CN204404239U - A kind of fuel-air blender with channels expending - Google Patents

Abstract

The utility model relates to a fuel-air mixer with a sudden expansion channel, which belongs to the technical field of gas turbine structure design. The fuel-air mixer includes a central body, an annular fuel-air passage, and a swirl device arranged in the annular fuel-air passage; the downstream section of the annular fuel-air passage has at least one section of sudden expansion passage formed by an annular sudden expansion section, and the end of the central body The axial position is within the axial range of the sudden expansion channel. At the end of the annular fuel air channel, the utility model forms a sudden expansion channel by setting an annular sudden expansion section, which suddenly decelerates the mixed air flow, and forms a local, independent and stable sudden expansion channel at the sudden expansion channel The recirculation zone, and the sudden expansion channel recirculation zone is not easily affected by other airflows in the downstream flame tube, which effectively improves the stability of the flame. At the same time, due to the structural improvement of the peripheral wall of the mixer, it has the characteristics of simple structure and easy processing and maintenance.

Description

A kind of fuel-air mixer with sudden expansion channel

technical field

The utility model relates to a combustion chamber structure of a gas turbine, more specifically relates to a fuel-air mixer for a combustion chamber, and belongs to the technical field of gas turbine structure design.

Background technique

With the energy shortage and the world's attention to environmental protection issues, countries have increasingly strict requirements on gas turbine combustor emissions and combustion efficiency. Generally, gas turbines are required to maintain a low level of combustion chamber emissions in the 50% and above load range. , while maintaining high combustion efficiency. In order to achieve the purpose of low emission, premixed combustion technology is widely used. Therefore, a device capable of pre-mixing fuel and air is needed, that is, a fuel-air mixer, and a fuel-air mixture that is uniformly mixed and has a certain speed is formed at the outlet of the mixer, and then enters the flame tube to participate in combustion.

Since the fuel injected from the fuel-air mixer burns in the form of a premixed flame in the combustion chamber, in order to achieve extremely low pollution emissions, the flame works near the combustible boundary, and the jet velocity of the fuel-air mixture injected from the mixer is relatively fast. The stability of the flame is relatively difficult. The solution in the prior art is usually that the axial length of the central body is less than the length of the outer wall of the fuel-air mixer, so that the fuel-air mixture flows to the central body head first when it flows out of the annular premixing channel. The central area downstream of the end wall of the center body expands, and a recirculation zone is formed in the central area downstream of the end wall of the central body head, and then enters the flame tube and further expands in the flame tube, thereby forming a larger recirculation area in the flame tube for flame However, these two recirculation areas are susceptible to the influence of other airflows in the flame tube, which makes the flame unstable or poor in stability.

In order to improve the stability of the flame, in the existing patent document CN1704574, an impingement air flow opposite to the main flow direction is produced near the central body of the mixer outlet to form a recirculation vortex, which reduces the amount of air injected into the recirculation zone. Thereby reducing the jet velocity near the outlet of the mixer and improving the flame stability. However, the structural processing and connection of the inner baffle plate of this mixer is relatively complicated, and it is not easy to maintain and replace, and the recirculation vortex is not easy to control, and it may be difficult to solve the problem of fire stability.

Utility model content

Aiming at the problems existing in the prior art, the utility model provides a fuel-air mixer with a sudden expansion channel, which aims to further improve the fire stabilization performance of the mixer, and has the characteristics of simple structure and easy processing and maintenance.

The technical scheme adopted in the utility model is as follows:

A fuel-air mixer with a sudden expansion passage, comprising a central body and an annular fuel-air passage arranged coaxially with the central body, a swirl device is provided in the annular fuel-air passage, and a central air injection hole is opened at the end of the central body. It is characterized in that: the downstream section of the annular fuel-air passage has at least one segment of the sudden expansion channel formed by the annular sudden expansion section, and the axial position of the end of the central body is within the axial range of the sudden expansion channel.

In the above technical solution, the annular sudden expansion sections are arranged in a ladder shape.

Preferably, the annular sudden expansion section is 2 to 5 sections.

The technical feature of the utility model is that: the annular sudden expansion section is provided with a wall cooling hole of the sudden expansion section; the wall cooling hole of the sudden expansion section is a straight hole or an oblique hole. The side wall of the central body located in the sudden expansion channel is provided with cooling holes on the side wall of the central body; the cooling holes on the side wall of the central body are straight holes or oblique holes.

Compared with the prior art, the utility model has the following advantages and outstanding effects: the utility model forms a sudden expansion channel by setting an annular sudden expansion section at the end of the annular fuel air channel, and the sudden expansion channel makes the mixed air flow suddenly Slow down, thereby forming a local, independent, and stable recirculation zone of the sudden expansion channel at the sudden expansion channel, and the sudden expansion channel recirculation zone is not easily affected by other airflows in the downstream flame tube, thus effectively improving the stability of the flame. At the same time, due to the improvement of the structure of the peripheral wall of the mixer, it is not restricted by other parts of the combustion chamber, there is no matching problem, and it has the characteristics of simple structure and easy processing and maintenance.

Description of drawings

Fig. 1 is a schematic diagram of a structural principle provided by the utility model.

Fig. 2 is an overall three-dimensional structure diagram.

Fig. 3 is a schematic diagram of the pneumatic principle of the utility model.

The symbols in the figure are explained as follows:

1-central body; 2-annular fuel air channel; 3-swirl device; 4-central body end; 5-central air injection hole; 6-annular sudden expansion section; 7-sudden expansion channel; Cooling holes; 9-cooling holes on the side wall of the center body; 10-swirl blades; 11-fuel holes; 12-fuel channels; 13-side walls of the center body in the sudden expansion section; body sudden expansion backflow area; 16-flame tube sudden expansion backflow area.

Detailed ways

The principle, structure and specific implementation of the present utility model will be further described below in conjunction with the accompanying drawings.

Figure 1 is a fuel-air mixer with a sudden expansion channel provided by the utility model, the fuel-air mixer includes a central body 1, an annular fuel-air passage 2 and a swirl device 3; the center body 1 is provided with a central air channel and annular fuel channel 12, the end of the center body 1 is provided with a central air injection hole 5; the annular fuel air channel 2 is coaxially arranged with the center body 1; the swirl device 3 includes a circumferentially arranged hollow swirl vane 10, A fuel hole 11 is arranged on the swirl vane, and an annular fuel channel 12 communicates with the fuel hole.

The downstream section of the annular fuel-air channel 2 has at least one section of the sudden expansion passage 7 formed by the annular sudden expansion section 6, and the axial position of the central body end 4 should be within the axial range of the annular sudden expansion section 6; the annular sudden expansion section 6. The quantity range is preferably 2 to 5 sections, and its diameter gradually increases and is arranged in steps; the annular sudden expansion section 6 is provided with a sudden expansion section wall cooling hole 8; the form of the sudden expansion section wall cooling hole 8 can be straight Holes and oblique holes; central body side wall cooling holes 9 are provided on the central body side wall 13 within the range of the annular sudden expansion section; the form of the central body side wall cooling holes 9 can be straight holes or oblique holes.

The working principle of the utility model is as follows:

Air flows into the interior of the mixer through the space defined by the annular fuel air channel 2, and forms a swirling airflow through the swirl device 3; fuel gas enters the hollow swirl vane 10 from the fuel channel 12, and is set on The fuel hole 11 is sprayed out; the air and fuel gas start to mix at the position where the swirl device 3 is located, flow through to the axial position of the end of the center body, and flow out with the central air injection hole 5 provided on the end 4 of the center body air confluence. The sudden expansion channel 7, which is defined by the annular sudden expansion section 6, decelerates the mixed air flow suddenly, and forms a local, independent and stable sudden expansion channel recirculation zone 14 at the sudden expansion channel 7, and the sudden expansion channel backflow Zone 14 is not easily affected by other airflows in the downstream flame tube, which helps to improve the reliability of flame stabilization; since the airflow expands downstream of the central body 1 head end wall 4, it will form in the central area downstream of the central body end 4. The central body suddenly expands the backflow zone 15; after the airflow enters the flame tube from the mixer, a larger flame tube suddenly expands the backflow zone 16 in the flame tube, and in the sudden expansion channel backflow zone 14, the central body suddenly expands the backflow zone 15, A reliable and stable combustion flame is finally realized under the joint action of the sudden expansion and reflow area 16 of the flame tube; at the same time, the cooling holes 8 on the wall surface of the sudden expansion section provided on the annular sudden expansion section 6 and the cooling holes 8 on the side wall 13 of the central body in the sudden expansion section are provided. Cooling gas flows out from the cooling hole 9 on the side wall of the central body to cool the wall here, and the cooling air flow will not significantly damage the nearby reflow area to ensure a stable reflow area.

Claims (7)

1. one kind has the fuel-air blender of channels expending, comprise centerbody (1) and the annular fuel air duct (2) coaxially arranged with centerbody (1), swirl-flow devices (3) is provided with in annular fuel air duct, centerbody end (4) has center air spray-hole (5), it is characterized in that: annular fuel air duct (2) tract at least has one section of channels expending (7) formed by annular sudden expansion section (6), and the axial location of centerbody end (4) is in the axial range of channels expending (7).

2. a kind of fuel-air blender with channels expending as claimed in claim 1, is characterized in that: the described stepped arrangement of annular sudden expansion section (6).

3. a kind of fuel-air blender with channels expending as claimed in claim 2, is characterized in that: described annular sudden expansion section (6) is 2 ~ 5 sections.

4. a kind of fuel-air blender with channels expending as described in claim 1,2 or 3, is characterized in that: described annular sudden expansion section (6) is provided with sudden expansion section wall cooling hole (8).

5. a kind of fuel-air blender with channels expending as claimed in claim 4, is characterized in that: sudden expansion section wall cooling hole (8) is straight hole or inclined hole.

6. as a kind of fuel-air blender with channels expending of claim as described in claim 1,2 or 3, it is characterized in that: the centerbody sidewall being positioned at channels expending (7) is provided with centerbody sidewall Cooling Holes (9).

7. a kind of fuel-air blender with channels expending as claimed in claim 6, is characterized in that: described centerbody sidewall Cooling Holes (9) is straight hole or inclined hole.