JP2010002096A - Combustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve ignitability in a combustor forming an air current of fast flow velocity in the vicinity of an inner wall of a combustion chamber. <P>SOLUTION: The combustor 1 is equipped with the combustion chamber 24 burning an air-fuel mixture including an oxidizer and fuel, and an ignition device 3 igniting the air-fuel mixture supplied to the combustion chamber 24. A low flow-velocity flow area forming means 5 is provided for forming an area wherein the ignition device 4 forms a flame kennel as a low flow-velocity flow area with velocity lower than an air current by separating the air current flowing along the inner wall of the combustion chamber 24. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a combustor including a combustion chamber in which an air-fuel mixture containing an oxidant and fuel is combusted, and an ignition device that ignites the air-fuel mixture supplied to the combustion chamber.

  As is well known, a combustor installed in a gas turbine engine or the like includes a combustion chamber, and an air-fuel mixture composed of an oxidant such as air and fuel is burned in the combustion chamber. Such a combustor includes an ignition device that forms flame nuclei inside the combustion chamber, and after the air-fuel mixture is supplied to the combustion chamber from the outside, mixing is performed by forming flame nuclei in the ignition device. I ignite.

For example, Patent Literature 1 and Patent Literature 2 disclose a combustor including an igniter as the ignition device.
And the combustor disclosed by patent document 1 and patent document 2 employ | adopts the structure which makes the front-end | tip of an igniter protrude inside a combustion chamber.
Patent Document 3 discloses a combustor in which a spark plug as the ignition device is protruded into the combustion chamber only at the time of ignition.
Japanese Patent No. 3990678 Japanese Patent No. 3109780 JP-A-8-213148

In the conventional combustor, as can be seen from Patent Documents 1 to 3, disposing the tip of the ignition device (location where the flame kernel is formed) from the inside of the combustion chamber is effective in improving the ignitability of the air-fuel mixture. It was thought to be.
However, in recent combustors, to improve combustion efficiency, the air-fuel mixture is swirled strongly in the combustion chamber, or an oxidant is supplied along the inner wall of the combustion chamber to cool the wall of the combustion chamber. To do. For this reason, an air flow having a considerably high flow velocity is formed in the vicinity of the inner wall of the combustion chamber.
When such an air flow having a high flow velocity is formed near the inner wall of the combustion chamber, the flame nuclei that are formed are converted into an air flow having a high flow velocity when the tip of the ignition device is disposed closer to the inside of the combustion chamber. It will be exposed. For this reason, before a flame kernel grows, it may be blown away by the flow of the air flow and the air-fuel mixture may not be ignited.
In other words, in a combustor in which an air flow having a high flow velocity is formed near the inner wall of a combustion chamber like a recent combustor, when a configuration in which the tip of a conventional ignition device is arranged from the inside of the combustion chamber, The ignitability will be reduced.

  The present invention has been made in view of the above-described problems, and an object thereof is to improve ignitability in a combustor in which an air flow having a high flow velocity is formed in the vicinity of the inner wall of a combustion chamber.

  The present invention adopts the following configuration as means for solving the problems.

  A first invention is a combustor comprising a combustion chamber in which an air-fuel mixture containing an oxidant and fuel is combusted, and an ignition device for igniting the air-fuel mixture supplied to the combustion chamber, wherein the combustion chamber A configuration is adopted in which a low-velocity flow field forming unit is used in which a region where the ignition device forms flame nuclei is made a low-velocity flow field whose speed is slower than that of the airflow by separating the airflow along the inner wall.

  According to 1st invention which employ | adopts such a structure, the area | region where an ignition device forms a flame kernel by peeling the airflow along the inner wall of a combustion chamber in a low flow velocity flow field formation means is the above-mentioned It is a low-velocity flow field that is slower than the air flow.

  According to a second aspect of the present invention, in the first aspect of the invention, the low flow velocity flow field forming means includes a recess that dents from the inner wall of the combustion chamber toward the outside of the combustion chamber and separates the airflow, A configuration is adopted in which the flame nucleus forming part of the ignition device is arranged.

  A third invention adopts a configuration in which, in the second invention, the recess is locally formed at a place where the flame nucleus forming portion of the ignition device is disposed.

  According to a fourth invention, in the second or third invention, the low flow velocity flow field forming means further includes a peeling promoting means for promoting the peeling of the airflow.

  In a fifth aspect based on the fourth aspect, the separation promoting means is disposed on the upstream side of the recess with respect to the flow direction of the airflow and protrudes from the inner wall toward the inside of the combustion chamber. The configuration of being is adopted.

According to the present invention, the region where the ignition device forms flame nuclei in the low flow velocity flow field forming means is separated from the air flow along the inner wall of the combustion chamber. It is considered a place.
For this reason, the flame kernel formed in the ignition device can grow in a low flow velocity flow field, and it can be suppressed that the flame kernel is blown away by a high-speed air stream. Therefore, it becomes possible to improve the ignitability in the combustor in which an air flow having a high flow velocity is formed near the inner wall of the combustion chamber.

  Hereinafter, an embodiment of a combustor according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

(First embodiment)
The combustor 1 of this embodiment is arrange | positioned, for example between the compressor of a gas turbine (gas turbine engine), and a turbine, and the shape setting is carried out in the cyclic | annular form centering on the shaft of a gas turbine. Since the structure of the gas turbine is well known, the description thereof is omitted here.

  FIG. 1 is a cross-sectional view showing a schematic configuration of a combustor 1 according to the present embodiment. One of two cross sections of a combustor that appears when the gas turbine is cut in half along the extending direction of the shaft. It shows one.

  As shown in FIG. 1, a combustor 1 according to this embodiment includes a combustion cylinder 2 disposed on a rear stage side of a compressor included in a gas turbine, and fuel is injected and mixed with air that is an oxidant, and the mixing The fuel injection nozzle unit 3 supplies gas to the combustion chamber 24 provided in the combustion cylinder 2 and the ignition plug 4 (ignition device) that ignites the air-fuel mixture supplied to the combustion chamber 24.

The combustion cylinder 2 includes an outer liner 21 arranged in a circumferential direction around the shaft of the gas turbine, an inner liner 22 arranged so as to be displaced from the outer liner 21 toward the shaft, and between the outer liner 21 and the inner liner 22. And a combustion partition wall 23 to be disposed. A space surrounded by the outer liner 21, the inner liner 22, and the combustion partition wall 23 is a combustion chamber 24.
That is, a combustion chamber 24 formed by being surrounded by the outer liner 21, the inner liner 22 and the combustion partition wall 23 is provided.

In the combustion cylinder 2, a part of the compressed air supplied from the compressor side of the gas turbine passes through the outer liner 21 and the inner liner 22 along the inner wall of the combustion chamber 24 (the surfaces of the outer liner 21 and the inner liner 22). It is configured to flow.
As described above, the compressed air is caused to flow along the inner wall of the combustion chamber 24, so that the walls of the combustion chamber 24 (the outer liner 21 and the inner liner 22) are cooled during combustion.

A plurality (for example, 12 or 18) of fuel injection nozzles 3 are installed in the combustor 1. These fuel injection nozzle portions 3 are arranged in an annular shape with a predetermined interval around the shaft of the gas turbine.
As shown in FIG. 1, each fuel injection nozzle section 3 is supported by an injection nozzle 31 supported by a combustion partition wall 23 of the combustion cylinder 2 and a combustion partition wall 23 of the combustion cylinder 2 so as to surround the injection nozzle 31. And an air supply unit 32.
The injection nozzle 31 is configured so that fuel supplied from the outside is atomized and injected toward the combustion chamber 24. The air supply unit 32 is configured to inject compressed air supplied from the compressor of the gas turbine toward the combustion chamber 24 so as to swirl within the combustion chamber 24.

According to the fuel injection nozzle unit 3 having such a configuration, fuel is injected from the injection nozzle 31 toward the combustion chamber 24, and the compressed air swirled from the air supply unit 32 disposed around the injection nozzle 31 is The fuel is injected toward the combustion chamber 24.
The fuel injected from the injection nozzle 31 and the compressed air injected from the air supply unit 32 are mixed to form an air-fuel mixture, which is supplied to the combustion chamber 24 while swirling.
In other words, the fuel mixture is supplied to the combustion chamber 24 by the fuel injection nozzle unit 3.

A plurality of (for example, two) spark plugs 4 are installed in the combustor 1. These ignition plugs 4 are arranged at symmetrical positions around the shaft of the gas turbine, for example.
Each spark plug 4 has a tip 41 (flame nucleus forming portion) disposed on the combustion chamber 24 side, and is configured to form a flame nucleus at the tip 41 and ignite the air-fuel mixture at the start of combustion. Yes.

And the combustor 1 of this embodiment is provided with the recessed part 5 (low flow velocity flow field formation means) which makes the area | region R in which the spark plug 4 forms a flame kernel as a low flow velocity flow field, as shown in FIG. Yes.
In the combustor 1 of the present embodiment, the low flow velocity flow field means a flow field having a slower speed than the airflow of the air-fuel mixture flowing along the inner wall of the combustion chamber 24.

The recess 5 is formed to be recessed in a cylindrical shape from the inner wall of the combustion chamber 24 (the surface of the outer liner 21) toward the outside of the combustion chamber 24. The tip 41 of the spark plug 4 is disposed at the bottom of the recess 5.
In addition, the recessed part 5 is locally formed in the combustion chamber 24 in the location where the front-end | tip 41 of each spark plug 4 is arrange | positioned.

FIG. 2 is a schematic diagram for explaining the operation of the recess 5.
As shown in this figure, the recess 5 separates the airflow X along the inner wall of the combustion chamber 24. In this way, the airflow X along the inner wall of the combustion chamber 24 is peeled off, whereby a vortex Y is formed in the recess 5, whereby the flow rate of the air-fuel mixture in the recess 5 becomes slower than the flow rate of the airflow X. As a result, the inside of the recess 5 (that is, the region R where the spark plug 4 forms a flame kernel) becomes the above-described low flow velocity flow field.

  When performing the ignition operation in the combustor 1 of the present embodiment configured as described above, first, an air-fuel mixture is supplied into the combustion chamber 24 by the fuel injection nozzle unit 3 and the outer liner 21 and the inner liner 22 are used. Compressed air is supplied into the combustion chamber 24.

The air-fuel mixture supplied to the combustion chamber 24 by the fuel injection nozzle unit 3 is supplied so as to swirl within the combustion chamber 24. The compressed air supplied into the combustion chamber 24 via the outer liner 21 and the inner liner 22 is supplied along the inner wall of the combustion chamber 24.
Then, due to the action of the air-fuel mixture and compressed air supplied to the combustion chamber 24, a high-speed airflow X is formed along the inner wall of the combustion chamber 24.

When air-fuel mixture and compressed air are supplied to the combustion chamber 24, the air-fuel mixture is subsequently ignited by the spark plug 4.
Here, in the combustor 1 of the present embodiment, the recess 5 forms a low flow velocity flow field having a slower flow velocity than the air flow X inside the recess 5 (that is, the region R in which the spark plug 4 forms a flame kernel). Is done. For this reason, the flame kernel formed at the tip 41 of the spark plug 4 grows without being blown away. Therefore, it is possible to reliably ignite the air-fuel mixture in the combustion chamber 24.

As described above, according to the combustor 1 of the present embodiment, the region R in which the spark plug 4 forms a flame kernel is formed by separating the airflow X along the inner wall of the combustion chamber 24 in the recess 5. The low-velocity flow field is slower than the airflow X.
For this reason, the flame kernel formed in the spark plug 4 can grow in a low flow velocity flow field, and the flame kernel can be prevented from being blown away by the fast airflow X. Therefore, it becomes possible to improve the ignitability in the combustor in which the airflow X having a high flow velocity is formed near the inner wall of the combustion chamber 24.

Further, the combustor 1 of the present embodiment employs a configuration in which a low flow velocity flow field is formed in the recess 5 and the tip 41 of the spark plug 4 is disposed at the bottom of the recess 5.
By adopting such a configuration, it is possible to separately form a low flow velocity flow field while ensuring a combustion space similar to that of the conventional combustor. Therefore, according to the combustor 1 of the present embodiment, it is possible to improve the ignitability while maintaining the combustion performance of the combustor.

FIG. 3 is a table showing the results of an ignition test in the combustor 1 of the present embodiment. As shown in this figure, the ignition test in the combustor 1 of this embodiment is non-ignited by the result of the ignition test in the conventional combustor (the result of the ignition test shown as “before application” in FIG. 3). The main conditions are used. As a result, as shown in the ignition test result shown as “after application” in FIG. 3, the ignition test in the combustor 1 of this embodiment is a non-ignition condition in the ignition test in the conventional combustor. It was found that all of them ignited.
In the ignition test shown in FIG. 3, the ignition test result is “ignition” when the ignition plug 4 has been ignited three times or more after the ignition energy is input (discharged for 10 seconds). “No ignition”.

  Further, in the combustor 1 of the present embodiment, the ignitability is particularly improved when the diameter of the recess 5 is 1.5 to 2 times the width of the tip 41 of the spark plug 4.

Moreover, the combustor 1 of this embodiment employ | adopted the structure in which the recessed part 5 was locally formed in the location where the front-end | tip 41 of the spark plug 4 is arrange | positioned. That is, in the combustor 1 of the present embodiment, when the two spark plugs 4 are installed, the cylindrical concave portion 5 is formed with respect to each arrangement portion of the tip 41 of each spark plug 4, A total of two recessed parts 5 will be formed.
By adopting such a configuration, it is possible to bring the combustion state in the internal space of the combustion chamber 24 due to the presence of the recess 5 as close as possible to the conventional combustor 1. Therefore, according to the combustor 1 of the present embodiment, it is possible to exhibit the same combustion performance as that of the conventional combustor.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the description of the second embodiment, the description of the same parts as in the first embodiment will be omitted or simplified.

FIG. 4 is a schematic view of the vicinity of the recess 5 provided in the combustor of the present embodiment. As shown in this figure, the combustor according to the present embodiment includes a protruding portion 6 (peeling promotion means) for promoting the peeling of the airflow X in the recess 5.
The protrusion 6 is disposed on the upstream side of the recess 5 with respect to the flow direction of the airflow X, and protrudes from the inner wall of the combustion chamber 24 toward the inside of the combustion chamber 24.

According to the combustor of this embodiment having such a configuration, the protrusion 6 becomes an obstacle to the airflow X, and the airflow X collides with the protrusion 6, whereby the airflow X is separated from the inner wall of the combustion chamber 24. Is promoted.
Therefore, the region R (see FIG. 2) in which the vortex Y (see FIG. 2) is reliably formed inside the recess 5 and the tip 41 of the spark plug 4 forms a flame kernel is more reliably set as the low flow velocity flow field. Is possible.
Therefore, according to the combustor of the present embodiment, it becomes possible to further improve the ignitability.

  As described above, the preferred embodiment of the combustor according to the present invention has been described with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, the combustor of the first embodiment employs a configuration in which the airflow X is separated at the recess 5, and the combustor of the second embodiment employs a configuration in which the airflow X is mainly separated at the recess 5. That is, the combustor of the above embodiment includes the recess 5 as the low flow velocity flow field forming means of the present invention.
However, the present invention is not limited to this, and as a low flow velocity flow field forming means of the present invention, a structure including a wall portion surrounding the tip 41 of the spark plug 4 and blocking the airflow X, or an air shield is formed. A configuration including an air shield forming device that blocks the airflow X may be employed.

Further, the combustor of the above embodiment employs a configuration in which the tip 41 of the spark plug 4 is disposed at the bottom of the recess 5.
However, the present invention is not limited to this. For example, the tip 41 of the spark plug 4 may be disposed on the side of the recess 5.
Even when the tip 41 of the spark plug 4 is arranged at the bottom of the recess 5, the tip 41 of the spark plug 4 does not need to be arranged at the center of the bottom, and is arranged at a position offset from the center. May be.

Moreover, the combustor of the said embodiment employ | adopted the structure in which the recessed part 5 is locally formed in the location where the front-end | tip 41 of the spark plug 4 is arrange | positioned.
However, the present invention is not limited to this, and one recess 5 may be formed for the tips 41 of the plurality of spark plugs 4. For example, when the spark plug 4 is disposed at the same position in the extending direction of the shaft of the gas turbine, only one groove-like recess may be formed over the entire circumferential direction of the combustion chamber 24.

Moreover, the combustor of the said embodiment employ | adopted the structure where the recessed part 5 has a cylindrical shape.
However, the present invention is not limited to this, and the shape of the recess 5 is arbitrary as long as the region R in which the tip 41 of the spark plug 4 forms a flame kernel is a low flow velocity flow field. For example, the shape may be set so that the side surface is gently inclined with the concave portion 5 facing the bottom surface.

Further, the combustor of the second embodiment employs a configuration in which the protrusion 6 promotes the separation of the airflow X in the recess 5. That is, the combustor according to the second embodiment includes the protruding portion 6 as the peeling promoting means of the present invention.
However, the present invention is not limited to this. When the recesses smaller than the recesses 5 are formed around the recesses 5 to disturb the flow of the airflow X, and the separation of the airflow X in the recesses 5 is promoted. May be provided with the above-mentioned small recess as the peeling promoting means of the present invention.
Moreover, the shape of the protrusion part 6 is arbitrary if peeling of the airflow X can be accelerated | stimulated.

Further, the combustor of the second embodiment employs a configuration in which the protruding portion 6 is arranged on the upstream side in the flow direction of the airflow X in the concave portion 5.
However, the present invention is not limited to this. For example, the protruding portion 6 is disposed so as to pass over the recessed portion 5 and is disposed at an intermediate position of the recessed portion 5, or the protruding portion 6 is disposed in the airflow in the recessed portion 5. If there is an effect when arranged on the downstream side in the flow direction of X, the protruding portion 6 may be arranged on the downstream side of the concave portion 5.

  In addition, the flow direction of the airflow X does not always go from the compressor side of the gas turbine to the extending direction of the shaft, and it may be difficult to predict the flow direction. For this reason, in order to be able to cope with the flow direction of the airflow X with respect to the concave portion 5, the protruding portion 6 may be arranged so as to surround the concave portion 5 over the entire circumference.

It is sectional drawing which shows schematic structure of the combustor of 1st Embodiment of this invention. It is a schematic diagram of the recessed part vicinity with which the combustor of 1st Embodiment of this invention is provided. It is a table | surface which shows the ignition test in the combustor of 1st Embodiment of this invention. It is a schematic diagram of the recessed part vicinity with which the combustor of 2nd Embodiment of this invention is provided.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Combustor, 2 ... Combustion cylinder, 24 ... Combustion chamber, 3 ... Fuel injection nozzle part, 4 ... Spark plug (ignition device), 41 ... Tip (flame nucleus formation part), 5 ... Recessed portion (low flow rate flow field forming means), 6 ... Projection (peeling promotion means), X ... Airflow, Y ... Eddy current, R ... Area where flame kernel is formed

Claims (5)

A combustor comprising a combustion chamber in which an air-fuel mixture containing an oxidant and fuel is burned, and an ignition device for igniting the air-fuel mixture supplied to the combustion chamber,
A low-velocity flow field forming unit is provided that causes a region where the ignition device forms flame nuclei to be a low-velocity flow field whose velocity is slower than that of the airflow by separating the airflow along the inner wall of the combustion chamber. And a combustor. The low flow velocity flow field forming means is provided with a recess that is recessed from the inner wall of the combustion chamber toward the outside of the combustion chamber and that separates the airflow;
The combustor according to claim 1, wherein a flame nucleus forming portion of the ignition device is disposed at a bottom portion of the concave portion.   The combustor according to claim 2, wherein the recess is locally formed at a place where a flame nucleus forming portion of the ignition device is disposed.   The combustor according to claim 2, wherein the low flow velocity flow field forming unit further includes a separation promoting unit that promotes separation of the air flow. 5. The combustion according to claim 4, wherein the separation promoting means is a projecting portion that is disposed on the upstream side of the concave portion with respect to the flow direction of the airflow and projects from the inner wall toward the inside of the combustion chamber. vessel.

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