JPS63150634A - Flame monitoring device for gas turbine combustor - Google Patents

Abstract

PURPOSE:To monitor a combustion state as an image at all times by inserting a fiber scope into a tubular probe and sending cooling air to between the tubular probe and fiber scope. CONSTITUTION:A probe 15 for flame monitoring is run through a casing wrapper 3 and fixed, and an observation window 16 for the probe 15 is positioned in the side wall surface 14 of a tail pipe. The side view type fiber scope 25 is inserted into the probe 15 and its observation direction is set to an upstream direction along the center axis of the combustor. The cooling air is sent to between the probe 15 and fiber scope 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a monitoring device created to be able to monitor the flame distribution situation in a gas turbine combustor as an image.

[Conventional technology]

Performance requirements for gas turbine combustors include low pollution and high temperatures. In terms of reducing pollution, there is a social need to reduce the concentration of NOx (nitrogen oxides), which is considered to be the cause of air pollution.

As a measure to reduce NOx, it is first necessary to avoid fuels with a high nitrogen content. The basic combustion method is to eliminate hot spots and burn at a lean and uniform concentration. From this point of view, premixed combustion is more effective in reducing NOx than diffusion type combustion. There are still many problems with combustion reliability in adopting a fully premixed combustor in an actual gas turbine, and it will probably take some time before it can be put into practical use. A multi-stage combustion system that actively performs dispersion is mentioned, and in particular, two-stage combustion is expected to become the mainstream of gas turbine combustors in the future.

Particularly important points in two-stage combustion technology are smooth flame transfer from the first-stage flame to the second-stage fuel, stable flame stability, and ensuring uniform flame distribution.

If the flame is uneven in the second stage or there is an unburned part, the fuel gas temperature distribution at the combustor outlet may deviate beyond the limit value, may not reach the predetermined average temperature, or cause even more harmful CO2. There is a risk that the conditions imposed on the combustor will no longer be met, such as the concentration of

[Problem that the invention seeks to solve]

For the above-mentioned reasons, a combustor employing a multi-stage combustion method requires some kind of flame monitoring method. As a device for monitoring the combustion state in the combustor for this purpose, Japanese Patent Laid-Open Nos. 61-62712 and 61. -93311
The number is publicly known.

However, these known techniques can only detect locally,
Since the flame distribution state cannot be grasped as an image, the effect of monitoring the combustion state is not sufficient.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a device that can constantly monitor the combustion state (flame distribution state) in a combustor as an image.

[Means for solving problems]

A gas turbine combustor flame monitoring device according to the present invention created to achieve the above object includes a plurality of fuel nozzles installed near the upstream end and near the midstream in the longitudinal direction of the gas turbine combustor. It is applied to a gas turbine combustor that performs staged combustion, and a tubular probe is fixed by penetrating the combustor casing, and the tip of the probe is attached to the intersection of the back side of the fuel device transition piece and the combustor central axis. At the same time, a side-viewing fiberscope is inserted into the tubular probe and the i-measurement direction is directed upstream, approximately along the combustor central axis, and the tubular probe and fiberscope are connected to each other. It is equipped with means for introducing cooling air between the two.

[Effect]

According to the above configuration, (a) maintenance of the fiber scope is easy because the fiber scope is inserted into the tubular probe, and (b) the fiber scope is of a side view type, so it is easy to maintain the fiber scope. Suitable for observing in the direction of the combustor center axis.

(c) Since it uses air cooling, it has excellent durability and reliability, and the state of flame distribution can be constantly monitored as an image via the fiber scope.

〔Example〕

A specific embodiment of the present invention is shown in FIGS. 1 to 6.

FIG. 2 shows the installation of an optical flame inspection device, mainly a fiberscope, for observing the flame condition in a gas turbine combustor, which is the basis of the present invention.

The gas turbine combustor liner 1 and the tail W2 following it are connected to the outer cylinder 3. The two-stage combustion type low NOx combustor of the six embodiments is housed in a high-pressure chamber sealed by a casing wrapper 4 and an outer cylinder front cover 5, and has two combustion chambers, the downstream combustion chamber being the upstream combustion chamber. The inner diameter is larger than that of the side combustion chamber. This upstream combustion chamber will be referred to as the auxiliary combustion chamber 6, and the downstream side will be referred to as the main combustion chamber 7. Since a cylindrical cylinder 8 is placed in the center of the sub-combustion chamber 6, the sub-chamber forms an annular combustion chamber 9.

A plurality of first-stage fuel nozzles 10 for first-stage fuel injection are installed at the upstream end of this annular combustion chamber.

On the other hand, the second-stage fuel is injected by a plurality of two-stage fuel nozzles 12 installed in an annular air swirl vane 11 circumscribing the rear end of the sub-combustion chamber 6 . The flame is an air swirler 1
A ring-shaped flame is formed in the vicinity of the exit of 1, and under uniform combustion conditions, a ring-shaped flame is formed.

The combustor ignition procedure is performed as follows. First, the first stage fuel is ignited, and the amount of fuel supplied to the first stage is increased to form a flame of sufficient length in the auxiliary combustion chamber 9.

The fuel ratio in the 1st and 2nd stages [1] at rated load is approximately 50
50, which results in an average combustion gas temperature at the transition pipe outlet 13 of 1000° or more.

The characteristics of this two-stage combustion method are that both the first-stage and second-stage combustion systems are equipped with multiple fuel nozzles to disperse the fuel and promote the mixing of combustion air and fuel, while keeping the air in a somewhat excessive state. The purpose is to supply so-called lean combustion.

What makes this method more difficult than the conventional single burner method is how to determine whether the fuel from all fuel nozzles is burning as planned. The only local detection method that has been used in the past, such as a photodiode, cannot grasp the overall flame condition and cannot be used in this two-stage combustion method.

The present invention improves the conventional single-local flame monitoring method, visualizes the entire flame image using optical means, and further processes the obtained flame image to detect the spread of the flame and unignited areas. Provided is a gas turbine combustor flame monitoring device characterized by having a function of determining the combustion state, diagnosing the combustion state, and determining whether or not combustion can continue.

In the two-stage combustor described above, the diameter of the main combustion chamber 7 is larger than that of the sub-combustion chamber 6, so in order to monitor the overall shape of the second-stage flame, it is necessary to start the combustion from a position on the downstream side of the combustor. It is essential to observe the upstream side of the vessel. Inserting a viewing probe into the combustor is impractical due to many problems such as the reliability of the probe and the disturbance of the combustion gas flow. As shown in the figure, the optimum observation position is the intersection of the tail pipe back wall surface 14 and the combustor upstream side X-x. Since this point is a point-symmetrical position, 1wt imaging can obtain an image with little distortion.

A fiber scope is used as the observation sensor, and it is installed inside the probe tube and is forcedly cooled by air. Figure 0 shows the probe tube 15 installed through the casing wrapper 4, and this observation probe and its installation method. The details will be explained from FIG. 1 onwards.

FIG. 1 shows a sectional view of the vicinity of the flame monitoring probe 15. The probe 15 is fixed by passing through the casing wrapper, and the observation window 16 of the probe 15 is positioned on the rear wall surface 14 of the tail tube. Specifically, the right-angled bent pipe 17 has a circular hole 34 (details will be described later with reference to FIG. 3) sufficient to secure the field of view of the probe at a position where the rear wall surface 14 of the tail pipe intersects with the central axis of the combustor. It is welded to the back wall surface 14. The upper end 18 of the right-angled bent pipe 17 is.

The inner diameter is made somewhat wider. This is because, as shown in the figure, the probe support circular tube is formed by being paired with the seal circular tube 19 inserted from the casing wrapper side. The purpose of using the seal tube 19 is to prevent air outside the transition piece 2 from flowing into the interior of the transition piece 2 through the right-angled bent tube 17. Therefore, the inside of the upper end 18 of the right-angled bent pipe 17 and the outer surface of the sealed circular pipe 19 are
Surface contact is maintained to the extent that thermal elongation can be absorbed. The seal tube 19 is fixed to the casing wrapper 4 by a plurality of bolts 20. In this way, a passage portion that is somewhat thicker than the probe diameter is secured between the casing wrapper 4 and the transition tube back wall surface 14. The probe 15 is inserted into the passage portion described above with the seal nut 21 fitted onto the probe 15 in advance. A threaded portion 22 is provided on the lower outer periphery of the seal nut 21. On the other hand, an X thread for fastening and fixing a seal nut is also cut in the upper part of the seal circular tube 19. There is an arc-shaped ring 2 inside the seal nut.
3 is fitted, and when the seal nut 21 is screwed in, the ring 23 is inserted into the probe tube 15 and fixed, and the space between the probe tube 15 and the seal nut 21 can be completely sealed. A parkin 24 is interposed at the contact portion between the lower surface of the seal nut 21 and the upper surface of the seal tube 19 to prevent air leakage.

Since the method for attaching the probe tube 15 has been described above, the outline of the probe tube 15 will be explained first.

The probe tube 15 includes a side-viewing type fiberscope 25, a fiberscope fixed tube 26. and an air-cooled pipe 27.

FIG. 3 shows details of the vicinity of the lower viewing window of this probe tube, with (A) being a front view and (B) being a cross-sectional side view.

A fiber scope uses thousands to tens of thousands of optical fibers1
When bundled, the outer diameter is usually about 2 to 3 mm.

Depending on how the lens system at the tip of the fiberscope is assembled, there are two types: a direct viewing type (in the same direction as the fiber wire) and a side viewing type (in the direction perpendicular to the fiber wire).1 The present invention uses an upper side viewing type mounting structure. is a feature. fiber scope 25
is fixed inside the fiberscope fixing tube 26.

A window portion 29A is provided at the lower part of the fiberscope fixed tube 26 on the surface facing the fiber lens.

The fiberscope fixed tube 26 is installed inside an air-cooled tube 27 having a double structure. A flow path 28 through which cooling air passes is formed in the air cooling tube 27, which is constructed of a double pipe, and the air flows in as shown by the arrow in the figure. In FIG. 3(B), two drawing reference numbers 28 of the flow path bypass are shown, and both are in communication.

An observation window 29B as shown in the figure is required on the side surface of the air-cooled pipe 27. Heat-resistant materials are usually used for window materials.
In this example, the observation window means a glass window. The observation window is fixed by a mechanism into which a push screw fitting 30 can be screwed, and a cross-shaped groove 31 is cut into the surface of the push screw fitting 30 as shown in FIG. 3(A). The 0M measuring window 29 has a structure that allows the push screw fitting 30 to be fixed in a predetermined position by engaging a dedicated screwdriver tool.
An O-ring groove 32 for inserting a sealing O-ring is provided on the surface into which the O-ring is inserted.

By the way, the primary purpose of the air-cooled tube 27 is, of course, to protect the fiberscope 25 from high heat, but the second purpose is to protect the fiberscope 25 from high heat.
The purpose of this is to cool the observation window and prevent the window from getting dirty.

In order to effectively solve these two problems.

Cooling air must be blown out to the outer surface of the observation window, that is, to the combustion gas side. The air that cools the affected area passes through a plurality of circular holes 34 made on the side wall circumference of the window fixing tube 33 provided for screwing the push screw fitting 3o, and is further provided in the push screw fitting 30. After all, it passes through the plurality of injection holes 35, becomes a jet, and collides with the observation window 29B. By creating an impinging jet in this manner, the cooling efficiency of the window surface is increased and the temperature can be significantly reduced. In addition, to prevent the windows from getting dirty, by constantly blowing clean air, we prevent dirt from adhering to the windows and ensure light transmission.

As explained above using the drawings, one of the features of the present invention is that the probe tube with a built-in side-viewing type phiscope can be easily inserted and installed from a part of the casing wrapper, so that it can be installed easily even if a situation such as dirt on the observation window occurs. Even so, the probe tube can be easily removed and the defective part can be easily repaired.

Next, as a modified example of the present invention, as shown in FIG. A leaf spring 37 is arranged on the circumference inside the bent pipe 36 in a configuration that allows some leakage of air flowing into the transition pipe.
The probe tube 15' is directly inserted into this plate spring portion and fixed. The probe tube 15' has a flange 38,
It is fastened to the casing wrapper 4 with a plurality of bolts 39. In this method, only the probe tube 15' is inserted, and if the plate spring 37 has a sufficient degree of freedom in deformation, it can be attached and detached very easily.

Next, a method for extracting a flame image using the apparatus of the present invention, a method for diagnosing the combustion state through image analysis, and a method for determining whether to continue operating the combustor will be described.

FIG. 5 is a diagram showing the flow of a method for diagnosing the combustion state.

In the two-stage combustion, a ring-shaped flame formation as shown in FIG. 6 is observed. The flame formed inside is caused by the first stage fuel, and the flame formed outside is caused by the second stage fuel. When the combustion is uniform, a ring-shaped flame is formed as shown in Figure 6. On the other hand, when the combustion is uneven, the ring is cut or becomes extremely thin. There is. The combustion state is determined based on these flame characteristics.

The flame image transmitted through the fiber scope 25 is guided to an industrial television camera 40, visualized, and displayed on a monitor 41 at all times. One of the analog video signals output from the camera 40 is converted into a digital signal via the A/D converter 42, and then sent to the image processor 43, where various calculations are performed on the image. These include etching processing to find the outer edge of the flame and area calculation of the area where the flame is distributed. As a comparison table for diagnosing the combustion state, the combustion load and flame area data for normal combustion are prepared in advance, and the deviation from these data is calculated by the comparator A44, and the deviation 1. If 3*-51 is smaller than the allowable deviation value ΔS of the flame area, it is determined that the operation can be continued; on the other hand, if it is larger, a signal to stop the continued operation is sent from the trip circuit 46.

On the other hand, if the flame area is good, the degree of connection of the flames is determined from the result of the flame edge etching process as a first determination. If the flame is partially misfired, connected edge lines will not be obtained on the circumference, but several independent edge lines will be generated.

Therefore, the number of allowable edge lines (No,) is determined,
Compare the number of edge lines with comparator B45.

If the number is larger than the allowable number, it is determined that the flame connection condition is poor, and control is activated to issue a trip signal from the trip circuit 46 and stop the combustor operation.

〔Effect of the invention〕

According to the present invention, a situation that has hitherto been completely unknown exists.

The distribution of flame inside the high-temperature, high-pressure gas turbine combustor is
It becomes possible to capture images at all times. In particular, in a two-stage combustor, the performance is greatly influenced by the second-stage flame distribution. A more reliable combustor can be provided than a type combustor.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention. FIG. 1 is a sectional view of the vicinity of the probe attachment part, FIG. 2 is a partial sectional view of one combustor, and FIG. 3 is a sectional view of the tip of the probe. It is an explanatory diagram. FIG. 4 is a sectional view of an embodiment different from the above. FIG. 5 is a system diagram of an image analysis device using the device of the present invention,
FIG. 6 is an explanatory diagram of the flame distribution state in the gas turbine combustor. 1... Combustor liner, 2... Transition tube, 3... Outer tube,
4...Casing wrapper, 8...Inner cylinder, 10...
1st stage combustion nozzle, 12... 2nd stage combustion nozzle, 15...
- Tubular probe, 25...side-viewing fiberscope.

Claims (1)

[Claims] 1. In a gas turbine combustor that performs two-stage combustion by installing a plurality of fuel nozzles near the upstream end and near the midstream in the longitudinal direction of the gas turbine combustor, a combustor casing is provided. A tubular probe is fixed therethrough, the tip of the probe reaches near the intersection of the back side of the combustor transition piece and the combustor center axis, and a side-viewing fiber is inserted into the tubular probe. A gas gas system characterized by having a means for inserting a scope and directing the observation direction in the upstream direction approximately along the central axis of the combustor, and for feeding cooling air between the tubular probe and the fiber scope. Turbine combustor flame monitoring device. 2. The tubular probe is provided with a viewing glass window at its tip, and is provided with a flow path configured to blow the cooling air onto the outer surface of the glass window. A gas turbine combustor flame monitoring device according to claim 1, wherein the gas turbine combustor flame monitoring device is a gas turbine combustor flame monitoring device. 3. The gas turbine combustor flame monitoring device according to claim 1 or 2, wherein the fiber scope is connected to a TV camera equipped with an image analysis circuit. .