JPH09210364A - Premixing combuster for gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent a back fire by providing an air inlet communicating a high pressure air passage with an annular channel, a valve for switching the inlet, and a valve driver for driving the valve, and controlling so as to open the inlet at the time of the back fire by sensing the back fire. SOLUTION: The premixing combustor for a gas turbine comprises a combustion chamber 2, a premixing chamber 1 for supplying mixed gas to the chamber 2, and a passage 16 for introducing pressurized air to the chamber 1. The chamber 1 communicates with the passage 16 via a swirler 15 and communicates with the chamber 2 via an annular channel 5. The channel 5 is formed between a baffle plate 6 and a partition wall 20. The combustor also comprises a valve for switching respective air inlets 22 and a valve driver 29 for rotating a rotary valve 23 with respect to the wall 20. A control unit 30 for controlling the driver 29 controls to open the inlets 22 via the valve 23 based on the detection signal of a back fire sensor 19 opposed to an annular nozzle 8 when the back fire is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a gas turbine premix combustor.

[0002]

2. Description of the Related Art There is known a gas turbine combustor provided with a premixing chamber in order to obtain a uniform mixture (see Japanese Patent Application Laid-Open No. 60-117008).

Explaining this, as shown in FIG. 8, a cylindrical combustion chamber 2 is formed on the inner circumference of a casing 4 via a heat insulating member 3, and an air-fuel mixture is supplied to this combustion chamber 2. A cylindrical premixing chamber 1 and a high-pressure air passage 16 for introducing pressurized air from a heat exchanger (not shown) or a compressor to the premixing chamber 1 are formed.

The pressurized air flowing into the premixing chamber 1 from the high-pressure air passage 16 is swirled by the swirler 15 and then mixed with the fuel injected from the main fuel injection valve 10. The premixing chamber 1 is disposed substantially parallel to the cylindrical combustion chamber 2, and the premixing chamber 1 communicates with the upstream of the combustion chamber 2 via an annular flow path 5.

The annular flow path 5 is defined at the base end of the combustion chamber 2 through a baffle plate 6 having a hole 6A. At the base end of the combustion chamber 2, a cylindrical flame stabilizer 7 having an auxiliary fuel injection valve 9 housed therein is disposed substantially coaxially with the combustion chamber 2, and an end portion 7A is formed on the baffle plate 6. 6A.

The flame stabilizer 7 is supported by the casing 4 via a guide 17 so as to be displaceable in the axial direction, and the end 7A is driven by a driving means (not shown) in a direction in which the end 7A moves toward and away from the combustion chamber 2. You.

The outer wall of the flame stabilizer 7 and the hole 6A of the baffle plate 6
And an annular nozzle 8 is defined. This annular nozzle 8
A taper portion 70 that spreads in a taper shape is formed on the outer periphery of the end portion 7A of the flame stabilizer 7 that faces the cross section area of the annular nozzle 8, that is, combustion, depending on the axial position of the flame stabilizer 7. The flow passage cross-sectional area of the air-fuel mixture flowing into the chamber 2 is changed according to the engine load, and the air distribution ratio of the air-fuel mixture blown out from the annular flow passage 5 to the combustion chamber 2 is changed.

The air-fuel mixture from the premixing chamber 1 is introduced into the combustion chamber 2 from an annular nozzle 8 between the flame stabilizer 7 and the baffle plate 6. The annular flow path 5 is formed in a spiral shape around the axis of the combustion chamber 2. The air-fuel mixture passing through the annular flow path 5 forms a swirling flow along the inner wall of the combustion chamber 2 around the flame stabilizer 7, and the flame in the combustion chamber 2 has a cone shape starting from the end 7 A of the flame stabilizer 7. Forms a flame.

Further, after the temperature of the combustion gas is lowered by the air flowing from the dilution port 12 opened to the dilution cylinder 13, the combustion gas flows into a turbine (not shown) through a scroll inlet 14.

As a combustor of such a gas turbine,
In addition to the above, ASME PAPER78-GT-155
(Issued April 9, 1978) is known.

[0011]

However, when the concentration of the air-fuel mixture introduced from the annular nozzle 8 into the combustion chamber 2 is high, a flashback phenomenon occurs in which the flame of the combustion chamber 2 flows back to the upstream side depending on the operating conditions. there's a possibility that. When this flashback phenomenon occurs, the passage member on the upstream side of the combustion chamber 2 is exposed to the flame. Therefore, the members defining the annular flow path 5 and the premix chamber 1 are also required to have high heat resistance.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a premixed combustor for a gas turbine capable of preventing a flashback phenomenon.

[0013]

A premixed combustor for a gas turbine according to a first aspect of the present invention comprises a high pressure air passage for introducing pressurized air, pressurized air from the high pressure air passage, and injection from a main fuel injection valve. Premixing chamber for mixing the fuel to be mixed, an annular flow passage for introducing the air-fuel mixture from the premixing chamber into the combustion chamber, a partition wall for partitioning the high pressure air passage and the annular flow passage, and a high pressure air passage opening to the partition wall. And an air inlet communicating with the annular flow path, an on-off valve that opens and closes the air inlet, a valve drive device that drives the on-off valve, and a flashback detection means that detects the occurrence of a flashback phenomenon,
Control means for opening the air inlet when a flashback phenomenon occurs.

A premixed combustor for a gas turbine according to a second aspect of the present invention is the premixed combustor according to the first aspect of the present invention, which is provided with a thermocouple facing an annular flow path as the flashback detection means.

A premixed combustor for a gas turbine according to a third aspect of the present invention is the premixed combustor for a gas turbine according to the first or second aspect, wherein the opening / closing valve includes a rotary valve that rotates in the circumferential direction of the annular flow passage.

According to a fourth aspect of the present invention, there is provided a premixed combustor for a gas turbine according to the first or second aspect of the present invention, which comprises a slide valve that moves in the axial direction of the annular flow path as the opening / closing valve.

[0017]

In the premix combustor of the gas turbine according to the first aspect, the pressurized air from the high-pressure air passage is mixed with the fuel injected from the main fuel injection valve in the premix chamber to form an air-fuel mixture. This air-fuel mixture is introduced into the combustion chamber through the annular flow path.

When a flashback phenomenon occurs in which the flame of the combustion chamber flows back to the upstream side due to operating conditions, the air inlet is opened by the opening / closing valve, so that part of the air introduced into the high pressure air passage is discharged from the air inlet. The concentration of the air-fuel mixture flowing into the annular flow passage through the annular passage and introduced into the combustion chamber from the annular flow passage is reduced, and the flame of the combustion chamber is prevented from flowing backward to the upstream side. By preventing the flashback phenomenon in this way,
It is possible to prevent thermal damage to the passage member that defines the annular passage or the premixing chamber upstream of the combustion chamber.

When the flashback phenomenon is subsided in this manner, the air inlet is closed by the opening / closing valve, and the air introduced from the air inlet to the annular passage is shut off so that the air-fuel mixture introduced from the annular passage into the combustion chamber is By making the concentration appropriate, the air distribution ratio in the combustion chamber is returned to the desired value, and the combustibility is maintained.

In the premixed combustor for a gas turbine according to claim 2, it is determined that a flashback phenomenon has occurred when the temperature rising rate detected by the thermocouple exceeds a predetermined value, and the thermocouple is detected. It can be determined that the flashback phenomenon has been eliminated when the temperature detected by the temperature is lower than a predetermined value.

By constructing the flashback phenomenon detecting means with a thermocouple, sufficient heat resistance is ensured, the degree of freedom in installation is wide, and the cost of the product can be reduced.

In the premixed combustor for a gas turbine according to a third aspect of the present invention, the opening area of the air inlet is 0 to 1 due to the structure of rotating the rotary valve to open and close the air inlet.
It is possible to finely control the air-fuel ratio of the air-fuel mixture introduced into the combustion chamber from the annular flow path by adjusting it between 00%.

In the premixed combustor for a gas turbine according to claim 4, the structure in which the slide valve is moved in the axial direction to quickly open and close the air introduction port enhances the control response of the air-fuel ratio in the annular passage. To be

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, the gas turbine includes a cylindrical combustion chamber 2 inside a casing 4 with a heat insulating member 3 interposed therebetween.
A cylindrical premixing chamber 1 for supplying air-fuel mixture to the combustion chamber 2 and a high-pressure air passage 16 for introducing pressurized air from a heat exchanger (not shown) to the premixing chamber 1 are formed.

The spark plug 1 is provided at a predetermined position facing the combustion chamber 2.
1 is provided. A plurality of dilution ports 1 are provided downstream of the combustion chamber 2.
The dilution cylinder 13 provided with 2 is fitted. The dilution port 12 communicates with the high-pressure air passage 16 to introduce pressurized air for dilution. The dilution cylinder 13 communicates with a turbine (not shown) via a scroll inlet 14 connected downstream.

The premixing chamber 1 is a swirler 1 arranged on the upstream side.
5 and a main fuel injection valve 10 inside.

The auxiliary fuel injection valve 9 increases the amount of fuel when the load is high, and is selectively driven by fuel supply means (not shown).

At the base end side of the combustion chamber 2, a cylindrical flame stabilizer 7 accommodating an auxiliary fuel injection valve 9 is arranged substantially coaxially with the combustion chamber 2. An end portion 7A of the flame stabilizer 7 on the combustion chamber 2 side is inserted into a hole portion 6A formed in the baffle plate 6.

Between the flame stabilizer 7 and the hole 6A of the baffle plate 6, an annular nozzle 8 having a predetermined gap according to the axial position of the flame stabilizer 7 is formed.

The flame stabilizer 7 is supported by a casing 4 via a guide 17 so as to be displaceable in the axial direction. The outer wall of the flame stabilizer 7 is in sliding contact with the partition wall 20 that defines the annular flow path 5 via the seal 18.

The flame stabilizer 7 is axially driven by a driving means (not shown). The flame stabilizer 7 performs relative displacement with respect to the hole 6A by displacement in the axial direction toward the combustion chamber 2.

The drive means expands and contracts the flame stabilizer 7 according to the engine load. As will be described later, the flame stabilizer 7 is driven to the most contracted position when the load is low, while it is driven when the load is high. The flame stabilizer 7 is driven to the most extended position.

The premix chamber 1 is connected to the combustion chamber 2 via the annular flow path 5.
Communicate with The annular flow path 5 is formed in an annular shape about the axis of the combustion chamber 2, and is configured to swirl the air-fuel mixture flowing into the combustion chamber 2. The annular flow path 5 is coaxial with the combustion chamber 2 and has a hole 6 </ b> A formed through the baffle plate 6 so as to penetrate the combustion chamber 2.
Communicate with

The annular flow path 5 is defined between the baffle plate 6 and the partition wall 20 at the base end of the combustion chamber 2. The annular flow path 5 and the high pressure air passage 16 are partitioned by a partition wall 20.

As shown in FIG. 2, the partition wall 20 has four air inlets 22 which connect the annular flow path 5 and the high-pressure air passage 16 to each other.
Is opened. Each air inlet 22 faces the annular nozzle 8 across the annular passage 5.

Each air inlet 22 is formed by a circular hole opened in the partition wall 20. The air inlets 22 are arranged at regular intervals in the circumferential direction.

The total opening area A ₂₂ of each of the air inlets 22, with respect to the cross-sectional area A ₁ of the premix chamber 1 is set in the range of 0.2 to 2 times. That is set to the relationship _{A 1/5 ≦ A 22 ≦} 2A 1.

The number of the air introduction ports 22 is not limited to four, and a plurality of air introduction ports 22 may be set according to the amount of introduced air (range satisfying the above relationship).

As an opening / closing valve for opening / closing each air inlet 22, a cylindrical rotary valve 23 is provided around the outer circumference of the flame stabilizer 7.
Is rotatably interposed.

The rotary valve 23 has a partition wall 2 at its end.
It has a valve body 25 that extends in a disk shape along the direction 0. Valve body 25
There are four air introduction valve ports 24 that are superposed on each air introduction port 22. The air introduction port 22 and each air introduction valve port 24 are arranged so that their opening positions have the same phase in the circumferential direction of the flame stabilizer 7.

The valve body 25 of the rotary valve 23 is a partition wall 20.
Slidably joined to. Lubricant is sprayed onto the surfaces of the valve body 25 and the partition wall 20 that are to be joined to each other, so that they can slide smoothly.

A valve drive device 29 for rotating the rotary valve 23 with respect to the partition wall 20 is provided. The valve drive device 29 includes a hydraulic cylinder (not shown), a potentiometer for position detection, and the like.

The control unit 30 for controlling the valve drive device 29 includes a flashback sensor 19 facing the annular nozzle 8.
Based on the detection signal of 1, the control is performed to open each air introduction port 22 via the rotary valve 23 when the occurrence of the flashback phenomenon is detected.

The flashback sensor 19 is provided so as to penetrate the casing 4, the heat insulating member 3 and the baffle plate 6, and the detection portion thereof is provided so as to face the annular nozzle 8 from the hole 6A.

The flashback sensor 19 has a detection part composed of a thermocouple and outputs a signal corresponding to the temperature to the fluid flowing through the annular nozzle 8. The detection part of the flashback sensor 19 is the hole 6
It is provided by retracting a predetermined amount within a range of 0.5 mm or less from the inner peripheral surface of A.

The flashback sensor 19 may detect the occurrence of flashback phenomenon from the reflectance by using an acura fiber in which a metal is welded to the tip of a sapphire glass rod instead of the thermocouple.

By constructing the flashback sensor 19 with a thermocouple, sufficient heat resistance can be ensured against a flashback rising to about 1500 ° C., and it can be installed as compared with the case where it is constructed with Acura fiber. The degree of freedom above is wide and the cost of the product can be reduced.

As shown in the timing chart of FIG. 4, the control unit 30 determines that the flashback phenomenon has occurred when the temperature rising rate detected by the flashback sensor 19 exceeds a predetermined value. , Rotary valve 23
Is driven to the position shown in FIG. 2 in which each air inlet 22 is fully opened. On the other hand, when the temperature detected by the flashback sensor 19 falls below a predetermined value, it is determined that the flashback phenomenon has been resolved, the rotary valve 23 is rotated by 45 °, and each air inlet 22 is fully closed. Control to switch to the position shown in FIG. 3 is performed.

With the above construction, the operation will be described below.

A part of the pressurized air sent from a heat exchanger (not shown) is introduced from the high-pressure air passage 16 through the swirler 15 into the premixing chamber 1, where the fuel injected from the main fuel injection valve 10 The mixture is mixed into an air-fuel mixture, and the air-fuel mixture becomes a swirl flow centered on the flame stabilizer 7 by being guided through the annular flow path 5, and an annular portion between the hole 6A of the baffle plate 6 and the flame stabilizer 7 is formed. It is introduced while swirling from the nozzle 8 to the combustion chamber 2.

The air-fuel mixture thus introduced into the combustion chamber 2 burns in the combustion chamber 2 while being further mixed with the fuel injected from the auxiliary fuel injection valve 9 under high load, and the dilution port 12 opened in the dilution cylinder 13 After the combustion gas temperature is lowered by the air flowing in from the above, it flows into the turbine (not shown) through the scroll inlet 14 to drive the compressor and the load.

Here, the flow passage cross-sectional area of the annular nozzle 8 is changed according to the load of the turbine, and at the time of medium and high load, the driving means (not shown) extends the flame stabilizer 7 toward the combustion chamber 2 and the flame stabilizer is expanded. A predetermined gap is formed between 7 and the hole 6A to increase the flow passage cross-sectional area of the annular nozzle 8. On the other hand, when the load is low, the driving means contracts and drives the flame stabilizer 7 to reduce the gap between the flame stabilizer 7 and the hole 6A.

When the flow rate of the air-fuel mixture passing through the annular nozzle 8 is sufficient and the load is high, the air-fuel mixture introduced from the premixing chamber 1 passes through the annular flow passage 5 and becomes a swirl flow to form the annular nozzle 8 Is introduced into the combustion chamber 2 and burns.

By the way, when the concentration of the air-fuel mixture introduced from the annular nozzle 8 into the combustion chamber 2 is high, there is a possibility that the flame in the combustion chamber 2 may flow back to the upstream side depending on the operating conditions.

To cope with this, in the present invention, as shown in the timing chart of FIG. 4, when the rate of temperature rise detected by the flashback sensor 19 exceeds a predetermined value, the control unit 30 causes the flashback phenomenon. Is determined to have occurred, the rotary valve 23 is switched to the position shown in FIG. 2 in which each air inlet 22 is fully opened.

By thus opening each air inlet 22 by the rotary valve 23, the high pressure air passage 1
A part of the air introduced to 6 flows into the annular nozzle 8 from the air introduction port 22 through the annular passage 5 to reduce the concentration of the air-fuel mixture introduced from the annular nozzle 8 into the combustion chamber 2, It is possible to prevent a flashback phenomenon in which the flame flows backward to the upstream side. By preventing the occurrence of a flashback phenomenon, the combustion chamber 2
It is possible to avoid giving thermal damage to the more upstream annular passage 5 or the passage member that defines the premixing chamber 1 or the like.

In this way, when each air inlet port 22 is opened by the rotary valve 23, and when the temperature detected by the flashback sensor 19 falls below a predetermined value, the rotary valve 23 fully closes each air-fuel mixture inlet port 21. Figure 3
It is switched to the position shown in.

By closing each air inlet 22 by the rotary valve 23 in this manner, the air inlet 2
The air introduced from 2 to the annular passage 5 is shut off, the concentration of the air-fuel mixture introduced from the annular nozzle 8 into the combustion chamber 2 is optimized, and the air distribution ratio in the combustion chamber 2 is returned to the desired value, and combustion is performed. Sex is maintained.

With the structure in which the rotary valve 23 is rotated to open and close each air inlet 22, the opening area of each air inlet 22 is adjusted between 0 and 100%, and the air is introduced into the combustion chamber 2 from the annular nozzle 8. It is also possible to finely control the air-fuel ratio of the generated air-fuel mixture.

Next, the embodiment shown in FIG. 5 will be described. The parts corresponding to those in FIG. 1 are designated by the same reference numerals.

In this embodiment, a cylindrical slide valve 33 is provided on the outer periphery of the flame stabilizer 7 as an opening / closing valve for opening / closing each air inlet 22 so as to be slidable in the axial direction.

The slide valve 33 has a partition wall 2 at its end.
It has a disc element 35 that extends in a disk shape along 0.

A sealing material 36 is provided around each air inlet 22 of the partition wall 20. The partition wall 20 seats the valve element 35 of the slide valve 33 via the sealing material 36 to ensure the hermeticity.

A valve driving device 39 for moving the slide valve 33 with respect to the partition wall 20 is provided. The control unit 30 that controls the valve drive device 39 separates the slide valve 33 from the partition wall 20 when the occurrence of the flashback phenomenon is detected based on the detection signal of the flashback sensor 19 facing the annular nozzle 8 and introduces each air. When the opening 22 is fully opened and it is detected that the flashback phenomenon has been resolved, the slide valve 33 is joined to the partition wall 20 through a sealing material, and control is performed to switch to a position where each air inlet 22 is fully closed. .

In this embodiment, the control response of the air-fuel ratio in the annular nozzle 8 is enhanced by the structure in which the slide valve 33 is moved in the axial direction to quickly open and close each air introduction port 22.

[0067]

As described above, in the premixed combustor for a gas turbine according to claim 1, when a flashback phenomenon occurs in which the flame in the combustion chamber flows back to the upstream side due to operating conditions, the air inlet is opened and closed. The opening by the valve lowers the concentration of the air-fuel mixture introduced into the combustion chamber from the annular flow passage, and prevents the flame in the combustion chamber from flowing back to the upstream side. By preventing the flashback phenomenon in this manner, it is possible to prevent thermal damage to the passage member that defines the annular passage or the premix chamber on the upstream side of the combustion chamber.

In the premixed combustor for a gas turbine according to the second aspect of the present invention, since the flashback detection means is composed of a thermocouple, sufficient heat resistance is ensured and the degree of freedom in installation is wide. Product cost can be reduced.

A premixed combustor for a gas turbine according to a third aspect of the present invention has a structure in which a rotary valve is rotated to open and close an air inlet, so that the opening area of the air inlet is 0 to 100%.
It is possible to finely control the air-fuel ratio of the air-fuel mixture introduced into the combustion chamber from the annular flow path.

A premixed combustor for a gas turbine according to a fourth aspect of the present invention has a structure in which a slide valve is moved in the axial direction to quickly open and close an air inlet to enhance control response of an air-fuel ratio in an annular flow path. To be

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a combustor showing an embodiment of the present invention.

FIG. 2 is a diagram showing the rotary valve when it is opened.

FIG. 3 is a diagram showing the rotary valve when it is closed.

FIG. 4 is a timing chart showing an example of rotary valve control.

FIG. 5 is a sectional view of the same combustor.

FIG. 6 is a diagram showing the same when the slide valve is opened.

FIG. 7 is a view showing the same when the slide valve is closed.

FIG. 8 is a sectional view of a combustor showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Premixing chamber 2 Combustion chamber 5 Annular flow path 7 Flame stabilizer 8 Annular nozzle 10 Main fuel injection valve 16 High pressure air passage 19 Flashback sensor 20 Partition wall 22 Air inlet port 23 Rotary valve 24 Air inlet port Valve port 29 Valve drive device 30 control unit 33 slide valve 39 valve drive device

Claims (4)

[Claims] 1. A high-pressure air passage for introducing pressurized air, a premixing chamber for mixing the pressurized air from the high-pressure air passage with fuel injected from a main fuel injection valve, and an air-fuel mixture from the premixing chamber. To the combustion chamber, a partition that separates the high-pressure air passage and the annular flow passage, an air inlet that opens in the partition to connect the high-pressure air passage and the annular passage, and an opening and closing that opens and closes the air inlet. A valve drive device for driving the on-off valve, a flashback detection means for detecting the occurrence of the flashback phenomenon, and a control means for opening the air inlet when the flashback phenomenon occurs. Premixed combustor for gas turbines. 2. The premixed combustor for a gas turbine according to claim 1, further comprising a thermocouple facing the annular flow path as the flashback detection means. 3. A premixed combustor for a gas turbine according to claim 1, further comprising a rotary valve that rotates in a circumferential direction of the annular passage as the opening / closing valve. 4. The premixed combustor for a gas turbine according to claim 1, further comprising a slide valve that moves in the axial direction of the annular flow path as the opening / closing valve.