JP2000046333A - Gas turbine combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce Nox by providing a burner for supplying a premixed gas with air at a fuel combustion chamber and forming a plurality of ejection openings of the premix burner in the inner circumferential side face of the combustion chamber along the axial direction thereof thereby making lean the premixed gas through effective use of cooling air. SOLUTION: Compressed air 50 from a compressor 10 passes between the outer tube 2 of a gas turbine combustor and a combustor liner 3 and then a part thereof flows into a premixer 12 as premix combustion air 49 while the remainder flows from a combustion air hole 14 and a cooling air hole 17 into a combustion chamber 1. Diffused combustion fuel 16 is ejected from a diffusion fuel nozzle 13 into the combustion chamber 1 to form a diffused flame 4 and premixing fuel 21 is ejected from a fuel nozzle 8 into an annular premixer 12 where it is mixed with air to produce premixed gas 22. The premixed gas 22 flows from a combustor liner 3 having a louver-like ejection opening into the combustion chamber 1 where it is fired by high temperature gas generated through diffused combustion to form a premixed flame 5 along the wall face of the liner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas turbine combustor, and more particularly to a low NOx combustor for performing lean premix combustion.

[0002]

2. Description of the Related Art In a combustion apparatus, in order to reduce the emission of NOx as an air pollutant, a premixed combustion method in which fuel and air are mixed in advance before entering a combustion chamber has been applied. FIG. 2 shows that diffusion combustion with excellent stability is performed at the center, and premixed combustion with excellent low NOx properties is arranged on the outer peripheral side to reduce NOx.
This is an example in which conversion is attempted. In FIG. 2, air 50 sent from the compressor 10 passes between the outer cylinder 2 and the combustor liner 3,
Part of the air is supplied to the combustion chamber 1 as cooling air 51 for the combustor liner.
Part of the air flows into the premixer 12 as premixed combustion air 49. The remainder flows into the combustion chamber 1 from the combustion air holes 14 and the cooling air holes 17 through a passage between the premixer flow path and the combustor end plate. The diffusion combustion fuel 16 is the diffusion fuel nozzle 13
Is injected into the combustion chamber 1 to form a stable diffusion flame 4.
The premixing fuel 21 is supplied from the fuel nozzle 8 to the annular premixer 1.
2 and is mixed with air to form a premixed gas 22.
The premixed gas 22 flows into the combustion chamber 1 and forms a premixed flame 5 which is held in a high-temperature circulating flow downstream of the flame holding ring 23. The generated high-temperature combustion gas enters the turbine 18 and performs work to be exhausted. Similar examples include JP-A-6-213445 and JP-A-7-280267.

[0003]

When a fuel such as natural gas which does not contain nitrogen atoms in fuel molecules is used, most of the NOx generated during high-temperature combustion has a high dependence on the combustion temperature called thermal NOx. This is caused by a mechanism. In order to reduce NOx, it is necessary to lower the combustion temperature, and it is effective to dilute the premixed gas.
In the prior art, the cooling air 51 of the combustor liner is N
It does not contribute to the dilution of the premixed gas necessary for reducing Ox and thus does not sufficiently contribute to combustion, and is wasteful in that sense.

On the other hand, the premixed flame stabilized by the flame holding ring tends to form a relatively short tropical zone in the axial direction, and is liable to cause a resonance pressure fluctuation phenomenon called combustion oscillation.

Therefore, the present invention provides a gas turbine combustor which can ensure the soundness of the combustor while sufficiently contributing to the dilution or combustion of the premixed air, with much of the air supplied at a high pressure by the compressor. Is to do.

[0006]

According to the present invention, there is provided a gas turbine combustor including a combustion chamber forming a combustion section for burning fuel, and a premix burner for supplying a premixed gas of fuel and air to the combustion chamber. A plurality of outlets of the premixed gas of the premixed burner are formed on a peripheral side surface of the combustion chamber along an axial direction of the combustion chamber.

More specifically, the gas turbine combustor includes a combustion chamber forming a combustion section for burning fuel, a pilot burner forming a pilot flame in the combustion chamber, and fuel and air in the combustion chamber. A premixed burner for supplying a premixed gas, wherein the premixed burner has a plurality of premixed gas injection ports formed from the upstream side to the downstream side of the combustion chamber around the combustion chamber, It is characterized by.

Alternatively, the gas turbine combustor includes a combustion chamber forming a combustion section for burning fuel, and a premix burner for supplying a premixed gas of fuel and air to the combustion chamber. The plurality of injection ports of the premixed gas of the mixing burner are formed on the peripheral side surface of the combustion chamber along the axial direction of the combustion chamber. It is characterized in that the region facing the combustion section of the plurality of injection ports for injecting the air-fuel mixture into the combustion chamber is formed to have a longer axial length.

Preferably, a plurality of premixed gas injection ports of the premixed burner are provided from the upstream side to the downstream side in the axial direction of the combustion chamber facing the combustion section.

[0010] It is preferable that the distance between the ejection ports located on the downstream side of the combustion chamber is larger than the distance in the radial direction of the combustion chamber between the ejection ports located on the upstream side of the combustion chamber.

Alternatively, the gas turbine combustor includes a combustion chamber forming a combustion section for burning fuel, and a premix burner for supplying a premixed gas of fuel and air to the combustion chamber. In the mixing burner, a premixing nozzle for ejecting fuel to the supplied air, and a premixed air of the fuel and air ejected from the premixing nozzle are branched and guided, and burned from upstream to downstream of the combustion chamber. And a plurality of premixed gas ejection ports formed on the inner peripheral side of the vessel.

Alternatively, in a gas turbine combustor which performs premixed combustion, all or a part of a wall constituting a combustion chamber is formed in a louver shape, and the premixed gas is supplied to an opening of the louver. It is characterized in that it is ejected more along the wall surface to form a premixed flame approximately along the wall surface.

In any of the above gas turbine combustors, the stability of the flame can be increased by installing a pilot burner for diffusion combustion or premix combustion as an ignition source. In any of the above gas turbine combustors, it is preferable that a turbulence promoter is disposed on the outer peripheral surface of the combustion chamber wall surface. By providing such a cooling wall structure, the combustor can be further easily heated to a desired temperature.

In any one of the gas turbine combustors, the premixed gas injection port (for example, the louver wall surface)
A second premixed gas outlet having an opening on the downstream side of the nozzle may be further provided. It is possible to adopt a form in which the opening is formed annularly or intermittently. The second premixed gas injection port forms a premixed gas using fuel jetted from a fuel spray nozzle whose flow rate can be controlled separately from the premixing nozzle for jetting fuel supplied to the premixed gas jet port already described. You can make it.

Alternatively, in any one of the above-described gas turbine combustors, a premixing accelerator is provided in the premixed gas flow path.

The premixing accelerator may be a structure that generates a vortex having a central axis of rotation in a direction along a mainstream flow of the premixed gas flow path. In other words, it can be a structure that generates a vortex having a central axis of rotation in the longitudinal direction of the premixed gas flow path. For example, it may be a structure having a facing angle with respect to the longitudinal direction of the flow path of the premixed gas and having a protruding portion projecting from the inner surface of the flow path of the premixed gas.

It is preferable that the premixing accelerator is located downstream of the premixing nozzle from the viewpoint of mixing. However, the premixing accelerator can be installed upstream of the premixing nozzle.

In any one of the gas turbine combustors, the opening width of the louver is less than the quenching distance of the premixed gas.

Alternatively, in a gas turbine combustor for performing premixed combustion, a large number of pores are provided on all or a part of a wall constituting a combustion chamber, and a premixed gas is ejected from the pores to form a wall. A premixed flame can be formed along the line.

It is sufficient that the air serves as an oxidizing agent for the fuel. The air may be taken in as it is, or may be exhaust gas discharged from a combustion device.

Further, in the present invention, by appropriately configuring the structure of the combustor liner and the premixed fuel nozzle, a premixed gas is jetted instead of the cooling air to form a lean premixed flame along the liner. To FIG. 3 shows a schematic diagram of a premixed flame. A flame formed in a premixed gas having a uniform concentration and flowing at a uniform flow velocity is formed to be inclined with respect to the flow, and the inclination is such that the propagation speed of the flame and the normal component to the flame of the flow approaching the flame are determined. It is preferable that the angles be balanced. Therefore, by providing a louver-shaped premixed gas injection port in the combustor liner with an inclination substantially along the flame, a stable lean premixed flame can be formed while maintaining the structure as a wall surface.

By ejecting the premixed gas from the liner, the wall surface can be cooled, and the premixed gas can be diluted without wasting the cooling air. For this reason, N
Ox can be reduced. Further, since the tropical zone is widely dispersed along the liner, it is possible to suppress the occurrence of combustion oscillation due to resonance.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIG. In FIG. 1, air 50 sent from a compressor 10 passes between an outer cylinder 2 and a combustor liner 3, and a part of the air 50 flows into a premixer 12 as premixed combustion air 49. The remainder flows into the combustion chamber 1 from the combustion air holes 14 and the cooling air holes 17 through a passage between the premixer flow path and the combustor end plate. The diffusion combustion fuel 16 is injected into the combustion chamber 1 from the diffusion fuel nozzle 13 to form a stable diffusion flame 4. The premixing fuel 21 is ejected from the fuel nozzle 8 into the annular premixer 12 and mixed with air to form a premixed gas 22. The premixed gas 22 flows out of the combustor liner 3 having a louver-shaped outlet into the combustion chamber 1 and is ignited by the high-temperature gas generated by diffusion combustion to form a premixed flame 5 along the liner wall. The generated high-temperature combustion gas enters the turbine 18 and performs work to be exhausted. With this configuration, during diffusion-only combustion at a low load, air is blown out from the louver-shaped combustor liner 3 along the wall surface, and the liner itself is sufficiently cooled. On the other hand, at the time of high load combustion, the premixed gas is blown out from the louver-shaped combustor liner 3 at a sufficient flow rate, and the premixed flame is stabilized without contacting the wall surface, and the liner wall surface does not become hot. As a result, the cooling air for the combustor liner becomes unnecessary, and accordingly, the premixed air-fuel mixture is made leaner, the combustion temperature is lowered, and NOx can be reduced. Further, since the flame is widely distributed over the entire wall surface and the tropics are widely dispersed, it is possible to suppress the occurrence of resonance combustion oscillation. At this time, the flow rate of the premixed gas ejected from the louver-shaped liner wall should be sufficiently large so that the flame formed as described in FIG. Is desirable. Also, it is desirable that the flow path width of the louver-shaped outlet be narrower, and that the flame enters the premixing flow path by setting it to be equal to or less than the quenching distance (the distance at which the flame cannot propagate due to the quenching effect of the wall surface). Can be prevented.

FIG. 4 shows another embodiment of the present invention. The present embodiment is an example in which the diffusion combustion burner 13 arranged at the center is made small and the premix nozzle 8a and the premix channel 12a are provided around the burner. With this configuration, premixed combustion can be performed under operating conditions where the load on the gas turbine is low, and low NOx operation can be performed over a wide load range.

FIG. 5 shows another embodiment of the present invention. This embodiment has basically the same configuration as the embodiment described with reference to FIG. 4, but is an example in which half of the liner is constituted by the cooling wall 3b with the turbulence promoting body. This is effective when a louver-like premixed gas injection port cannot be formed over the entire combustion chamber in terms of the amount of premixed gas.

FIG. 6 shows another embodiment of the present invention. The basic configuration is the same as that of the embodiment shown in FIGS. 4 and 5, except that a premixed fuel nozzle 8b is installed and an annular or circumferential intermittent is provided downstream of the louver-like ejection wall 3a in the combustion chamber. This is an example in which a jet port 12b is provided and a lean premixed gas is jetted from the jet port 12b. The lean premixture injected from the annular flow path is heated by the high-temperature gas flowing from the upstream side, and the combustion reaction proceeds gently.

FIG. 7 shows another embodiment of the present invention. The basic configuration is the same as that of the embodiment shown in FIG. 4, except that an airfoil premix accelerator 10 disclosed in Japanese Patent Application Laid-Open No. 7-91661 is installed in the premix channel. In order to more stably realize the configuration of the present invention, it is important to ensure the uniformity of the concentration of the premixed gas. However, by installing the premixing accelerator, a uniform gas mixture can be obtained. In addition, uniformity can be achieved with a short mixing distance, and the premixing channel can be shortened.
Of course, the NOx reduction effect is also promoted.

FIG. 8 shows another embodiment of the present invention. This embodiment has basically the same configuration as the embodiment described with reference to FIG. 4, but is an example in which a plate 3c having a large number of pores is provided instead of the louver-like combustion chamber liner. With such a configuration, an effect similar to that of the above embodiment can be obtained, and the number of manufacturing steps can be reduced.

[0029]

According to the present invention, the premixed air can be diluted without wasting the cooling air, and the NOx can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory view of a conventional example.

FIG. 3 is an explanatory view of the means of the present invention.

FIG. 4 is an explanatory view of a second embodiment of the present invention.

FIG. 5 is an explanatory view of a third embodiment of the present invention.

FIG. 6 is an explanatory view of a fourth embodiment of the present invention.

FIG. 7 is an explanatory view of a fifth embodiment of the present invention.

FIG. 8 is an explanatory view of a sixth embodiment of the present invention.

[Explanation of symbols]

3a: louver-like premixed gas ejection wall surface, 8: premixing fuel nozzle, 12: premixer.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuyuki Ito 7-2-1, Omika-cho, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Power and Electricity Development Division (72) Inventor Narika Kobayashi Hitachi, Ibaraki Prefecture 7-2-1, Omika-cho Hitachi, Ltd. Power / Electricity Development Division

Claims (4)

[Claims] A combustion chamber that forms a combustion section for burning fuel; a pilot burner that forms a pilot flame in the combustion chamber; and a premix burner that supplies a premixed mixture of fuel and air to the combustion chamber. A gas turbine combustor, characterized in that the premix burner has a plurality of premixed gas injection ports formed from the upstream side to the downstream side of the combustion chamber on the peripheral side of the combustion chamber. 2. A combustion chamber that forms a combustion section for burning fuel, and a premix burner that supplies a premixed air of fuel and air to the combustion chamber, wherein the premix burner is supplied air. A premixed nozzle for injecting fuel into the combustor; and a premixed air of fuel and air ejected from the premixed nozzle is branched and guided, and is formed on the inner peripheral side of the combustor from the upstream side to the downstream side of the combustion chamber. A plurality of premixed gas outlets;
A gas turbine combustor comprising: 3. A gas turbine combustor performing premixed combustion, wherein all or a part of a wall constituting a combustion chamber is formed in a louver shape, and a premixed gas is injected from an opening of the louver along the wall. A gas turbine combustor characterized by forming a premixed flame approximately along a wall. 4. The gas turbine combustor according to claim 1, wherein a premixing accelerator is provided in a premixed gas flow path.