JPH07233908A - Gas turbine burner - Google Patents

Abstract

PURPOSE:To eliminate a damage of a flame stabilizer for a gas turbine burner by providing a plurality of notches opened at an upstream side end face of a cylindrical base and each having a depth toward a downstream side of a combustible premixed gas flowing direction. CONSTITUTION:A cylindrical base 22 of a flame stabilizer 13 is set, for example, by six flame stabilizer indicating plates 26. A peripheral length of the base 22 between the plates 26 is divided into three zones at an equal interval. Twelve notches 31 of a total amount each having a depth in a longitudinal direction of the stabilizer 13 are radially formed at the base 22 in each of the divided zones. That is, the notches are radially disposed with respect to an axis of a burner, and passed between inner and outer peripheries of the base 22. A circular hole 32 having a diameter of about three times as large as the width of the notch 31 is formed at the end of the notch 31 to prevent cracking from the notch 31. In this case, the more the number of the notches is increased, the greater a thermal stress generated at a connected part 27 of the base 22 to the plate 26 is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine combustor, and more particularly to a gas turbine combustor having a flame stabilizer.

[0002]

2. Description of the Related Art A conventional gas turbine combustor will be described with reference to FIGS. FIGS. 6, 7 and 8 are explanatory views of each state of initial combustion, intermediate combustion and steady combustion in the gas turbine combustor, and FIGS. 9 and 10 are structures of conventional flame stabilizers and flame states during combustion. FIG. 11 is an explanatory view of a deformation state in the conventional flame stabilizer, FIG. 12 and FIG. 13 are examples of deformation at the time of attachment structure in the conventional flame stabilizer, FIG.
FIG. 15 is an explanatory diagram of a maximum thermal stress generation point in a conventional flame stabilizer in a mounting structure. 1 is a gas turbine combustor, 2 is first stage fuel, 3 is auxiliary burner fuel, 4 is second stage fuel, 5 is first stage combustion cylinder, 6 is second stage combustion cylinder, 7 is first stage fuel nozzle, 8 Is a second stage fuel nozzle, 9 is an air inlet, 10 is fuel, 11 is air, 12 is a premixer, 13 is a flame stabilizer, 14 is an auxiliary burner fuel nozzle, 15 is a second stage premix air flow, 16 Is the first-stage combustion chamber, 17 is the second-stage combustion chamber,
18 is a first-stage combustion flame, 19 is an auxiliary burner flame, 20 is a second-stage combustion flame, 21 is a trapezoidal stepped ring-shaped disc, 2
2 is a cylindrical base, 23 is an end surface, 24 is a hypotenuse of a trapezoidal cross section, 25 is an inner and outer peripheral surface of the cylindrical base, 26 is a flame holding support plate, 27
Is a joining portion, 28 is upper and lower end portions of the flame stabilizer support plate, 29 is a premixing cylinder, 30A is an outer peripheral cylinder, and 30B is an inner peripheral cylinder.

The gas turbine combustor 1 guides high pressure air 11 supplied from a compressor (not shown) into the gas turbine combustor 1, and the first stage fuel 2, the auxiliary burner fuel 3 and the second stage fuel. 4, the fuel supplied to the gas turbine combustor 1 is burned.

That is, the gas turbine combustor 1 has a first-stage combustion cylinder 5 and a second-stage combustion cylinder 6, and the first-stage combustion cylinder 5 has a first-stage fuel nozzle 7 and an auxiliary burner fuel nozzle 14. The second-stage combustion cylinder 6 has a second-stage fuel nozzle 8
But each is installed. The second-stage combustion cylinder 6 has an air inlet 9 beside the second-stage fuel nozzle 8, and the fuel 10 and the air 11 from the second-stage fuel nozzle 8 are mixed with each other, so that the second-stage premixed air flow is generated. It becomes 15, and this mixing place is called a premixer 12. Further, the flame stabilizer 13 is installed on the flow passage of the second-stage premixed airflow 15 immediately after the second-stage premixed airflow 15 is lost from the premixer 12.

The operation of the gas turbine combustor 1 will be described below. First, the first stage fuel 2 and the auxiliary burner fuel 3 are introduced from the first stage fuel nozzle 7 and the auxiliary burner fuel nozzle 14 into the first stage combustion chamber 16 and ignited. The operation of the gas turbine is started in this state, and the state of the flame formed at this time is shown in FIG.

Next, when the gas turbine reaches a certain load, the second-stage combustion chamber 17 is ignited. The second-stage fuel 4 is mixed with the air 11 in the premixer 12 to form the second-stage premixed air flow 15 in the second-stage combustion chamber 1
7 and is ignited by the first stage combustion flame 18 to become the second stage combustion flame 20. In this case, flame stabilizer 1
By installing 3, even if the fuel concentration of the second-stage premixed air flow 15 is low, stable combustion is achieved, and the first-stage combustion flame 1
Even if 8 is extinguished, stable combustion of only the second stage combustion flame 20 is obtained. The state of the flame formed at this time is shown in FIG.

Subsequently, the supply of the auxiliary burner fuel 3 from the auxiliary burner fuel nozzle 14 is stopped, and the auxiliary burner fuel 3
Is fed to the first-stage fuel 2 and supplied from the first-stage fuel nozzle 7, and the auxiliary vane flame 19 is extinguished. After that, the first-stage combustion flame 18 is caused to flow in a vortex flow, the flame holding of the first-stage combustion chamber 16 disappears, and the flame is maintained by the second-stage combustion flame 20. The state of the flame maintained at this time is shown in FIG.

As described above, the gas turbine combustor 1 has three stages of combustion processes, and the flame stabilizer 13 plays an important role in these combustion processes. The flame stabilizer 13 has a role of ensuring the stability of combustion in the second and third stages and reducing the NOx concentration.

FIG. 9 shows the structure of the flame stabilizer 13 and the state of the flame during combustion. The flame stabilizer 13 is provided at a position immediately after the second-stage premixed airflow 15 flows out of the premixer 12, and
In the case of, the flame stabilizer support plate 26 is fixed to the end of the premixer 12. The flame stabilizer 13 comprises a cylindrical base 22 installed on the flow passage of the combustible premixed airflow 15 at the outlet of the premixer 12 and a ring-shaped disc 21 having a trapezoidal cross section with an increased wall thickness. A ring-shaped disc 21 having a trapezoidal cross section is connected to the end of the cylindrical base 22.

As shown in FIG. 9, the flame is generated only on the end face 23 side which is the bottom of the trapezoidal cross section of the flame stabilizer 13,
Only the end face 23 comes into contact with the flame. The second stage premixed airflow 15 is in contact with the hypotenuse portion 24 of the trapezoidal cross section and the inner and outer peripheral surfaces 25 of the cylindrical base 22. Since this air flow is not combusted, it is close to the temperature of the compressed air 11, and therefore the hypotenuse portion 24 and the cylindrical base 22 of the trapezoidal cross section.
The temperature of the inner and outer peripheral surfaces 25 is relatively low.

From the above, the flame stabilizer 13 is in a deformed state as shown in FIG. That is, at the time of normal combustion, a high temperature flame is generated on the end face 23, which is the bottom of the trapezoidal cross section of the flame stabilizer 13, and the oblique side portion 24 of the trapezoidal cross section and the cylindrical base 2
On the inner and outer peripheral surface 25 of 2, the low-temperature second-stage premixed air flow 15
Since they come into contact with each other, the end surface 23 becomes hot, and the temperature of the hypotenuse portion 24 of the trapezoidal cross section and the inner and outer peripheral surfaces 25 of the cylindrical base 22 becomes lower as the distance from the end surface 23 increases. As a result, the tip portion of the flame stabilizer 13 having a high temperature is deformed by thermal expansion, and conversely, the upstream side portion having a relatively low temperature has a small deformation amount, and the flame stabilizer 13 has a cylindrical shape. As shown in FIG. 11, a trumpet-shaped deformed state is obtained.

On the other hand, the flame stabilizer 13 needs to be fixed by some method. 9 and 10 show examples of fixing methods. In FIG. 9, the flame stabilizer support plates 26 are attached to the welded portion 2 at a plurality of positions (for example, 16 positions) in the circumferential direction of the cylindrical base 22 of the flame stabilizer 13.
7, the upper and lower end portions 2 of the flame stabilizer support plate 26
8 is an example fixed to the premix cylinder 29 by welding. FIG. 10 shows that the flame stabilizer support plate 26 is fixed to both the cylindrical base 22 of the flame stabilizer 13 and the ring-shaped disc 21 having a trapezoidal cross section by the welded portion 27, and the upper and lower portions of the flame stabilizer support plate 26 are fixed. This is the case where 28 is fixed to the premix cylinder 29 by welding.

Deformation states of the flame stabilizer support plate 26 and the flame stabilizer 13 in the case of the fixing method shown in FIGS. 9 and 10 are shown in FIGS. 12 and 13, and the places where the maximum thermal stress is generated are shown in FIGS. Shown in. 12 and 14 show the case where the flame holder 13 is fixed on the cylindrical base 22, and FIGS. 13 and 15 show the flame holder 1
In this example, both the cylindrical base 22 and the ring-shaped disc 21 having a trapezoidal cross section are fixed. Since the ring-shaped disc 21 having a trapezoidal cross section of the flame stabilizer 13 becomes hot, the flame stabilizer 13 deforms as shown in FIG. As a result, in any of the fixing methods, the ring-shaped disc 21 and the cylindrical base 22 have a deformed state in which the vicinity of the tips is opened outward, but the deformation of the ring-shaped disc 21 and the cylindrical base 22 is supported by the flame stabilizer. Since it is constrained by the plate 26, a large thermal stress is generated. When the maximum stress is fixed on the cylindrical base 22 of the flame stabilizer 13 in FIG. 14, the maximum stress is generated on the side of the cylindrical base 22 of the welded portion between the flame stabilizer support plate 26 and the cylindrical base 22. When it is fixed by both the cylindrical base 22 and the ring-shaped disc 21 having a trapezoidal cross section, it occurs on the flame stabilizer support plate 26.

This thermal stress is repeated due to ignition and stop of the combustion gas, and as a result, a crack may be generated and propagate from the place where the maximum thermal stress occurs. In this case, the flame stabilizers may scatter and damage the downstream gas turbine components to a great extent, which greatly affects not only the gas turbine combustor 1 but also the life of the gas turbine plant. Therefore, the conventional combustor has a problem in reliability due to the structure of the flame stabilizer 13. It should be noted that there is no related structure for relaxing the thermal stress of the gas turbine combustor flame stabilizer.

[0015]

In the gas turbine combustor, the flame stabilizer is indispensable for reducing NOx, but in the conventional flame stabilizer, excessive thermal stress is generated,
This caused serious damage to the flame holder.

The object of the present invention is to eliminate damage to the flame stabilizer,
It is to improve the reliability of the gas turbine combustor.

[0017]

SUMMARY OF THE INVENTION The above object is to provide the combustible premix at the annular outlet of a double cylindrical premixer for mixing combustible fuel and air to create a combustible premixed gas. On a gas flow passage, a cylindrical base that is installed concentrically with the premixer and a downstream end of the cylindrical base are connected, and the wall thickness increases toward the downstream side of the combustible premixed gas. In a gas turbine combustor having a flame stabilizer including a ring-shaped disc having a trapezoidal cross section, an opening is made on an upstream end face of the cylindrical stand, and the downstream side is arranged in the flow direction of the combined flammable premixed gas. This is achieved by providing a plurality of cuts having a depth.

The length of the cut is determined by the ratio of the stress and the allowable stress generated at the joint between the cylindrical base and the flame stabilizer support plate and the ratio of the stress and the allowable stress generated at the circular hole at the tip of the cut. Equal lengths should be used, and if the ratio of the generated stress to the allowable stress in this case exceeds 1.0, the number of cuts must be increased to make the ratio of the generated stress to the allowable stress below 1.0.

The width of the cut is b, the linear expansion coefficient of the flame stabilizer material is α, the temperature difference between the room temperature and the temperature of the break of the flame stabilizer during gas turbine operation is T ₀ , the radius of the flame stabilizer is r, When the number of breaks is n, it is preferable that the following expression is satisfied.

B ≧ αT ₀ · 2πr / n (1)

[0021]

[Function] Since a cut is made in the cylindrical stand of the flame stabilizer,
The thermal stress generated when no cut is made is released and greatly reduced at the time of ignition and extinction of the second-stage premixed air stream 15. Therefore, the repeated thermal stress generated by the repeated ignition and extinction of the second-stage premixed airflow 15 is significantly reduced, and the reliability of the flame stabilizer is improved.

Further, since the break is provided in the flame stabilizer at a portion where thermal stress is likely to occur, the thermal stress can be efficiently reduced.

Further, since the boundary conditions on the inner and outer peripheral sides of the flame stabilizer are symmetrical, even if a break is made, the flame stabilizing performance can be normally maintained without being deformed.

Further, even if the flame stabilizer expands, the width of the break is set to such a degree that the break is closed, so that the reduction of the thermal stress is not impeded. Moreover, since the cut is completely closed, the premixed air flow does not leak from the cut, and the flame holding performance can be normally maintained.

[0025]

Embodiments Embodiments will be described below with reference to the drawings.

FIG. 1 is a schematic vertical sectional view of a main part of a flame stabilizer according to an embodiment of the present invention, FIG. 2 is a plan view as seen in the direction A of FIG. 1, and FIG. 3 is a side view as seen in the direction B of FIG. FIG. 4 is an explanatory diagram of the relationship between the number of cuts and the stress ratio, FIG. 5 is an explanatory diagram of the relationship between the cut length and the stress ratio, 31 is a break, 32 is a circular hole, and the other symbols are the same as those described above. Is.

As described above, the gas turbine combustor 1 is arranged concentrically with the first-stage combustion cylinder 5 on the outer periphery of the first-stage combustion cylinder 5 on the downstream side of the first-stage combustion cylinder 5. The second stage combustion cylinder 6 forming an annular premixer 12 between the first stage combustion cylinder 5 and the first stage fuel nozzle 7 and the auxiliary burner fuel nozzle 14. Second-stage fuel nozzles 8 are installed in the second-stage combustion cylinders 6, respectively. The second-stage combustion cylinder 6 has a second-stage fuel nozzle 8
The air inflow port 9 is arranged next to, and the fuel 10 from the second-stage fuel nozzle 8 and the air 11 from the air inflow port 9 are mixed with each other to form the second-stage premixed airflow 15. It is called the premixer 12. Also, the premixer 12
The flame stabilizer 13 is installed on the flow passage of the second-stage premixed airflow 15 immediately after the outflow of the second-stage premixed airflow 15.

FIG. 1 shows a cross section of a flame stabilizer 13 arranged downstream of the premixer 12. The premixer 12 is an outer cylinder 30A and an inner cylinder which are concentric with the axis of the first-stage combustion cylinder 5. 30B and a plurality of flame stabilizer support plates 26 on a flat plate extending in the axial direction, which are arranged between both cylinders in a radial direction and are connected to each other, are formed. The downstream end of the flame stabilizer support plate 26 is located upstream of the downstream end portions of the outer peripheral cylinder 30A and the inner peripheral cylinder 30B. The flame stabilizer 13 is the outer peripheral cylinder 3
A cylindrical base 22 that has a diameter approximately midway between the inner diameter of 0 A and the outer diameter of the inner cylinder 30B and is arranged concentrically with the inner cylinder 30B.
And a ring-shaped circular plate 21 having a trapezoidal cross section and having the same diameter as that of the cylindrical base 22 and connected to the downstream end of the cylindrical base 22. The upstream end of the cylindrical base 22 is fitted into a notch formed in the flame stabilizer support plate 26 and fixed by welding.

In this embodiment, the cylindrical base 22 of the flame stabilizer 13 is used.
Are installed by six flame stabilizer support plates 26, and the circumferential length of the cylindrical base 22 between the flame stabilizer support plates 26 is divided into three at equal intervals, and each divided area has a cylindrical shape. A cut 31 having a depth in the radial direction on the table 22 and in the longitudinal direction of the flame stabilizer 13.
There are 12 in total. That is, the cuts 31 are arranged radially with respect to the axis of the combustor, and penetrate between the inner peripheral surface and the outer peripheral surface of the cylindrical base 22. If the cut is left, the stress concentration factor at the tip of the cut 31 becomes large, and this has a bad effect. Therefore, at this tip, a circular hole 3 having a diameter of about three times the width of the cut 31 is formed.
2 is provided to prevent the occurrence of cracks from the cut 31.

In the present embodiment, as described above, the cylindrical base 2
Although 12 cuts 31 are provided in 2, the heat generated in the joint portion 27 between the cylindrical base 22 and the flame stabilizer support plate 26 is increased as the number of cuts is increased, that is, the distance between the cuts is shortened. Stress is reduced. FIG. 4 shows an example of the relationship between the number of cuts and thermal stress. The horizontal axis represents the ratio n / m of the number n of the cuts 31 and the number m of the flame stabilizer support plate 26, and the vertical axis represents the thermal stress σ generated when the number of the cuts is arbitrary and the thermal stress σ generated when there is no break. The ratio to ₀ is σ / σ ₀ . The illustrated stress ratio indicates the stress value of the joint portion 27 of the flame holder support plate 26 and the cylindrical base 22 which is the maximum thermal stress generating portion. Further, according to this result, if the number of the cuts 31 is infinitely increased,
Thermal stress is infinitely small, but this is not realistic.
Therefore, the optimum number of breaks may be selected from the relationship between the number of man-hours required to make a break, the generated thermal stress, the allowable stress, and the length of the break shown below.

Regarding the relationship between the length of the cut 31 inserted in the flame stabilizer 13 and the thermal stress, the thermal stress generated at the joint 27 between the flame stabilizer support plate 26 and the cylindrical base 22 decreases as the cut length increases. On the contrary, the thermal stress generated in the circular hole 29 at the tip of the cut 31 increases. That is, even if the stress of the joint portion 27, which is the maximum thermal stress generating portion, can be reduced by inserting the cut 31, if the stress generated in the circular hole 29 at the tip of the cut 31 exceeds the allowable stress, 31 is not effective. Therefore, the length of the cut 31 to be inserted in the flame stabilizer 13 must be selected to be an appropriate length. FIG. 6 shows the relationship between the thermal stress generated in the joint portion and the circular hole at the tip of the cut and the cut length 1 when the number n of the cuts is 6 and when n is 12 in this embodiment. The vertical axis represents the ratio σ / σ _{b of} the thermal stress σ and the allowable stress σ _b generated at an arbitrary cut length, and the horizontal axis represents the cut length l. The cut length l is such that both the thermal stress generated in the joint and the thermal stress generated in the circular hole at the tip of the cut are less than or equal to the allowable stress σ _b , that is, the value of the point M at which both σ / σ _b are equal is 1 The length must be 0.0 or less. When the number of breaks is 6, M point is 1.0
Will exceed. In this case, if the number n of the cuts is increased, the decrease rate of the stress of the joint portion with the increase of the cut length l is large, and conversely, the increase rate of the stress of the circular hole at the cut end is small. The point moves in the direction in which σ / σ _b decreases. In the case where the number n of breaks is 12 in this embodiment, σ / σ _{b at the} point M is 1.0 or less, so the break length l at the point M is 1.
Adopted _M.

Further, the width of the cut was determined as follows. That is, if the cut is blocked by thermal expansion and the adjacent part is restrained, the cut does not contribute to the release of thermal stress. Therefore, the width of the break which does not block the break even if it thermally expands was determined by the following equation.

B ≧ αT ₀ · 2πr / n where b is the width of the slit, α is the coefficient of linear expansion of the flame stabilizer material, T ₀ is the room temperature and the temperature of the flame stabilizer slit during gas turbine operation. Temperature difference, r is the radius of the flame stabilizer, and n is the number of cuts.

[0034]

According to the present invention, in a flame stabilizer for a gas turbine combustor, repetitive thermal stress, start-up, and stop caused by repetition of normal combustion of the gas turbine combustor and flame backfire are generated. It is possible to reduce the repetitive stress and the like that occur, and prevent damage to the flame stabilizer. Therefore, the reliability of the gas turbine combustor can be improved.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a main part of a flame stabilizer according to an embodiment of the present invention.

FIG. 2 is a plan view as seen in the direction of arrow A in FIG.

FIG. 3 is a plan view as seen from the direction of arrow B in FIG.

FIG. 4 is an explanatory diagram of a relationship between the number of cuts and a stress ratio.

FIG. 5 is an explanatory diagram of a relationship between a cut length and a stress ratio.

FIG. 6 is an explanatory diagram of an initial combustion state in the gas turbine combustor.

FIG. 7 is an explanatory diagram of an intermediate combustion state in the gas turbine combustor.

FIG. 8 is an explanatory diagram of a steady combustion state in the gas turbine combustor.

FIG. 9 is an explanatory view of a structure of a conventional flame stabilizer and a state of flame during normal combustion.

FIG. 10 is an explanatory view of a structure of a conventional flame stabilizer and a state of flame during normal combustion.

FIG. 11 is an explanatory diagram of a deformation state of a conventional flame stabilizer.

FIG. 12 is a diagram showing an example of a modification of a conventional flame stabilizer with a mounting structure.

FIG. 13 is a diagram showing an example of a modification of a conventional flame stabilizer with a mounting structure.

FIG. 14 is a diagram showing a location where maximum thermal stress is generated in a conventional flame stabilizer with a mounting structure.

FIG. 15 is a diagram showing a location where maximum thermal stress is generated in a conventional flame stabilizer with a mounting structure.

[Explanation of symbols]

1 ... Gas turbine combustor, 2 ... First stage fuel, 3 ... Auxiliary burner fuel, 4 ... Second stage fuel, 5 ... First stage combustion cylinder, 6 ... 2
Stage combustion cylinder, 7 ... First stage fuel nozzle, 8 ... Second stage fuel nozzle, 9 ... Air inlet, 10 ... Fuel, 11 ... Air, 12
... premixer, 13 ... flame stabilizer, 14 ... auxiliary burner fuel nozzle, 15 ... second-stage premix air flow, 16 ... first-stage combustion chamber, 1
7 ... 2nd stage combustion chamber, 18 ... 1st stage combustion flame, 19 ... Auxiliary burner flame, 20 ... 2nd stage combustion flame, 21 ... Trapezoidal stepped ring disk, 22 ... Cylindrical stand, 23 ... End face, 24 ...
The hypotenuse part of the trapezoidal cross section, 25 ...
... Flame holding support plate, 27 ... Joined portion, 28 ... Upper and lower end portions of flame holder support plate, 29 ... Premixed cylinder, 30A ... Outer peripheral cylinder, 3
0 ... B inner peripheral cylinder, 31 ... break, 32 ... circular hole.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Iizuka 3-1-1, Saiwai-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Kaichi Moritomo 3-chome, Hitachi-shi, Ibaraki 1-1 Hitachi Stock Co., Ltd. Hitachi Factory (72) Inventor Nakayama ▲ Osamu 3-1 Osamu-cho, Hitachi City, Ibaraki Prefecture 1-1 1-1 Hitachi Co., Ltd. Hitachi Factory

Claims (3)

[Claims] 1. The premixing is provided on a flow passage of the combustible premixed gas at an annular outlet portion of a double cylindrical premixer for mixing a fuel for combustion and air to produce a combustible premixed gas. A cylindrical base that is installed concentrically with the container, and a ring-shaped circle that has a trapezoidal cross section that is connected to the downstream end of the cylindrical base and that increases in wall thickness toward the downstream side of the combustible premixed gas. A gas turbine combustor having a flame stabilizer including a plate, having a plurality of cuts that are open to the upstream end surface of the cylindrical base and have a depth toward the downstream side in the flow direction of the combustible premixed gas A gas turbine combustor characterized by the above. 2. The length of the cuts and the number of cuts are adjusted to reduce the thermal stress generated in the flame stabilizer and the repeated thermal stress, thereby improving the life of the flame stabilizer. A gas turbine combustor as described. 3. The width of the cut, b, the coefficient of linear expansion of the flame stabilizer material, α, the temperature difference between room temperature and the temperature of the flame stabilizer cut portion during gas turbine operation, T ₀ , and the radius of the flame stabilizer. The gas turbine combustor according to claim 1 or 2, wherein the following expression is satisfied, where r is the number of cuts and n is the number of cuts. b ≧ αT ₀ · 2πr / n