalence ratio φl is an equivalence ratio calculated based on the flow rate of fuel injected from the fuel supply pipe 31 into the combustor liner 20 and the flow rate of oxygen injected from the oxidizer supply pipe 32 into the combustor liner 20.

[0077] The total equivalence ratio φt is an equivalence ratio calculated based on the fuel flow rate and oxygen flow rate supplied to the combustor 10. That is, the total equivalence ratio φt is calculated taking into consideration the oxygen flow rate contained in the circulation gas supplied into the combustor liner 20. In other words, the total equivalence ratio φt is an equivalence ratio calculated based on the flow rate of fuel injected from the fuel supply pipe 31 into the combustor liner 20, the flow rate of oxygen injected from the oxidizer supply pipe 32 into the combustor liner 20, and the flow rate of oxygen contained in the circulation gas introduced into the combustor liner 20.

[0078] The local equivalence ratio φl and the total equivalence ratio φt are calculated by dividing the fuel-air ratio by the stoichiometric fuel-air ratio.

[0079] In Fig. 4, the turbine startup operation is from time t1 to time t4 (longer than time t1 and shorter than time t4). Within the turbine startup operation, the initial stage of the turbine startup operation is from time t1 to time t3 (longer than time t1 and shorter than time t3). The turbine load operation is from time t4 to time t5 (longer than time t4 and shorter than time t5).

[0080] In the gas turbine facility 1, before the turbine is started, i.e., before combustion starts in the combustor 10 (before time t1), the mixed gas previously filled in the gas circulation system 60 is circulated to the combustor 10 as circulating gas. That is, the mixed gas circulates through the piping 61, the combustor 10, and the turbine 70. When circulating, the mixed gas is pressurized by the compressor 63.

[0081] Here, the mixed gas is carbon dioxide containing a predetermined concentration of oxygen. The oxygen concentration of this mixed gas is set in the range of 10 to 15 wt%. Figure 4 shows an example where the oxygen concentration of the mixed gas is set to 15 wt%. The reason for setting the oxygen concentration of the mixed gas in this range will be explained later.

[0082] (At the time of ignition: time t1) With the mixed gas circulated to the combustor 10, an oxidizer and a fuel are supplied to the combustor 10 and ignited by an ignition device. Here, the time of ignition (time t1) functions as the first time.

[0083] As shown in FIG. 5, the fuel-oxidizer flow rate determining unit 132 of the control device 100 determines whether or not an ignition start signal has been input to the input unit 110 (step S10).

[0084] In the determination of step S10, when it is determined that the ignition start signal has not been input (No in step S10), the fuel-oxidizer flow rate determining unit 132 executes the process of step S10 again.

[0085] In the determination of step S10, when it is determined that the ignition start signal has been input (Yes in step S10), the fuel-oxidizer flow rate determining unit 132 executes control for ignition (step S11).

[0086] In step S11, the fuel-oxidizer flow rate determination unit 132 identifies the fuel flow rate and the oxidizer flow rate to be supplied to the combustor 10 at the time of ignition, with reference to the turbine startup operation data 121. Then, the fuel-oxidizer flow rate determination unit 132 outputs a signal to the output unit 140 to supply the oxidizer and the fuel to the fuel-oxidizer supply unit 30 of the combustor 10.

[0087] The output unit 140 outputs the signal from the fuel-oxidizer flow rate determination unit 132 to the flow rate control valve 52 and the flow rate control valve 42. As a result, the openings of the flow rate control valve 52 and the flow rate control valve 42 are adjusted, and predetermined flow rates of fuel and oxidizer are supplied into the combustor liner 20 via the fuel-oxidizer supply unit 30.

[0088] At this time, the local equivalence ratio is set to a first equivalence ratio. Here, the first equivalence ratio is set in the range of 0.8 to 0.9. Fig. 4 shows an example where the first equivalence ratio is set to 0.84. The reason for setting the first equivalence ratio in this range will be described later.

[0089] As a result, fuel is ejected from the fuel supply pipe 31 and oxidizer is ejected from the oxidizer supply pipe 32 into the combustor liner 20, forming a flame.

[0090] (Time t1 to time t2) As shown in FIG. 5, the fuel-oxidant flow rate determining unit 132 determines whether or not a detection signal has been input from the flame detector at the input unit 110 (step S12).

[0091] In the determination of step S12, when it is determined that a detection signal has not been input within a predetermined time period (No in step S12), the fuel-oxidizer flow rate determining unit 132, for example, stops the supply of fuel and oxidizer to the combustor 10. Then, for example, the operation of the combustor 10 is stopped.

[0092] In the determination of step S12, when it is determined that the detection signal has been input (Yes in step S12), the fuel-oxidizer flow rate determining unit 132 executes control to decrease the local equivalence ratio φl (step S13).

[0093] 4, in step S13, the fuel-oxidizer flow rate determining unit 132 executes control to reduce the local equivalence ratio φl, for example, after detecting the detection signal from the flame detector input by the input unit 110, that is, during a second time period (time t2) after ignition (after time t1) (a period after time t1 but before time t2). Note that time t2 functions as the second time period.

[0094] Here, in the combustor 10, the fuel flow rate and the oxidizer flow rate are increased while the local equivalence ratio φl is gradually decreased from a first equivalence ratio to a second equivalence ratio that is smaller than the first equivalence ratio.

[0095] At this time, the oxygen concentration in the circulation gas circulated to the combustor 10 is maintained at the same concentration (15 wt % in FIG. 4) as the oxygen concentration in the mixed gas circulated to the combustor 10 before ignition. In other words, the local equivalence ratio φl is reduced while the total equivalence ratio φt is maintained constant.

[0096] Here, the second equivalence ratio is set in the range of 0.35 to 0.45. An example where the second equivalence ratio is 0.40 is shown in Figure 4. The reason for setting the second equivalence ratio in this range will be described later.

[0097] Specifically, the elapsed time determination unit 131 determines the elapsed time from time t1 based on the output signal from the timer, and outputs the determination information to the fuel-oxidizer flow rate determination unit 132. The fuel-oxidizer flow rate determination unit 132 specifies the fuel flow rate and oxidizer flow rate to be supplied to the combustor 10 according to the elapsed time from time t1 based on the determination information from the elapsed time determination unit 131 and the turbine startup operation data 121.

[0098] Then, the fuel-oxidizer flow rate determining unit 132 outputs to the output unit 140 a signal for supplying the oxidizer and fuel at predetermined flow rates to the fuel-oxidizer supply unit 30 of the combustor 10 every predetermined elapsed time.

[0099] The output unit 140 outputs the signal from the fuel-oxidizer flow rate determination unit 132 to the flow rate control valve 52 and the flow rate control valve 42. As a result, the openings of the flow rate control valve 52 and the flow rate control valve 42 are adjusted, and predetermined flow rates of fuel and oxidizer are supplied into the combustor liner 20 via the fuel-oxidizer supply unit 30.

[0100] (Time t2 to time t3) As shown in FIG. 5, the elapsed time determination unit 131 determines whether or not time t2 has been reached based on the output signal from the timer (step S14).

[0101] In the determination of step S14, if it is determined that the time t2 has not been reached (No in step S14), the elapsed time determination unit 131 outputs the determination result to the fuel-oxidizer flow rate determination unit 132. Then, the fuel-oxidizer flow rate determination unit 132 continues the processing of step S13.

[0102] In the determination of step S14, when it is determined that time t2 has been reached (Yes in step S14), the elapsed time determination unit 131 outputs the determination result to the fuel-oxidizer flow rate determination unit 132. Then, the fuel-oxidizer flow rate determination unit 132 executes control to maintain the local equivalence ratio φl constant (step S15).

[0103] 4, the fuel-oxidizer flow rate determining unit 132 executes control to maintain the local equivalence ratio φl constant from time t2 to a third time period (time t3) thereafter (the time period from time t2 to less than time t3). Note that time t3 functions as the third time period.

[0104] Here, in the combustor 10, the fuel flow rate and the oxidizer flow rate are increased while the local equivalence ratio φl is maintained at the second equivalence ratio.

[0105] At this time, the oxygen concentration in the circulation gas circulated to the combustor 10 is maintained at the same concentration (15 wt % in FIG. 4) as the oxygen concentration in the mixed gas circulated to the combustor 10 before ignition. In other words, the total equivalence ratio φt is maintained constant, while the local equivalence ratio φl is maintained at the second equivalence ratio. At time t3, the combustion conditions satisfy the stable combustion conditions, and the combustion state reaches the stable combustion region described below.

[0106] Furthermore, the elapsed time determination unit 131 determines, for example, the elapsed time from time t2 (or the elapsed time from time t1) based on the output signal from the timer. The elapsed time determination unit 131 outputs determination information of the elapsed time to the fuel-oxidizer flow rate determination unit 132.

[0107] The fuel-oxidizer flow rate determining unit 132 determines the fuel flow rate and oxidizer flow rate to be supplied to the combustor 10 according to the elapsed time from time t2, based on the determination information from the elapsed time determining unit 131 and the turbine startup operation data 121.

[0108] Then, the fuel-oxidizer flow rate determining unit 132 outputs to the output unit 140 a signal for supplying the oxidizer and fuel at predetermined flow rates to the fuel-oxidizer supply unit 30 of the combustor 10 every predetermined elapsed time.

[0109] The output unit 140 outputs the signal from the fuel-oxidizer flow rate determination unit 132 to the flow rate control valve 52 and the flow rate control valve 42. As a result, the openings of the flow rate control valve 52 and the flow rate control valve 42 are adjusted, and predetermined flow rates of fuel and oxidizer are supplied into the combustor liner 20 via the fuel-oxidizer supply unit 30.

[0110] (Time t3 to time t4) As shown in FIG. 5, the elapsed time determination unit 131 determines whether or not time t3 has been reached based on the output signal from the timer (step S16).

[0111] In the determination of step S16, if it is determined that time t3 has not been reached (No in step S16), the elapsed time determination unit 131 outputs the determination result to the fuel-oxidizer flow rate determination unit 132. Then, the fuel-oxidizer flow rate determination unit 132 continues the processing of step S15.

[0112] In the determination of step S16, when it is determined that time t3 has been reached (Yes in step S16), the elapsed time determination unit 131 outputs the determination result to the fuel-oxidizer flow rate determination unit 132. Then, the fuel-oxidizer flow rate determination unit 132 executes control to increase the local equivalence ratio φl (step S17).

[0113] In step S17, as shown in FIG. 4, the fuel-oxidant flow rate determination unit 132 executes control to increase the local equivalence ratio φl during the period from time t3 to a fourth time period (time t4) thereafter (the period from time t3 to less than time t4).

[0114] This example shows an example in which the local equivalence ratio φl is increased from the second equivalence ratio to a third equivalence ratio that is larger than the second equivalence ratio by increasing the fuel flow rate while maintaining the oxidizer flow rate constant in the combustor 10. Note that the local equivalence ratio φl may also be increased from the second equivalence ratio to the third equivalence ratio that is larger than the second equivalence ratio by increasing the fuel flow rate while increasing the oxidizer flow rate.

[0115] At this time, the oxygen concentration in the circulation gas circulated to the combustor 10 decreases from the same oxygen concentration (15 wt % in FIG. 4) as the oxygen concentration in the mixed gas circulated to the combustor 10 before ignition.

[0116] Here, the third equivalence ratio is set to 1.0. In the gas turbine equipment 1, it is preferable that no excess oxygen or fuel remains in the combustion gas discharged from the combustor 10 when the turbine is at rated load. Therefore, from time t3 to time t4, the local equivalence ratio φl is increased to 1.0 to reduce the oxygen concentration in the circulation gas.

[0117] Furthermore, the elapsed time determination unit 131 determines, for example, the elapsed time from time t3 (or the elapsed time from time t1) based on the output signal from the timer. The elapsed time determination unit 131 outputs determination information of the elapsed time to the fuel-oxidizer flow rate determination unit 132.

[0118] The fuel-oxidizer flow rate determining unit 132 determines the fuel flow rate and oxidizer flow rate to be supplied to the combustor 10 according to the elapsed time from time t3, based on the determination information from the elapsed time determining unit 131 and the turbine startup operation data 121.

[0119] Then, the fuel-oxidizer flow rate determining unit 132 outputs to the output unit 140 a signal for supplying the oxidizer and fuel at predetermined flow rates to the fuel-oxidizer supply unit 30 of the combustor 10 every predetermined elapsed time.

[0120] The output unit 140 outputs the signal from the fuel-oxidizer flow rate determination unit 132 to the flow rate control valve 52 and the flow rate control valve 42. As a result, the openings of the flow rate control valve 52 and the flow rate control valve 42 are adjusted, and predetermined flow rates of fuel and oxidizer are supplied into the combustor liner 20 via the fuel-oxidizer supply unit 30.

[0121] (Time t4~Time t5) As shown in FIG. 5, the elapsed time determination unit 131 determines whether or not time t4 has been reached based on the output signal from the timer (step S18).

[0122] In the determination of step S18, if it is determined that time t4 has not been reached (No in step S18), the elapsed time determination unit 131 outputs the determination result to the fuel-oxidizer flow rate determination unit 132. Then, the fuel-oxidizer flow rate determination unit 132 continues the processing of step S17.

[0123] In the determination of step S18, when it is determined that time t4 has been reached (Yes in step S18), the elapsed time determination unit 131 outputs the determination result to the fuel-oxidizer flow rate determination unit 132. Then, the fuel-oxidizer flow rate determination unit 132 executes control to maintain the local equivalence ratio φl constant (step S19).

[0124] In step S19, as shown in FIG. 4, the fuel-oxidant flow rate determination unit 132 executes control to maintain the local equivalence ratio φl constant from time t4 to a subsequent fifth time (time t5) (the time from time t4 to less than time t5).

[0125] Here, in the combustor 10, the fuel flow rate and the oxidizer flow rate are increased while the local equivalence ratio φl is maintained at the third equivalence ratio.

[0126] At this time, the oxygen concentration in the circulation gas circulated to the combustor 10 decreases from the oxygen concentration in the circulation gas at time t4. Then, the oxygen concentration in the circulation gas at time t5 becomes "0" wt%. In other words, at time t5, the circulation gas does not contain oxygen. Also, at time t5, the total equivalence ratio φt becomes the third equivalence ratio (1.0), which is the same as the local equivalence ratio φl.

[0127] The turbine load begins to be removed at time t4, and the turbine is at its rated load at time t5.

[0128] After time t4 (time t4 or later), control based on the load adjustment operation is executed. The fuel-oxidizer flow rate determination unit 132 determines the fuel flow rate and the oxidizer flow rate to be supplied to the combustor 10 based on the load request signal and the turbine load operation data in order to increase the fuel flow rate and the oxidizer flow rate during the load adjustment operation while maintaining the local equivalence ratio φl at the third equivalence ratio.

[0129] Then, the fuel-oxidizer flow rate determining unit 132 outputs to the output unit 140 a signal for supplying the oxidizer and fuel at predetermined flow rates to the fuel-oxidizer supply unit 30 of the combustor 10 .

[0130] The output unit 140 outputs the signal from the fuel-oxidizer flow rate determination unit 132 to the flow rate control valve 52 and the flow rate control valve 42. As a result, the openings of the flow rate control valve 52 and the flow rate control valve 42 are adjusted, and predetermined flow rates of fuel and oxidizer are supplied into the combustor liner 20 via the fuel-oxidizer supply unit 30.

[0131] (Basis for the ranges of oxygen concentration, first equivalence ratio and second equivalence ratio of mixed gas) Here, the reasons for setting the oxygen concentration, the first equivalence ratio, and the second equivalence ratio of the mixed gas within the above-mentioned ranges will be explained.

[0132] Fig. 6 is a diagram for explaining a flame stabilization range at the initial stage of turbine startup operation of the combustor 10 according to the embodiment. Fig. 7 is a diagram for explaining a stable combustion region in the combustor 10 according to the embodiment.

[0133] In Fig. 6, the horizontal axis represents the oxygen concentration (wt%) in the circulating gas, and the vertical axis represents the local equivalence ratio φl. In Fig. 6, the solid line represents the flame stabilization range from time t1 to time t3, which is the initial stage of turbine startup operation, and the dashed line represents the flame stabilization range in the stable combustion region.

[0134] Figure 6 also shows the relationship between the oxygen concentration in the circulating gas and the local equivalence ratio φl from time t1 to time t3, which is the initial stage of turbine startup operation. At time t1 in Figure 6, the oxygen concentration in the mixed gas is 15 wt%, and the local equivalence ratio φl is 0.9. At times t2 and t3 in Figure 6, the oxygen concentration in the mixed gas is 15 wt%, and the local equivalence ratio φl is 0.35.

[0135] Here, the flame-holding range is the range in which a flame can be maintained in the combustor 10. The flame-holding range is between the two solid lines and the two dashed lines.

[0136] In Figure 7, the horizontal axis represents the time from ignition (time t1) to the rated turbine load (time t5), and the vertical axis represents the turbulent burning velocity ratio. In Figure 7, the turbulent burning velocity ratio from ignition (time t1) to the rated turbine load (time t5) is shown by a solid line. Also, in Figure 7, the stable combustion region is shown by a diagonal line.

[0137] Here, the turbulent burning velocity ratio indicates the ratio of the turbulent burning velocity in the combustor liner 20 at each time, assuming that the turbulent burning velocity in the combustor liner 20 at the time of ignition (time t1) is 1. The turbulent burning velocity was obtained by numerical analysis.

[0138] The flame-holding range shown in Figure 6 and the stable combustion region shown in Figure 7 were obtained based on test results using an actual engine.

[0139] As shown in Figure 6, the flame-holding range at the beginning of turbine startup operation is narrower than that in the stable combustion region. Also, the flame-holding range for the local equivalence ratio φl at the beginning of turbine startup operation is narrower as the oxygen concentration in the circulating gas increases. Add It becomes wider as it grows.

[0140] When the oxygen concentration in the circulating gas is in the range of 10 to 15 wt%, the flame-holding range remains even if the local equivalence ratio φl is reduced to the local equivalence ratio φl at times t2 and t3 while maintaining the oxygen concentration in the circulating gas constant.

[0141] Furthermore, by setting the local equivalence ratio φl and the oxygen concentration in the circulating gas from time t1 to time t3 within the aforementioned ranges, the flame can be maintained within the flame-holding range even if each condition fluctuates within a predictable range.

[0142] For these reasons, the oxygen concentration, the first equivalence ratio, and the second equivalence ratio of the mixed gas are set within the above-mentioned ranges.

[0143] 7, the turbulent burning velocity ratio increases rapidly after ignition (after t1) and during the initial stage of turbine startup operation (time t1 to time t3). This increase in the turbulent burning velocity ratio is due to an increase in the turbulent burning velocity accompanying the rise in pressure inside the combustor 10 (inside the combustor liner 20).

[0144] Generally, flame stability improves as the turbulent burning velocity increases. In the combustor 10, a stable combustion region is obtained when the turbulent burning velocity ratio is in the range of 5 or more. In other words, the combustion conditions that result in the stable combustion region satisfy the stable combustion condition of a turbulent burning velocity ratio of 5 or more.

[0145] This stable combustion region is a region where a stable flame can be obtained during turbine startup and load operation, regardless of the oxygen concentration in the circulating gas. For example, in the stable combustion region, a stable flame can be obtained even when the oxygen concentration in the circulating gas is zero.

[0146] Generally, the turbulent burning velocity increases as the pressure inside the combustor increases. In the combustor 10, as shown in FIG. 4, the pressure increases from time t1 to time t5, so the turbulent burning velocity also increases. After time t3 (time t3 or later), stable combustion region This is thought to be because the turbulent combustion velocity exceeds a certain level, making it difficult to extinguish the flame.

[0147] The combustion conditions at the beginning of the turbine startup operation (time t1 to time t3) in the combustor 10 are not within the stable combustion region. However, a stable flame is maintained by setting the combustion conditions at the beginning of the turbine startup operation to the oxygen concentration of the mixed gas, the first equivalence ratio, and the second equivalence ratio described above.

[0148] That is, during the initial stage of turbine startup operation (time t1 to time t3), by maintaining the oxygen concentration in the circulating gas in the range of 10 to 15 wt%, as shown in Figure 4, sufficient oxygen is supplied to the flame, and a stable flame is maintained, even in a range where the turbulent burning velocity ratio is less than 5.

[0149] Furthermore, the combustion conditions from time t3 to time t5 fall within the stable combustion region, so a stable flame is maintained even if the oxygen concentration in the circulating gas is set to less than 10 wt %, or even to zero.

[0150] As described above, according to the operation method of the gas turbine combustor of the embodiment, by including oxygen in the circulation gas during turbine startup operation, oxygen can be supplied not only from the fuel-oxidizer supply unit 30 but also from the circulation gas introduced into the combustion region in the combustor liner 20. This allows a sufficient supply of oxygen to the flame, making it possible to maintain a stable flame.

[0151] Furthermore, during the initial stage of turbine startup operation, when the turbulent combustion velocity is low and the flame becomes unstable, maintaining the oxygen concentration in the circulating gas constant within the range of 10 to 15 wt% ensures that sufficient oxygen is supplied to the flame, preventing it from being extinguished. As a result, a stable flame can be maintained even during the initial stage of turbine startup operation.

[0152] According to the embodiment described above, stable combustion is possible at the initial stage of turbine startup operation.

[0153] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0154] 1...gas turbine equipment, 10...combustor, 15...combustor casing, 20...combustor liner, 21...upstream end wall, 21a...through hole, 22...cooling hole, 23...dilution hole, 30...fuel-oxidizer supply section, 31...fuel supply pipe, 31a, 32a...outlet, 32...oxidizer supply pipe, 33...swirler, 40...fuel supply section, 41, 51, 61...piping, 42, 52...flow control valve, 50...oxidizer supply section, 60...gas circulation system, 6 2...condenser, 63...compressor, 70...turbine, 75...generator, 80...regenerative heat exchanger, 90...transition piece, 100...control device, 110...input section, 120...memory section, 121...turbine startup operation data, 122...turbine load operation data, 130...calculation section, 131...elapsed time determination section, 132...fuel-oxidizer flow rate determination section, 140...output section, φl...local equivalence ratio, φt...total equivalence ratio.

Claims

1. A casing; a combustor liner disposed within the casing for combusting fuel and oxidizer; a fuel supply unit that supplies fuel to the combustor liner; an oxidizer supply unit that supplies an oxidizer to the combustor liner; a control device that controls the flow rate of the fuel supplied from the fuel supply unit and the flow rate of the oxidizer supplied from the oxidizer supply unit; an exhaust gas discharged from the turbine is circulated as circulation gas into the casing through a circulation system connecting an outlet of the turbine and the casing, and the circulation gas is introduced into the combustor liner through a through-hole formed in the combustor liner, Before ignition in the gas turbine combustor, a mixed gas containing a predetermined concentration of oxygen circulates as the circulation gas, During the operation time from the time of ignition in the gas turbine combustor to the time of rated load of the turbine, the time from the time of ignition to the time of reaching a stable combustion condition where stable combustion in which a flame can be maintained is: The control device a flow rate of the fuel supplied from the fuel supply unit and a flow rate of the oxidizer supplied from the oxidizer supply unit are controlled to circulate, as the circulating gas, a combustion gas in which the same oxygen concentration as that of the mixed gas is maintained in order to prevent flame quenching; The control device At a first time when the ignition occurs, burning the fuel at a first equivalence ratio, the first equivalence ratio being a local equivalence ratio calculated from a flow rate of the fuel supplied from the fuel supply unit and a flow rate of the oxidizer supplied from the oxidizer supply unit; From the first time to a later second time, combustion is performed while gradually decreasing the local equivalence ratio from the first equivalence ratio to a second equivalence ratio that is smaller than the first equivalence ratio while increasing a flow rate of the fuel and a flow rate of the oxidizer, and circulating the combustion gas in which the oxygen concentration is maintained the same as the oxygen concentration in the mixed gas as the circulation gas; From the second time until a third time thereafter, when the stable combustion condition is reached, while increasing a flow rate of the fuel and a flow rate of the oxidizer, the fuel and the oxidizer are combusted while maintaining the local equivalence ratio at the second equivalence ratio, and the combustion gas in which the oxygen concentration is maintained the same as the oxygen concentration in the mixed gas is circulated as the circulation gas; From the third time until a later time of rated operation of the turbine, controlling a fuel flow rate and an oxidizer flow rate to increase the local equivalence ratio from the second equivalence ratio; During rated operation of the turbine, A method for operating a gas turbine combustor, comprising: setting the oxygen concentration in the circulating gas, which is combustion gas, to zero.

2. A method for operating a gas turbine combustor as described in claim 1, characterized in that the first equivalence ratio is 0.8 to 0.

9.

3. A method for operating a gas turbine combustor according to claim 1 or 2, characterized in that the second equivalence ratio is 0.35 to 0.

45.

4. A method for operating a gas turbine combustor according to claim 1, wherein the oxygen concentration in the mixed gas is 10 to 15 wt %.

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