CN108800206A - A kind of poor premix mould nozzle that fuel is sprayed from blade and loopful combustion chamber - Google Patents

Abstract

The invention relates to a lean premixed mode nozzle and a full-ring combustor in which fuel is injected from the blades. The lean premixed combustion technology is adopted, and the fuel injection ports are uniformly distributed in the radial direction on the blades of the axial swirler to improve the fuel/air ratio. The uniformity of the radial distribution, and the combustion equivalent ratio of the swirl nozzle is 0.55-0.75, which ensures that the temperature of the combustion zone is low and evenly distributed without hot spots, effectively reducing the generation of thermal nitrogen oxides; the axial swirl is low The swirling flow can not only shorten the residence time of high-temperature gas, reduce the formation of nitrogen oxides, but also reduce the turbulent pulsation of the swirling airflow, and reduce the risk of flashback and oscillating combustion; the divergent holes on the upper wall of the swirler outer wall can reduce the wall temperature and boundary layer The fuel/air ratio reduces the risk of spontaneous combustion and backfire; in the actual combustion chamber, a multi-point lean premixed combustion chamber head is formed by rationally arranging a certain number of swirl nozzles of the same size, and the main model fuel is supplied in stages, It can realize the low pollution emission level of the combustion chamber in the whole range of working conditions.

Description

A lean premixed nozzle with fuel injected from vanes and a full-ring combustor

technical field

The invention belongs to the field of gas turbine combustors, and relates to a lean premixed nozzle and a full-ring combustor in which fuel is injected from blades, in particular to a low-swirl nozzle scheme suitable for low-pollution combustors and based on lean premixed combustion technology .

Background technique

In recent years, as the problem of environmental pollution has become more and more serious, people's awareness of environmental protection has become stronger and stronger. Whether it is for aero-engines or ground gas turbines, the requirements for pollutant emissions have become increasingly stringent. For example, a series of standards formulated by the Committee on Environmental Protection (CAEP) under the International Civil Aviation Organization (ICAO) set strict regulations on the emissions of carbon monoxide, unburned hydrocarbons and nitrogen oxides. Only engines that meet the emission requirements can obtain airworthiness certification; For ground gas turbines, although there is no uniform pollution emission standard, due to the characteristics of long-term work on the ground, various regions have successively formulated pollutant emission standards in their own regions, and their emission standards are more stringent than those of aircraft engines. Therefore, it is necessary to Vigorously develop low-pollution combustion technology to reduce the emission level of gas turbine pollutants, so as to meet the higher emission requirements now and in the future.

At present, low-pollution combustion technologies for ground gas turbines mainly include: "wet" low-emission combustion technology, catalytic combustion ultra-low emission technology and "dry" low-emission combustion technology. Due to the negative impact of "wet" low-emission combustion technology on CO emissions and component life, as well as the technical bottleneck encountered by catalytic combustion technology, dry low-emission combustion technology is still the main development direction of gas turbines in the future. Due to the stringent pollutant emission requirements, the current "dry" low-emission combustion technology mainly adopts the premixed combustion method. The fuel is fully mixed with excess air before entering the combustion zone for combustion. The combustion zone is controlled by adjusting the equivalence ratio of the fuel-air mixture. Flame temperature, and avoid local hot spots, so as to achieve the purpose of reducing NOx emissions.

The swirler is an important component of the gas turbine combustor, and its role is to stabilize the flame and promote fuel/air mixing. In the past, in order to pursue the effect of fuel/air mixing uniformity and combustion stability, swirlers with high swirl strength were usually used. However, after theoretical and experimental research in recent years, high swirl intensity swirlers will increase the residence time of high-temperature gas in the combustion chamber on the one hand, increase the generation of nitrogen oxides, and increase the amount of nitrogen oxides in the combustion chamber on the other hand. Gas turbulent pulsation increases the risk of flashback and oscillating combustion in lean premixed mode. Therefore, the use of low-swirl nozzles is the development trend of low-pollution combustors.

In recent years, there have been many patent applications for lean premixed low-pollution combustors in China. Patent 201410697493.9 discloses a gas turbine combustor swirl jet nozzle, including a jet nozzle assembly and a swirl nozzle assembly, which reduces the swirl intensity of the combustion chamber gas by increasing the mixture ratio of the jet nozzle assembly, reducing the flame temperature and gas residence time, Thereby reducing nitrogen oxide emissions; patent 2011510117272.4 discloses a low-swirl premix nozzle for a low-pollution combustion chamber of a gas turbine, which uses a radial swirl with weak swirl strength to reduce the residence time of high-temperature gas, and uses a swirl The runner and the center runner jointly inject fuel to improve the uniformity of fuel/air mixing. Through the analysis, it is found that the nozzle structure of the above-mentioned combustion chamber adopts the fuel combination injection method to enhance the fuel/air mixing, and the structure is complicated. Moreover, the swirlers all use straight blades, which are prone to flow separation and large flow loss, and there is no clear prevention of backfire and spontaneous combustion measures.

Contents of the invention

technical problem to be solved

In order to avoid the deficiencies of the prior art, the present invention proposes a lean premixed nozzle and a full-ring combustor in which the fuel is injected from the blades, and is suitable for the lean premixed nozzle in which the fuel of the low-pollution combustion chamber of the gas turbine is injected from the blades, The structure of this scheme is simple, which can not only ensure sufficient mixing of fuel/air, but also reduce flow separation and flow resistance loss, and at the same time take measures to reduce the risk of flashback, spontaneous combustion and oscillating combustion. The scheme can be applied to combustion chambers of large, medium and small power gas turbines through reasonable arrangement and classification.

Technical solutions

A lean premixed nozzle for fuel injection from blades, comprising a swirler outer wall and an axial swirler; it is characterized in that: the axial swirl is a low-swirl axial swirl, and the low-swirl axial swirl The inner wall 6 of the swirler toward the center of the swirler 7 is the fuel pipeline inlet 7, and the inner wall 6 of the swirler between the blades of the low-swirl axial swirler 9 is provided with a rectangular hole to form a blade fuel flow path inlet 8 , on the blade back of each vane of the low-swirl axial swirler 9, a plurality of injection holes 13 are provided, so that fuel enters from the fuel pipeline inlet 7, passes through the blade fuel flow inlet 8, and enters through the injection holes 13 The premixing section 2; the outer wall of the premixing section 2 between the low-swirl axial swirler 9 and the outlet converging section 11 is provided with a plurality of divergent small holes 10 on the wall surface, and the outlet converging section 11 is followed by a low swirl flow Nozzle outlet 12; the blades of the low-swirl axial swirler 9 are curved blades, uniformly distributed along the circumference, and the blade angle is 30°-45°; the inner diameter D of the low-swirl nozzle outlet 12 is 25mm ~60mm, the ratio of the length S of the premixing section to the inner diameter D is 0.5~1.2.

The number of vanes in the low-swirl axial swirler 9 is 6-20, which is equal to the number of vane fuel flow path inlets 8 between the vanes.

There are 2-5 injection holes 13 on the back of the blade.

The blade angle of the curved blade of the low-swirl axial swirler 9 is 30°-45°.

The small diverging holes 10 on the wall surface are evenly distributed along the axial and circumferential directions, and the axial distance and the circumferential distance of the small divergent holes are 4 mm to 7 mm.

The angle α between the convergent section of the outlet of the cyclone and the horizontal direction is 35°-55°.

The equivalent ratio of the combustion zone of the low swirl nozzle scheme is 0.55-0.75.

A full-ring combustor composed of lean premixed nozzles that inject fuel from blades, including an outer flame tube 15, an inner flame tube 19, and a head flange 14; The pre-mixed mold nozzles are arranged on the head flange 14 in three layers from inside to outside in the radial direction, and the main mold of a group of three nozzles and the secondary mold of a group of two nozzles are distributed at intervals along the radial direction.

The vane-injecting lean premixed nozzles of the same group share a fuel supply pipe.

The distance S1 between the outer swirl nozzle and the outer flame tube and the distance S4 between the inner swirl nozzle and the inner flame tube are 4mm-8mm, the radial distances S2 and S3 between the swirl nozzles are 3mm-5mm, and the distance between the swirl nozzles is 3mm-5mm. The circumferential distance D1 is 10mm-30mm.

Beneficial effect

The invention proposes a lean premixed nozzle and a full-ring combustor in which fuel is injected from blades, and adopts lean premixed combustion technology. The uniformity of the ratio distribution in the radial direction, in addition, the combustion equivalent ratio of the swirl nozzle is 0.55-0.75, which ensures that the temperature of the combustion zone is low and evenly distributed without hot spots, effectively reducing the generation of thermal nitrogen oxides; the axial swirler is Low swirling flow can not only shorten the residence time of high-temperature gas, reduce the formation of nitrogen oxides, but also reduce the turbulent pulsation of the swirling airflow, and reduce the risk of flashback and oscillating combustion; the divergent holes on the upper wall of the swirler outer wall can reduce the wall temperature and adhesion Layer fuel/air ratio to reduce the risk of spontaneous combustion and flashback; in the actual combustion chamber, a multi-point lean premixed combustion chamber head is formed by rationally arranging a certain number of swirl nozzles of the same size, and the main model fuel is supplied in stages , which can realize the low pollution emission level of the combustion chamber in the whole range of working conditions.

Compared with the prior art, the present invention has the following advantages:

The angle of the swirler in the swirl nozzle scheme is 30°-45°, which is a weak swirl. On the one hand, it can weaken the turbulent pulsation intensity of the airflow, reduce the risk of flashback and oscillating combustion, and on the other hand, it can shorten the temperature of the high-temperature gas in the combustion chamber. Residence time; the lean fuel combustion method is adopted, and the working equivalence ratio is between 0.55-0.75. At this time, the temperature of the combustion zone is low, which effectively reduces the formation of NOx; by opening a certain number of fuel injection holes in the radial direction on the swirler blade , can improve the distribution uniformity of the fuel/air ratio along the radial direction, thereby effectively avoiding the occurrence of hot spots in the combustion zone and reducing NOx emissions; the divergent holes on the outer wall of the swirler can reduce the wall temperature and the fuel/air ratio of the wall boundary layer, Thereby effectively reducing the risk of spontaneous combustion and backfire; because the air is accelerated out of the swirl nozzle through the converging section, the risk of backfire can be reduced; the structure is simple and compact, easy to process and assemble, and a certain number of the same swirl nozzles can pass through a reasonable arrangement. The distribution pattern can form a multi-point lean premixed combustor head.

Description of drawings

Figure 1: Sectional view of the low-swirl lean premix nozzle of the present invention

Figure 2: Axonometric view of the low-swirl lean premix nozzle of the present invention

Figure 3: Axonometric view of the axial swirler of the low-swirl lean premix nozzle of the present invention

Figure 4 is an axonometric view of the head of the multi-point lean premixed combustion full-ring combustor of the embodiment of the present invention

Figure 5: Left view of the head of the multi-point lean premixed full-ring combustor according to the embodiment of the present invention

In the figure: 1-low swirl lean premix nozzle, 2-premix section, 3-swirl outer wall, 4-blade fuel flow path, 5-swirl flow channel, 6-swirl inner wall, 7-fuel Pipeline inlet, 8-vane fuel flow inlet, 9-low-swirl axial swirler, 10-wall divergence small hole, 11-exit convergence section, 12-low-swirl nozzle outlet, 13-fuel injection hole, 14-head flange, 15-outer flame tube, 16-partial view of combustion chamber head, 17-secondary mold, 18-main mold, 19-inner flame tube, 20-partial view of low-swirl nozzle.

Detailed ways

Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

The present invention adopts the following technical solutions: a premixed mold nozzle structure in which fuel is injected from blades, including a low-swirl axial swirler, swirler outer wall, swirler inner wall, swirl flow channel, fuel pipeline inlet, The vane fuel flow path inlet, the vane fuel flow path, the fuel injection hole, the premixing section, the exit converging section, the swirl nozzle exit and the divergent small hole on the wall surface. The swirl channel is surrounded by the outer wall of the swirl, the low-swirl axial swirl and the inner wall of the swirl, the downstream of the swirl channel is a premixing section, followed by the outlet convergence section and the outlet of the swirl nozzle , used to increase the velocity of the fuel/air mixture flowing downstream, reducing the risk of flashback. The small wall divergence holes are located on the outer wall of the swirler at the premixing section, and are used to reduce the wall temperature and fuel/air ratio in the boundary layer, reducing the risk of flashback and spontaneous combustion. The blades of the low-swirl axial swirler are hollow, and are blade fuel flow paths, and the inlets of the blade fuel flow paths are located on the inner wall of the swirler. The fuel injection ports are evenly opened on the back of each swirler vane from inside to outside in the radial direction, which can improve the mixing uniformity of the fuel/air ratio in the radial direction. The certain number of low swirl lean premixed nozzles can be applied to large, medium and small power gas turbine combustors through reasonable arrangement and fuel classification.

The equivalence ratio of the combustion zone of the low-swirl lean premix nozzle solution is 0.55-0.75.

The swirler blades are curved blades, uniformly distributed along the circumference, and the number of blades is 6-20.

The swirler is a low-swirl flow with a blade angle of 30°-45°.

The inlet of the vane fuel flow path and the vane fuel flow path are consistent with the number of swirler vanes, which are 6-20.

The fuel injection holes are radially opened on the back of the swirler blades, and each swirler blade has 2-5 injection holes according to the size of the swirler blades.

The angle α between the convergent section of the outlet of the cyclone and the horizontal direction is 35°-55°.

The inner diameter D of the swirl nozzle scheme is 25mm-60mm, and the ratio of the length S of the premixing section to the inner diameter D is 0.5-1.2.

The said divergent holes on the wall surface are evenly distributed on the outer wall of the cyclone at the premixing section along the axial direction and the circumferential direction, and the axial distance and the circumferential distance of the divergent holes are 4mm-7mm.

The arrangement of the swirl nozzles on the full ring combustion chamber is arranged in three layers from the inside to the outside, each swirl nozzle is the same, three groups or two groups along the radial direction, three One group is the main model, two groups are the secondary model, and the swirl nozzles of the same group share a fuel supply pipe.

The arrangement of the swirl nozzles on the full ring combustion chamber, the distance S1 between the outer swirl nozzles and the outer flame tube and the distance S4 between the inner swirl nozzles and the inner flame tube is 4mm-8mm, the diameter between the swirl nozzles The distances S2 and S3 are 3mm-5mm, and the circumferential spacing D1 between swirl nozzles is 10mm-30mm.

Specific examples:

As shown in Figures 1-3, the embodiment of the present invention provides a low-swirl lean premix nozzle in which fuel is injected from vanes, including a low-swirl axial swirler 9, a swirler outer wall 3, a swirler Inner wall 6, swirl flow channel 5, fuel pipeline inlet 7, blade fuel flow path inlet 8, blade fuel flow path 4, fuel injection hole 13, premixing section 2, outlet convergence section 11, swirl nozzle outlet 12 and wall surface Divergent small hole 10. The swirl channel 5 is surrounded by the swirl outer wall 3, the low-swirl axial swirl 9 and the swirl inner wall 6, and the swirl angle of the low-swirl axial swirl is 30° -45°, is a weak swirl, which can not only reduce the turbulent pulsation of the swirling airflow, but also shorten the residence time of high-temperature gas in the combustion chamber. The number of swirler blades is 6-20. Downstream of the swirl channel 5 is the premixing section 2, followed by the outlet convergence section 11 and the swirl nozzle outlet 12, the outlet convergence section 11 and the horizontal line angle α is 35°-55°, improving the fuel/air mixture Outflow speed reduces risk of flashback. The fuel injection holes 13 are evenly distributed radially on the blades of the axial swirler 9. According to the size of the swirler blades, 2-5 fuel injection holes are opened on each blade to improve the fuel/air mixture in the radial direction. uniformity of mixing. The fuel flows in from the fuel pipeline inlet 7, flows into the blade fuel flow path 4 through the vane fuel flow path inlet 8 on the swirler inner wall 6, and finally is ejected from the fuel injection hole 13 on the swirler vane, and is connected with the axial direction. The swirling airflow generated by the swirler meets and mixes in the swirl flow channel, and then further mixes evenly at the premixing section, and finally accelerates through the outlet convergence section, and flows from the swirl nozzle outlet to downstream combustion, and the combustion equivalent ratio downstream of the swirl nozzle is low , controlled between 0.55-0.75, it is lean premixed combustion, which can effectively reduce the generation of nitrogen oxides. The wall divergence small holes 10 are evenly distributed on the outer wall 3 of the cyclone along the axial and circumferential directions, and the axial and circumferential distances are 4mm-7mm, which can effectively reduce the fuel/air ratio of the wall temperature and the wall boundary layer, and reduce the Small risk of spontaneous combustion and flashback.

As shown in Figure 4-5, according to the actual gas turbine combustor power and size, a multi-point lean premixed combustor head can be formed by rationally arranging a certain number of low-swirl lean premixed nozzles of the same size. The low-swirl lean premix nozzle 1 can be distributed on the head flange 14 in three layers from inside to outside in the radial direction, the number of swirl nozzles in the outer layer and the middle layer is the same, and the number of swirl nozzles in the inner layer is the same. The number is half of the outer layer, wherein two swirl nozzles along the radial direction form the combustion chamber sub-mold 17, and three swirl nozzles along the radial direction form the combustion chamber main mold 18, and all the sub-molds are completely Fuel injection work, the main mold is staged fuel injection work with the increase of the working conditions of the combustion chamber, the number of stages of the main mold classification work can be selected from 6 to 15 according to the working conditions of the combustion chamber, and the distance between the outer swirling nozzles The distance S1 between the outer flame cylinder 15 and the distance S4 between the inner swirl nozzle and the inner flame cylinder 19 is 4mm-8mm, the radial distance S2 and S3 between adjacent swirl nozzles is 3mm-5mm, and the circumferential distance D1 is 10mm- 30mm.

Working process of the present invention is as follows:

The air passes through the low-swirl axial swirler 9 to generate a weak swirling flow, while the fuel flows in from the fuel pipeline inlet 7, flows through the vane fuel flow passage inlet 8 and the vane fuel flow passage 4 in turn, and finally sprays out from the fuel injection hole 13 . The injected fuel and the swirling air flow meet and mix in the swirling flow channel 5, and further mix in the premixing section 2, and then the uniformly mixed fuel/air mixture passes through the acceleration of the exit converging section 11, and flows from the low swirl nozzle outlet 12 to Downstream, stable combustion takes place downstream. In addition, part of the air will flow into the swirl nozzle through the wall divergence holes 10 on the outer wall 3 of the swirler, forming a uniform air film attached to the wall inside the outer wall 3 of the swirler, reducing the wall temperature on the one hand, and lowering the wall surface on the other hand. Boundary layer fuel/air ratio, thereby reducing the risk of spontaneous combustion and flashback.

Claims (10)

1. A lean premixed nozzle for fuel injection from blades, comprising a swirler outer wall and an axial swirler; it is characterized in that: the axial swirl is a low-swirl axial swirl, and the low-swirl The swirler inner wall (6) at the center of the flow axial swirler (7) is the fuel pipeline inlet (7), and the swirler inner wall (6) between the blades of the low-swirl axial swirler (9) A rectangular hole is provided on the vane to form the inlet (8) of the vane fuel flow path, and on the back of each vane of the low-swirl axial swirler (9), a plurality of injection holes (13) are provided so that the fuel flows from the fuel pipe into the premixing section (2) through the vane fuel flow inlet (8) through the injection hole (13); The outer wall of the cyclone in the inter-premixing section (2) is provided with a plurality of wall surface divergence small holes (10), and the exit convergence section (11) is followed by a low-swirl nozzle outlet (12; the low-swirl axial swirl The blades of the device (9) are curved blades, uniformly distributed along the circumferential direction, and the blade angle is 30°～45°; the inner diameter D of the low swirl nozzle outlet (12) is 25mm～60mm, and the length S of the premixing section and The ratio of the inner diameter D is 0.5-1.2. 2. According to claim 1, the fuel is injected from the lean premixed nozzle of the vane, characterized in that: the low-swirl axial swirler (9) has 6-20 vanes, and the vanes between the vanes The number of fuel flow path inlets (8) is equal. 3. The lean premixed nozzle for fuel injection from blades according to claim 1 or 2, characterized in that: there are 2-5 injection holes (13) on the back of the blade. 4. According to claim 1 or 2, the fuel is injected from the lean premixed nozzle, characterized in that: the blade angle of the curved blade of the low-swirl axial swirler (9) is 30°-45° . 5. According to claim 1, the lean premixed nozzle for injecting fuel from blades is characterized in that: the divergent holes (10) on the wall are evenly distributed along the axial and circumferential directions, and the axial spacing of the divergent holes is And the circumferential spacing is 4mm ~ 7mm. 6 . The lean premixed nozzle for injecting fuel from blades according to claim 1 , wherein the angle α between the converging section of the swirler outlet and the horizontal direction is 35°-55°. 7 . The lean premixed nozzle for injecting fuel from blades according to claim 1 , wherein the equivalent ratio of the combustion zone of the low-swirl nozzle solution is 0.55-0.75. 8. A full-circle combustor utilizing any one of claims 1 to 7 in which fuel is injected from blades to form a full-circle combustion chamber comprising an outer flame tube (15), an inner flame tube (19) and a head method Lan (14); it is characterized in that: a plurality of poor premixed nozzles sprayed from the blades are arranged on the head flange (14) in three layers from inside to outside in the radial direction, and three nozzles are arranged in three layers along the radial direction. The interval between the main mold and the secondary molds of the two nozzles is distributed. 9 . The full-ring combustor according to claim 8 , wherein the same group of lean premixed nozzles injecting from the blades share one fuel supply pipe. 10. The full-ring combustion chamber according to claim 8, characterized in that: the distance S1 between the outer swirl nozzle and the outer flame tube and the distance S4 between the inner swirl nozzle and the inner flame tube are 4mm-8mm, and the swirl flow The radial distances S2 and S3 between the nozzles are 3mm-5mm, and the circumferential distance D1 between the swirl nozzles is 10mm-30mm.