JPS6183813A - Fuel injecting device - Google Patents

Abstract

PURPOSE:To contrive to protect the top end and side wall of a nozzle arranged protrusively in a burning chamber from the overheating due to a high temperature burning gas by a method wherein a fuel is flowed uniformly along the inner surface other than the top end part thereof for a convection forced cooling caused by the structure having impingement cooling effect. CONSTITUTION:A nozzle core top end 18 and an outer pipe top end 19 are formed into a spherical shape, a fuel inlet hole 20 is extended to the nozzle top end 18 at the central part of a nozzle core 16. An outer pipe 17 is mounted for forming a channel 22 and a space 23 between the outer pipe 17 and a core outer wall 21 of the nozzle core 16. A low temperature fuel flowed through the fuel inlet hole 20 is flowed out from the core top end 18, then flowed back through the channel 22 with striking the inner surface of the outer pipe top end 19, injected into an annular burning chamber 7 through plural fuel injecting holes 24. The heat resistance is made larger by providing the space 23, the heat flux produced in the core 16 is restrained under small condition, accordingly, the temperature gradient between the core outer wall 21 and the inner wall of the fuel inlet hole 20 is made small and the generation of thermal stress can be restrained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a fuel injection nozzle for a gas turbine combustor;
In particular, it relates to a cooling structure for the nozzle side wall and tip.

[Background of the invention]

Air pollutants such as NOx, CO, and Sox are emitted from gas turbine combustors, and the basic measures to reduce NOx are particularly important when reducing NOx at high temperatures in the NOx generation scene. It is necessary to reduce the area (hot spot) and achieve uniform combustion. To achieve this, (1) the fuel must be dispersed to reduce the combustion load per fuel nozzle, and (2) the fuel must be burned in a lean mixed state with excess air.

In order to burn with excess air, it is desirable to inject fuel at a point where the target average excess air ratio is obtained, and for this it is also necessary to place the fuel nozzle so that it protrudes into the combustion chamber. becomes.

FIG. 10 shows a conventional annular combustion cylinder IK with a plurality of protruding combustion nozzles 2 arranged therein. FIG. 11 is an enlarged view of the vicinity of the combustion nozzle, in which the fuel flows through a plurality of injection holes 4 arranged on the side wall near the nozzle tip 3, and at almost right angles to the opposing combustion wall 5 of the combustion tube 1. It is ejected in the same direction. The reason why the jet holes 4 are arranged in such a direction is related to the flame holding mechanism. That is, in the annular combustion tube 1, it is necessary to form a strong combustion gas circulation area near the corner where the upstream plate 6 of the combustion tube 1 and the combustion wall 5 connect, and in order to achieve stable flame holding, a strong combustion gas circulation area must be formed near the corner where the upstream plate 6 of the combustion tube 1 and the combustion wall 5 connect. Interference with the mainstream air,
The above-mentioned requirements need to be met from the viewpoint of shunting and the like.

As described above, the problem with the conventional method in which the fuel nozzle is disposed so as to protrude into the combustion chamber is that the nozzle wall is easily overheated by the combustion gas, and in particular, the nozzle tip 3 becomes hot.

[Purpose of the invention]

An object of the present invention is to provide a fuel nozzle in a fuel injection nozzle of a gas turbine combustor, which is equipped with a cooling structure for protecting the nozzle tip and side wall, which are arranged to protrude into the combustion chamber, from overheating due to high-temperature combustion gas. It's about doing.

[Summary of the invention]

In the present invention, the fuel nozzle is constructed with a double pipe, and the fuel flows at the tip of the nozzle so as to collide with the tip.
It has a structure that performs impingement cooling, and is characterized in that the fuel is uniformly flowed along the inner surface of the nozzle side wall other than the tip, and forced convection cooling is performed.

[Implementation sequence of the invention]

A specific example of the present invention is shown in FIG. 9, FIGS. 1 to 5, and FIG. 12.

FIG. 9 shows a cooled fuel nozzle structure that is the basis of the present invention. FIG. 9 is a diagram showing in detail the annular combustion chamber section and the fuel nozzle section of the entire combustor configuration of FIG. 10 used to explain the prior art.

The annular combustion chamber 7 includes a combustion chamber outer wall 8, a combustion chamber inner wall 9, and a front cover 1.
The fuel nozzles 11 having a plurality of cooling structures are installed in this space at equal intervals in the circumferential direction, protruding into the annular combustion chamber 7 as shown in the figure. FIG. 12 is a view taken along the line (■) in FIG. 9 and shows how the fuel nozzle is installed in the annular portion.

The root portion of the fuel nozzle 11 is attached so as to be integral with the end cover 12, and is configured to be independent from the annular combustion chamber 7. That is, the nozzle insertion hole 13 provided in the front cover 1° is made sufficiently larger than the nozzle diameter,
When the fuel nozzle 11 is inserted, the fuel nozzle 11 is installed so as to have a sufficient concentric air flow gap 14, and there is no contact between the fuel nozzle 11 and the constituent members of the combustion chamber 7.

As shown in the figure, the portion of the fuel nozzle 11 disposed from the upstream side of the front cover 1o of the annular combustion chamber into the combustion chamber has a double pipe structure. This part consists of a nozzle core 16 manufactured to have a smaller diameter than the nozzle root part 15, and a thin outer tube 17 covering the nozzle core 16. The nozzle core tip 18 and the outer tube tip 19 are formed into spherical shapes, and a fuel inlet hole 20 extends to the nozzle core tip 18 at the center of the nozzle core 16 .

The outer tube 17 is attached to the core outer wall 21 of the nozzle core 16 so as to form a flow path 22 and a gap 23 between the outer tube 17 and the core outer wall 21 of the nozzle core 16 . The fuel flowing through the fuel inlet hole 20t flows out from the core tip 18, then flows backward through the flow path 22 without colliding with the inner surface of the outer tube tip 19, and flows through several 4JI fuel holes provided on the outer tube side wall. It passes through the injection hole 24 and is injected into the annular combustion chamber 7. In order to prevent the fuel that has passed through the flow path 22 from flowing into the gap 23, an annular subena 25 is arranged in the gap.

In particular, the reason why the void 23 is provided is to increase the thermal resistance in this part, suppress the heat flux flowing into the core 16, and reduce the temperature gradient between the core outer wall 21 and the inner wall of the fuel inlet hole 2o. This suppresses the generation of stress. On the other hand, the outer tube 17 is constructed of a thin-walled tube, which is designed to minimize the temperature gradient inside and outside the plate thickness and suppress the generation of thermal stress even if the metal temperature level in this section rises. An advantage of the present invention is that the cooling of the nozzle tip, which is a problem, can be efficiently achieved by the flow of the fuel itself with a relatively simple structure.

The embodiment shown in FIG. 1 has the same basic structure as that shown in FIG. 9 described above, except for the cooling structure for the nozzle tip. The feature of this structure is that an air chamber 26 is provided downstream of the nozzle core 16, the tip has a spherical structure with a uniform plate thickness, and the spherical plate has radial ejection holes 27 facing the center of the sphere. . FIG. 2 shows how a plurality of pores 27 are attached to the spherical plate.

The jet stream 28 exiting the pore 27 collides with the spherical inner wall 29 of the distal end portion of the outer tube 17 disposed opposite to each other, passes through the flow path 22, and is emitted from the fuel injection hole 24.

Although this method makes the tip a little more complicated, the impingement/impingement cooling can be performed by the impingement jet generated by the fine holes 28, so the tip can be cooled efficiently even though the cooling efficiency is affected. can.

Next, the embodiment shown in FIG. 3 will be described.

This embodiment is the same as the embodiment shown in FIG. 1 in that impulse cooling is performed at the nozzle tip, and also,
An air chamber 30 is provided near the tip of the nozzle core, and after the pressure in the air chamber is uniformly restored, the refrigerant fuel is jetted out through the jet pores 27.

The feature of this embodiment lies in the passage of the refrigerant flowing into the air chamber 30. In the embodiment, the fuel entered the air chamber through the flow path provided in the center of the nozzle core, but in the present invention, the fuel enters the air chamber through the flow path provided in the center of the nozzle core, but in the present invention, the fuel enters the center of the nozzle core 16 up to the nozzle position corresponding to the front lid 10 of the annular combustion chamber 7. The fuel is guided through the provided fuel inlet hole 20,
Beyond this, a plurality of upstream branch paths 31 are provided diagonally.
It flows through the annular gap 23 between the nozzle core outer wall 21 and the outer tube 17 . The fuel that has flowed forcibly through the air [23] to the downstream side of the nozzle flows into the air chamber 30 through a plurality of downstream branch passages 32 that are opened so as to be guided to the air chamber 30. By changing the flow path in this way, forced convection cooling can be performed on the outer tube, which is easily exposed to combustion gas and tends to reach a high temperature, and the temperature can be kept below a predetermined temperature.

Furthermore, since the heat flux to the nozzle core 16 can be suppressed, there is an advantage that the reliability of the nozzle core 16 can be improved.

The embodiment shown in FIG. 4, like the embodiment shown in FIG. 3, cools the outer tube side wall and the tip of the outer tube at the same time. The fuel is allowed to flow through the annular gap 23 formed between the outer tube 17 and the nozzle core outer wall 21,
Perform forced convection heat transfer. On the other hand, the tip of the outer tube
In the illustrated embodiment, the spherical shape is replaced by a smooth disk 33 that is easy to manufacture, and a plurality of heat transfer fins 34 are arranged on the inner surface of the nozzle of the disk. At the tip of the nozzle core 16 facing this fin, an air chamber 35 is also provided for the purpose of equalizing the flow rate balance in the air gap 23, and the downstream outlet of the air chamber 35 is provided with respect to the finned disk 33. The ejection holes 36 are provided vertically. In this structure, the fuel that has exited the nozzle 36 collides with the opposing disc 33, flows between the rows of heat transfer fins, and is finally jetted out from the fuel nozzle 24.

The basic idea of this invention is to achieve both impingement cooling and forced convection heat transfer with a disk or heat transfer fins for the nozzle tip, by attaching fins to the disk. However, since the nozzle tip is a disk and is relatively easy to manufacture, it is also relatively easy to arrange the jet holes 36 so that the colliding flow perpendicularly hits the flat plate. It is possible to increase the efficiency of moisture cooling.

Next, the embodiment shown in FIG. 5 will be described.

This embodiment is a modification of the embodiment shown in FIG.
Fuel flows through the three sections to perform forced convection heat transfer. On the other hand, the nozzle tip is composed of a disk 36 that is easy to manufacture, and the nozzle core tip is provided with an air chamber 37 for pressure adjustment, as in the previous embodiments, and the outlet of the air chamber 37 is , an injection disk 38 is provided to face the disk 33, and this disk 38 has fine holes 39 for fuel injection densely arranged near the center of the disk, as shown in FIG. , are arranged sparsely in areas far from the center to strengthen cooling near the center of the disk 36. The fuel exiting the pores 39 becomes a jet and collides with the inner surface of the disc 36, thereby efficiently performing impingement cooling.

The advantages of this embodiment are that the tip part is relatively easy to manufacture, and that a high cooling efficiency can be achieved with sufficient cooling efficiency. You can also change the degree.

〔·Effect of the invention〕

According to the present invention, the tip and side wall of the fuel injection nozzle installed protruding into the combustion chamber can be prevented from being overheated by combustion gas, and the fuel injection nozzle can be operated while being maintained at a predetermined temperature or lower.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the present invention, with impingement/
Fig. 2 is an enlarged view of the vicinity of the pores at the tip of the nozzle, and Fig. 3 is an embodiment of the present invention, in which the nozzle tip and side wall are simultaneously cooled. A structural diagram, FIG. 4 is an embodiment of the present invention, and a diagram of a cooling structure in which the nozzle tip is a flat plate and heat transfer fins are arranged on the inner surface. FIG. 5 is an embodiment of the present invention. is a flat plate,
A flat plate with multiple pores attached to the IL is arranged to improve cooling efficiency.
Fig. 7 is a cross-sectional view taken along arrows, and Fig. 7 is a cross-sectional view taken along arrows 8
The figure is a sectional view taken along arrows -■ in Figure 5, Figure 9 is a diagram of the cooling type fuel nozzle that is the basis of the present invention, and Figure 10 is a diagram showing the positional relationship of the fuel nozzle in a combustor with a conventional structure. , Fig. 11 is an enlarged view of the vicinity of the fuel nozzle in Fig. 10, and Fig. 12 is an enlarged view of the vicinity of the fuel nozzle in Fig. 10.
The figure is a store-to-store arrow view in Figure 9, showing the arrangement of multiple fuel nozzles. - Interstitial injection hole, 5... Combustion wall, 6... Upstream plate, 7... Annular combustion chamber, 8... Combustion chamber outer wall, 9...
Combustion chamber wall, 10... Front cover, 11... Fuel nozzle,
12... Machining/Dokaper, 13... Nozzle insertion hole, 1
4... Air passage gap, 15... Nozzle root, 1
6... Nozzle core, 17... Outer pipe, 18... Nozzle core tip, 19... Outer'u tip, 20... Fuel inlet hole, 21... Core outer wall, 22... Channel , 23...
・Gap, 24...Fuel injection hole, 25...Spacer,
26... Air chamber, 27... Pore, 28... Jet flow,
29...Tip portion spherical inner wall, 30...Air chamber, 31...
... Upstream branch road, 32... Downstream branch road, 33...
・Disk, 34... Heat transfer fin, 35... Air chamber, 3
6... Ejection hole, 37... Air chamber, 38... Injection disk, 39... Pore.

Claims (1)

[Claims] 1. A fuel injection device installed protruding inside a gas turbine combustion chamber, the fuel injection device including an inner support core and an annular gap formed inside the inner support core, covering the inner support core. and a thin-walled outer tube installed as shown in FIG. Injection device. 2. Claim 1, wherein a portion of the fuel injection device inserted into the combustion chamber circulates fuel in the annular gap, and a tip portion of the fuel injection device circulates a plurality of the fuels. 2. A fuel injection device, characterized in that a flow path is formed in an inner surface of the tip to perform impingement cooling.