JP2006329587A - Swirl burner for liquid fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a swirl burner for liquid fuel of low emission. <P>SOLUTION: The swirl burner 2 for liquid fuel provided at the top of a combustion cylinder 1 is formed by disposing a main low swirl burner 6 in concentric circle shape outside a pilot low swirl burner 5, wherein the pilot low swirl burner 5 is provided with swirlers 10, 12 different in the swirling direction, at a premixing pipe 7, and the main low swirl burner 6 is provided with swirlers 14, 16 different in the swirling direction, at a main mixing pipe 8. Since both pilot and main swirl burners are low swirl burners, combustion is stabilized to carry out complete combustion, and low emission of NOx or the like can be attained. Further, since a flame is a lifted flame narrow in the contact range of a flame root with the burner, the burner itself is hard to overheat. Durability is thereby high. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a swirl burner for liquid fuel applied to a combustion apparatus for burning liquid fuel in a gas turbine, a boiler, or the like.

The present applicant has proposed a swirl burner for gas or liquid fuel in Patent Document 1 below. This swirl burner is provided with a first swirler that turns left and a second swirler that turns right on the outside, with a fuel nozzle for gas or liquid fuel as the center. It has a substantially circular truncated cone shape that is circular and has a cross-sectional area that decreases toward the outlet. According to this swirl burner, it is possible to make it difficult for backfire to occur without impairing the flame holding promoting effect due to the swirling of the air-fuel mixture.
JP 2003-194337 A

  However, when the conventional swirl burner is to be applied to a low swirl burner for liquid fuel, four fuel valves (two pilots and two mains) are required and interference between the pilot and the main can be avoided. There was a practical problem of not being. On the other hand, in the case of a low swirl burner for gas fuel, as a member for obtaining a uniform turbulent velocity field downstream of the burner, a punching plate (a flat plate member having a large number of through holes formed in the center of the burner) ) Etc. are usually provided. Even in the case of a swirl burner for liquid fuel, a similar flow field is required for premixed lean combustion by the same flame holding mechanism, and therefore, similar to the punching plate in the swirl burner for gas fuel. A mechanism is considered necessary.

  However, in the swirl burner for liquid fuel, in order to pre-mix lean combustion of the liquid fuel, the process of fuel atomization, pre-evaporation, and pre-mixing is necessary. Usually, pre-evaporation and pre-mixing are performed in the same space. However, if a member such as the punching plate as described above is present, unevaporated components may adhere to the punching plate and hinder the evaporation process.

  Therefore, the present invention solves the above-mentioned problems, and its object is to reliably atomize, pre-evaporate, and pre-mix liquid fuel, and to achieve a wide operating range while maintaining a stable flame. Thus, the present invention is to provide a liquid fuel swirl burner capable of realizing a low emission low swirl burner for liquid fuel.

The swirl burner for liquid fuel according to claim 1 is:
In the swirl burner for liquid fuel provided at the top of the combustion cylinder,
A pilot low swirl burner having a premixing pipe connected and opened at the top of the combustion cylinder, and a plurality of annular swirlers with different swirl directions provided at the inlet of the premixing pipe;
A main mixing pipe disposed concentrically outside the premixing pipe and connected and opened to the top of the combustion cylinder; and a swivel direction provided at an inlet between the main mixing pipe and the premixing pipe A main low swirl burner having a plurality of different annular swirlers;
A frame holder provided at a connection portion between the pilot low swirl burner premixing tube and the combustion cylinder, and preventing interference between the flow of the pilot low swirl burner and the flow of the main low swirl burner;
It is characterized by having.

  The liquid fuel swirl burner according to claim 2 is characterized in that, in the liquid fuel swirl burner according to claim 1, the inner diameter of the premixing tube is gradually reduced toward the frame holder. And

  Therefore, according to the first aspect of the present invention, since both the pilot and main swirl burners are low swirl burners, the combustion is stable and complete combustion is achieved, and the emission of NOx, CO, THC, etc. can be prevented. Emissions can be achieved.

  In addition, the air-vaporized fuel mixture that enters the combustion cylinder from the main low swirl burner comes into contact with the flame from the pilot low swirl burner that blows out from the tip of the frame holder and blows out the flame into the combustion cylinder. Since the range of contact with the burner is a narrow rising flame, the burner itself is not easily overheated and has high durability.

  In addition, the pilot and main swirl burners are arranged concentrically, so that compared to the case where multiple pilot burners and main burners are independently arranged in parallel, a single burner can be used, reducing the number of components. And a significant reduction in control is possible.

  According to the second aspect of the present invention, a straight flow centered on the premixing pipe can be formed, the flow velocity of the air-vaporized fuel mixture is maximized at the maximum constricted position, and the pilot flame is generated from the enlarged diameter portion of the tip. Since it comes out in a combustion cylinder, there is no flame retraction and the quenching prevention effect accompanying the flame blowing from the main low swirl burner can be acquired.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a side sectional view showing the overall configuration of a turbine combustor according to the present invention, FIG. 2 is a perspective view of a liquid fuel swirl burner used in the combustor as seen from the flame outlet side, and FIG. 3 is a top view of the burner. FIG. 4 is an enlarged sectional view showing a state in which a pilot flame is blown from the burner, and FIG. 5 is an enlarged sectional view showing a state in which a main flame is blown from the burner.

  In FIG. 1, the turbine combustor is closed at the top, opened at the bottom, and the bottom opening communicated with the supply side of the turbine (not shown), and the center position of the top of the combustion cylinder 1. And a swirl burner 2 for liquid fuel with its lower opening directed into the combustion cylinder 1, an outer cylinder 3 for air intake surrounding the top and outer periphery of the combustion cylinder 1, and the top of the outer cylinder 3. A pilot fuel injection nozzle 4 which penetrates and is connected to the upper center of the liquid fuel swirl burner 2 and a main fuel supply pipe 30 which is connected to the upper side of the liquid fuel swirl burner 2. I have.

  As shown in FIGS. 2 to 4, the liquid fuel swirl burner 2 includes a pilot low swirl burner 5 formed on the center side, and a main low swirl burner concentrically disposed around the pilot low swirl burner 5. 6.

  The pilot low swirl burner 5 on the center side includes a premixing pipe 7 that is connected to the top of the combustion cylinder 1 and two annular swirlers 10 that have different swirling directions and that are provided at an enlarged diameter inlet of the premixing pipe 7. , 12 and an annular partition wall 11 that partitions the swirlers 10, 12.

  The premixing tube 7 is an inverted frustoconical cylinder whose inner diameter is gradually reduced toward the combustion cylinder 1, and a cone whose inner diameter increases toward the combustion cylinder 1 at the narrowest maximum constriction position 7 a. The frame holder 20, which is a trapezoidal cylinder, is connected to and communicated with the frame holder 20, and the frame holder 20 has a connection opening at the top of the combustion cylinder 1.

  The fuel injection nozzle 4 is inserted into the center of the central swirler 10 at the top of the pilot low swirl burner 5 and is configured to supply pilot liquid fuel.

  Since the pilot low swirl burner 5 includes two annular swirlers 10 and 12 having different swirl directions, a relatively weak swirl can be generated and an expanded flow can be formed downstream of the burner. The flame can be held where the flow velocity of the combustion field is balanced, and the flame can be held in a lifted state.

  The main low swirl burner 6 on the outer peripheral side is disposed concentrically outside the premixing tube 7 and is connected to the top of the combustion cylinder 1 to open and connected to the top of the combustion cylinder 1. Two annular swirlers 14 and 16 having different swirl directions provided at the entrance between the pipes 7 and an annular partition 15 partitioning the two swirlers 14 and 16 are provided.

  The shape of the main mixing tube 8 is substantially along the outer surfaces of the premixing tube 7 and the frame holder 20 having a constricted portion, and a gap of a predetermined dimension is provided between the mixing tubes 7 and 8.

  A fuel supply groove 7b is formed on the outer periphery of the top portion of the premixing pipe 7, and the fuel supply pipe 30 is configured to supply main liquid fuel to the fuel supply groove 7b. . The liquid fuel supplied to the fuel supply groove 7b is blown outward by the swirling flow by the inner swirler 14, forms a thin film on the partition wall 15, is atomized by the air flow at the tip, and evaporates. .

  Since the main low swirl burner 6 includes two annular swirlers 14 and 16 having different swirl directions, a relatively weak swirl can be generated and an expanded flow can be formed downstream of the burner. As in 5, flame holding is possible where the turbulent combustion speed and the flow velocity of the combustion field are balanced, and the flame can be held in a lifted state.

The combustion state in the above configuration will be described with reference to FIGS.
First, FIG. 4 shows a state in which only the pilot low swirl burner 5 is ignited, and relatively fine droplets of liquid fuel ejected from an injection hole (not shown) formed in the fuel injection nozzle 4 have their swirling directions as they are. On the other hand, the droplets mixed with the air flow formed by the two swirlers 10 and 12 are mixed, and the droplet having a large penetrating force collides with the partition wall 11 to form a liquid film and is then atomized and mixed with the air. From the front end of the nozzle toward the inside of the combustion cylinder 1. In this state, the mixed airflow is ignited by an ignition plug (not shown) provided in the combustion cylinder 1, and a flame F 1 is formed at the tip of the maximum constriction position 7 a where the flow velocity becomes maximum, and its diameter is expanded from the tip of the frame holder 20. It becomes a shape bulging in accordance with the shape and blows out into the combustion cylinder 1 and thereafter the outlet portion of the frame holder 20 is heated, so that the ignition state is maintained and the flame is held in the shape.

  The mixed air flow created in the pilot low swirl burner 5 has a relatively rich air-fuel ratio, and a stable combustion mode can be obtained in the full load region from the start.

  Next, as shown in FIG. 5, the main low swirl burner 6 is burned while the pilot low swirl burner 5 is ignited. That is, when the liquid fuel is supplied from the fuel supply pipe 30 to the fuel supply groove 7b provided on the outer periphery of the top portion of the premixing pipe 7, the liquid fuel is directed outward by the swirl flow by the swirler 14 inside. Is blown off, collides with and adheres to the partition wall 15, forms a thin film, is atomized by the air flow at the tip, further evaporates by the swirling flow and mixes with the air, and between the premixing tube 7 and the main mixing tube 8. The gas is ejected toward the combustion cylinder 1 through the space formed in the above. Then, at the moment when this mixed airflow reaches the inside of the combustion cylinder 1, it comes into contact with the flame F1 of the pilot low swirl burner 5 and ignites, and a strong flame F2 is ejected. Thereafter, this state continues.

  The mixed air flow created in the main low swirl burner 6 has a relatively thin air-fuel ratio, which stabilizes combustion and complete combustion, thereby preventing emission of NOx, CO, THC, etc., and achieving low emissions. .

  Further, the pilot low swirl burner 5 has the maximum flow velocity at the maximum constriction position 7a of the frame holder 7. Therefore, the flame F1 does not retreat inward from the constriction position 7a. The quenching prevention effect accompanying a fluctuation | variation can be acquired.

  Further, the flame F2 from the main swirl burner 6 is generated in the combustion cylinder 1, and the flame F1 of the pilot low swirl burner 5 is generated before the frame holder 20, both of which are so-called floating flames. There is no excessive temperature rise in the main mixing pipe 8 and the premixing pipe 7, thereby preventing thermal deterioration.

  In addition, according to the swirl burner for liquid fuel of this example, the pilot burner and the main burner are integrally configured with a concentric structure, so the pilot burner and the main burner are configured separately and separately. Manufacture is easy and cost is low compared with the case of attaching to a combustion cylinder. In addition, the swirler of each burner is configured to reduce the swirl number by combining multiple swirlers that rotate in opposite directions, so that the flame is stable for both the pilot and the main, inside the mixing tube and behind the frame holder A floating flame that does not enter the flame is realized, and the durability of the device is improved.

It is a sectional side view showing the whole turbine combustor composition concerning the present invention. It is the perspective view which looked at the swirl burner for liquid fuel used for the combustor from the flame outlet side. It is the perspective view which looked at the burner from the top side. FIG. 4 is an enlarged cross-sectional view showing a state in which a pilot flame is blown from the burner. It is an expanded sectional view which shows the state which is blowing out the flame for mains from the burner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion cylinder 2 Swirl burner for liquid fuel 5 Low swirl burner for pilot 6 Low swirl burner for main 7 Premixing pipe 7a Maximum constriction position 8 Main mixing pipe 10, 12 The 1st, 2nd swirler whose rotation directions are mutually opposite (Low swirl burner side for pilot)
14, 16 First and second swirlers whose main turning directions are opposite to each other (the main low swirl burner side)
20 Frame holder F1, F2 Flame

Claims (2)

In the swirl burner for liquid fuel provided at the top of the combustion cylinder,
A pilot low swirl burner having a premixing pipe connected and opened at the top of the combustion cylinder, and a plurality of annular swirlers with different swirl directions provided at the inlet of the premixing pipe;
A main mixing pipe disposed concentrically outside the premixing pipe and connected and opened to the top of the combustion cylinder; and a swivel direction provided at an inlet between the main mixing pipe and the premixing pipe A main low swirl burner having a plurality of different annular swirlers;
A frame holder provided at a connection portion between the pilot low swirl burner premixing tube and the combustion cylinder, and preventing interference between the flow of the pilot low swirl burner and the flow of the main low swirl burner;
A swirl burner for liquid fuel, comprising: The swirl burner for liquid fuel according to claim 1, wherein an inner diameter of the premixing tube is gradually reduced toward the frame holder.

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