阅读说明：本技术 一种预燃级凹腔值班主燃级贫油直混的燃烧室及工作方法 (Pre-combustion-stage concave cavity class main-combustion-stage lean-oil direct-mixing combustion chamber and working method ) 是由 李明玉 王谦 肖建昆 于 2021-06-24 设计创作，主要内容包括：本发明公开了一种预燃级凹腔值班主燃级贫油直混的燃烧室及工作方法,包括燃烧室,所述的燃烧室包括机匣、火焰筒和火焰筒壁面,所述的火焰筒与火焰筒壁面之间形成凹腔,包括内凹腔和外凹腔,所述的外凹腔上连接有电嘴,所述的火焰筒壁面上阵列有多个旋流器和与之匹配的主燃级喷嘴。本发明通过对预燃级与主燃级的特殊的结构设计和布置,使得预燃级中的流动状态及几乎不受主燃级的流动影响,提高点火性能,拓宽火焰稳定范围；使进入主燃级的燃油和空气均匀混合,降低了NOx等污染物的排放；结构简单,燃烧室头部更加紧凑,减轻燃烧室重量；火焰筒壁面可以使更多的空气参与到壁面冷却,减少火焰筒壁面的热负荷,延长火焰筒寿命。(The invention discloses a pre-combustion-stage concave cavity class main-combustion-stage lean-oil direct-mixing combustion chamber and a working method thereof. According to the invention, through the special structural design and arrangement of the pre-combustion stage and the main combustion stage, the flow state in the pre-combustion stage is hardly influenced by the flow of the main combustion stage, the ignition performance is improved, and the flame stability range is widened; the fuel oil entering the main combustion stage is uniformly mixed with the air, so that the emission of pollutants such as NOx is reduced; the structure is simple, the head of the combustion chamber is more compact, and the weight of the combustion chamber is reduced; the wall surface of the flame tube can enable more air to participate in the wall surface cooling, the heat load of the wall surface of the flame tube is reduced, and the service life of the flame tube is prolonged.)

1. The utility model provides a burning chamber that main grade lean oil of burning directly mixes is fired to precombustion level cavity value class, includes combustion chamber (1), combustion chamber (1) include receiver, flame tube (19) and flame tube wall (10) between form the cavity, including interior cavity (16) and outer cavity (15), its characterized in that, outer cavity (15) on be connected with electric nozzle (11), flame tube wall (10) on the array have a plurality of swirlers (9) and the main grade nozzle of burning who matches with it.

2. A pre-combustion stage cavity class main combustion stage lean-oil direct-mixing combustor according to claim 1, characterized in that the swirler (9) is a single-stage axial swirler.

3. The pre-combustion stage cavity class main combustion stage lean direct-mixed combustor of claim 2, wherein an outlet of the single-stage axial swirler is flush with an outlet of a main combustion stage nozzle.

4. A pre-combustion stage cavity class main combustion stage lean-oil direct-mixing combustor according to claim 2 or 3, characterized in that the distance between the single-stage axial swirlers is 1.2-1.5 times the diameter of the swirler (9).

5. The pre-combustion stage concave cavity class main combustion stage lean oil direct mixing combustor as claimed in claim 4, wherein the blade installation angle of the single-stage axial swirler is 25-35 degrees, and the number of the blades is 10-12.

6. The lean direct-mixing combustor of the pre-combustion stage concave cavity class main combustion stage according to claim 1, characterized in that the main combustion stage nozzle is a one-way centrifugal nozzle (8).

7. A pre-combustion stage cavity class main stage lean direct-mixed combustion chamber as claimed in claim 1 or 6, characterized in that the main combustion stage nozzle is connected with the main combustion stage oil supply pipe (7).

8. The pre-combustion stage cavity class-main-combustion stage lean-oil direct-mixing combustor as claimed in claim 1, wherein a cavity front wall air inlet seam (12) is arranged between the combustor basket wall surface (10) and the cavity, and a cavity rear wall air inlet seam (13) is arranged between the combustor basket (19) and the cavity, wherein the cavity rear wall air inlet seam (13) is located above the cavity front wall air inlet seam (12).

9. The pre-combustion stage cavity class main-combustion stage lean-oil direct-mixing combustor as claimed in claim 8, wherein the cavity front wall air inlet seam (12) is provided with a duty nozzle (6) and a duty oil supply pipe (5).

10. A working method of lean oil direct mixing of a precombustion stage concave cavity class main combustion stage is characterized by comprising the following steps:

(1) air enters the cavity from the air inlet seam of the front wall of the cavity to form jet flow, the flow direction of the jet flow is bent under the limitation of the rear wall of the cavity, and the jet flow flows back under the action of the air inlet seam of the rear wall of the cavity to form cavity vortex;

(2) the on-duty fuel is sprayed out from the on-duty nozzle and enters the concave cavity together with the jet flow on the front wall of the concave cavity to form combustible mixed gas;

(3) the electric nozzle ignites the mixed gas nearby the electric nozzle, flame spreads around, a stable ignition source is formed at the vortex center of the cavity vortex, and the ignition source in turn continuously heats and ignites the fresh mixed gas;

(4) the main combustion stage fuel oil is ejected from the centrifugal nozzle and fully mixed with air flowing out of the swirler to reach a lean oil combustion state, and is quickly ignited by flame of the outer concave cavity and continuously combusted under the action of the wall surface of the flame tube;

(5) the mixed gas in the inner concave cavity and the outer concave cavity meets in the main combustion stage, and the burnt high-temperature fuel gas of the outer concave cavity ignites the mixed gas of the inner concave cavity, so that the mixed gas of the whole trapped vortex combustion chamber is ignited.

Technical Field

The invention relates to a staged combustion chamber and a combustion process, in particular to a pre-combustion stage concave cavity class main combustion stage lean oil direct-mixing combustion chamber and a working method.

Background

The reduction of pollutant emissions and the improvement of combustor performance have been the most fundamental requirements of modern gas turbines. Based on this, current research faces the following technical challenges: 1. the combustion stability in a low-power state, invisible exhaust smoke and combustion 2 in a high-power state, pollutant emission reduction in a large state and nitrogen oxide NOx emission are mainly solved. Approaches for solving the problems can be divided into two categories, one is to adopt reasonable measures to optimize a conventional swirl stable combustion chamber, and feasible measures mainly comprise lean oil premixing and pre-evaporation, lean oil direct mixing, multi-stage swirl and the like; the other category is to explore a brand new combustion organization mode and develop a new concept combustor on the basis of mastering basic principles, such as a Trapped Vortex Combustor (TVC), an Ultra Compact Combustor (UCC) and the like.

The exhaust emissions from the combustion chamber are mainly nitrogen oxides NOx, carbon monoxide CO, hydrocarbons CH, carbon particles, etc., and the nitrogen oxides NOx emission is a heavy burden of low emission technology. Given the conditions of formation and consumption of nitrogen oxides (NOx), in order to obtain lower NOx, it is necessary to ensure a combustion environment with a temperature as low as possible. The low temperature combustion environment may be achieved by lean operating conditions. The most representative of these are the lean Premixed and pre-vaporized lpp (lean Premixed and pre-vaporized) combustion technology and the lean direct-mixed ldi (lean direct injection) combustion technology.

The LPP combustion technology is characterized in that fuel oil which is evaporated in advance and excess air are uniformly mixed in advance and then are supplied to a combustion chamber for combustion, so that the whole combustion chamber is in a lean combustion state. By reducing the fuel-air ratio and the combustion temperature, the emission of nitrogen oxides (NOx) can be greatly reduced. The LPP combustion technique, however, presents technical difficulties in that auto-ignition and flashback can occur upstream of the relatively hot combustion chamber due to the time required to mix the fuel with air.

The LDI combustion technology is developed on the basis of the LPP combustion technology, and the steps of evaporating fuel in advance and mixing the fuel with air are omitted by directly injecting the fuel into the combustion chamber, so that the technical problems of self-ignition, tempering and the like of the LPP combustion are solved. Meanwhile, the LDI combustion technology faces technical challenges such as uneven oil-gas mixing and unstable flame combustion. To this, adopt swirler and fuel feeding nozzle integrated design to solve the inhomogeneous problem of oil-gas mixture. The air passing through the cyclone is both combustion air and air which assists in atomisation and facilitates the dispersion of the oil mist. Can effectively realize good atomization of fuel oil and quick mixing of oil and gas, and can form uniform and leaner combustible mixed gas at the head part of the combustion chamber. The problem of flame instability can be solved by reasonably organizing the jet flow entering the concave cavity to form a stable flame. The trapped vortex combustor is known to be widely used as a new concept combustor at present. The combustion area of the trapped vortex combustor is divided into a concave cavity area and a main combustion area. The cavity is in class, and is responsible for stabilizing flame and combustion organization under a small state. By properly organizing the jets at the front/back walls of the cavity, a stable vortex flow structure is formed within the cavity. Because the vortex is protected by the cavity, the flame can be stabilized over a wide range of operating conditions.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a pre-combustion-stage concave cavity class main-combustion-stage lean-oil direct-mixing combustion chamber and a working method, which can further reduce the emission of NOx while keeping flame combustion stable.

The technical scheme is as follows: the invention comprises a combustion chamber, wherein the combustion chamber comprises a casing, a flame tube and a flame tube wall surface, a concave cavity is formed between the flame tube and the flame tube wall surface and comprises an inner concave cavity and an outer concave cavity, the outer concave cavity is connected with an electric nozzle, and a plurality of swirlers and main combustion stage nozzles matched with the swirlers are arrayed on the flame tube wall surface.

The swirler is a single-stage axial swirler.

The outlet of the single-stage axial cyclone is flush with the outlet of the single-way centrifugal nozzle.

The distance between the single-stage axial cyclones is 1.2-1.5 times of the diameter of each cyclone.

The blade installation angle of the single-stage axial swirler is 25 degrees to 35 degrees, the number of the blades is 10-12, the swirl number of the swirler is guaranteed to be 0.4-0.6, a backflow area cannot be generated, the residence time of main combustion-stage fuel oil is shortened, and the generation of NOx is reduced.

The main combustion stage nozzle is a one-way centrifugal nozzle.

The main combustion stage nozzle is connected with the main combustion stage oil supply pipe.

And a cavity front wall air inlet seam is arranged between the flame tube wall surface and the cavity, and a cavity rear wall air inlet seam is arranged between the flame tube and the cavity, wherein the cavity rear wall air inlet seam is positioned above the cavity front wall air inlet seam.

The air inlet seam of the front wall of the concave cavity is provided with an on-duty nozzle and an on-duty oil supply pipe.

A working method of lean oil direct mixing of a precombustion stage concave cavity class main combustion stage comprises the following steps:

(1) air enters the cavity from the air inlet seam of the front wall of the cavity to form jet flow, the flow direction of the jet flow is bent under the limitation of the rear wall of the cavity, and the jet flow flows back under the action of the air inlet seam of the rear wall of the cavity to form cavity vortex;

(2) the on-duty fuel is sprayed out from the on-duty nozzle and enters the concave cavity together with the jet flow on the front wall of the concave cavity to form combustible mixed gas;

(3) the electric nozzle ignites the mixed gas nearby the electric nozzle, flame spreads around, a stable ignition source is formed at the vortex center of the cavity vortex, and the ignition source in turn continuously heats and ignites the fresh mixed gas;

(4) the main combustion stage fuel oil is ejected from the centrifugal nozzle and fully mixed with air flowing out of the swirler to reach a lean oil combustion state, and is quickly ignited by flame of the outer concave cavity and continuously combusted under the action of the wall surface of the flame tube;

(5) the mixed gas in the inner concave cavity and the outer concave cavity meets in the main combustion stage, and the burnt high-temperature fuel gas of the outer concave cavity ignites the mixed gas of the inner concave cavity, so that the mixed gas of the whole trapped vortex combustion chamber is ignited.

Has the advantages that:

(1) according to the invention, through the special structural design and arrangement of the pre-combustion stage and the main combustion stage, the flow state in the pre-combustion stage is hardly influenced by the flow of the main combustion stage, the ignition performance is improved, and the flame stability range is widened;

(2) the fuel oil and the air entering the main combustion level are uniformly mixed, so that the emission of pollutants such as NOx is reduced;

(3) the invention has simple structure, the head of the combustion chamber is more compact, and the weight of the combustion chamber is reduced;

(4) the wall surface of the flame tube is not provided with conventional mixing holes and main combustion holes, so that more air can participate in cooling the wall surface, the heat load of the wall surface of the flame tube is reduced, and the service life of the flame tube is prolonged.

Drawings

FIG. 1 is a schematic three-dimensional structure of the present invention;

FIG. 2 is a schematic diagram of the operation of the present invention;

FIG. 3 is a schematic view of the swirler, centrifugal nozzle, and main stage fuel supply of the present invention;

fig. 4 is a schematic view of the cyclone structure of the present invention.

Detailed Description

The invention will be further explained with reference to the drawings.

As shown in fig. 1 and 2, the present invention includes a combustion chamber 1, the combustion chamber 1 includes a casing, a flame tube 19 and a flame tube wall 10, the casing includes an outer casing 3 and an inner casing 4, and a diffuser 2 is connected to the head of the casing. A concave cavity is formed between the flame tube wall surface 10 and the flame tube 19 and comprises an outer concave cavity 15 and an inner concave cavity 16, wherein the top of the outer concave cavity 15 is connected with the electric nozzle 11. A concave cavity front wall air inlet seam 12 is respectively formed between the inner concave cavity and the outer concave cavity and the flame tube wall surface 10, a concave cavity rear wall air inlet seam 13 is respectively formed between the inner concave cavity and the outer concave cavity and the flame tube 19, wherein the concave cavity rear wall air inlet seam 13 is positioned above the concave cavity front wall air inlet seam 12. The on-duty nozzle 6 and the on-duty oil supply pipe 5 matched with the on-duty nozzle are arranged at the air inlet seam 12 of the front wall of the concave cavity and enter the concave cavity together with air to participate in combustion, and the on-duty oil supply pipe 5 and the on-duty nozzle 6 respectively supply fuel for the outer concave cavity 15 and the inner concave cavity 16.

The flame tube wall surface 10 is provided with a plurality of cyclones 9 in a rectangular array and a single-way centrifugal nozzle 8 matched with the cyclones 9, the cyclones 9 are single-stage axial cyclones and are directly connected with the flame tube wall surface 10, the distance between the axial cyclones is 1.2-1.5 times of the diameters of the cyclones 9, and the single-way centrifugal nozzle 8 is communicated with the main combustion stage oil supply pipe 7. As shown in fig. 3 and 4, the mounting angle of the blades of the swirler 9 is 25 ° to 35 °, the number of the blades is 10 to 12, the number of the swirls is guaranteed to be stabilized below 0.6, a backflow zone is not generated, the residence time of the main combustion stage fuel oil is shortened, and the generation of NOx is reduced. The main fuel level oil supply pipe 7, the single-way centrifugal nozzle 8 and the swirler 9 are designed in series, and the outlet of the single-way centrifugal nozzle 8 is flush with the outlet of the swirler 9, so that the atomization cone angle is controlled between 45 degrees and 120 degrees.

Air enters the combustion chamber 1 from the diffuser 2, is subjected to speed reduction and pressure increase through the diffuser 2 and then reaches the head of the flame tube 19 so as to be beneficial to the tissues to be combusted. After leaving the diffuser 2, the air is divided into an inner and outer annular flow and a main flow, the inner and outer annular flows flowing along the inner and outer annular passages 18 and 17, respectively, and entering the outer and inner cavities 15 and 16 from the cavity front wall inlet slots 12 and the cavity rear wall inlet slots 13, respectively. The primary air enters the liner 19 through the flow area of the swirler 9, and the ratio of the cavity air to the primary air flow is 3/7. The outer cavity 15 and the inner cavity 16 each include a front wall and a rear wall, wherein the front wall is opened on a side deviating from the main airflow for air intake, the rear wall is opened on a side close to the main airflow for air intake, the opening area ratio of the front wall and the rear wall is 3/2, and the intake airflow ratio is 5/3.

The working process of the invention is shown in figure 2, air enters the cavity from the air inlet seam 12 of the front wall of the cavity to form jet flow, the flow direction of the jet flow is bent under the limitation of the rear wall of the cavity, and then the jet flow flows back under the action of the air inlet seam 13 of the rear wall of the cavity to form standing cavity vortex 14. The on-duty fuel is sprayed out from the on-duty nozzle 6 and enters the concave cavity together with the jet flow on the front wall of the concave cavity to form combustible mixed gas. The electric nozzle 11 releases high-energy electric sparks to ignite the mixed gas near the electric nozzle 11, flame begins to spread all around, and a stable ignition source is formed at the vortex center of the cavity vortex 14 and is used for continuously heating and igniting the fresh mixed gas. The main combustion level fuel oil is ejected from the one-way centrifugal nozzle 8 and is quickly and fully mixed with air flowing out of the swirler 9, and a lean oil combustion state is achieved. The flame stabilized by the outer cavity 15 is rapidly ignited by the flame tube wall 10 and continues to burn. The mixture in the inner and outer pockets will meet in the main combustion stage and the burnt hot gases in the outer pocket 15 will ignite the mixture in the inner pocket 16. As the flame propagates further, the mixture throughout the trapped vortex combustor will be ignited. The outer cavity of the class is ignited by the high-energy ignition electric nozzle to form stable flame, and the flame is smoothly transmitted to the inner cavity of the class on duty through the wall surface of the flame tube and the main combustion stage, namely the ignition is smoothly finished.

The cyclone 9 introduces a large amount of fresh air, so that the airflow can be accelerated, the contact area of the fresh air and the fuel gas is increased, and the aim of rapid mixing is fulfilled. Due to the addition of large amounts of fresh air, the equivalence ratio is reduced to 0.5-0.8. The main combustion level fuel oil and gas mixture enters the periphery of the flame tube and is provided with high-temperature fuel gas and flame, so that the high-temperature fuel gas and the flame can be fully combusted, the main combustion level fuel oil can be combusted under the lean oil condition, a lean oil combustion area is formed, and the emission of nitrogen oxides (NOx) can be effectively reduced. By combining the standing vortex combustion technology and the lean oil direct-mixing combustion technology, the invention not only can effectively reduce the emission of NOx, but also can stably combust in a wider working condition range, and has good lean oil flameout performance. The stable flame in the concave cavity of the duty level is transmitted along the wall surface of the flame tube, so that a continuous and stable ignition source is provided for the main combustion level, and the defect of unstable combustion caused by a lean oil direct mixing technology is overcome. The staged combustion chamber only works on duty in the states of slow driving and approach, and simultaneously works on main combustion stage and duty stage in the states of takeoff, climbing and cruising.