JPH0415409A - Mixer - Google Patents

Abstract

PURPOSE:To reduce a pressure loss, to form a simple structure by alternately continuously forming crests and troughs circumferentially of the outer surface of an inner cylinder, increasing the crests in diameter smoothly in flowing direction of second fluid, providing a wall crossing the flowing direction of the second fluid at the end, and opening a first fluid jet port, and surrounding it with an outer cylinder. CONSTITUTION:A premixer 30 is composed of a pedal-shaped fuel nozzle 32 having crests 34 smoothly increasing in an outer diameter in the flowing direction of the air and troughs 33 parallel to the flowing direction of the air to be alternately circumferentially provided at a predetermined interval, and an air supply tube 31 for surrounding the nozzle in such a manner that the air flowing through the troughs 33 flows to a negative pressure part formed at the downstream side of the crests 34 to mix the air with fuel. The fuel jet port 35 of the nozzle 32 is opened at the wall 36 of the crest 34 to inject in the air flowing direction. The air of second fluid flows through the troughs 33 of the nozzle 32. Thus, fuel can be diffused without increasing the pressure loss of an air stream.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mixer. More specifically, the present invention relates to a mixer suitable for premixing fuel and air in a narrow space.

(Prior Art) A typical conventional mixer is a Venturi mixer, which jets air from a nozzle and uses the kinetic energy of the jet to suck and mix scum.

This mixer is used in various industrial gas burners as a mixer for premixed gas burners.

On the other hand, in developing a low NOx combustor for a cast turbine, the present inventors segmented and combined a small-sized catalytic combustion section and a premixture supply section that have been put into practical use industrially.
The idea was to configure one large burner and use combined combustion of catalytic combustion and gas-phase combustion to maintain the catalyst temperature below the catalyst's heat resistance temperature to prevent catalyst deterioration while increasing the temperature of the combustion scum at the combustor outlet. . However, in this combustor, the pressure loss in the catalytic combustion section is large, so for practical use of the combustor, a mixer that is small and capable of premixing without increasing pressure loss is required.

(Problem to be solved by the invention) However, for example, in a venturi mixer aimed at reducing pressure loss, in order to obtain uniform mixing, many venturi parts must be provided, making the structure complicated and expensive to manufacture. There is a problem. In addition, other methods result in a considerably large pressure loss, which is not preferable in cases where mixing is attempted using pressurized air from a compressor, such as in a gas turbine combustor. Further, there is a problem that the device becomes large and expensive.

That is, it is difficult to apply the conventional mixer as a premixer for a small catalytic combustion section due to manufacturing problems and pressure drop problems.

An object of the present invention is to provide an inexpensive mixer with a simple structure and low pressure loss.

(Means for Solving the Problems) In order to achieve the above object, the mixer of the present invention includes an inner cylinder through which a first fluid flows and a passage surrounding the inner cylinder through which a second fluid flows. and an outer cylinder formed between the inner cylinder and the inner cylinder, and an unevenness is formed in the outer shape of the inner cylinder by alternately and continuously providing peaks and valleys in the circumferential direction, and the peak is a second The diameter of the first fluid is gradually expanded in the flow direction of the fluid, and a wall surface intersecting the flow direction of the second fluid is provided at the end thereof, and an ejection port for the first fluid is opened in the wall surface.

Further, the mixer of the present invention has a burner function by providing an igniter in the center of the inner cylinder.

Further, in the mixer of the present invention, a flow path through which the second fluid flows is also formed in the center of the inner cylinder.

Further, in the mixer of the present invention, a plurality of inner cylinders are provided in one outer cylinder.

(Function) Therefore, the second fluid flows around from the trough to the negative pressure portion generated after the crest, that is, downstream, collides with and mixes with the first fluid ejected from the wall surface of the crest.

At this time, the second fluid is gradually divided by the peaks that gradually increase in the flow direction, so the speed increases without significantly increasing pressure loss, and the negative pressure that is formed downstream of the peaks causes the first fluid to be divided. It easily goes around in front of the injection port and mixes and diffuses the first fluid and the second fluid.

(Example) Hereinafter, the configuration of the present invention will be described in detail based on an example shown in the drawings. Note that this example was implemented as a premixer for a combustor that combines catalytic combustion and gas phase combustion.

FIG. 1 shows a schematic diagram of a catalytic combustion type gas turbine combustor to which the mixer of the present invention is applied. The catalytic combustion gas turbine combustor of this embodiment includes a burner section 1 in which a premixed gas supply section 4 and a catalytic combustion section 3 are arranged in parallel, and a premixed combustion section formed downstream of the burner section 1. 2, the premixture from the premixture supply section 4 is subjected to lean premix combustion using the catalytic combustion gas from the catalytic combustion section 3 as a flame stabilizing source.

Although not shown, the combustor usually has a double-tube structure consisting of a kering (not shown) and a liner 1, and air is supplied from the gas turbine side to the air passage formed between the liner and the casing. Compressed air is introduced into the liner 1 through the burner section 1 consisting of a premix supply section 4 and the catalytic combustion section 3, cooling air holes (not shown) in the liner 1, and bypass passages (not shown). It is provided so as to be supplied to the inner premix combustion section 2.

In addition, the premix combustion section 2 is surrounded by ceramics, and due to the presence of high-temperature walls that hardly require cooling,
It is provided to minimize heat loss in the premix combustion section 2, which is in a state where gas phase combustion is difficult to occur, and to achieve uniform and complete combustion. For example, by using the metal tube 11a as the structural material and the inner wall 11b made of ceramics as shown in the figure, a combustor with more uniform temperature and stability can be obtained. in this case,
Ceramics may be tile-like or fibrous. It is also possible to mold the entire liner from ceramics.

The premixture supply section 4 is constituted by an air supply pipe 20 and a fuel nozzle 21, which are opened into gauging, for example. The premixture supply section 4 is composed of an air supply pipe 20 and a fuel nozzle 21, which are opened into gauging, and is supplied with compressed air distributed according to the opening area ratio and fuel ejected from the fuel nozzle 21. It is provided to obtain a concentrated premixture. In addition, the premixture supply section 4
A swirler 22 is installed at the outlet of the air supply pipe 20 constituting the air supply pipe 20, and is provided so as to inject the premixed gas toward the flow of the catalytic combustion gas and mix it with the catalytic combustion residue to some extent.

The catalytic combustion section 3 preferably consists of a tube segment filled with a catalyst 18, and is provided with a premixer 30 upstream thereof. For example, it consists of one ceramic catalyst cylinder containing a catalyst 18 and a baffle plate 40, and a premixer 30 constituted by an air supply pipe 31 and a fuel nostle 32.

As shown in FIG. 2, the premixer 30 has a flow path between an inner cylinder or fuel nozzle 33 through which a first fluid such as fuel flows and an inner cylinder 32 through which a second fluid such as air does not flow. It consists of an outer cylinder, that is, an air supply pipe 31, and a crest 34 whose outer diameter gradually increases in the air flow direction and a trough 3 parallel to the air flow direction.
3 are arranged alternately at regular intervals in the circumferential direction, and an air supply pipe 31 that surrounds the petal-shaped fuel nostle 32, and the air flowing through the valley part 33 is formed downstream of the peak part 34. The air and fuel are mixed by flowing into the negative pressure section. The fuel injection port 35 of the fuel nozzle 32 is opened in the wall surface 36 of the mountain portion 34 that intersects with the air flow, and the fuel is injected in the same direction as the air flow.

Air, which is the second fluid, flows through a flow path surrounded by the side wall surfaces of the troughs 33, that is, the peaks 34 of the fuel nostle 32, and the air supply pipe 31. Further, the outer diameter of the peak portion 34 is gradually increased to form a valley portion 33 as if to divide the air flow path. Therefore, the airflow is gradually accelerated without significantly increasing pressure loss, and is divided along the outer peripheral surface of the fuel nozzle 32.

When the air flowing between the air supply pipe 31 and the fuel nozzle 32 reaches the downstream side of the peak 34, due to the negative pressure created downstream of the fuel nozzle 32 and the flow interference effect caused by this, The fuel flows over the entire surface of the fuel nozzle 32, that is, in the downstream of the fuel injection port 35, so as to be caught in the flow. As a result,
Fuel and air are evenly mixed. In this case, the strength of mixing can be adjusted by adjusting the diameter of the fuel injection port 35 and the area of the entire surface of the fuel nozzle 32.

Incidentally, an opening 38 is provided in the center of the fuel nozzle 32 to open the ignition I.
- 37 is arranged so that the premixer 30 also has the function of a burner.

A baffle plate 40 is provided downstream of the catalyst 18, that is, at the outlet of the catalytic combustion section 3. This baffle plate 4
0 is made of, for example, a cross-shaped plate that blocks the flow of catalytic combustion gas, and generates a gentle swirling flow that does not collide with each other from the notches between the moons protruding in the radial direction toward the negative pressure section 42 at the center. .

This gentle swirling flow entrains a portion of the lean premixed gas injected from the surrounding premixed gas supply section 4 to achieve appropriate mixing.

It should be noted that the above-described embodiments are merely examples of preferred embodiments of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in FIG. 1, the ignition torch 37 is installed in the center of the fuel supply section,
Although this application example has the function of a low NOx burner capable of uniform combustion, if the purpose is only for mixing, the ignition torch 37 is not necessarily necessary, and the air supply pipe 31 is installed in the space of the ignition torch 37. It is also possible to further improve the mixing property by providing a pipe through which the air separated from the air flow path flows between the fuel nozzle 32 and the fuel nozzle 32.6Furthermore, FIG. There is no need to stick to an axially symmetrical shape, and the shape of the fuel nozzle (inner [32] and the air supply pipe (outer cylinder) if necessary) should be adjusted according to the shape of the flow path.
The inner shape of 31 may be changed. In this case, what is important is to gradually increase the outer diameter toward the downstream direction of the flow, and to add peaks 34 and valleys 3 to the outer shape so as to divide the flow path.
3.

Furthermore, there is no need to be particular about the size of the flow path.

In this case, a plurality of fuel nozzles 32 may be arranged in one air supply pipe 31 to improve the mixing performance.

Further, in the present invention, the outer cylinder and the inner cylinder are constructed of cylindrical tubes, but they are not particularly limited to this, and may be constructed with a rectangular or triangular cross section.

Furthermore, although the fluids to be mixed are fuel and combustion air in the case of this embodiment, other fluids may be used, or air may flow toward the inner cylinder and fuel may flow toward the outer cylinder.

(Effects of the Invention) As is clear from the above description, the present invention provides an inner cylinder through which a first fluid flows and a passage surrounding the inner cylinder through which a second fluid flows between the inner cylinder and the inner cylinder. an outer cylinder to be formed, and an unevenness is formed by alternately and continuously providing peaks and valleys in the circumferential direction on the outer shape of the inner cylinder, and the peaks are arranged so that the second fluid can flow. The diameter is gradually expanded in the direction, and a wall surface intersecting the flow direction of the second fluid is provided at the end thereof, and a first
Since the fluid ejection port is opened, the fuel supply portion can be diffused into the air flow without significantly increasing the pressure loss of the air flow. In addition, the outer shape is provided with peaks and valleys to separate the air flow path between the outer cylinder and the inner cylinder, which further reduces pressure loss and allows air to flow into the fuel supply area. It can easily wrap around the neck.

These effects allow fuel and air to be mixed uniformly without increasing pressure loss.

Furthermore, the structure can be easily and inexpensively manufactured by pipe expansion and welding.

Furthermore, by providing the igniter in the center, combustion can be achieved in a state where fuel and air are evenly mixed, and the fuel can be used as a low NOx burner.

[Brief explanation of drawings]

FIG. 1 is a central longitudinal sectional view showing a specific example of a burner portion of a catalytic combustion type gas turbine combustor to which the mixer of the present invention is applied. FIGS. 2(A) and 2(B) are a central vertical sectional view and a partially cutaway front view showing one embodiment of a premixer. 30... Premixture, 31... Air supply pipe (outer cylinder),
32...Fuel nozzle (inner cylinder), 33...Trough, 34
... Mountain part, 35 ... Injection port, 36 ... Wall surface.

Claims (4)

[Claims] (1) An inner cylinder through which the first fluid flows, and a second inner cylinder surrounding this inner cylinder.
and an outer cylinder forming a flow path between the inner cylinder and the inner cylinder, through which a fluid flows; and the diameter of the mountain portion is gradually expanded in the flow direction of the second fluid, and a wall surface intersecting with the flow direction of the second fluid is provided at the end thereof, and a jet port for the first fluid is provided on the wall surface. A mixer characterized by having an opening. (2) The mixer according to claim 1, characterized in that an igniter is provided in the center of the inner cylinder and has a burner function. (3) The mixer according to claim 1, wherein a flow path for flowing the second fluid is also formed in the center of the inner cylinder. (4) The mixer according to claim 1, characterized in that a plurality of inner cylinders are provided in one outer cylinder.