JP4584054B2 - Fuel nozzle for gas turbine combustor - Google Patents

Description

  The present invention relates to a fuel nozzle for a gas turbine combustor.

  In general, in diffusion combustion of liquid fuel, a large number of minute fuel droplet groups are mixed with air and burned. The combustion reaction by this combustion method proceeds through processes such as evaporation of oil droplets in the sprayed fuel, diffusion of vapor, mixing with ambient air, and combustion of the gas mixture generated thereby. For this reason, the larger the fuel droplet diameter injected from the fuel nozzle, the more the fuel evaporates, and as a result, the worse the mixed state of air and fuel, the more the oxidation reaction delays. Particles may be enlarged. For this reason, it is generally considered to be most effective to reduce soot dust by promoting atomization of liquid fuel and mixing with combustion air and ensuring a large contact area between fuel droplets and combustion air.

  From such a point of view, in a liquid fuel-fired combustor, a two-fluid type fuel nozzle that atomizes the liquid fuel by using a shearing force such as air is often used. Since this fuel nozzle can mix fuel and air in the process of atomization, there is an advantage that an extremely fuel rich region is not formed. However, if a two-fluid fuel nozzle is used, air must be supplied, so an air source and its control device must be installed separately. In addition, since the nozzle structure is complicated, it is disadvantageous in terms of initial cost and running cost as compared to a one-fluid type nozzle (see Patent Document 1, etc.).

  The one-fluid type fuel nozzle increases the liquid fuel supply pressure and increases the liquid fuel injection speed to atomize the fuel. A swirl component is given to the liquid fuel to form a swirl flow inside the fuel nozzle. By injecting fuel from the ejection holes of the nozzles, a group of fuel droplets that expands downstream in the injection direction is formed. When this one-fluid nozzle is adopted, incidental facilities such as an air supply system are unnecessary.

Japanese Patent Laid-Open No. 2004-21558

  In general, in a gas turbine combustor, a fuel nozzle is disposed at an upstream position of the center of the combustor shaft, and a swirler that imparts a swirl component to combustion air is disposed on the outer periphery of the fuel nozzle. The liquid fuel injected from the fuel nozzle forms a circulating flow by the swirling air injected from the swirler, and mixes with the combustion air flowing into the combustion chamber from the side of the combustor inner cylinder and burns.

  Since the fuel nozzle disclosed in Japanese Patent Application Laid-Open No. 2004-212558 described above imparts a swirling component to the liquid fuel to atomize it, the injected fuel droplets are concentrated on the outer peripheral side of the fuel droplet group by the action of centrifugal force. A high density droplet layer is formed there. Normally, the inertial force of fuel droplets is larger than the penetration force of combustion airflow etc., so the combustion air flowing from the outside of the fuel droplet group is blocked by the high-density droplet layer and the inside of the fuel droplet group Hard to reach. As a result, the inside of the region where the fuel droplet group is formed is deficient in air, so that the mixing of fuel and air becomes insufficient and dust is likely to be generated. Further, when the mixing of combustion air and fuel becomes insufficient, a fuel rich region is formed, and a local high temperature region is generated in the diffusion flame, which may increase the NOx emission amount.

  An object of the present invention is to provide a fuel nozzle for a gas turbine combustor that can sufficiently supply air to the inside of the injected liquid fuel droplet group and promote mixing of fuel and air.

(1) In order to achieve the above object, according to the present invention, in a fuel nozzle used in a liquid fuel-fired gas turbine combustor, a swirler for imparting a swirl component to liquid fuel, and a swirl component provided by the swirler A circular fuel injection hole for injecting liquid fuel into the combustion chamber and atomizing it, and means for adding density to the number density of fuel droplets injected from the fuel injection hole into the combustion chamber, A plurality of groove portions provided at predetermined intervals in the circumferential direction on the wall surface, and gas with respect to a group of fuel droplets provided at predetermined intervals in the circumferential direction around the fuel injection holes and injected through the fuel injection holes A plurality of air ejection holes that inject and collide with each other, and the air ejection holes are out of phase with the groove so as to guide air to a region where the number density of fuel droplets ejected from the fuel ejection holes is low. and it is provided Te That.

In (2) above (1), good Mashiku, the air ejection holes is characterized in that inclined to at least one of the circumferential direction or radial direction of the fuel injection holes.

  According to the present invention, since the outer peripheral portion of the fuel droplet group injected from the fuel nozzle can be shaded in the circumferential direction, the liquid fuel droplets injected through the region where the number density of the fuel droplets is low A sufficient amount of air can be supplied to the inside of the group to promote mixing of fuel and air.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a configuration example of a gas turbine plant to which a fuel nozzle for a gas turbine fuel device according to the present invention is applied.
The gas turbine plant shown in FIG. 1 mixes a compressor 1 that compresses air to generate high-pressure combustion air, combustion air 13 introduced from the compressor 1 and fuel, and generates combustion gas 14. A combustor 3 to be generated and a turbine 2 into which the combustion gas 14 generated by the combustor 3 is introduced. In this example, the turbine 2 is a single-shaft type and is integrally connected to the compressor 1 and the generator 4, but a two-shaft type may also be used. In the case of the two-shaft type, one of the turbines is connected to the compressor and the other is connected to the generator. In this example, the generator 4 is illustrated as a load device, but a pump or the like may be used.

  The combustor 3 includes an inner cylinder 7 that generates combustion gas, a fuel nozzle 9 that atomizes and injects liquid fuel, a swirler 10 that imparts a swirl component to the combustion air 13, and an ignition that ignites the combustor 3. The stopper 11 is composed of a pressure vessel sealed with an outer cylinder 5 and an end cover 6. The fuel nozzle 9 is disposed at the axial center position upstream of the inner cylinder 7, and a swirler 10 for holding the diffusion flame 16 is provided around the fuel nozzle 9. An inner cylinder cap 12 that seals the upstream side of the inner cylinder 7 is provided on the outer periphery of the swirler 10.

  With such a configuration, the combustion air 13 from the compressor 1 passes through the annular air flow path formed between the outer cylinder 5 and the inner cylinder 7, and the outer peripheral wall surface of the inner cylinder 7 and the inner cylinder cap 12. Is introduced into the inner space (combustion chamber) of the inner cylinder 7 through a combustion hole, a cooling hole, or a swirler 10 provided in the inner cylinder 7 and mixed with fuel. Then, the mixed gas is ignited and burned by the spark plug 11, and the generated combustion gas 14 is supplied to the turbine 2 through the transition piece 8, and shaft power is given to the turbine 2 by the expansion work. A part of the shaft power of the turbine 2 is transmitted to the generator 4 and converted into electric energy, and the remaining shaft power is transmitted to the compressor 1 and used for compression power.

  The liquid fuel for the combustor 3 is stored in the fuel tank 18 and guided from the viscous flow tail tank 18 through the fuel pipe 17. The fuel pipe 17 includes a booster pump 19 that discharges and boosts the liquid fuel in the fuel tank 18, a fuel cutoff valve 22 that shuts off the supply of fuel, a flow rate adjustment valve 21 that adjusts the flow rate of the supplied fuel, and a flow rate of the supplied fuel. A fuel flow meter 23 for detection is provided. The bypass line of the fuel pump 19 is provided with a pressure control valve 20 that adjusts the pressure of the fuel supplied to the combustor 3. By such a fuel supply system, the liquid fuel boosted by the fuel pump 19 is boosted to the set pressure by the pressure control valve 20, and then adjusted to the set flow rate by the flow rate control valve 21, and the fuel cutoff valve 22, fuel flow meter The fuel is passed through the fuel nozzle 9 and supplied to the fuel nozzle 9.

Here, FIG. 2A is a cross-sectional view showing a schematic configuration of a general one-fluid type fuel nozzle, and FIG. 2B is a cross-sectional view taken along a line AA in FIG.
The illustrated one-fluid type fuel nozzle mainly includes a nozzle cap 102, a nozzle body 103, and a nozzle tip 104. The fuel 109 passes through the fuel passages 101 and 106 provided in the nozzle body 103 and the nozzle tip 104, and flows into an annular passage 107 formed between the nozzle cap 102 and the nozzle tip 104. The nozzle tip 104 is provided with a swirler 112 that imparts a swirling component to the liquid fuel 109 flowing through the annular flow path 107. The annular channel 107 wraps around the front side of the nozzle tip 104 and is connected to the swirl chamber 108. The swirler 112 is constituted by the swirl chamber 108 and a plurality of swirl grooves 113 that connect the swirl chamber 108 and the annular channel 107. Yes. As shown in FIG. 2B, the swirl groove 113 is provided so as to be connected to the swirl chamber 108 from the tangential direction when viewed from the nozzle axis direction. With such a configuration, the liquid fuel 109 forms a swirl flow 110 inside the swirl chamber 108 and is atomized through the ejection holes 105 formed at the tip of the nozzle cap 102 so as to face the combustion chamber. Is injected into. The fuel droplets injected from the ejection holes 105 form a fuel droplet group 111 in a conical region that expands toward the downstream in the injection direction (rightward in FIG. 2A) by the action of the swirl component.

3A is a sectional view of the gas turbine combustor equipped with the fuel nozzle shown in FIGS. 2A and 2B, and FIG. 3B is the gas turbine combustion shown in FIG. 3A. It is the front view which looked at the vessel from the combustion chamber side.
As shown in these drawings, in a one-fluid type fuel nozzle, in general, a swirl component is given to the fuel for injection, so that the fuel droplets injected from the fuel nozzle 9 are subjected to the action of centrifugal force. Therefore, the fuel droplets are concentrated on the outer peripheral side of the fuel droplet group 111, and the spatial number density on the outer peripheral side of the fuel droplet group 111 tends to increase.

  Usually, the liquid fuel injected from the fuel nozzle 9 is mixed with the combustion air flowing into the combustion chamber from the outer peripheral wall surface of the inner cylinder 7, the air hole 115 provided in the inner cylinder cap 12, the swirler 10 or the like, and burned. To do. However, as described above, the high-density fuel droplet layer 116 (see FIG. 3B) having a high spatial number density of the fuel droplets is formed on the outer peripheral portion of the fuel droplet group 111. Therefore, for example, the combustion air flow 114 or the like flowing from the air hole 115 is inhibited by the high-density fuel droplet layer 116 and hardly reaches the low-density fuel droplet layer 117 inside the fuel droplet group 111. Therefore, in the low density fuel droplet layer 117, mixing of liquid fuel and air is not promoted due to air shortage, which may lead to an increase in the amount of generated dust. Further, if the mixed state of fuel and air becomes insufficient, a fuel-rich region is formed, and a local high-temperature region is generated in the diffusion flame, which may increase the NOx emission amount. Moreover, it is conceivable that the combustion efficiency at the time of low-load combustion is lowered, and there is a possibility of increasing the discharge of unburned components such as CO and THC.

4 (a) is a cross-sectional view of the fuel nozzle according to the first embodiment of the present invention, FIG. 4 (b) is a partially enlarged view of the part taken along the line BB in FIG. 4 (a), and FIG. (c) is a schematic diagram of the liquid fuel injected from the fuel nozzle according to the first embodiment of the present invention. In these drawings, the same parts as those in the previous drawings are given the same reference numerals, and the description thereof will be omitted.
In the fuel nozzle of the present embodiment, a plurality of grooves 202 are provided at predetermined intervals in the circumferential direction on the inner wall surface of a circular ejection hole 201 formed at the tip of the nozzle cap 102 as shown in FIG. Except for this point, the configuration is substantially the same as that of the fuel nozzle shown in FIGS. 2 (a) and 2 (b). These grooves 202 play a role of adding density to the number density of the fuel droplets injected from the fuel injection holes 201 into the combustion chamber.

  In general, as shown in FIG. 4C, the atomization mechanism of the one-fluid fuel nozzle gives a strong swirling component to the liquid fuel, so that a thin liquid film 203 is formed on the inner wall surface of the ejection hole 201. When the liquid film 203 is ejected from the ejection hole 201, the liquid film 203 is split and ejected into the combustion chamber as fine droplets. In the present embodiment, grooves 202 are provided at predetermined intervals on the inner wall surface of the ejection hole 201 where the liquid film 203 is formed. As a result, as shown in FIG. 4C, a liquid film 206 whose thickness is increased by the depth of the groove 202 is formed at a portion corresponding to the groove 202 of the liquid film 203. Accordingly, the portion where the liquid film 206 is split to become droplets is a region 204 in the fuel droplet group 111 where the number density of droplets is high.

  A plurality of regions 204 in which the number density of the fuel droplets is high are formed on the outer peripheral portion of the fuel droplet group 111 corresponding to the arrangement of the groove portions 202, and other regions corresponding to the increase in the density of the fuel droplets in these regions 204 are provided. The number density of the fuel droplets in the portion is reduced. For this reason, regions 204 with high number density of fuel droplets and regions 205 with low number density of fuel droplets are alternately formed on the outer periphery of the fuel droplet group 111, and the density of the number density of fuel droplets varies in the circumferential direction of the fuel droplet group 111. It comes to stick.

FIG. 5A is a sectional view of the gas turbine combustor equipped with the fuel nozzle according to the first embodiment of the present invention, and FIG. 5B is a combustion of the gas turbine combustor shown in FIG. It is the front view seen from the room side. In these drawings, the same parts as those in the previous drawings are given the same reference numerals, and the description thereof will be omitted.
As shown in FIGS. 5A and 5B, in the fuel nozzle according to the present embodiment, a region 204 having a high number density of fuel droplets and a region 205 having a low number density in the circumferential direction of the fuel droplet group 111. Therefore, the combustion air 207 flowing toward the low density area 205 easily reaches the area inside the fuel droplets 111. Further, since the combustion air 206, 207 is also supplied from the surroundings to the region 204 where the number density of the fuel droplets is high, the fuel droplets can be brought into contact with more air.

  In this way, a spatial number density density of the fuel droplets is given in the circumferential direction of the fuel droplet group injected from the fuel nozzle, and air is actively supplied to a region where the number density of the fuel droplets is low. Thus, it is possible to promote the mixing of fuel and air and suppress the generation of dust. Further, since the mixing of air and fuel is promoted, the generation of a fuel rich region can be suppressed, so that the formation of a local high temperature region of the diffusion flame can be suppressed, and NOx, CO, THC, etc. can be discharged. A reduction in the amount can also be expected.

FIG. 6A is a cross-sectional view of a fuel nozzle according to the second embodiment of the present invention, and FIG. 6B is a partially enlarged view taken along the line CC in FIG. 6A. In these drawings, the same parts as those in the previous drawings are given the same reference numerals, and the description thereof will be omitted.
The fuel nozzle of the present embodiment has an air nozzle on the outer periphery. In this air nozzle, an air nozzle body 301 is disposed so as to cover the outer periphery of the nozzle cap 102, and air flows through an air flow path 302 formed between the air nozzle body 301 and the nozzle cap 102. At the tip of the air nozzle body 301, an air ejection hole 303 for injecting air flowing through the air flow path 302 into the combustion chamber is provided.

  As shown in FIG. 6B, the air ejection holes 303 are provided at a plurality of locations around the fuel ejection holes 105 at predetermined intervals in the circumferential direction so as to surround the fuel ejection holes 105. The gas (air) injected from the air injection holes 303 collides with the fuel droplet group 111 injected through the fuel injection holes 105, and thereby the fuel droplets injected from the fuel injection holes 105 into the combustion chamber. The number density is shaded. With respect to other configurations, the present embodiment is the fuel injection nozzle of FIGS. 2 (a) and 2 (b).

  In the present embodiment, for example, a compressor (not shown) provided separately is supplied to the outer peripheral air nozzle, and the compressed air 304 from the compressor is formed between the nozzle cap 102 and the air nozzle body 301. The fuel is ejected from the plurality of air ejection holes 303 toward the fuel droplet group 111 through the annular air flow path 302. As an air source of the air nozzle, in addition to a separately installed compressor, it is conceivable to use, for example, extracted air from the compressor 1 (see FIG. 1), combustion air, or a medium other than air (such as steam). .

  According to the present embodiment, the high-density droplet layer in the outer peripheral portion of the fuel droplet group 111 injected from the fuel injection hole 105 is blown off by the high-pressure air injected from the air injection hole 303 at a predetermined interval in the circumferential direction. A place arises. Since the number density of the fuel droplets is lowered at the location blown by the high-pressure air, air from the surroundings can easily flow. Furthermore, when the high pressure air injected from the air ejection holes 303 collides with the fuel droplets, the fuel droplets can be further atomized by the shearing force of the high pressure air.

  As described above, since the density of the number of fuel droplets can be given in the circumferential direction of the fuel droplet group 111, the same effect as that of the first embodiment can be obtained. Further, FIG. As shown in FIG. 5, the large droplet region 305 and the small region 306 can be alternately formed in the circumferential direction of the fuel droplet group 111. Needless to say, since the inertia force of the droplet is small in the region 306 where the fuel droplet is small, it is possible to supply the air flow into the fuel droplet group 111 more effectively. Further, since the air flow itself from the air ejection hole 303 is mixed with the fuel droplets ejected from the fuel ejection hole 105, the mixing property of fuel and air can be further improved.

  In the present embodiment, the air ejection holes 303 are formed so that the direction of the air ejection holes 303 is along the axial direction of the combustor. For example, as shown in FIG. By inclining the fuel injection hole 105 inward in the radial direction toward the axial center of the fuel, compressed air 304 can be supplied toward the center of the fuel droplet group 111, further promoting the mixing of fuel and air. can do. Further, as shown in FIG. 7B, the air ejection holes 303 are formed in the circumferential direction of the fuel ejection holes 105 so that the swirling component opposite to the fuel swirling direction (see arrow 110) is given to the high-pressure air 307. By inclining, since the fuel droplet and the high-pressure air can be opposed to each other, the relative velocity between the fuel droplet and the high-pressure air 307 can be increased, and further effect of promoting atomization is expected. Of course, it is also conceivable to incline the air ejection holes 303 in the radial direction and the circumferential direction of the fuel ejection holes 105 by combining the configurations of FIGS. 7A and 7B.

FIG. 8A is a cross-sectional view of a fuel nozzle according to the third embodiment of the present invention, and FIG. 8B is a partially enlarged view of a DD arrow portion in FIG. 8A. In these drawings, the same parts as those in the previous drawings are given the same reference numerals, and the description thereof will be omitted.
As shown in FIGS. 8A and 8B, the fuel nozzle according to the present embodiment is a combination of the previous first and second embodiments. A groove 202 is provided on the wall surface, and an air injection hole 303 is provided around the fuel injection hole 201 in the same volume as in FIGS. 6A and 6B. The groove 202 and the air injection hole 303 are circumferential. Are shifted in phase.

  In the present embodiment, the air 401 supplied to the air nozzle provided in the outer peripheral portion is assumed to branch and guide a part of the combustion air 13 supplied to the combustor 3, for example. However, a compressor separately provided as in the previous embodiment may be used as the air source. It is also conceivable that the air ejection holes 303 are configured to incline in at least one of the radial direction and the circumferential direction of the fuel ejection holes 201 as shown in FIGS. 7 (a) and 7 (b). About another structure, it is the same as that of each previous embodiment.

  According to the fuel nozzle configured as described above, the effects of the first and second embodiments can be obtained together. In addition, since a region 204 with a low number density of fuel droplets and a region 205 with a high number of fuel droplets are generated corresponding to the groove portion 202, the air ejection holes 303 are provided out of phase with the groove portion 202. High pressure air is jetted into the lower region 204. Therefore, high-pressure air can be caused to enter the fuel droplet group 111 more efficiently. When a part of the combustion air 13 is branched and ejected from the air ejection hole 303, it is difficult to ensure a sufficient penetration force of the air flow, but the air is injected where the fuel density is reduced as described above. Thus, even an air flow having a small penetration force can be efficiently mixed with the fuel. Therefore, it is also a great merit that the system can be easily configured using the compressed air from the compressor 1 without newly providing a dedicated compressor.

It is a schematic block diagram of one structural example of the gas turbine plant to which the fuel nozzle for gas turbine fuel devices of this invention is applied. FIG. 3 is a cross-sectional view showing a schematic configuration of a general one-fluid type fuel nozzle, and a cross-sectional view taken along a line AA in FIG. 1 is a cross-sectional view of a gas turbine combustor equipped with a general one-fluid type fuel nozzle, and a front view of the gas turbine combustor shown in FIG. A fuel nozzle according to the first embodiment of the present invention, a cross-sectional view of the fuel nozzle according to the first embodiment of the present invention, and a partial enlarged view of the BB arrow portion in this figure It is a schematic diagram of a liquid fuel. It is sectional drawing of the gas turbine combustor which mounts the fuel nozzle which concerns on the 1st Embodiment of this invention, and the front view which looked at the gas turbine combustor shown in this figure from the combustion chamber side. It is sectional drawing of the fuel nozzle which concerns on the 2nd Embodiment of this invention, and the elements on larger scale of the CC arrow part in this figure. It is a sectional side view of the other structural example of the fuel nozzle which concerns on the 2nd Embodiment of this invention, and the partially expanded front view of the further another structural example of the fuel nozzle which concerns on the 2nd Embodiment of this invention. . It is sectional drawing of the fuel nozzle which concerns on the 3rd Embodiment of this invention, and the elements on larger scale of the DD arrow view part in this figure.

Explanation of symbols

3 Combustor 9 Fuel nozzle 105 Fuel ejection hole 109 Fuel 111 Fuel droplet group 112 Swivel unit 201 Fuel ejection hole 202 Groove 303 Air ejection hole 304 Air 401 Air

Claims (2)

In a fuel nozzle used in a liquid fuel-fired gas turbine combustor,
A swirler that imparts a swirl component to the liquid fuel;
A circular fuel injection hole for injecting and atomizing the liquid fuel to which the swirl component is imparted by the swirler;
A means for adding density to the number density of fuel droplets injected from the fuel injection holes into the combustion chamber, and a plurality of grooves provided at predetermined intervals in the circumferential direction on the inner wall surface of the fuel injection holes;
A plurality of air ejection holes that are provided around the fuel ejection holes at predetermined intervals in the circumferential direction and inject gas into and collide with a group of fuel droplets ejected through the fuel ejection holes;
The fuel for a gas turbine combustor, wherein the air ejection hole is provided out of phase with the groove so as to guide air to a region where the number density of fuel droplets injected from the fuel ejection hole is low nozzle. 2. The fuel nozzle for a gas turbine combustor according to claim 1 , wherein the air ejection hole is inclined in at least one of a circumferential direction and a radial direction of the fuel ejection hole. 3.

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