JP3826200B2 - Premix combustor - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a premix combustor used in a gas turbine or a jet engine. More specifically, the present invention relates to a premixed combustor used for a gas turbine or a jet engine in which generation of NOx is reduced while maintaining high combustion efficiency.
[0002]
[Prior art]
Conventionally, a premix combustor has been proposed in order to reduce NOX generated by a combustor of a gas turbine or a jet engine (hereinafter simply referred to as a gas turbine). As this premix combustor, for example, a swirler is provided on the downstream side of the fuel injection nozzle, and a mixture of fuel and combustion air is swirled by the swirler to premix, or fuel and combustion air are swirled. There has been proposed a premixing tube without premixing.
[0003]
For example, the one belonging to the former is proposed, for example, in JP-A-4-43220. That is, one or more diffusion combustion type pilot burners for directly injecting fuel into the combustion chamber are provided in the center on the upstream side of the combustion chamber, and four or more premixed combustions are injected into the combustion chamber after the fuel is mixed with air. In the combustor of the gas turbine in which the number of premix burners to be ignited is changed according to the load fluctuation, the combustion chamber side is provided as a premix burner. A fuel pipe having a distributed nozzle is inserted into an air inflow pipe provided with a swirl swirler at the end of the nozzle from the side opposite to the combustion chamber, and the distributed nozzle is radially formed in the radial direction of the fuel pipe. It has been proposed that a plurality of nozzle holes are formed in a plurality of pipes extending and closed at the tips, and the distributed nozzle is positioned in the vicinity of the swirl swirler.
[0004]
As the latter, there is one proposed in Japanese Utility Model Publication No. 63-30070, for example. That is, it comprises a pilot part and a main part, and surrounds the pilot part to form a premixing passage, and this premixing passage is a cylindrical shape made up of inner and outer wall peripheral surfaces. There has been proposed a premixing combustor that is provided on the inner wall circumferential surface of a shaped premixing passage so as to open in a radial direction.
[0005]
However, the conventional premix combustor has the following problems.
[0006]
For example, in the former type in which the premixed gas is swirled by a swirler, there is a problem that the premixed gas is backfired or self-ignited. This tendency is promoted as the combustion air becomes higher in pressure and temperature. Further, the latter type in which premixed gas is obtained by a premixing tube without swirling combustion air has a problem that flame stability is poor.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the prior art, and can stabilize the flame, and there is no risk of back-fire or self-ignition of the premixed gas, and the combustion efficiency is reduced while reducing the generation of NOx. An object of the present invention is to provide a premixed combustor such as a gas turbine that can be improved.
[0008]
[Means for Solving the Problems]
The premixing combustor of the present invention includes a cylindrical or annular premixing combustor forming body that is open on the downstream side, and imparts a swirling force to combustion air at the head of the forming body, and the premixing circulating premixing unit comprising a plurality of premix tubes allowed to rise to flow is disposed, the pilot fuel in the central portion is surrounded by said plurality of premixer tubes of the head for flame holding in the combustor forming the body Injection means is provided, fuel injection means is disposed in each of the plurality of premixing pipes, and the inclination angle of each of the plurality of premixing pipes is a central axis or an annular shape of the cylindrical premixing combustor forming body The premixed combustor forming body is set at 5 to 80 degrees with respect to the central axis, and at 5 to 90 degrees with respect to the reference axis of the head .
[0012]
Here, each of the inclination angles of the plurality of premixing tubes, is 25 degrees to 50 degrees with respect to the central axis of the central axis or annular premixed combustors formation of cylindrical premixed combustors forming body The angle is preferably 25 to 50 degrees with respect to the reference axis of the head.
[0013]
In the premixing combustor of the present invention, the annular premixing combustor forming body is formed of an annular cylindrical body, and has a plurality of premixing portions at the head thereof, each of the premixing portions being the head portion. A premixing means comprising a plurality of premixing pipes, or a plurality of premixing pipes arranged in a single concentric circle at equal intervals, or a fuel injection means as a fuel injection nozzle, A fuel injection nozzle is preferably inserted into the premixing tube .
[0014]
Here, the position of the fuel injection nozzle may be adjusted such that the fuel injection position is the inlet, center, or outlet of the premixing tube. Alternatively, it may be disposed outside the inlet of the premixing tube.
[0015]
The fuel injection nozzle includes a hollow main material and a plurality of projecting members that project from the side surface of the main material and communicate with the main material, and the projecting member has a required number of fuels. It is preferable that the injection holes are provided in a predetermined arrangement.
[0017]
[Action]
In the premixing combustor according to the present invention, premixing means including a cylindrical body group that causes a swirling flow of combustion air is disposed in the premixing portion of the forming body constituting the premixing space. Therefore, a circulation flow is formed in the premixed combustion chamber by the combustion air ejected from the premixing means. Therefore, lean mixed combustion can be performed while stabilizing the flame. Therefore, NOx generation can be reduced while maintaining high combustion efficiency.
[0018]
【Example】
Hereinafter, although the present invention is explained based on an example, referring to an accompanying drawing, the present invention is not limited only to this example.
[0019]
FIG. 1 shows an embodiment of a premix combustor according to the present invention. In this embodiment, the premix combustor C is a so-called can-type, and has a flat end plate inside the outer cylinder 1 at one end. The cylindrical body 2 having 21 and having the other end open is configured with the end plate 21 facing the upstream side. That is, the end plate 21 is used as a head. In this end plate (head) 21, the combustion air supplied from the outer cylinder 1 is swirled and introduced into the premix combustor C. Installed.
[0020]
As shown in FIG. 2, the premixing tube 3 is attached to the end plate 21 in a concentric manner at equal intervals. In the example shown in FIG. 2, the number of the premixing tubes 3 is 6. However, the number is not limited to this, and is appropriately selected according to the size of the premixing combustor C. As shown in FIG. 3, the premixing tube 3 is attached at a predetermined inclination angle α with respect to the axis (center axis) L ₁ of the cylindrical body 2, and as shown in FIG. It is attached to the reference line (reference axis) L _{2 at} a predetermined inclination angle β. The inclination angles α and β are from 5 degrees so that a desired swirl force is applied to the combustion air and a circulation flow for flame holding is formed in the premixed combustor C. The range is 80 degrees, preferably 25 degrees to 50 degrees, and the inclination angle β is in the range 5 degrees to 90 degrees, preferably 25 degrees to 50 degrees.
[0021]
Further, as shown in an exploded view in FIG. 3, a fuel injection nozzle 4 is mounted inside the premixing tube 3. As shown in FIG. 4, a plurality of fuel injection holes 41, 41... Are concentrically formed at the tip of the fuel injection nozzle 4. The size and number of the fuel injection holes 41 are appropriately selected using a conventional method in accordance with the amount of injected fuel. Note that the fuel injection nozzle 4 is not limited to that shown in FIG. 3, and as shown in FIG. 5, a protruding pipe 43 is provided on the body portion 42 of the fuel injection nozzle 4, and fuel injection holes 41, 41 ... may be formed.
[0022]
The position of the fuel injection hole 41 may be the inlet portion, the center portion, or the outlet portion of the premixing pipe 3. However, in an ordinary combustor, the inlet is preferably used from the viewpoint of improving the uniformity of the premixed gas. In a combustor operating at a high temperature and high pressure, the outlet is used from the viewpoint of preventing flashback. Is preferred.
[0023]
The fuel injection nozzle 5 may be disposed outside the inlet of the premixing tube 3 at a position facing the inlet.
[0024]
The portion of the end plate 21 surrounded by the premixing tube 3 may be exposed to the flame and burned out, so it is not shown in the figure. The required number of through holes having a diameter of about 1 mm are provided for cooling.
[0025]
Further, as shown in FIG. 6, a required number, for example, eight fuel injection holes 51 are provided at the center of the portion of the head 21 surrounded by the premixing tube 3 as shown in FIG. May be provided at equal intervals.
[0026]
As shown in FIG. 1, a secondary air supply opening 22 is provided at the rear of the cylindrical body 2 so that the secondary air is supplied into the premixed combustor C. Thereby, since combustion gas is cooled and diluted, generation | occurrence | production of NOX is suppressed. As shown in FIG. 8, the secondary air opening 22 may be configured such that the opening area is adjusted by the valve body 23 to control the secondary air flow rate. In this way, the secondary air flow rate can be set to the optimum flow rate.
[0027]
Example and Comparative Example With the configuration shown in FIG. 1, a premix combustor C was manufactured and a combustion test was performed. The result is shown by a solid line in FIG. The main points of the premixed combustor C in this embodiment are as follows. That is, the premixing tube has an inner diameter of 25 mm, the number of tubes is 6, the inclination angles α and β are both 45 degrees, the cylindrical body has an inner diameter of 140 mm, a length of 350 mm, and the secondary air supply port has a diameter of 18 mm. Is four.
[0028]
For comparison, a combustion test was performed using a conventional diffusion combustor. The result is shown by a dotted line in FIG.
[0029]
As can be seen from FIG. 9, in the example, the amount of NOx generated is reduced despite the fact that the combustion efficiency is maintained as high as the conventional one.
[0030]
As mentioned above, although this invention has been demonstrated based on the Example, this invention is not limited only to the said Example, A various change is possible. For example, the premixing tube is not limited to a circular pipe, and may be a square pipe, for example.
[0031]
In the embodiment, the combustor is a so-called can type, but may be a multi-can type or an annular type in which a plurality of premixed combustion portions are formed in an annular cylindrical body.
[0032]
【The invention's effect】
As described above, according to the present invention, the swirling force is applied to the combustion air by the premixing tube and supplied into the premixing combustor, so that a circulating flow is generated in the premixing combustor. However, premixed combustion can be performed. Therefore, the flame can be stabilized without causing backfire or self-ignition. Therefore, it is possible to obtain an excellent effect that the amount of NOx generated can be reduced while maintaining the combustion efficiency as in the conventional case.
[0033]
Further, in the present invention, since the combustion air is supplied into the premixed combustor together with the fuel by the plurality of premixing tubes, an effect that a uniform premixed gas can be formed is also obtained. Therefore, the premixed combustor of the present invention can be suitably used for a high temperature / high pressure combustor.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a premix combustor according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of arrangement of premixing tubes in the same embodiment.
FIG. 3 is a longitudinal cross-sectional view of a premixing tube showing an exploded fuel injection nozzle.
4 is a longitudinal sectional view of the fuel injection nozzle shown in FIG. 3. FIG.
FIG. 5 is a front view of another example of a fuel injection nozzle.
FIG. 6 is a schematic view of a premix combustor provided with a pilot fuel injection nozzle at the head.
FIG. 7 is a schematic view of a pilot fuel injection nozzle.
FIG. 8 is an explanatory diagram of an opening for secondary air whose opening area can be adjusted.
FIG. 9 is a graph of combustion characteristics of examples and comparative examples.
[Explanation of symbols]
1 outer cylinder 2 cylindrical body 21 end plate (head)
22 Opening for secondary air 23 Valve body 3 Premix pipe 4 Fuel injection nozzle 41 Fuel injection hole 5 Pilot fuel injection nozzle 51 Fuel injection hole C Premix combustor L ₁ Central axis L ₁ Cylindrical center axis L ₂ End plate reference axis

Claims (10)

A cylindrical or annular premix combustor forming body that is open on the downstream side;
A premixing means comprising a plurality of premixing tubes is provided at the head of the forming body to apply a swirling force to the combustion air and to generate a circulation flow for flame holding in the premixing combustor forming body. A pilot fuel injection means is provided in a central portion of the head surrounded by the plurality of premixing tubes;
A fuel injection means is disposed in each of the plurality of premixing tubes,
The inclination angle of each of the plurality of premixing tubes is 5 to 80 degrees with respect to the central axis of the cylindrical premixing combustor forming body or the central axis of the annular premixing combustor forming body, The premixed combustor is set to 5 to 90 degrees with respect to a reference axis of the part . Each of the inclination angles of the plurality of premixing tubes, is 25 degrees to 50 degrees with respect to the central axis of the central axis or annular premixed combustors formation of cylindrical premixed combustors forming body, the head The premixed combustor according to claim 1 , wherein the premixed combustor is set at 25 to 50 degrees with respect to the reference axis. Annular premixed combustors forming body is a circular cylinder having a plurality of premixing portion its head, premixing means each premixing unit comprises a plurality of premix tubes to the head premixed combustors according to claim 1, characterized by being perforated with. The premix combustor according to claim 1 or 3, wherein the plurality of premix tubes are arranged in a single concentric circle at equal intervals. Fuel injection means is a fuel injection nozzle, the fuel injection nozzle, premixed combustors according to claim 1, 3 or 4, wherein the composed is inserted in the premixing tube. 6. A premix combustor according to claim 5 , wherein the fuel injection position of the fuel injection nozzle is an inlet portion of the premix pipe. 6. A premix combustor according to claim 5 , wherein the fuel injection position of the fuel injection nozzle is the center of the premix pipe. 6. A premix combustor according to claim 5 , wherein the fuel injection position of the fuel injection nozzle is an outlet of the premix pipe. Fuel injection means is that the fuel injection nozzle, the fuel injection nozzle, premixed combustors according to claim 1, 3 or 4, wherein the composed disposed at the entrance outside the premixer tubes. The fuel injection nozzle includes a hollow main material, and a plurality of projecting members protruding from the side surface of the main material and communicating with the main material,
Claim 5, 6, 7, 8 or premixed combustor according 9, the required number of fuel injection holes are characterized by being provided with a predetermined sequence to said projecting member.

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