JP5460846B2 - Combustion device and control method of combustion device - Google Patents

Description

  The present invention relates to a combustion apparatus used for a gas turbine engine, a boiler, or the like that requires a supply of high-temperature gas, and a method for controlling the fuel concentration of the combustion apparatus, particularly in the radial direction of a premixed gas.

  Gas turbine engines have strict environmental standards regarding the composition of exhaust gas emitted by combustion, considering environmental conservation, and it is required to reduce harmful substances such as nitrogen oxides (hereinafter referred to as NOx). It has been. On the other hand, large-scale gas turbine engines for ground facilities and aircraft gas turbine engines tend to have a high pressure ratio due to demands for low fuel consumption and high output. The combustion temperature tends to increase as the inlet temperature of the combustion apparatus increases, and there is a concern that it may be a factor that rather increases NOx.

  Therefore, in recent years, a combustion method that adopts a lean premixed combustion method that effectively reduces the amount of NOx generated, for example, a combined combustion method that combines a lean premixed combustion method and a diffusion combustion method has been proposed (patents). References 1, 2). In the lean premix combustion method, air and fuel are premixed and burned as an air-fuel mixture with a uniform fuel concentration, so there is no combustion region where the flame temperature is locally high, and the fuel is diluted. As a result, the flame temperature can be lowered as a whole, so that there is an advantage that the amount of NOx generated can be effectively reduced, but blowout tends to occur during low load combustion. In addition, the diffusion combustion method burns fuel and air while diffusing and mixing them, so it is difficult to blow out even at low loads and has the advantage of excellent flame holding performance, while reducing the amount of NOx generated. There are challenges. Therefore, according to the combined combustion method, it is possible to reduce the amount of NOx generated by premixed combustion at high load while ensuring combustion stability by diffusion combustion at start-up and low load.

  In a conventional combined combustion type combustion apparatus, for example, as shown in FIG. 6, a fixed swirl vane is provided so as to surround the outside of a diffusion combustion burner (pilot burner) 82 disposed at the top 81 a of the combustion cylinder 81 of the combustion apparatus 80. A swirl type burner unit 85 is provided, in which a premixed combustion burner (main burner) 84 having a radial swirler 83 is disposed, and the premixed gas P is injected into the combustion chamber as a swirling flow.

JP-A-8-28871 Japanese Patent Application Laid-Open No. 8-210441

  In the conventional combustion apparatus 80 using the swirl type main burner 84 having the radial swirler 83 as described above, when the flame holding is to be strengthened, in order to increase the backflow R of the premixed gas, Set to make the turn stronger. For this purpose, it is necessary to increase the vane angle of the fixed swirl vane of the radial swirler 83. In that case, in order to secure the passage area of the premixed gas P, it is necessary to simultaneously increase the vane height in the axial direction. The entrance height of the radial swirler 83 is also increased. Thereby, the axial direction dimension of the inlet part into which air and fuel are introduced also becomes large.

  By the way, in the conventional combustion apparatus 80, in order to reduce the size of the apparatus, an air passage 86 from the gas turbine compressor is formed between the combustion cylinder 81 and the housing H covering the outside thereof, and the air A is generated. Some of them are introduced from the downstream end of the combustion cylinder 81 toward the top 81a which is the upstream end in the direction opposite to the combustion gas. In that case, the air A that has passed through the air passage 86 is introduced into the premixing passage from the inlet of the radial swirler 83 that opens radially outward, mixed with fuel, and in the direction opposite to the flow of compressed air as premixed air Is injected into the combustion cylinder.

  That is, since the air A introduced into the radial swirler 83 has its flow direction changed by approximately 90 ° via the radial swirler 83, the axial force of the air in the upstream portion of the premixing passage is caused by the centrifugal force accompanying the change in direction. There is a bias in the flow distribution in the direction. In addition, when the vane angle of the swirl vanes of the radial swirler is increased to stabilize the flame holding as described above, the axial direction dimension of the inlet portion is increased, so that the deviation of the flow distribution is further increased. . As a result, the fuel concentration distribution in the radial direction of the premixed gas injected into the combustion chamber from the premixing passage is also biased, so that the fuel concentration distribution in the radial direction is made uniform or intentionally adjusted to the fuel concentration. There was a problem that it was difficult to control the distribution.

  The present invention maintains a large vane angle of the swirl vanes of the radial swirler and generates a strong backflow in the combustion chamber to stabilize the flame holding, while dividing the radial swirler into a plurality of axial directions to achieve air and fuel. By providing a plurality of inlet portions into which the gas is introduced, the combustion device capable of easily controlling the radial concentration distribution of the premixed gas injected from the burner to the combustion chamber, and the diameter of the premixed gas in the combustion device It is an object of the present invention to provide a method for controlling a combustion apparatus that easily controls the directional fuel concentration distribution.

  In order to achieve the above-described object, a combustion apparatus according to the present invention includes a combustion cylinder that forms a combustion chamber on the inside, a top portion of the combustion cylinder, and a fuel and air preliminarily disposed in the combustion chamber. A main burner having a premixing passage for injecting air-fuel mixture, a radial swirler for introducing fuel and air into the premixing passage radially inward, and a fuel injection pipe for injecting fuel into the radial swirler from its inlet side; The main burner comprises an outer peripheral cylindrical portion disposed concentrically with the combustion cylinder, and an outer peripheral disk portion extending in a disk shape in a radial direction from an upstream end of the outer peripheral cylindrical portion. A burner outer cylinder, an inner peripheral cylindrical part located radially inside the outer peripheral cylindrical part, and an inner peripheral disk extending radially from the upstream end of the inner peripheral cylindrical part on the upstream side of the outer peripheral disk part A burner inner cylinder made up of parts, The space between the burner outer cylinder and the burner inner cylinder forms the premixing passage, and the radial swirler is connected to the outermost peripheral part of the disk part of the burner outer cylinder and the disk of the burner inner cylinder. And a plurality of swirler stages divided in the axial direction by the dividing plate, the radial length of the dividing plate being an upstream portion of the premixing passage Shorter than the straight line portion along the radial direction forming.

  According to this configuration, since the radial swirler is divided as a plurality of swirler stages in the axial direction by the dividing plate, it is possible to prevent the flow rate of air introduced into the radial swirler from being biased in the axial direction. it can. Moreover, when the air that has passed through the air passage changes direction toward the radial swirler, it receives the largest centrifugal force at the inlet of the radial swirler, so that the deviation of the air flow rate in the axial direction at this portion is suppressed. A sufficient radial length is sufficient, and the premixing passage after exiting the radial swirler is lengthened by the short radial length of the radial swirler, so that premixing is promoted.

  In the combustion apparatus control method according to the present invention, in the above combustion apparatus, the diameter of the premixed gas injected from the main burner into the combustion chamber is controlled by controlling the flow rate of the fuel supplied for each swirler stage. Control the fuel concentration distribution in the direction.

  In the control method of the combustion apparatus according to the present invention, the radial swirler is divided in the axial direction so that the flow distribution in the axial direction of the air is made uniform, so the flow rate of the fuel supplied to each swirler stage is Only by controlling, the radial fuel concentration distribution of the premixed gas injected into the combustion chamber can be easily controlled.

  As described above, according to the combustion device and the control method of the combustion device according to the present invention, the radial swirler is divided into a plurality of radial swirlers in the axial direction, and a plurality of inlet portions for introducing air and fuel are provided. While maintaining a large vane angle of the swirl vanes to stabilize flame holding, the concentration distribution in the radial direction of the premixed gas injected from the burner to the combustion chamber is easily controlled to reduce NOx during combustion. It becomes possible.

1 is a schematic view showing a gas turbine engine to which a combustion apparatus according to an embodiment of the present invention is applied. It is sectional drawing which shows the combustion apparatus of FIG. It is sectional drawing which expands and shows the principal part of the combustion apparatus of FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. It is a schematic diagram for demonstrating the effect of the combustion apparatus of FIG. It is sectional drawing which shows the conventional combustion apparatus.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a simplified configuration diagram showing a gas turbine engine to which a combustion apparatus according to an embodiment of the present invention is applied. The gas turbine engine GT includes a compressor 1, a combustion device 2, and a turbine 3 as main components. The compressed air supplied from the compressor 1 is combusted by the combustion device 2, and high-pressure combustion gas generated thereby. Is supplied to the turbine 3. The compressor 1 is connected to the turbine 3 via the rotating shaft 5 and is driven by the turbine 3. The load 4 such as an aircraft rotor or generator is driven by the output of the gas turbine engine GT. The fuel F fed from the fuel supply device 9 is supplied to the combustion device 2 via the fuel control device 8.

  FIG. 2 is a cross-sectional view showing the combustion apparatus 2. This combustion apparatus 2 is a can type that is arranged in a ring shape around the engine rotation axis, and is attached to a combustion cylinder 12 that forms a combustion chamber 10 on the inner side and a top portion 12a of the combustion cylinder 12, and is a combustion chamber. 10 is provided with a burner unit 14 for injecting a premixed mixture of fuel and air. The combustion cylinder 12 and the burner unit 14 are accommodated concentrically in a substantially cylindrical housing H that is an outer cylinder of the combustion apparatus 2. An end cover 18 is fixed to the front end of the housing H with bolts 20.

  This combustion device 2 is of a reverse flow type, and compressed air A from the compressor 1 is disposed between the housing H and the side wall 12b of the combustion cylinder 12 in the direction of the burner unit 14, as shown by the arrows, that is, in the combustion chamber 10. An air passage 30 is formed that leads in the direction opposite to the flow direction of the combustion gas G.

  One or a plurality of spark plugs 36 are fixed to the housing H through the housing H and the combustion cylinder 12 on the upstream peripheral wall of the combustion cylinder 12, and are injected from a pilot burner 44 described later of the burner unit 14. The premixed gas is ignited to form a combustion region S in the upstream portion of the combustion cylinder 12. In addition, a plurality of dilution air holes 38 formed by penetrating a short pipe are disposed downstream of the combustion region S in the combustion cylinder 12.

  FIG. 3 is a cross-sectional view showing a main part of the combustion apparatus 2 of FIG. The burner unit 14 includes a main burner 42 that injects an annular premixed gas P <b> 1 that includes a swirling component, and a pilot burner 44 that is disposed inside the main burner 42. Specifically, the burner unit 14 has an outer peripheral cylindrical portion 46a concentric with the axial center O of the combustion cylinder 12, and an outer periphery extending in a disk shape in a direction perpendicular to the axial center O from the upstream end of the outer peripheral cylindrical portion 46a. A burner outer cylinder 46 comprising a disc portion 46b, an inner peripheral cylindrical portion 48a positioned radially inward of the outer peripheral cylindrical portion 46a, and an outer peripheral disc portion from the vicinity of the upstream end of the inner peripheral cylindrical portion 48a. It has a burner inner cylinder 48 composed of an inner peripheral disc portion 48b extending parallel to the outer peripheral disc portion 46b on the upstream side of 46b. The space between the burner outer cylinder 46 and the burner inner cylinder 48 forms an annular first premixing passage 42 a of the main burner 42, and the inner space of the burner inner cylinder 48 is the second premixed gas of the pilot burner 44. A passage 44a is formed.

  A radial swirler 50 is attached to the upstream portion of the first premixing passage 42a of the main burner 42 facing radially outward, that is, between the outermost peripheral portions of the two disk portions 46b and 48b. The radial outer side of the radial swirler 50 is formed as an inlet portion 50a that introduces the air A and the fuel F1 into the first premixing passage 42a radially inward, and further on the radially outer side of the inlet portion 50a, A first fuel injection pipe 52 that forms a fuel passage for supplying the fuel F <b> 1 is disposed through the end cover 18. A plurality of first fuel injection pipes 52 are provided side by side at equal intervals in the circumferential direction.

  The radial swirler 50 is fixed to the main burner 42 by being fitted into a fitting portion 42b formed between the outermost peripheral portions of the two disc portions 46b and 48b. As shown in FIG. 4, which is a cross-sectional view taken along line IV-IV, the radial swirler 50 has a fixed swirl blade 54 that swirls the air A and the fuel F <b> 1 introduced into the first premixing passage 42 a. Yes. Further, the radial swirler 50 is provided with an annular dividing plate 56.

  As shown in FIG. 3, the radial swirler 50 is formed with a plurality of swirler stages 50 b that are divided in the axial direction by the dividing plate 56. In the present embodiment, the radial swirler 50 is divided into five swirler stages 50 b by four dividing plates 56. Due to the swirl provided by the fixed swirl blade 54 of the radial swirler 50, the mixing proceeds in the first premixing passage 42a to generate the premixed gas P1, and the swirl flow centered on the axis O of the combustion device 2 is The fuel is injected into the combustion chamber 10 from an injection port 42c formed of an opening on the downstream side of the one premixing passage 42a.

  If the dividing plate 56 has a radial length sufficient to deflect the compressed air A that has passed through the air passage 30 radially inward and introduce it into the first premixing passage 42a. The preferred range of the radial length L1 of the dividing plate 56, that is, the radial length of the radial swirler 50, is 1/2 of the length L2 of the straight portion along the radial direction on the upstream side of the first premixing passage 42a. 6 to 2/3, and more preferably 1/4 to 1/2. In the present embodiment, the radial length L1 of the dividing plate 56 is set to 1/3 of the radial straight portion length L2 of the first premixing passage 42a.

  In the first fuel injection pipe 52, the same number of fuel injection ports 52a as the plurality of swirler stages 50b are arranged in the axial direction. Each fuel injection port 52a is disposed so as to face the inlet side of each swirler stage 50b, and the fuel F1 is injected into each swirler stage 50b via each of the plurality of fuel injection ports 52a. In the present embodiment, the diameters of the fuel injection ports 52a are the same, and the flow rate of the fuel F1 injected into each swirler stage 50b is set to be uniform.

  The upstream portion of the second premixing passage 44a has an annular first passage plate 63 supported by the pilot burner 44, and a bolt 65 so as to face the first passage plate 63 in the axial direction with a spacer 64 interposed therebetween. It is formed between the disc-shaped second passage plate 66 attached in the above. A second fuel injection pipe 67 for supplying fuel F2 is disposed through the end cover 18 on the radially outer side of the upstream end of the second premixed gas passage 44a. The first fuel injection pipe 52 that supplies the fuel F1 to the main burner 42 and the second fuel supply passage 67 that supplies the fuel F2 to the pilot burner 44 are provided as fuel supply systems independent of each other. By individually controlling each, the fuel concentration (air-fuel ratio) of the air-fuel mixture can be adjusted independently.

  Next, the operation of the combustion apparatus 2 configured as described above will be described.

  As shown in FIG. 3, the compressed air A from the compressor 1 passes through an air passage 30, which is a backflow passage formed between the side wall 12 b of the combustion cylinder 12 and the housing H, and passes through the air passage 30 of the main burner 42. 1 It guide | induces to the entrance part 50a of the radial swirler 50 attached to the upstream part of the pre-mixing passage 42a. Since the compressed air A is deflected 90 ° radially inward and further 90 ° when entering the downstream portion of the first premixing passage 42a, a large centrifugal force is generated when it is introduced into the radial swirler 50. receive.

  In this case, in the case of the conventional radial swirler 50 having no dividing plate, the flow rate of the air A is influenced by the centrifugal force as shown in FIG. Bias occurs so that (left side) increases. However, in the radial swirler 50 of the combustion apparatus 2 according to the present embodiment, as shown in FIG. 5B, the air A is introduced into a plurality of swirler stages 50 b divided in the axial direction by the dividing plate 56. . Therefore, although a slight deviation of the axial flow rate occurs in each swirler stage 50b, the deviation of the axial flow rate of the air A in the radial swirler 50 as a whole is greatly suppressed.

  Further, since the fuel injection ports 52a of the first fuel injection pipes 52 provided corresponding to the respective swirler stages 50b in FIG. 3 have the same diameter, the fuel injected into each swirler stage 50b. The flow rate of F1 is also controlled almost uniformly.

  That is, in the radial swirler 50 used in the present embodiment, the flow rates of the air A and the fuel F1 introduced into each swirler stage 50b divided in the axial direction by the dividing plate 56 are controlled almost uniformly. Therefore, the fuel concentration distribution in the axial direction of the premixed gas P1 formed in the upstream portion of the first premixing passage 42a is made uniform. As a result, the fuel concentration distribution in the radial direction of the premixed gas P1 injected from the first premixing passage 42a into the combustion chamber 10 can be made uniform.

  Further, as in the present embodiment, the diameters of the fuel injection ports 52a of the first fuel injection pipes 52 may not be the same but may be set individually. The optimal fuel concentration distribution of the premixed gas P1 injected into the combustion chamber 10 for realizing low NOx combustion is the shape of the combustion chamber 10, the structure of the pilot burner 44 used in combination with the main burner 42, etc. May vary due to various factors. That is, there is a case where the fuel concentration of the premixed gas P1 injected into the combustion chamber 10 is not necessarily uniform and should be controlled to have an intentionally distributed distribution.

  Even in such a case, according to the combustion apparatus 2 according to the present invention, since the radial swirler 50 is divided in the axial direction, the flow distribution in the axial direction of the air A is made uniform. Only by controlling the flow rate of the fuel F1 supplied to 50b, the radial fuel concentration distribution of the premixed gas P1 injected into the combustion chamber 10 can be easily controlled.

  Control of the flow rate of the fuel supplied to each swirler stage 50b can be easily performed, for example, by individually setting the diameter of the fuel injection port 52a corresponding to each swirler stage 50b as described above.

  In addition, the swirl 50 multi-staged in the axial direction can obtain a particularly great effect in the case of the present embodiment. In other words, in the combustion device 2, the air A introduced into the radial swirler 50 receives a large centrifugal force when the flow direction is changed by 90 ° through the radial swirler 50, but the dividing plate 56 is provided on the radial swirler 50. By providing, the deviation of the flow distribution in the axial direction of the air A introduced into the radial swirler 50 can be minimized. Therefore, while the combustion apparatus 2 has a compact configuration, low NOx combustion can be realized by optimizing the radial fuel concentration distribution of the premixed gas P1 in the combustion chamber 10.

  In the present embodiment, as an example, the radial swirler 50 is divided into five swirler stages 50b by four dividing plates 56, but the number of swirler stages 50b provided separately is not limited to five. May be set as appropriate.

  In the above embodiment, the fixed swirl vane 54 and the split plate 56 of the radial swirler 50 are configured to have substantially the same radial length, but the fixed swirl vane 54 and the split plate 56 have different radial lengths. You may have. Further, the radial length and the axial length of each swirler stage 50b may be different for each swirler stage.

  The shape of the corner portion 42d on the inner diameter side connecting the upstream portion along the radial direction and the downstream portion along the axial direction of the first premixed gas passage 42a is an ellipse as shown by a two-dot chain line in FIG. It may be an arc shape. In the above embodiment, the pilot burner 44 has been described as a burner that injects the premixed gas P2 into the combustion chamber 10, but the parrot burner 44 separately supplies the fuel F2 and air A into the combustion chamber 10, respectively. It may be a diffusion combustion burner for injection. Moreover, in the said embodiment, although the example which applied the combustion apparatus 2 to gas turbine engine GT was demonstrated, the combustion apparatus which concerns on this invention requires supply of high temperature gas, such as a boiler, not only a gas turbine engine. It can be applied to other devices.

2 Combustion device 10 Combustion chamber 12 Combustion cylinder 12a Top 14 Burner unit 30 Air passage 42 Main burner 42a First premix passage 50 Radial swirler 50a Radial swirler inlet 50b Swirl stage 52 Fuel injection pipe 52a Fuel injection port 54 Fixed swirl vane 56 Dividing plate F1 Fuel A Air L1 Radial length L2 of divided plate Radial linear portion length P1 of first premixing passage Premixed gas O Combustion cylinder axis

Claims (2)

A combustion cylinder forming a combustion chamber inside;
A premixing passage disposed at the top of the combustion cylinder and injecting a premixed mixture of fuel and air into the combustion chamber in an annular shape, and a radial swirler for introducing fuel and air into the premixing passage radially inward A main burner having
A combustion device comprising a fuel injection pipe for injecting fuel from the inlet side to the radial swirler,
The main burner includes an outer peripheral cylindrical portion disposed concentrically with the combustion cylinder, a burner outer cylinder including an outer peripheral disk portion extending in a disk shape in a radial direction from an upstream end of the outer peripheral cylindrical portion, and the outer peripheral cylinder. An inner circumferential cylindrical portion located on the radially inner side of the portion, and a burner inner cylinder comprising an inner circumferential disk portion extending radially from the upstream end portion of the inner circumferential cylindrical portion on the upstream side of the outer circumferential disk portion. A space between the burner outer cylinder and the burner inner cylinder forms the premixing passage,
The radial swirler is provided between the outermost peripheral part of the disk part of the burner outer cylinder and the outermost peripheral part of the disk part of the burner inner cylinder, and is divided in the axial direction by a dividing plate. Has a swirler stage,
The radial length of the division plate, the rather short than straight portion along the radial direction to form the upstream portion of the premix passage,
A combustion apparatus in which the axial lengths of the swirler stages are set to be equal .   The method for controlling a combustion apparatus according to claim 1, wherein a radial direction of premixed gas injected from the main burner into the combustion chamber by controlling a flow rate of fuel supplied to each swirler stage. Of controlling a combustion apparatus for controlling the fuel concentration distribution of the fuel.

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