JP2009085456A - Gas turbine combustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce residual carbon-derived ash dust generated in combustion of low-quality oil by promoting atomization of liquid fuel. <P>SOLUTION: This gas turbine combustor uses low-quality fuel including residual carbon as the fuel, and comprises a fuel nozzle disposed near a central portion of a fuel spray nozzle device, a first spray air supply nozzle disposed at an outer peripheral side of the fuel nozzle for spraying the air for atomizing the fuel, and a second spray air supply nozzle disposed at an outer peripheral side of the first spray air supply nozzle for spraying the air for atomizing the fuel. Fly ash resulting from residual carbon the combustion of low-quality oil can be reduced by promoting the atomization of the liquid fuel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gas turbine combustor.

  In recent years, diversification of fuels has been studied in gas turbines, and the use of by-product oil (low quality oil) generated in petroleum refineries and chemical plants is being studied. Low quality oil is less expensive than light oil or heavy fuel oil A, which is mainly used as gas turbine fuel, and has the advantage that the running cost of fuel cost can be greatly reduced if it can be used as gas turbine fuel.

  When burning liquid fuel such as by-product oil, it is necessary to first atomize the fuel and inject it into the combustion chamber. The atomized fuel droplets evaporate in the combustion chamber, and the evaporated fuel vapor and the combustion air mix to form a flame. Therefore, promotion of atomization of liquid fuel is very important even in the combustion of low quality oil.

  Patent Document 1 discloses a technique in which a diffusion combustion burner using liquid fuel is applied to a gas turbine combustor.

  Patent Document 2 discloses a fuel injection valve using liquid fuel. A plurality of air nozzles are arranged on the outer peripheral side of the fuel injection valve described in Patent Document 2.

JP 2004-3730 A JP 2005-90884 A

  In the gas turbine combustor for diffusion combustion described in Patent Document 1, when low quality oil containing a large amount of residual carbon is burned, a shell is formed on the surface of a droplet in which a part of the residual carbon is atomized. In the combustion chamber, since the fuel inside the shell must be evaporated, it takes time to evaporate droplets and complete combustion compared to light oil and A heavy oil. In addition, after the droplet (fuel inside the shell) evaporates, only the shell formed on the surface of the droplet called cenosphere remains. Although this cenosphere disappears in the process of combustion, it takes time to disappear. Therefore, cenosphere that has not been completely burned in the combustion chamber is discharged from the combustor to the outside (outside) as dust. It has also been pointed out that the diameter of the shell increases as the fuel evaporates by breaking through the shell during the fuel evaporation process.

  FIG. 6 shows the relationship between the residual carbon concentration in the fuel and the soot concentration at the combustor outlet. As the residual carbon concentration increases, soot concentration at the combustor outlet also increases. This tendency is considered to be due to an increase in the above-mentioned residual carbon-derived cenosulfa.

  Further, Patent Document 2 does not disclose the structure of the fuel injection nozzle itself. The technique of Patent Document 2 aims to atomize fuel at the downstream end (lip portion) of the air nozzle.

  Promotion of atomization of fuel is effective for these problems. By making the spray droplet diameter of the liquid fuel fine, the evaporation speed of the droplet is increased, and the particle size of the sonosphere particles generated by combustion is also reduced. For this reason, the time required for burning (extinguishing) the Cenosuspha can be shortened, and the dust can be burned out in the combustion chamber.

  Therefore, an object of the present invention is to reduce soot from residual carbon generated by low quality oil combustion by promoting atomization of liquid fuel.

  The present invention uses a low-quality oil fuel containing residual carbon as the fuel, a fuel nozzle arranged in the vicinity of the center of the fuel spray nozzle device, and an outer peripheral side of the fuel nozzle to atomize the fuel. A first spray air supply nozzle that sprays air for the purpose, and a second spray air supply nozzle that is disposed on the outer peripheral side of the first spray air supply nozzle and sprays air to atomize the fuel. It is characterized by having.

  According to the present invention, by promoting atomization of liquid fuel, it is possible to reduce residual carbon-derived dust generated by low quality oil combustion.

  Hereinafter, a gas turbine combustor which is an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a simple cycle gas turbine 1 and a partially enlarged view of a combustor head provided with a fuel spray nozzle device 60 for spraying liquid fuel onto the gas turbine combustor 3.

  The gas turbine includes an air compressor 2, a combustor 3, a turbine 4, a generator 6, a starting motor 8 for driving the gas turbine, and the like. A fuel spray nozzle device 60 for injecting fuel is provided at the head of the gas turbine combustor 3. In this embodiment, low quality oil containing a large amount of residual carbon is used as fuel. The outlet of the fuel spray nozzle device 60 faces the combustion chamber 3a that burns fuel and air to generate combustion gas. A flow sleeve 11 is disposed on the outer peripheral side of the combustor liner 3b forming the combustion chamber, and an end cover 3c capable of supplying steam, which will be described later, is disposed on the upstream side of the flow sleeve 11. The end cover 3c is provided with a steam injection nozzle for reducing NOx. The fuel spray nozzle device 60 attached to the fuel nozzle body 61 is attached to the end cover 3c and is disposed so as to engage with the combustor liner 3b. An outer cylinder 10 is arranged on the outer peripheral side of the flow sleeve 11.

  The fuel nozzle body 61 is provided with a system through which low-quality oil fuel and spray air flow. A fuel nozzle pipe 200b is disposed on the central axis of the fuel nozzle body 61, and an atomizing air inner cylinder 103a-2 is disposed on the outer peripheral side thereof.

  A fuel spray nozzle device 60 having a fuel nozzle / spray air supply nozzle is disposed downstream of the fuel nozzle body 61 so as to communicate with the respective low-quality oil fuel / spray air systems. Specifically, the fuel nozzle pipe 70a is arranged on the downstream side of the fuel nozzle pipe 200b, and the first atomizing air supply nozzle pipe 71a is arranged on the downstream side of the atomizing air inner cylinder 103a-2. Further, a second atomizing air supply nozzle pipe 72 a is installed on the downstream side of the fuel nozzle body 61.

  A fuel nozzle body 61 located upstream of the fuel spray nozzle device 60 is provided with a low quality oil fuel system 200 for supplying low quality oil fuel to the combustion chamber 3a. The low quality oil fuel 200a is disposed in a fuel nozzle pipe 200b. Flows inside. The first atomizing air 103a-1 for atomizing the low quality oil fuel 200a flows between the fuel nozzle pipe 200b and the atomizing air inner cylinder 103a-2, and the second atomizing air 103b-1 is an atomizing air inner cylinder. It flows between 103a-2 and the fuel nozzle body 61. The first atomizing air 103a-1 and the second atomizing air 103b-1 are such that a part of the combustion air pressurized by the air compressor 2 reaches a predetermined pressure by the atomizing booster compressor 14. After the pressure is raised, the air is supplied through the atomizing air supply system 103. The spray air supply system 103 is branched into two systems immediately before the spray air is supplied to the fuel nozzle body 61. In this embodiment, the first spray air supply system is 103a, and the second spray air supply system is 103b. Further, the spray air supply system 103 includes a pressure control valve 15 for adjusting the pressure of the spray air and a check valve 16 for preventing the backflow of air.

On the other hand, the combustion air 102 supplied to the gas turbine combustor 3 is supplied from compressed air pressurized by the air compressor 2. The combustion air 102 flows between the cylindrical combustor liner 3 b that forms the combustion chamber 3 a of the gas turbine combustor 3 and the flow sleeve 11.
A part of the combustion air 102 flows into the combustion chamber 3a from the combustion air holes provided in the combustor liner 3b, and the remaining combustion air 102a flows into the combustion chamber 3a from the swirler 52. Further, a steam injection system 104 for injecting and mixing the steam 104a into the combustion air 102a flowing into the combustion chamber 3a from the swirler (air swirler) 52 is provided. It is possible to reduce NOx by injecting steam into the combustion air 102a.

  In this embodiment, it is assumed that the gas turbine is started by using the low-quality oil fuel 200a alone. However, when the low-quality oil fuel 200a has a high viscosity and it is necessary to heat the low-quality oil fuel 200a to ensure atomization characteristics, the fuel spray nozzle device 60 is activated with light oil or heavy fuel oil A when the gas turbine is activated. It is also possible to supply the fuel and switch the fuel to the low-quality oil fuel 200a under a low load condition after starting the gas turbine.

  Hereinafter, the operation method of this plant is demonstrated.

  At startup, the gas turbine is driven by external power such as a starter motor 8. Then, the gas turbine combustor 3 is ignited using the combustion air 102 from the air compressor 2 and the low quality oil fuel 200a. Thereafter, the combustion gas 110 is supplied to the turbine 4. As the flow rate of the low-quality oil fuel 200a increases, the turbine 4 increases in speed, and when the starter motor 8 is detached, the gas turbine enters a self-sustaining operation and reaches a no-load rated rotational speed.

After the gas turbine reaches the no-load rated rotational speed, the inlet gas temperature of the turbine 4 increases and the load also increases due to the addition of the generator 6 and the increase in the flow rate of the low quality oil fuel 200a.
After loading, the steam 104a is injected into the combustor 3 to reduce the NOx concentration. The steam 104 a supplied to the combustor 3 is adjusted to an appropriate flow rate by the steam flow rate adjustment valve 302 via the shut-off valve 301. The steam 104a is mixed with the combustion air 102a flowing from the swirler 52 provided on the outer peripheral side of the fuel spray nozzle device 60. The combustion air 102a in which the steam 104a is mixed and the oxygen concentration is lowered burns the low-quality oil fuel 200a at a low oxygen concentration, so that the local flame temperature can be lowered and the generation of NOx can be suppressed.

  Air necessary for atomizing the fuel in the fuel spray nozzle device 60 is supplied from the booster compressor 14 for spray air. This air further pressurizes a portion 103 of the combustion air 102 supplied from the air compressor 2 by the boost compressor 14. And after adjusting a pressure with the pressure control valve 15, it is supplied as atomization air of the low quality oil fuel 200a from the fuel spray nozzle apparatus 60. FIG.

  Specifically, the spray air supply system 103 is branched into two systems, a first spray air supply system 103a and a second spray air supply system 103b, immediately before flowing into the fuel nozzle body 61, and the first air is supplied by pressure balance. Supplied to the first and second atomizing air supply nozzles. In this way, by diverging from the single spray air supply system 103, the spray air supply system can be simplified.

  Next, in the fuel spray nozzle device 60 of FIG. 1, a partial enlarged cross-sectional view on the combustion chamber side is shown in FIG. Out of the combustion air 102 supplied to the gas turbine combustor, combustion air 102 a supplied by pressure balance is supplied to an air swirler (swirler) 52 on the outer peripheral side of the fuel spray nozzle device 60. This air swirler 52 holds the flame 300.

  A fuel nozzle 70 for injecting the low quality oil fuel 200a into the combustion chamber 3a is provided in the vicinity of the central portion in the radial direction of the fuel spray nozzle device 60, and the first spray air for assisting atomization of the fuel is provided on the outer periphery thereof. A supply nozzle 71 and a second atomizing air supply nozzle 72 for re-atomizing the sprayed droplets are provided on the outer periphery thereof.

  The fuel nozzle 70 is formed by a fuel nozzle tube 70a, and the outlet portion of the fuel nozzle tube 70a has a tapered shape in which the flow path diameter decreases. The first spray air 103a-1 flows through an annular space provided between the fuel nozzle pipe 70a and the first spray air supply nozzle pipe 71a after flowing through the first spray air supply system 103a. . The second spray air 103b-1 is provided between the first spray air supply nozzle pipe 71a and the second spray air supply nozzle pipe 72a after flowing through the second spray air supply system 103b. Flowing through an annular space. Here, the central axes of the first spray air supply nozzle pipe 71a and the second spray air supply nozzle pipe 72a are arranged so as to coincide with the central axis of the fuel nozzle pipe 70a, and the outlet portions of both are also fuel. It has the same shape as the outlet of the nozzle tube 70a. Each spray air supply system is provided with spray air swirlers 80 and 81 for swirling the spray air. As the first spray air 103a-1 and the second spray air 103b-1 pass through the spray air swirlers 80 and 81, a swirl component is given to the spray air.

  The low-quality oil fuel 200a supplied to the fuel nozzle 70 is swirled in the fuel nozzle 70 and injected as a fuel liquid film 150. The outlets of the first spray air supply nozzle 71 and the second spray air supply nozzle 72 provided on the outer peripheral side of the fuel nozzle 70 are the first spray air 103a-1 in the direction intersecting the central axis of the fuel nozzle 70. The second atomizing air 103b-1 is sprayed. Therefore, by supplying the first spray air 103a-1 from the first spray air supply nozzle 71 to the fuel liquid film 150, the liquid film is sheared and the liquid film is atomized. The droplets atomized here are further supplied with the second atomizing air 103b-1 from the second atomizing air supply nozzle 72 provided on the outer periphery thereof, so that they cannot be atomized completely and have a large particle size. The droplets are also sheared, and the droplets are deformed to break up and further promote atomization. As the atomization is promoted, the evaporation of the fuel is accelerated, and the mixing with the surrounding air is also promoted to suppress the generation of soot. In addition, since the particle size of Senospha is reduced, the dust concentration can be reduced.

  Here, consider a case where the second atomizing air supply nozzle 72 is not provided as a comparative example. Even in the comparative example, since the swirl component is given to the spray air ejected from the first spray air supply nozzle 71, fuel droplets having a relatively large diameter gather on the outer peripheral side of the fuel spray nozzle device by centrifugal force, The particle size distribution is such that droplets with small diameters gather on the central axis (radial center) of the fuel nozzle 70. The injected fuel droplets are evaporated by receiving heat from the combustion air or flame, and the combustion is continued by mixing the evaporated fuel vapor and the ambient air. However, since droplets with a large spray particle size take time to evaporate the fuel, mixing with ambient air is also delayed. In addition, since the periphery of the droplet is a fuel-rich region, soot is generated in the process of evaporation and combustion, and the soot concentration increases. And when burning a low quality oil fuel, cenosphere derived from residual carbon is also generated. For this reason, in the case of a droplet having a large initial particle size, the particle size of Senospha also increases, and as a result, these particles do not burn in the combustion chamber but are discharged outside the combustor as soot. Therefore, in this embodiment, it is possible to promote atomization by re-atomizing droplets that could not be made fine with the first atomizing air by using the second atomizing air.

  FIG. 3 is a front view of the fuel spray nozzle device 60 viewed from the combustion chamber. A fuel nozzle 70 is disposed at the center in the radial direction of the fuel spray nozzle device, and first and second spray air supply nozzles 71 and 72 are provided on the outer periphery thereof to promote atomization of the fuel. A swirler 52 is provided on the outer peripheral side of these fuel nozzles, and a flame is formed by mixing atomized fuel and combustion air flowing in from the swirler. By swirling the combustion air by the swirler, a low speed region (circulation flow) is formed on the inner periphery of the swirler, and the flame holding is strengthened.

  Next, FIG. 4 shows an AA arrow view of the nozzle cross section of FIG. The first and second spray air supply nozzles 71 and 72 provided on the outer peripheral side of the fuel nozzle 70 are provided with spray air swirlers 80 and 81, respectively. Each atomizing air swirler has air holes 80a and 81a that are configured to swirl the first atomizing air 103a-1 and the second atomizing air 103b-1. Here, the flow direction of the atomizing air when the swirling direction of the atomizing air is reversed is shown. By reversing the swirling direction of the atomizing air, the fuel droplets atomized by the first atomizing air are swirled in the opposite direction by the second atomizing air, and the droplets are deformed by shearing. For this reason, the droplets are split, and re-atomization can be performed to promote atomization. Compared to the case where two systems of spray air are swirled in the forward direction, the reverse direction is more effective for promoting atomization.

  FIG. 5 shows an outline of the system when the atomizing air supply system 103 is supplied to the fuel nozzle body 61 as a single system.

  When the spray air supply system 103 is connected to the fuel nozzle body 61 in one system, the spray air is divided into two systems (the first spray air 103a-1 and the second spray air in the fuel nozzle body 61 or the fuel spray nozzle device 60). 103b-1). Therefore, in this embodiment, the atomizing air connected to the fuel nozzle body 61 is one system, and the fuel nozzle body 61 uses the housing 3d-a used for connecting and fixing each pipe to the fuel spray nozzle device 60. When supplying atomizing air, it distributes to two systems. The housing 3d-a is disposed as a separate member on the center side of the annular flange 3d. However, the housing 3d-a and the flange 3d can be integrated. Here, the area of the hole for branching the spray air provided in the housing 3d-a into two systems is made larger than the hole area of the spray air swirler provided to give the swirl component to the spray air. Care must be taken not to increase pressure loss. Moreover, the shape of the hole provided in the housing 3d-a may be a circle or an ellipse, and by providing a plurality of holes in the circumferential direction, variation in air in the circumferential direction can be reduced.

  As in the embodiment of FIG. 1, the distribution of the spray air flow rate to the first and second spray air supply systems is substantially determined by the cross-sectional area ratio of each spray air nozzle. A predetermined spray air flow rate ratio can be obtained by determining a flow rate ratio required in the first and second spray air supply systems in advance. The fuel spray nozzle device 60 includes the first and second spray air supply nozzles, but the spray air supply system is integrated into the fuel nozzle body 61 so that the spray air can be operated with simple control. Is possible.

It is the figure which showed the Example of the power plant by this invention. It is a partial expanded sectional view of the fuel spray nozzle apparatus by this invention. It is a front view of the fuel spray nozzle apparatus by this invention. It is the figure which showed the AA arrow line view of FIG. It is the figure which showed Example 2 of the power plant by this invention. It is a figure which shows the relationship between the residual carbon concentration in a fuel, and a dust concentration.

Explanation of symbols

1 Gas turbine
2 Air compressor 3 Combustor 3a Combustion chamber 4 Turbine 6 Generator 8 Motor 10 for start-up 10 Outer cylinder 14 Booster compressor 15 Pressure control valve 16 Check valve 52 Swirler (air swirler)
60 fuel spray nozzle device 61 fuel nozzle body 70 fuel nozzle 71 first spray air supply nozzle 72 second spray air supply nozzles 80, 81 spray air swirlers 102, 102a combustion air 103 spray air supply system 103a first Sprayed air supply system 103a-1 First sprayed air 103b Second sprayed air supply system 103b-1 Second sprayed air 104 Steam injection system 110 Combustion gas 150 Liquid film 200 of fuel Low quality oil fuel system 200a Low quality oil fuel

Claims (4)

A gas turbine combustor comprising a combustion chamber for burning fuel and air, a fuel spray nozzle device for supplying fuel to the combustion chamber, and a swirler for supplying combustion air from the outer peripheral side of the fuel spray nozzle device ,
Using a low-quality oil fuel containing residual carbon as the fuel, a fuel nozzle disposed near the center of the fuel spray nozzle device;
A first spray air supply nozzle disposed on the outer peripheral side of the fuel nozzle and spraying air to atomize the fuel;
A gas turbine combustor comprising a second spray air supply nozzle that is disposed on an outer peripheral side of the first spray air supply nozzle and sprays air to atomize the fuel. A gas turbine combustor according to claim 1,
A spray air supply system for supplying air to the first and second spray air supply nozzles;
A gas turbine combustor comprising a spray air compressor that pressurizes and supplies air to the first and second spray air supply nozzles through the spray air supply system. A gas turbine combustor according to claim 2,
A fuel nozzle body for fixing the fuel spray nozzle device;
A gas turbine combustor, wherein a single atomizing air supply system provided in the fuel nozzle body is branched into two atomizing air supply systems in the fuel nozzle body. A gas turbine combustor according to claim 1,
A gas turbine combustor, wherein a swirler is disposed in the spray air supply nozzle so that swirl directions of the spray air supplied from the first and second spray air supply nozzles are opposite to each other.

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