JP3820772B2 - gas turbine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas turbine in which a plurality of can-type combustors are provided for one gas turbine, and the combustors are connected by a flame propagation tube.
[0002]
[Prior art]
In a gas turbine facility in which a plurality of can-type combustors are provided for one gas turbine, the combustors are usually arranged in an annular shape around the gas turbine. Adjacent combustors are connected to each other by a flame propagation tube, and an ignition device is installed in one or several of the combustors. When starting the gas turbine, when the combustor is ignited by activating the ignition device, the pressure becomes higher than the unignited adjacent combustor can by the combustion gas. It can flow into the can and eventually ignite the entire combustor can.
[0003]
The flame propagation tube is a component necessary for reliably performing the above-described operation, and conventional techniques related to this are disclosed in JP-A-57-142423, JP-A-62-200112, and JP-A-3. -158619.
[0004]
[Problems to be solved by the invention]
The flame propagation tube allows the flame to pass through the tube due to a pressure difference generated between adjacent combustors when the combustor is ignited. Thus, once all combustor cans have ignited, there should be no pressure differential and no flow through the flame propagation tube. However, in practice, there is a variation in the air flow rate and the fuel flow rate pressure for each combustor can, and thus there may be a pressure difference between adjacent combustors. In such a case, the flame propagation tube is adapted to allow the cooling air to flow appropriately so that the high-temperature combustion gas does not pass through the flame propagation tube and cause damage.
[0005]
Generally, the air leaving the compressor is distributed to a plurality of combustors, and the combustors are manufactured and managed so that their pressure loss falls within a certain range, so that the air flowing into each combustor The inlet pressure is almost uniform. Therefore, on average, the combustion air flow rate of each combustor can is substantially the same. However, the pressure distribution at the compressor outlet is not always constant in time, and may change suddenly. For example, when a time zone in which the combustion temperature differs for each combustor due to a change in the calorific value of the fuel, the pressure in the combustor changes, and the pressure distribution of air flowing into the combustor also changes. Further, when the separation vortex is released from the structure in the air flow path to the combustor, the time distribution of the pressure distribution may locally occur due to the flow disturbance. In a gas turbine in which a combustor is connected by a flame propagation tube whose periphery is covered with an outer cylinder, when the pressure difference occurs in the outer cylinder portion of an adjacent combustor can due to such a cause, the outer cylinder Since the gap between the inner wall and the outer wall of the flame propagation tube becomes a flow path, air flows through the gap. As a result, on average, even if the flow rate of air flowing into each combustor can is uniform, the gap between the outer wall of the flame propagation tube and the inner wall of the outer cylinder covering it before reaching the actual combustion field. Due to the movement of the combustion air, a local air imbalance occurs in the combustion field for each combustor can.
[0006]
In recent years, in order to reduce nitrogen oxide (NOx) in exhaust gas, a premix burner is frequently used in a combustor, and a premix combustion ratio is increasing year by year. However, premixed combustion has a narrower range of fuel-air ratio (ratio of fuel flow rate to air flow rate) that allows stable combustion than diffusion combustion, and tends to cause flame blowout and combustion vibration. Therefore, the fuel-air ratio management of the premixed burner is performed finely, but as described above, air flows to the adjacent combustor can through the gap between the inner wall of the flame propagation tube outer wall and the outer wall of the flame propagation tube. In some cases, the fuel-air ratio at the combustion field deviates from the set value and enters the unstable combustion range. In particular, when the flame propagation tube is connected to the combustion chamber of the premixing burner, the air inflow portion of the premixing burner is inevitably located downstream from the outside of the flame propagation tube. Locally affects the fuel-air ratio of the premix burner.
[0007]
An object of the present invention is to provide a gas turbine capable of maintaining the fuel-air ratio of a combustor can within a predetermined stable combustion range.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is provided with a plurality of can-type combustors, and in the gas turbine in which the combustors are connected by a flame propagation tube, the flame propagation tube and the flame propagation tube that the flow reduction means comprising a cylindrical block or ring-shaped partition plate to reduce the flow rate of fluid between can flow the gap between the outer tube covering the outer periphery of which is characterized in that disposed on the inner peripheral wall of the outer cylinder It is.
[0009]
In order to achieve the above object, the present invention is provided with a plurality of can-type combustors having a premix burner, and the flame propagation in the gas turbine in which the combustors are connected by a flame propagation tube. arranged a tube, a flow reduction means comprising a cylindrical block or ring-shaped partition plate to reduce the flow rate of fluid between can flow the gap between the outer tube covering the outer periphery of the flame propagation pipe to the inner wall of the outer cylinder it is characterized in that the.
[0010]
Further, the gas turbine is characterized in that a cylindrical block provided with a plurality of grooves serving as resistance to fluid flow is used as the flow rate reducing means.
[0011]
Further, in the gas turbine, as the flow rate reducing means, a partition plate that is movable in a direction perpendicular to the fluid flow path formed by the gap and that serves as a fluid flow resistance is used. And
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of a gas turbine according to the present invention. A can-type combustor 1a constituting a gas turbine includes a diffusion burner 7 having a fuel nozzle 3 for injecting a fuel 10 for diffusion combustion into an inner cylinder 19 constituting a combustion chamber 2, and a fuel 11 for premixed combustion. Is provided with a premix burner 8 having a fuel nozzle 5 for injecting the fuel into the premixer 4.
[0013]
Combustion air 12 is supplied to a combustor 1 a from a compressor (not shown) through a flow path 32 formed between an inner cylinder 19 of the combustion chamber 2 and an outer cylinder 21 covering the outer periphery of the inner cylinder 19. The In the diffusion burner 7, the combustion air 12 and the fuel 10 supplied from the fuel nozzle 3 form a circulation vortex of combustion gas in the combustion chamber 2 of the inner cylinder 19 by the swirler 6 to form a stable diffusion flame. On the other hand, the combustion air 12 flowing into the premixer 4 is mixed with the fuel injected from the fuel nozzle 5 by the swirler 9 and injected into the combustion chamber 2 of the inner cylinder 19 to burn. A flame propagation pipe 20 connected to the adjacent combustor 1b is disposed on the wall surface of the combustion chamber 2 located on the downstream side of the premixing burner 8. The flame propagation tube 20 is covered with an outer cylinder 21 a that is a part of the outer cylinder 21. A flow path 22 is formed between the outer wall of the flame propagation tube 20 and the outer cylinder 21, and a flow rate reducing means 30 to be specifically described later is disposed in the flow path 22.
[0014]
As shown in FIG. 2, in the can-type combustors 1a to 1n according to the present embodiment, for example, 14 cans are disposed around one gas turbine (not shown), and flame propagation tubes 20a to 20n (see FIG. 2). (Not shown) and outer cylinders 21a to 21n covering the flame propagation tubes 20a to 20n. When the gas turbine is started, for example, when a spark plug 13 provided in the combustors 1m and 1n is operated to form a flame in the combustion chamber 2 of the combustor shown in FIG. Therefore, the combustion gas flows through the inside of the flame propagation tube 20 to the adjacent can 1a or 1l and ignites the adjacent combustor cans 1b to 1k one after another. Thus, when the ignition of all the combustors 1a to 1n is completed, the pressure difference between the combustors becomes small, so that the combustion gas passing through the inside of the flame propagation tube 20 is substantially eliminated.
[0015]
On the other hand, as described with reference to FIG. 1, the flow path 22 is formed in the gap between the outer wall of the flame propagation tube 20 and the inner wall of the outer cylinder 21a covering the outer wall. For this reason, even if the flow rate of air supplied from the compressor to the combustor is uniform in each of the combustor cans 1a to 1n, the inner cylinder 19 and the outer cylinder 21 of the combustion chamber 2 may be caused by a cause such as flow disturbance. When a difference in pressure distribution occurs in the circumferential direction in the outer flow path 32, the combustion air flows in the flow path 22 communicating with the flow path 32. As a result, the amount of air finally flowing into each combustor locally unbalances. When the premix burner 8 is arranged on the inner wall side in the inner cylinder 19 constituting the combustion chamber 2 as in the present embodiment, the local unbalance of the air flow rate generated in the flame propagation tube 20 is Since the flow rate of air flowing into the premix burner 8 is affected, if the air flow unbalance increases, the fuel / air ratio of the premix burner 8 may fall outside the set stable combustion range and enter an unstable combustion region. There is. Therefore, in this embodiment, means 30 that can reduce the flow rate of air flowing in the flow path 22 even if a circumferential pressure distribution is generated in the flow path 32 outside the combustion chamber 2 is disposed.
[0016]
FIG. 3 shows a specific embodiment of the flow rate reducing means 30 shown in FIG. In the present embodiment, a cylinder provided with a plurality of annular grooves 41 inside an annular outer cylinder 21a covering the outer periphery of a flame propagation tube 20 connecting the inner cylinders 19 constituting the combustion chamber 2 of the adjacent combustor can. A block 40 is arranged. Here, the distance d between the inner peripheral wall of the block 40 installed in the flow path 22 and the outer wall of the flame propagation pipe 20 is set to 1 to 5 mm. By providing a plurality of annular grooves 41 on the inner wall side of the block 40, when the combustion air flows into the flow path 22 and a flow along the inner peripheral wall of the block 40 is generated, a vortex is generated in the groove 41 to provide fluid resistance. Compared with the case where the groove 41 is not provided, the flow rate of air flowing with respect to the same gap d distance and the differential pressure between the combustors can be reduced. Accordingly, since the distance d of the gap d can be set relatively large, it is possible to minimize a decrease in workability when assembling the flame propagation tube 20 by providing the block 40. Further, during operation of the gas turbine, it is possible to avoid the possibility that the block 40 comes into contact with the flame propagation tube 20 due to thermal expansion or vibration and is worn or damaged in some cases.
[0017]
In this embodiment, the block 40 provided with the groove 41 is arranged on the inner peripheral wall of the outer cylinder 21a. However, it is obvious that the same effect can be obtained even if the block 40 is arranged on the outer peripheral wall of the flame propagation pipe 20. It is.
[0018]
According to the present embodiment, the means for reducing the air flow rate that can flow in the flow path between the flame propagation tube 20 and the outer cylinder 21a covering the flame propagation tube 20 does not deteriorate the workability when assembling the flame propagation tube. Also, damage to the components such as the flame propagation tube can be avoided by thermal elongation and vibration during operation of the gas turbine. Therefore, a different pressure distribution is generated in the combustor inflow air flow path for each can of the gas turbine combustor, and even if a differential pressure is generated between the outer cylinders 21a covering the flame propagation tube 20, the air flow rate of each can is kept uniform. Therefore, there is an effect that the fuel-air ratio of each can can be managed to the set value of the stable combustion range.
[0019]
FIG. 4 shows another specific example of the flow path reducing means 30. In the present embodiment, the position of the flow path 22 formed between the outer wall of the flame propagation tube 20 and the inner wall of the outer cylinder 21a covering the flame propagation pipe 20 can be moved in a direction perpendicular to the flow path 22. A partition plate 50 serving as resistance to the flow of air flowing through is disposed. A support plate 51 is arranged on the inner wall of the outer cylinder 21a so as to hold the partition plate 50 in order to hold the movable partition plate 50. Here, as shown in FIGS. 5 and 6, a hole 52 through which the flame propagation tube 20 can be passed is formed in the center side of the partition plate 50, and the flame propagation tube 20 is formed in the combustion chamber 2 of the combustor. When arranged, the hole 52 is closed by the outer wall of the flame propagation tube 20, and the flow path 22 can be substantially closed. Further, since the partition plate 50 can move in a direction perpendicular to the flow path 22, the flame propagation tube 20 can be easily inserted into the hole 52 of the partition plate 50 when the flame propagation tube 20 is assembled. Can be made, and assembly workability is not deteriorated. Further, even if there is thermal elongation or vibration during the operation of the gas turbine, it is possible to avoid applying excessive stress to these components. The partition plate 50 may be a divided partition plate that is divided in the circumferential direction and has a ring shape as a whole.
[0020]
In the present embodiment, the flow rate of air flowing through the flow path 22 can be more reliably reduced by making the gap between the support plate 50 and the flame propagation tube 20 as small as possible. However, if it is too small, the contact surface may be worn, and the partition plate 50 contacts either the upper or lower support plate 51 due to a pressure difference or gravity, so that the gap need not be excessively reduced. This part is substantially closed. Therefore, the gap is desirably set to 0.5 to 3 mm. It is also desirable to provide a wear resistant coating on the contact surface.
[0021]
According to this embodiment, the workability of the assembly of the flame propagation tube is not deteriorated, and stress generation of components due to thermal elongation and vibration during gas turbine operation is avoided, and the outer wall of the flame propagation tube and The gap with the inner wall of the outer cylinder to be covered can be substantially closed, and the flow rate of air flowing through the gap can be reduced.
[0022]
【The invention's effect】
According to the present invention, a gas turbine capable of reducing the flow rate of air flowing through a gap between a flame propagation tube and an outer cylinder covering the flame propagation tube and maintaining the fuel-air ratio of each combustor can within a predetermined stable combustion range can be realized. The effect is achieved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a combustor disposed in a gas turbine according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of a plurality of combustor cans arranged in a gas turbine according to the present invention.
FIG. 3 is a cross-sectional view of a flame propagation tube portion that is an embodiment of the present invention.
FIG. 4 is a cross-sectional view of a flame propagation tube portion that is another embodiment of the present invention.
FIG. 5 is a three-dimensional view of a flame propagation tube portion shown in FIG. 4;
6 is a cross-sectional view of the partition plate shown in FIG.
[Explanation of symbols]
1a to 1n: combustor, 2 ... combustion chamber, 3 ... diffusion fuel nozzle, 4 ... premixer, 5 ... premix fuel nozzle, 6 ... swirler, 7 ... diffusion burner, 8 ... premix burner, 9 ... swirl , 10, 11 ... fuel, 12 ... air, 13 ... spark plug, 19 ... inner cylinder, 20 ... flame propagation pipe, 21, 21a ... outer cylinder, 22, 32 ... flow path, 30 ... air flow reduction means, 40 ... Block, 41 ... Groove, 50 ... Partition plate, 51 ... Support plate, 52 ... Hole, d ... Gap.

Claims (4)

A plurality of can-type combustor is provided, in a gas turbine wherein the combustor is connected by cross-fire tube, and the fire tube, between gap the outer tube covering the outer periphery of the flame propagation pipe A gas turbine characterized in that a flow rate reducing means comprising a cylindrical block or ring-shaped partition plate for reducing the flow rate of a fluid that can flow is disposed on an inner peripheral wall of the outer cylinder . In a gas turbine provided with a plurality of can-type combustors having a premix burner, and the combustors are connected by a flame propagation tube, the outer tube that covers the flame propagation tube and the outer periphery of the flame propagation tube gas turbine characterized in that arranged on the inner peripheral wall of the outer cylinder of the flow reduction means comprising a cylindrical block or ring-shaped partition plate to reduce the flow rate of fluid between can flow the gap between. In the gas turbine according to claim 1 or 2, wherein the flow rate of reduction means, in the gas turbine characterized by using a plurality of cylindrical blocks having a groove serving as the fluid flow resistance. In the gas turbine according to claim 1 or 2, as the flow rate reducing means, the partition plate is its position in the perpendicular direction becomes resistive flow of a fluid movable relative fluid flow path the gap is formed A gas turbine that is used.

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