JP2006105534A - Gas turbine combustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas turbine combustor hardly generating an unburned material or hardly causing thermal deterioration of a part such as a main mixer tube. <P>SOLUTION: The gas turbine combustor comprises a combustion cylinder 1 the bottom of which is connected to the suction side of a gas turbine, and the main mixer tube 3 and a premixer tube 2 connected to the top of the combustion cylinder 1. The premixer tube 2 is connected to the combustion cylinder 1 through a flame holding cylinder 8 having an internal space for stably holding flame. Since the position of the premixer tube is retreated in relation to the axial line of the combustion cylinder by the portion of the flame holding cylinder, completely burned gas from the premixer tube is combined with air-fuel mixture ejected from the main mixer tube, and ignited. Therefore, satisfactory combustion efficiency can be ensured, and the unburned material is hardly generated. Further, since the tip of the main mixer tube is not protruded into the combustion cylinder, a problem such as thermal deterioration of parts is not caused. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas turbine combustor, and in particular, appropriately sets the positional relationship between a premixing pipe and a main mixing pipe with respect to a combustion cylinder to improve combustion efficiency, and causes thermal deterioration of the main mixing pipe and the like due to heat of the combustion cylinder. The present invention relates to a structure that can prevent this.

  In a gas turbine combustor, as a combustion method that can achieve both high combustion efficiency and low NOx emission concentration, a stable ignition flame is formed with a rich mixture by a pilot nozzle, and the flame from this pilot nozzle is transferred from the main nozzle to the flame. A system is known in which a lean air-fuel mixture is blown to ignite and burn.

  However, in this method, when a low-temperature gas mixed with fuel and air is directly sprayed from the main nozzle in a state where the pilot nozzle for ignition is burning at a high temperature, the temperature drops and incomplete combustion occurs. In general, however, the combustion efficiency that can be expected to be about 99% is reduced to about 90%, and a combustion state in which unburned substances such as CO and HC are likely to be generated is caused.

  In order to avoid such inconvenience, for example, as shown in Patent Document 1, a gas turbine combustor having a structure shown in FIG. 7 has been developed. This gas turbine combustor is disposed at the top of the combustion cylinder 100 having a closed top and a lower opening end communicating with the intake side of the turbine, and at the top of the combustion cylinder 100. The pilot nozzle 102 for ignition provided with a cone 101 as a flame-holding plate at the tip thereof is disposed around the pilot nozzle 102, and the outlet thereof And a main nozzle 104 having a variable valve 103 which is an adjustment mechanism corresponding to the load of the area.

  In this structure, the tip of the pilot nozzle 102 provided with the cone 101 is protruded into the combustion cylinder 100, so that the combustion position in the combustion cylinder 100 in the axial direction of the combustion cylinder 100 is set to the main nozzle 104. The mixture is shifted from the combustion position of the air-fuel mixture ejected from (staging, that is, set so that the position in the axial direction is different), and the two air-fuel mixtures are joined together.

As a result, the air-fuel mixture injected from the pilot nozzle 102 is ignited by an ignition plug (not shown) and completely burned, and the combustion gas from the pilot nozzle 102 is joined to the thin air-fuel mixture discharged from the main nozzle 104 to ignite and burn. Therefore, generation of unburned substances such as THC and CO can be efficiently prevented.
Japanese Patent No. 3197101

  However, in this structure, the tip of the pilot nozzle 102 to which the cone 101 is attached is in the combustion cylinder 100, but the temperature in the combustion cylinder 100 becomes high due to the generated high-temperature and high-pressure gas. For this reason, the tip portion of the pilot nozzle 102 including the cone 101 and the like in the combustion cylinder 100 is easily exposed to the combustion gas to cause thermal deterioration, and there is a problem in heat resistance.

  Therefore, the present invention solves the above-mentioned problems, and the object of the present invention is to provide an unburned substance in the axial arrangement of the premixing pipe (pilot nozzle) and the main mixing pipe (main nozzle) related to the combustion cylinder. It is an object of the present invention to provide a gas turbine combustor that has a layout relationship that is difficult to generate and has good combustion efficiency, and that can prevent thermal deterioration of components such as a main mixing pipe.

  In order to achieve the above object, a gas turbine combustor according to claim 1 is a gas turbine combustor having a combustion cylinder for supplying combustion gas to a turbine, and a main mixing pipe and a premixing pipe connected to the combustion cylinder. The premixing tube is connected to the combustor via a flame holding cylinder having an internal space for stably holding the flame.

  The gas turbine combustor according to claim 2 is the gas turbine combustor according to claim 1, wherein a cross section of the flame holding cylinder is frustoconical in a cut surface parallel to a gas injection direction of the premixing tube. It is characterized by.

  A gas turbine combustor according to a third aspect is the gas turbine combustor according to the first aspect, wherein swirlers are respectively provided in the air intake ports of the main mixing pipe and the premixing pipe, and the swirler of the main mixing pipe is The swirler of the premixing tube is characterized by generating a slow swirling flow and a strong swirling flow.

  The gas turbine combustor according to claim 4 is the gas turbine combustor according to claim 1, wherein the main mixing pipe and the premixing pipe are arranged in a combustion cylinder in a pair, and the main mixing pipes are spaced apart from each other. Where L is 1.5 and the diameter of the main mixing tube is d, L = 1.5 to 2.0d.

  The gas turbine combustor according to claim 5 is the gas turbine combustor according to claim 1 or 2, wherein a cover is disposed on the outer periphery of the flame holding cylinder with a gap, and a plurality of cooling covers are provided on the cover. The vent is opened.

  As described above, in the first aspect of the present invention, the position of the premixing pipe is retreated in the axial direction of the combustion cylinder by the amount of the flame holding cylinder, whereby the flame from the premixing pipe is ejected from the main mixing pipe in a completely burned state. Because it is ignited by merging with the air-fuel mixture, the combustion efficiency is high and it is difficult to generate unburned substances, and the tip of the main mixing pipe does not protrude into the combustion cylinder, so problems such as thermal deterioration of parts can be solved at the same time .

  According to the second aspect of the present invention, there is no backflow region of the combustion gas to the premixing tube, and the ignited air-fuel mixture diffuses into the combustion cylinder along the frustoconical taper shape.

  In the invention of claim 3, since the air-fuel mixture ejected from the premixing tube generates a strong swirl flow by the swirler, a stable flame can be obtained, while the air-fuel mixture ejected from the main mixing tube is decelerated in the axial direction. Since it becomes a flow, it can ignite reliably by the flame which ejects from a premixing pipe, avoiding interference with the flame which ejects from a premixing pipe.

  In the invention of claim 4, a state where the value L falls below the range of 1.5 to 2.0d means that the main mixing tubes are close to each other, and the flow of the premixed gas flame interferes. The overall flow rate is faster. Conversely, the state within the above numerical range indicates that the main mixing tubes are sufficiently separated from each other, and the axial flame flows between the main mixing tubes do not interfere with each other, and the premixing tubes Since the flame flow from the main flame and the flame flow from the main mixing tube do not interfere with each other, a stable combustion mode can be obtained at an appropriate temperature.

  According to the fifth aspect of the present invention, air easily flows around the outer periphery of the flame holding cylinder main body through the vent of the cover, and the flame holding cylinder is easily cooled.

The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.
1 to 6 show an embodiment of the present invention, FIG. 1 is a side sectional view of a gas turbine combustor according to the present invention, FIG. 2 (a) is a perspective view showing the top of a combustion cylinder, and FIG. Fig. 3 (a) is a partially enlarged sectional view of the flame holding cylinder shown in Fig. 3 (a), Fig. 3 (a) is a side view showing the arrangement interval of the main mixing pipes at the top of the combustion cylinder, and Fig. 3 (b) is the plan view. 4 is an explanatory plan view showing the flow velocity distribution of the combustion gas at an ideal arrangement interval between the main mixing pipes, and FIG. 5 is an explanatory plan view showing the flow velocity distribution of the combustion gas when the arrangement interval between the main mixing pipes is reduced. FIGS. 6A and 6B are side views showing an example of a cross-sectional shape of the flame holding cylinder in the premixing tube.

  In FIG. 1, a gas turbine combustor is disposed at a top portion of a combustion cylinder 1 having a generally cylindrical shape in which a top portion is closed and opened and communicated with a supply side of the turbine. An ignition premixing tube 2 and a main mixing tube 3 that open toward the inside, an air intake outer tube 4 that surrounds the top and outer periphery of the combustion tube 1, and the top of the outer tube 4 pass through. Fuel injection nozzles 6 and 7 connected to the upper centers of the premixing pipe 2 and the main mixing pipe 3 are provided. In addition, the gas injection direction by the premixing pipe 2 and the main mixing pipe 3 is substantially parallel to the axial direction of the combustion cylinder.

  The premixing tube 2 is attached to the top of the combustion cylinder 1 via a flame holding cylinder 8 having a truncated cone shape when viewed in a cross section parallel to the gas injection direction of the premixing pipe 2 or the axial direction of the combustion cylinder. Are combined. The gas injected from the premixing pipe 2 is ignited by a spark plug (not shown) in the flame holding cylinder 8 and is jetted toward the inside of the combustion cylinder 1 while burning. That is, the gas combustion position by the premixing pipe 2 is set back in the axial direction of the combustion cylinder 1 with respect to the ejection position of the main mixing pipe 3 by the length of the flame holding cylinder 8 in the axial direction of the combustion cylinder 1. ing. Due to the arrangement of the premixing pipe 2 and the main mixing pipe 3 in the axial direction, the front end opening of the main mixing pipe 3 does not protrude into the combustion cylinder 1, and there is no problem with respect to the heat resistance of the parts.

  The air introduced into the outer cylinder 4 from the periphery of the bottom of the outer cylinder 4 as indicated by the arrow flows into the combustion cylinder 1 from the through hole provided in the peripheral wall of the combustion cylinder 1, and the premixing pipe 2 and It flows into the combustion cylinder 1 from the openings formed in the portions where the nozzles 6 and 7 are connected to the main mixing pipe 3, and is mixed with the fuel gas introduced from the nozzles 6 and 7 at an appropriate air-fuel ratio. Then, the fuel gas is burned in the combustion cylinder 1. The combustion gas is supplied from the opening at the lower end of the combustion cylinder 1 to the supply side of the gas turbine.

  In the premixing pipe 2, the mixing ratio becomes relatively high so that stable combustion can be obtained, whereas in the main mixing pipe 3, the mixing ratio becomes relatively small and It is the same as in the prior art that it is ignited by the jetting combustion gas.

  Further, the lower side of the combustion cylinder 1 is narrowed to have a small diameter, and is supplied to the gas turbine side while further taking in air through a plurality of air intake openings 1a.

  FIG. 2A shows the configuration of the upper side of the combustion cylinder 1. In the figure, the pair of main mixing pipes 3 and 3 described above are erected at the top of the combustion cylinder 1 at a position opposite to the center by 180.degree. Premixing tubes 2 and 2 are erected. A cover 9 made of a metal plate is provided on the outer periphery of the flame holding cylinder 8 with a gap, and a plurality of vent holes 9a are opened as shown in an enlarged view in FIG. Air flows through the outer periphery of the flame holding cylinder 8 and cools this portion.

Inverted swirlers 10 are respectively provided at the air intakes in the outer periphery of the nozzle mounting base of the premixing tube 2. The swirler 10 is provided to generate a swirling flow in the air mixed with the fuel gas or fuel spray (liquid fuel) to make the mixing uniform and stabilize the flame.
Similarly, a swirler 11 having an inverted shape is provided on the outer periphery of the air inlet at the outer periphery of the nozzle mounting base of each main mixing pipe 3. The swirler 11 is provided to generate a decelerated direct current in order to avoid interference with the air-fuel mixture flow in the premixing tube 2, and the arrangement interval, pitch, etc. of the swirler 11 are set accordingly. Yes.

FIGS. 3A and 3B show the arrangement interval between the main mixing tubes 3 at the top of the combustion cylinder 1, where the maximum diameter of the main mixing tube 3 is d and the separation interval of the mounting base with respect to the combustion cylinder 1 is shown. When L is set, L = 1.5 to 2.0d is a preferable separation interval.
This is because the main mixing pipes 3 are sufficiently separated from each other in the numerical range, whereas the premixing pipes 2 may be relatively close to each other. As indicated by the constant velocity line in the axial direction of the combustion gas, the premixing tubes 2 are surrounded by a closed curve, but the constant velocity lines of the two main mixing tubes 3 and 3 are independent from each other. The flow from the main mixing pipe 3 does not interfere with the flow of the flame from the front, so that the flame from the premixing pipe 2 is stabilized, and the mixture from the main mixing pipe 3 ignited thereby is efficient. Burn well. Further, the velocity distribution in the combustion cylinder 1 is relatively smooth, and a stable flame is generated in the combustion cylinder 1.

  On the other hand, FIG. 5 shows the combustion gas in the combustion cylinder 1 when L <1.5 to 2.0d, that is, when the interval between the main mixing tubes 3 and 3 is made smaller than the ideal value. This shows the constant velocity distribution in the axial direction, and the position of the constant velocity line (5) in this case is a closed loop curve surrounding each mixing tube 2, 3, and the flow is fast as a whole. Since the flows from the main mixing pipe 3 interfere with each other, an unstable flame is generated in the combustion cylinder 1. Therefore, the interval between the main mixing pipes 3 and 3 is preferably within the numerical range.

  6 (a) and 6 (b) show examples of the shape of the flame holding cylinder 8 connected to the premixing pipe 2. First, (a) is a cut surface parallel to the axis of the combustion cylinder 1 as described above. Shows a flame holding cylinder 8 having a frustoconical cross section when viewed in FIG. 1. In this case, the flow of the air-fuel mixture from the premixing pipe 2 flows continuously without causing a backflow region. Because there is no ideal flame flow. In this case, the cone angle is preferably about 30 to 70 °.

  On the other hand, the flame holding cylinder 8 'shown in (b) has a cylindrical shape larger in diameter than the tip diameter of the premixing tube 2, and there is a possibility that a backflow region may occur in a portion A indicated by a broken line in the figure. When the region is generated, the portion becomes high temperature, so cooling is necessary, and vortexes are generated in this portion A, so that the flame in the combustion cylinder 1 is not stable. Compared to the flame holding cylinder 8 of FIG. However, even with such a shape, the arrangement of the premixing tube and the main mixing tube in the axial direction of the combustion cylinder is shifted in the axial direction so that unburned substances are not easily generated, and at the same time, Similar to the flame holding cylinder 8 of FIG. 6 (a), it can be adopted that a sufficient effect can be obtained in that heat deterioration of components such as the main mixing pipe can be prevented.

1 is a longitudinal sectional view of a gas turbine combustor according to the present invention. (A) is a perspective view which shows the top part of the same combustion cylinder, (b) is a partially expanded sectional view of a flame holding cylinder. (A), (b) is the side view and top view which show the arrangement | positioning space | interval of the main mixing pipe | tube in a combustion cylinder top part. It is a plane explanatory view showing the flow velocity distribution of combustion gas in the ideal arrangement interval between main mixing tubes. It is a plane explanatory view showing the flow velocity distribution of the combustion gas when the arrangement interval between the main mixing pipes is reduced. (A), (b) is side explanatory drawing which shows the cross-sectional example of the flame holding cylinder in a premixing pipe. It is a longitudinal cross-sectional view of the conventional gas turbine combustor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion cylinder 2 Premixing pipe 3 Main mixing pipe 6,7 Fuel injection nozzle 8,8 'Flame holding cylinder 10,11 Swirler

Claims (5)

In a gas turbine combustor having a combustion cylinder for supplying combustion gas to a turbine, and a main mixing pipe and a premixing pipe connected to the combustion cylinder,
The gas turbine combustor, wherein the premixing tube is connected to the combustor via a flame holding cylinder having an internal space for stably holding a flame. 2. The gas turbine combustor according to claim 1, wherein a cross section of the flame holding cylinder has a truncated cone shape in a cut surface parallel to a gas injection direction of the premixing tube. A swirler is provided at each of the air intake ports of the main mixing pipe and the premixing pipe, and the swirler of the main mixing pipe generates a decelerating straight flow, and the swirler of the premixing pipe generates a strong swirling flow. The gas turbine combustor according to claim 1, wherein the gas turbine combustor is provided. When the main mixing pipe and the premixing pipe are arranged in a pair in the combustion cylinder, the spacing between the main mixing pipes is L, and the diameter of the main mixing pipe is d, L = 1.5 to The gas turbine combustor according to claim 1, wherein the gas turbine combustor is 2.0 d. The gas turbine combustor according to claim 1 or 2, wherein a cover is disposed on the outer periphery of the flame holding cylinder with a gap, and a plurality of cooling vents are opened in the cover. .

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