JP2006090602A - Lobe mixer and premixer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lobe mixer for mixing fuel and an oxidizer quickly and uniformly. <P>SOLUTION: The lobe mixer is provided with a lobe nozzle part 1 composed of a double lobe wall and having a fuel injection port 1c of lobe slit shape at the end face, and a cylindrical part 2 composed of a double pipe wall and having a plurality of fuel supply pipes 2b disposed on the outer peripheral surface. Fuel is uniformly injected from the fuel injection port 1c through a clearance 2c between double pipe walls and a clearance 1d between double lobe walls and quickly and uniformly mixed with the oxidizer flowing inside the nozzle from the cylinder interior and with the oxidizer flowing in a clearance between the cylinder part 2 and lobe nozzle part 1 and a sleeve 3, to produce lean fuel mixed gas with the fuel and oxidizer uniformly mixed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lobe mixer and a premixer, in particular, to quickly and uniformly mix fuel and oxidant while suitably suppressing flashback, thereby contributing to stable lean combustion and reduction of nitrogen oxides in the combustion gas. The present invention relates to a lobe mixer and a premixer that can be used.

Nitrogen oxides in the combustion gas discharged from the internal combustion engine are referred to as NOx, and are classified into heat-generated NO generated in the process of combustion and fuel-derived NO contained in the fuel. In the above NO, heat generation NO has a strong temperature dependency, and generation thereof can be suppressed by lowering the combustion flame temperature.
Therefore, in an industrial gas turbine, an aircraft engine, a combustion furnace, or the like, a premixed combustion method in which a mixed gas in which a fuel and an oxidant are premixed is burned is employed because the flame temperature can be controlled. Among the premixed combustion systems, a lean premixed combustion system that burns with a fuel lean mixed gas has attracted particular attention because of the advantage that nitrogen oxides in the combustion gas can be greatly reduced.
However, in the lean premixed combustion method, when the stroke required to complete the mixing of fuel and oxidant (hereinafter referred to as “mixing distance”) is long, self-ignition or flashback occurs and the engine is damaged. Has been reported. Therefore, in the lean premixed combustion method, it is required to generate a fuel lean mixed gas in which the fuel and the oxidant are uniformly mixed in an extremely short time.
In the conventional premixer, the nozzle outlet portion is formed in a lobe shape to generate a vortex in the mixed gas flow of fuel and oxidant to promote the mixing of fuel and oxidant. In particular, premixing is performed by mixing fuel and oxidant while supplying primary air from the inside and secondary air from the outside to the fuel, and further promoting mixing of the fuel and oxidant by a vortex formed at the nozzle outlet. A container is known (see, for example, Patent Document 1).
A premixer disposed around the pilot combustor, and the premixer includes a premixed pre-evaporating pipe extended to the downstream side and main fuel injection means for injecting fuel into the airflow. In addition, a gas turbine combustion apparatus that includes a lobe mixer that mixes a pilot chamber with a plurality of inner and outer flows divided in the circumferential direction is known (see, for example, Patent Document 2).
JP-A-8-145361 JP-A-8-14562

  In the former known premixer, the fuel injection port is provided in the lobe upstream portion of the inner wall surface of the nozzle. For this reason, the injected fuel is mixed to some extent with the primary air inside the nozzle, then ejected from the lobe outlet to the outside, and further mixed with the secondary air at the outlet downstream. With this method, there is no assurance that the fuel will flow along the lobe shape, and the radial mixing of the nozzles will be uneven at the lobe peaks and troughs, resulting in a uniform mixing of the fuel and oxidant. In addition, there is a possibility that the lean fuel mixed gas is not generated. In addition, since mixing starts inside the lobe, flashback may occur in a place where the flow velocity near the inner wall of the lobe is slow. Furthermore, since there are two air supply systems, the structure of the premixer may be complicated, resulting in an increase in the number of parts and an increase in manufacturing cost.

  On the other hand, in the latter known premixer, a vortex of the pilot combustion gas and the unburned mixed gas of the main fuel and air is formed by the lobe mixer, and these fluids stay to improve ignition performance and flame holding performance. This is intended to improve the above, and is not intended to shorten the mixing distance of the main mixed gas.

  Therefore, the present invention was devised in view of the above circumstances, and it is possible to rapidly and uniformly mix fuel and oxidant while suitably suppressing flashback, so that stable lean combustion and nitrogen oxides in combustion gas can be obtained. An object of the present invention is to provide a lobe mixer and a premixer that can contribute to the reduction of the above.

The lobe mixer of the present invention that solves the above problems is a lobe mixer that includes a cylindrical portion and a lobe nozzle portion provided at the tip of the cylindrical portion, and at least the lobe nozzle portion is disposed in the circumferential direction of the downstream end face. A double-lobe wall having a slit formed along the first lobe wall to form a first fluid path, an inner side of the double-lobe wall to form a second fluid channel, and an outer side to form a third fluid channel. The first fluid is ejected from the slit, and the second fluid and the third fluid ejected from the second fluid channel and the third fluid channel are mixed with the first fluid. It is characterized by that.
In the lobe mixer having the above-described configuration, the first fluid flows through the double lobe wall and is ejected from the slit formed along the circumferential direction of the nozzle end surface, while the second fluid and the third fluid oxidant are in the double lobe wall. Since it is injected from the inside and the outside, a concentric three-layer flow of the third fluid-first fluid-second fluid is formed. Thereby, the mixing of the first fluid, the second fluid, and the third fluid in the nozzle axial direction is promoted uniformly. In addition, since the three-layer flow simultaneously forms a longitudinal vortex at the nozzle outlet by the lobe wall, the mixing of the first fluid, the second fluid, and the third fluid in the nozzle radial direction is promoted. Thereby, the first fluid, the second fluid, and the third fluid can be rapidly and uniformly mixed.

In the lobe mixer configured as described above, a double pipe wall communicating with the double lobe wall formed in the lobe nozzle part is formed in the cylindrical part, and communicated with the inside of the double pipe wall on the outer peripheral surface of the cylindrical part. A first fluid supply pipe is provided.
In the lobe mixer having the above-described configuration, the first fluid flows through the first fluid supply pipe, flows through the double tube wall and the double lobe wall, and is ejected from the slit at the end face of the downstream portion. Mixing of the first fluid and the second fluid does not occur. Thereby, it becomes possible to suppress the backfire with respect to a lobe nozzle part suitably.

In the lobe mixer of the upper structure, a sleeve is provided at least downstream from the lobe nozzle portion, and a third fluid flow path is formed between the outer peripheral surface of the lobe nozzle portion and the inner peripheral surface of the sleeve. .
In the lobe mixer having the above configuration, the sleeve is provided outside the downstream portion from the lobe nozzle portion, so that the third fluid flow path is suitably formed. As a result, a sufficient amount of the third fluid can be supplied to the lobe nozzle portion.

In the lobe mixer having an upper structure, an upstream end of the cylindrical portion is opened to serve as the second fluid inlet, and an upstream end of the sleeve is opened to serve as a third fluid inlet, and the second fluid inlet and The third fluid inlet is open coaxially.
In the lobe mixer configured as described above, the upstream end of the cylindrical portion and the upstream end of the sleeve are coaxially opened to form the second fluid inlet and the third fluid inlet, so that the fluid flows while sandwiching the first fluid. Can be co-flowed coaxially. Further, the fluid can be split coaxially by a single supply system, and the supply system is simplified.

In the lobe mixer of the upper configuration, the first fluid channel is a fuel channel, and the second fluid channel and the third fluid channel are oxidant channels.
In the lobe mixer configured as described above, the fuel injected from the slit forms a vertical vortex while forming a three-layer flow of oxidant-fuel-oxidant together with the oxidant flowing out from the inside and outside of the lobe nozzle. The fuel and oxidant can be mixed rapidly and uniformly. In addition, since the fuel flows through the first fluid flow path and the oxidant flows through the second fluid flow path and the third fluid flow path, the fuel and the oxidant flow inside and outside the cylindrical portion or inside and outside the lobe nozzle portion. Backfire is suitably suppressed without mixing. Furthermore, since the oxidant can be split coaxially with a single oxidant supply system, the oxidant supply system is simplified.

A premixer according to the present invention for solving the above-described problems is characterized by including the lobe mixer having the above-described configuration.
In the premixer having the above configuration, the fuel and the oxidant are rapidly and uniformly mixed to obtain a fuel lean mixed gas, and the fuel lean mixed gas can be suitably supplied to the combustion chamber. As a result, lean combustion in the combustion chamber is stabilized, and generation of nitrogen oxides during combustion is suitably suppressed.

  According to the lobe mixer and the premixer according to the present invention, it becomes possible to quickly and uniformly mix the fuel and the oxidant while suitably suppressing the backfire, and as a result, the lean combustion is stabilized and the combustion is in progress. Formation of nitrogen oxides is preferably suppressed.

Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.
FIG. 1 is a front view showing a lobe mixer 10 according to an embodiment of the present invention.
The lobe mixer 10 includes a lobe nozzle portion 1 that injects fuel and forms a longitudinal vortex of a mixed gas of fuel and oxidant, a cylindrical portion 2 that introduces fuel and oxidant into the lobe nozzle portion 1, and the lobe nozzle. A sleeve 3 that forms an oxidant flow path together with the part 1 and the cylindrical part 2 is provided.

  The lobe nozzle portion 1 has a structure having double lobe walls composed of lobe peaks 1a and lobe valleys 1b. A slit-like fuel injection port 1c is formed in the end surface of the nozzle portion along the circumferential direction.

  The fuel injected from the fuel injection port 1c is uniformly distributed along the circumferential direction of the nozzle end face. On the other hand, the oxidant flows out from the inside of the lobe nozzle part 1 and the gap between the lobe nozzle part 1 and the sleeve 3 and forms a concentric three-layer flow of oxidant-fuel-oxidant together with the fuel. This three laminar flow promotes mixing in the axial direction of the nozzle. At the same time, this three-layer flow forms a longitudinal vortex near the exit of the lobe nozzle, and this longitudinal vortex promotes mixing in the radial direction. In this way, the fuel injected from the fuel injection port 1c and the oxidant flowing out from the inside and outside of the rose nozzle portion 1 are uniformly and rapidly mixed by the simultaneous action of the concentric three-layer flow and the longitudinal vortex, and the fuel is diluted. Become gas. The fuel is methane or natural gas, and the oxidant is air, oxygen, or excess air combustion gas.

2 is a cross-sectional view taken along the line AA ′ of FIG.
The cylindrical portion 2 includes a fuel flow path 2a having a double pipe wall structure and a fuel supply pipe 2b having a single pipe structure (not shown). The fuel passes through the inside of the fuel supply pipe 2b, passes through the double pipe wall 2c and the double lobe wall 1d, and is injected to the outside from the fuel injection port 1c. On the other hand, the oxidant flows through the inside of the cylindrical part 2 and the inside of the lobe nozzle part 1 and the gap formed by the cylindrical part 2, the lobe nozzle part 1 and the sleeve 3, and the oxidant-fuel-oxidant concentric with the fuel. A vertical vortex is formed while forming a three-layer flow. In particular, since a sufficient flow area for the oxidant is secured inside the cylindrical portion 2 and the lobe nozzle portion 1, a sufficient amount of oxidant can be supplied to the fuel.

3 is a cross-sectional view taken along the line BB ′ of FIG.
In the cylindrical portion 2, a fuel supply pipe 2b having a single pipe structure is disposed on the outer peripheral surface. For convenience of illustration, two fuel supply pipes 2b are arranged on the outer peripheral surface, but one or more fuel supply pipes 2b are actually arranged on the outer peripheral surface.

  According to the lobe mixer 10, the injected fuel forms a concentric three-layer flow of oxidant-fuel-oxidant together with the oxidant flowing out from the inside and outside of the lobe nozzle portion 1, while causing the vertical direction due to the lobe shape A vortex is formed. As a result, the fuel and the oxidant are rapidly and uniformly mixed to become a fuel lean mixed gas. Further, since the fuel is emitted from the fuel injection pipe 1c from the fuel supply pipe 2b disposed on the outer peripheral surface of the cylindrical part 2 through the double pipe wall 2c and the double lobe wall 1d of the lobe nozzle part 1, A sufficient flow path area is secured inside the cylindrical portion 2 and the lobe nozzle portion 1 with respect to the oxidant. As a result, a fuel lean mixed gas in which the fuel and the oxidant are uniformly mixed can be generated quickly and suitably. Further, since the fuel and the oxidant are mixed in the downstream portion of the lobe nozzle portion 1, it is possible to suitably suppress backfire on the inside and outside of the lobe nozzle portion 1. Further, the cylindrical portion 2 and the sleeve 3 make it possible to divide the fuel while sandwiching the fuel with a single oxidant supply system.

FIG. 4 is an explanatory cross-sectional view of a main part showing the premixer 100 according to the embodiment of the present invention.
The premixer 100 includes the lobe mixer 10 and a fuel system 20 that supplies fuel to the lobe mixer 10. For convenience of illustration, the premixer 100 is drawn in a state where it is incorporated in the combustor N.

  The fuel lean mixed gas rapidly generated by the lobe mixer 10 is guided to the combustion chamber CH for combustion. At this time, a swirl flow is generated by the swirler SW to suitably hold the flame and stabilize the combustion. The combustion gas passes through the exhaust pipe EX, enters the turbine chamber (not shown), is taken out as work, and is then exhausted to the outside.

  According to the premixer 100, it is possible to suitably supply the fuel lean mixed gas in which the fuel and the oxidant are uniformly mixed to the combustion chamber CH. As a result, lean combustion is stabilized and generation of nitrogen oxides during combustion is suitably suppressed.

  INDUSTRIAL APPLICABILITY The lobe mixer and premixer according to the present invention can be used in the field of using a mixture in which a plurality of fluids are rapidly and uniformly mixed, including an internal combustion engine such as an industrial gas turbine or a combustion furnace such as a boiler. .

It is a front view which shows the lobe mixer 10 which concerns on embodiment of this invention. It is AA 'sectional drawing of FIG. It is BB 'sectional drawing of FIG. It is principal part cross-sectional explanatory drawing which shows the premixer 100 which concerns on embodiment of this invention.

Explanation of symbols

1 Lobe nozzle part 1a Robe mountain 1b Robe valley 1c Fuel injection port 1d Between double lobe walls
2 Cylindrical portion 2a Fuel flow path 2b Fuel supply pipe 2c Between double pipe walls 3 Sleeve 10 Lobe mixer 20 Fuel system

Claims (6)

  A double lobe wall comprising a cylindrical portion and a lobe nozzle portion provided at a tip portion of the cylindrical portion, wherein at least the lobe nozzle portion has a slit formed along a circumferential direction of a downstream end face To form a first fluid path, an inner side of the double lobe wall forms a second fluid channel, and an outer side forms a third fluid channel, and the first fluid passes through the slit. The lobe mixer, wherein the second fluid and the third fluid ejected from the second fluid channel and the third fluid channel and the first fluid are mixed by ejecting.   A double pipe wall communicating with the double lobe wall formed in the lobe nozzle part is formed in the cylindrical part, and a first fluid supply pipe communicating with the inside of the double pipe wall is formed on the outer peripheral surface of the cylindrical part. The lobe mixer according to claim 1 which is arranged.   The sleeve according to claim 1 or 2, wherein a sleeve is provided at least downstream from the lobe nozzle portion to form a third fluid flow path between the outer peripheral surface of the lobe nozzle portion and the inner peripheral surface of the sleeve. Robe mixer.   The upstream end of the cylindrical portion opens to become the second fluid inlet, and the sleeve upstream end opens to become the third fluid inlet, and the second fluid inlet and the third fluid inlet are coaxial. The lobe mixer according to claim 3, which opens in a heart shape.   The lobe mixer according to any one of claims 1 to 4, wherein the first fluid channel is a fuel channel, and the second fluid channel and the third fluid channel are oxidant channels.   A premixer comprising the lobe mixer according to claim 5.

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