JP2001141242A - Gas turbine combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas turbine combustor the vortex generator of which can be manufactured easily and can be attached to a premixer in a short time even when the premixer has a complicated shape. SOLUTION: A gas turbine combustor is provided with a premixer 10 which supplies a mixed gas to a combustion chamber, a vortex generator 9 which generates vortexes in a flowing gas, and a fuel nozzle 8 which injects fuel into the flowing gas in the premixer 10. The vortex generator 9 is formed by cutting parts of the wall constituting the outer peripheral wall of the premixer 10 in, for example, mountain-like shapes, and erecting the cut parts by bending the parts toward the inside of the premixer 10 so that the erected projections may generate vortexes in the flowing gas.

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 for performing premix combustion and having a vortex generator inside the premixer to promote mixing. It is about a vessel.

[0002]

2. Description of the Related Art In an industrial gas turbine, it is required to reduce the amount of NOx emitted in a combustor in consideration of environmental problems. In general, NOx generated from a gas turbine using a fuel having a low nitrogen content is as follows.
Most of the thermal NOx is generated when nitrogen in the air is oxidized by a high-temperature atmosphere. Since the generation of thermal NOx is highly temperature-dependent, the basic idea of the low NOx combustion method is to reduce the flame temperature as much as possible.

[0003] In a gas turbine combustor generally used in the past, the fuel flow rate changes according to the load of the gas turbine, but the air flow rate is almost constant, and the partial load is 100 to 100%.
The fuel-air ratio, which is the mass flow ratio between fuel and air, greatly changes between the% rated loads. In addition, even near the rated load where the fuel flow rate is maximum, the theoretical air amount required for complete combustion of the fuel is 2 times.
Nearly twice as much air is supplied. Therefore, lean combustion in which a flame is formed by excess air can be applied, and this is the mainstream technology of the NOx reduction method employed in current combustors.

[0004] As a combustion method of gaseous fuel, a diffusion combustion method in which fuel is injected into the air and the fuel and air are mixed and burned, and a fuel and air are mixed in advance and then injected from a nozzle and burned. It is roughly divided into the premix combustion method.

[0005] The former diffusion combustion method has the advantages that the flame is excellent in stability and the flame can be formed in a wide fuel-air ratio range. However, since fuel and air are mixed and burned, even if lean combustion is attempted, the fuel-air ratio in the flame is almost stoichiometric. Therefore, there is a problem that the flame temperature locally increases and a large amount of NOx is easily generated.

On the other hand, in the latter premix combustion method, fuel and air are mixed before being charged into a combustion chamber. Therefore, in this combustion method, it is easier to make the fuel-air ratio in the flame uniform than in diffusion combustion, and it is possible to avoid formation of a local high-temperature portion due to uneven mixing. Therefore, reduction of NOx can be achieved by utilizing premixed combustion in which fuel and air are mixed and burned before combustion, and by burning in a state where the fuel-air ratio is smaller than the stoichiometric mixture ratio.

However, if the uniformity of fuel and air at the outlet of the premixer is not sufficient, not only is it difficult to obtain the above-described NOx reduction effect, but also the NOx generation amount becomes larger than that of the diffusion flame, Since it is conceivable that a so-called flashback occurs due to the propagation of the flame through the dark portion and the combustor components are melted, the flashback prevention mechanism is likely to be complicated. Therefore, as disclosed in, for example, JP-A-07-91661 and JP-A-06-307640, a vortex generator for generating a vortex is provided inside the premixer to actively mix the fuel and air. I try to promote it.

[0008]

When a structure (vortex generator) for generating a vortex is provided inside the premixer as described above,
Generally, as disclosed in the above-mentioned publication, a member having a triangular pyramid shape or the like is fixed to a wall surface in a gas passage by welding. However, especially when the NOx value is 10 pp
low NOx such as "single NOx" combustor
In the case of a combustor, the premixer itself becomes large, and the number of vortex generators to be installed increases due to the increase in the number of premixers arranged in the combustor, and a simple shape such as a triangular pyramid However, the installation work became complicated, and this would have required a lot of time.

The present invention has been made in view of the above, and it is an object of the present invention to make it possible to easily manufacture a vortex generator without increasing the size of a premixer itself and to prepare a premixer having a complicated shape. It is an object of the present invention to provide a gas turbine combustor of this type that can install a vortex generator in a short time even with a mixer.

[0010]

That is, the present invention comprises a premixer for supplying a mixed gas to a combustion chamber, and a vortex generator for generating a vortex in a flowing gas inside the premixer;
In a gas turbine combustor comprising a fuel nozzle for injecting and supplying fuel into a flowing gas, the vortex generator is cut into a part of a wall constituting an outer peripheral wall of the premixer, for example, a mountain shape, or A notch such as a trapezoidal shape was formed, and the cut portion was bent toward the inside of the premixer to be erected, and formed so as to generate a vortex in the flowing gas at the erected projection, thereby achieving the intended purpose. Things.

Further, in this case, the upstanding projection is formed so as to have an elevation angle of 10 to 30 degrees with respect to the flowing direction of the flowing gas. Further, the height of the upstanding projection is formed to be 1/3 to 1/2 of the height of the premixer. Further, the upstanding projection is formed so as to be located on the upstream side of the flowing gas from the fuel injection port of the fuel nozzle. Further, a sleeve concentric with the premixer is fitted around the outer periphery of the premixer.

That is, in the gas turbine combustor formed as described above, the vortex generator has a notch in the upright projection formed by cutting and bending the outer peripheral wall of the premixer, ie, a part of the outer peripheral wall of the premixer. Since the cut portion is formed by the raised projections that are bent and erected, the premixer itself does not become large without increasing the physical size particularly from the outer peripheral wall of the premixer, and the cut portion is bent. The vortex generator is easy to fabricate and does not need to be mounted because only the upright raised projections are formed. Therefore, even if the premixer has a complicated shape, the vortex generator can be shortened. It can be completed in time.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is a diagram illustrating the gas turbine combustor and its peripheral devices. This gas turbine equipment mainly includes a compressor 1 for generating compressed air, a combustor 2 for generating high-pressure high-temperature combustion gas, and a turbine 3 driven by the combustion gas, and
The generator 4 is rotated by the output of the turbine to obtain electric power.

The combustor 2 includes a gas turbine casing 5,
The diffusion pilot burner 21 is disposed in the center of the upstream end of the combustor outer cylinder 6 and the combustor cover 7. Also, on the outer periphery of the pilot burner 21,
An annular premix burner 22 is arranged. The premix burner 22 includes a plurality of premix burner fuel nozzles 8, a vortex generator 9, a premixer 10 for mixing fuel and air, and a flame stabilizer 11.

The compressed air of the air system in the gas turbine is distributed as follows. That is, the high-pressure air 100 from the compressor 1 is supplied to the combustor outer cylinder 6 and the combustor liner 12.
Of the liner cooling air 103
And flows into the combustor. The remaining air is premixed burner air 102 and diffusion pilot burner air 101.
And supplied into the combustor.

On the other hand, the fuel system includes a main fuel system 200,
A diffusion pilot burner fuel system 201 and a premix burner fuel system 202 branch from this system. The main fuel system 200 is provided with a flow control valve 210 so that the fuel flow can be adjusted according to the load of the gas turbine. The fuel flow rate of the diffusion pilot burner fuel system 201 can be adjusted by a flow rate control valve 211. Similarly, the fuel flow rate of the premix burner fuel system 202 can be adjusted by a flow rate control valve 212.

In the premix burner air 102 flowing into the premix burner 12, a vortex having a rotation axis in the flow direction is generated by the vortex generator 9 projecting into the premixer 10.
Premix burner fuel is jetted from a plurality of premix burner fuel nozzles 8 located downstream of the vortex generator 9 and uniformly mixed by the action of the vortex in the premixer, and then installed at the premix burner outlet. The flame is held by the flame stabilizer 11 and premixed combustion is performed.

By injecting the fuel downstream of the vortex generator 9 in this manner, since there is no fuel in the vortex generator portion, fluctuations in the air or fuel flow rate or unexpected foreign matter such as foreign matter flying may occur. Even if flashback occurs, erosion of the vortex generator can be prevented. In addition, by ensuring a sufficient air flow velocity from the vortex generator to the flame stabilizer and eliminating the structure that holds the flame, flashback can be returned to a normal combustion state temporarily and immediately. .

Next, the premixer 10 having the vortex generator 9 will be described. The wall material constituting the premixer 10 is a plate material in consideration of workability and weight reduction of the entire premixer. The thickness is preferably about 1 to 3 mm in consideration of the structural strength and workability of the premixer, the thickness of the vortex generator, and the like. In addition, since the temperature of the air sent from the compressor is about 400 ° C., stainless steel or the like is selected as the material in consideration of temperature resistance.

In this material, a mountain-shaped cut as shown by the solid line in FIG. 3 is made by a usual means such as a wire cutter.
Thereafter, the plate material 10 is placed on the concave base 15 as shown in FIG. 4, and a bending process such as pressing with the convex base 16 is performed so that the dotted line in FIG. create. An example of the vortex generator manufactured in this manner is shown in FIG.
(B). Similarly, after a predetermined number of vortex generators are sequentially manufactured, the entire plate is bent into a cylindrical shape so that the vortex generator is on the inner peripheral side as shown in FIG. 5, and the seam portion 17 is welded or the like. Joining to make the outer cylinder part of the premixer.

Similarly, the inner cylinder portion of the premixer is manufactured by bending the entire plate into a cylindrical shape so that the vortex generator is on the outer peripheral side. A flow sleeve 13 concentric with the premixer is mounted on the outer surface of the premixer so as to cover the notch hole remaining after the vortex generator is bent. Thereby, the flow of the air flowing into the premixer through the cutout hole can be prevented, and the generation of the vortex having the rotation axis in the flow direction can be made effective.

Further, since the flow sleeve 13 is disposed so as to protrude to the upstream side of the premixer, the airflow in the premixer serves as a leading section until the air flows to the vortex generator. The generation of a vortex having a rotation axis in the direction can be made effective, and the mixing of fuel and air can be promoted.
As a result, NOx emitted from the combustor can be suppressed, and the flame propagates through the dense portion of the fuel, so-called flashback occurs, and the possibility of melting and destroying the components of the combustor becomes extremely small. It is possible to simplify or eliminate the flashback prevention mechanism.

FIG. 6 shows another embodiment of the premixer with a vortex generator according to the present invention. As shown in this figure, when a tube material is used as a member of the premixer, if the concave and convex bases are made of a material suitable for the curvature of the tube material, it can be manufactured in the same manner as the case using the flat plate described above. Also, when using a plate material, by using the concave and convex bases that are suitable for the predetermined curvature, the production of the vortex generator and the cylindrical bending of the premixer can be performed at the same time. The manufacturing process of the container can be reduced.

FIGS. 2, 7 and 8 show another embodiment. As shown in FIG. 8, by selecting appropriate shapes for the concave and convex bases, the attachment angle of the vortex generator to the premixer wall can be set arbitrarily. For example, a vortex generator having a shape as shown in FIG. 2 can also be manufactured by cutting a trapezoidal shape (or a mountain shape) as shown in FIG. 7 and then setting the bending angle to 30 degrees.

As shown in FIGS. 1 and 2, the ridges (8a-8b) of the vortex generator need to have an elevation angle α with respect to the main flow direction 102a. At this time, the elevation angle α is 1
More preferably, the angle is about 0 ° to 30 °. The height (8b-8c) of the vortex generator is about 1 / of the height of the premixer flow path.
It is desirable to set it to 3 to 1/2.

If the flow sleeve 13 is not provided, an air flow which flows into the premixer from the cutout portion 14 when the vortex generator is manufactured is generated. At this time, the flow direction of the mainstream air changes in a complicated manner depending on the ratio of the air flowing in from the premixer inlet and the air flowing in from the cutout portion 14.
It is difficult to determine the elevation angle of the vortex generator, which causes the mixing to not be uniform. Therefore, as described above, the flow sleeve 1
Provision of 3 enables more effective vortex generation.

In the above embodiment, the case where one premix burner is provided in the combustor has been described. However, even if there are a plurality of premixers or a plurality of premix burners, a premix burner having a vortex generator is similarly provided. It is possible to produce

The operation of the gas turbine provided with the premixer with the vortex generator manufactured as described above is performed as follows.

In the range from the start up to the rated rotation speed and in a small range of the gas turbine load, the fuel is supplied to the diffusion pilot burner fuel system 201 to operate the diffusion pilot burner 21. At a predetermined load, while decreasing the fuel flow rate of the diffusion pilot burner fuel system 201, the fuel flow rate of the premix burner fuel system 202 is increased, and the operation is performed by the diffusion pilot burner 21 and the premix burner 22. Do. In the premix burner, the flame is held by the circulating flow downstream of the flame stabilizer, thereby enabling stable combustion.

Further, by changing most of the diffusion combustion to the premix combustion, it is possible to suppress NOx discharged from the combustor. At this time, the vortex generator projecting into the premixer generates a vortex with a rotation axis in the flow direction in the premixer, promoting the mixing of fuel and air, and a uniform concentration distribution at the premixer outlet. Is obtained, the NOx discharged from the premix burner becomes almost zero. That is, most of the NOx discharged from the combustor is the NOx discharged from the diffusion burner. Since the diffusion burner is smaller than the premix burner, the total NOx amount can be suppressed.

Then, after increasing the fuel flow rate of the diffusion pilot burner fuel system 201 and the premix burner fuel system 202 to increase the load, the fuel flow rate of the diffusion pilot burner fuel system 201 at a predetermined load is increased. Is reduced to 0, and the operation is performed using only the premix burner 22. At this time, since the diffusion burner 21 is not ignited at all, only the premix combustion is operated, and the NOx generated from the combustor can be extremely reduced.

The diffused air 101 mixes with the combustion gas of the premixed gas in the combustor, reaches a predetermined temperature, and is sent to the turbine. At this time, when another appropriate amount of fuel (not shown) is introduced into the diffusion air 101, the air for diffusion pilot burner 1
01 and then flows into the combustion chamber, where it mixes with the combustion gas of the premix burner 22 to reach a high temperature of about 1100 ° C. or higher, so that the injected fuel sufficiently reacts in the combustor,
High combustion efficiency can be obtained even if the fuel-air ratio is extremely small. Therefore, the output of the gas turbine can be increased without increasing the generated NOx. Alternatively, in the case of the constant load control, the fuel-air ratio of the premixed gas can be reduced correspondingly, so that effects such as improvement of the life of the high-temperature components such as the liner and securing of a margin against flashback can be obtained.

At this time, when the diffusion pilot burner fuel system 201 is supplied with fuel at a flow rate controlled such that the diffusion flame does not hold flame and the flow in the diffusion fuel system does not stagnate, Since the fuel in the fuel pipe can be prevented from being replaced by air, the diffusion burner can be ignited immediately in an emergency such as when the load is cut off, which is more preferable.

As described above, in the gas turbine combustor formed as described above, a predetermined cut is made in a thin plate-like material forming the wall of the premixer, and the cut portion is bent to substantially make the plate. The vortex generator can be easily manufactured by forming a vortex generator having a shape of a circle. In addition, by generating a vortex having a rotation axis in the flow direction, the mixing of fuel and air is made uniform and NOx is generated. It becomes possible to suppress.

Further, by arranging the flow sleeve on the outer peripheral side so as to cover the notch after the vortex generator is bent, the flow of air flowing into the premixer from the notch can be prevented, and the flow direction can be reduced. A vortex having a rotation axis can be effectively generated.

Also, an object provided with a vortex generator manufactured by making a cut in a part of a wall constituting the cylinder and bending the part toward the inside of the cylinder is premixed. By arranging a plurality of vortex generators in a vessel, a vortex generator can be easily manufactured even with a premixer having a relatively complicated shape. Further, by injecting the fuel into the roughly cylindrical object, the penetration of the fuel jet into the air flow becomes uniform, so that the fuel-air mixture can be made uniform.

With the vortex generator manufactured in this manner,
A vortex having a rotation axis in the flow direction is generated in the air flow in the premixer, and the vortex homogenizes the fuel-air mixing, so that an ultra-low NOx combustor having less than 10 ppm of NOx can be realized. Further, by injecting the fuel downstream of the vortex generator, even if flashback occurs, the vortex generator can be immediately returned to a normal combustion state without being melted.

[0038]

As described above, according to the present invention, a vortex generator can be easily manufactured without increasing the size of the premixer itself, and the premixer has a complicated shape. This kind of gas turbine combustor in which the vortex generator can be mounted in a short time can be obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a gas turbine combustor of the present invention and an enlarged view of a main part of a vortex generator.

FIG. 2 is an enlarged perspective view of a main part showing another embodiment of the vortex generator of the gas turbine combustor of the present invention.

FIG. 3 is an enlarged view (cutting operation) of a main portion showing an embodiment of the vortex generator of the gas turbine combustor according to the present invention.

FIG. 4 is an enlarged view (bending work) of a main part of an embodiment of the vortex generator of the gas turbine combustor according to the present invention.

FIG. 5 is a perspective view showing one embodiment of a vortex generator of the gas turbine combustor of the present invention.

FIG. 6 is an enlarged view (bending work) of a main part showing another embodiment of the vortex generator of the gas turbine combustor of the present invention.

FIG. 7 is an enlarged view (cutting operation) of a main part showing another embodiment of the vortex generator of the gas turbine combustor of the present invention.

FIG. 8 is an enlarged view (bending work) of a main part showing another embodiment of the vortex generator of the gas turbine combustor of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 compressor, 2 combustor, 3 gas turbine, 4 generator, 5 gas turbine casing, 6 combustor outer cylinder, 7
... combustor cover, 8 ... premixed fuel nozzle, 9 ... vortex generator, 10 ... premixer, 11 ... flame stabilizer, 12 ... combustor liner, 13 ... flow sleeve, 14 ... notch, 21 ... diffusion pilot Burner, 22: Premixed burner, 100: Combustor inflow air, 101: Diffusion combustion air, 102: Premixed combustion air, 103: Cooling air, 200: Total fuel, 2
01: diffusion fuel, 202: premixed fuel, 210: fuel flow control valve, 211: diffusion fuel flow control valve, 212: premixed fuel flow control valve.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Narika Kobayashi 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Power & Electric Development Laboratory, Hitachi, Ltd. (72) Masaya Otsuka Inventor Masaka Otsuka, Ibaraki Prefecture 7-2 cho-cho, Hitachi, Ltd. Power and Electric Development Laboratory

Claims (6)

[Claims] 1. A premixer for supplying a mixed gas to a combustion chamber, wherein a vortex generator for generating a vortex in the flowing gas and a fuel for injecting fuel into the flowing gas are provided inside the premixer. In a gas turbine combustor comprising a nozzle, the vortex generator is cut into a part of a wall constituting an outer peripheral wall of the premixer, and the cut portion is bent toward the inside of the premixer. A gas turbine combustor characterized in that the gas turbine combustor is formed so as to be erected and generate a vortex in the flowing gas at the erected projection. 2. A premixer for supplying a mixed gas to a combustion chamber, wherein a vortex generator for generating a vortex in the flowing gas and a fuel for injecting fuel into the flowing gas are provided inside the premixer. A gas turbine combustor comprising a nozzle, wherein the vortex generator has a mountain-shaped or trapezoidal cut in a part of a wall constituting an outer peripheral wall of the premixer, and the mountain-shaped or trapezoidal cut is formed. A gas turbine combustor characterized in that a trapezoidal apex is bent in the direction toward the inside of the premixer so as to be erected and formed so as to generate a vortex in the flowing gas at the erected projection. 3. The gas turbine combustor according to claim 1, wherein the upstanding projection is formed to have an elevation angle of 10 to 30 degrees with respect to the flow direction of the flowing gas. 4. The height of the upstanding projection is formed to be 1/3 to 1/2 of the height of the premixer.
Or the gas turbine combustor according to 3. 5. The gas turbine combustor according to claim 1, wherein the upstanding projection is formed so as to be located on an upstream side of a flowing gas from a fuel injection port of the fuel nozzle. 6. The gas turbine combustor according to claim 1, wherein a sleeve concentric with the premixer is fitted around an outer periphery of the premixer.