Combustion chamber capable of doping hydrogen in fuel oil for emission reduction and control method of combustion chamber

Abstract

A combustion chamber for reducing emission by doping hydrogen in fuel oil comprises a pre-combustion stage, the pre-combustion stage comprises a venturi tube, the venturi tube is a pre-film forming device of the fuel oil of the pre-combustion stage, and in the venturi tube, a hydrogen supply channel is used for receiving hydrogen; a plurality of hydrogen injection holes are formed in the expansion section of the venturi tube in the circumferential direction and used for injecting hydrogen conveyed by the hydrogen supply channel. According to the control method of the combustion chamber, the pollutant emission level of the whole combustion chamber is reduced by injecting hydrogen to assist combustion.

Description

Technical Field

[0001] The invention relates to a combustion chamber of a gas turbine or an aircraft engine and a control method thereof. Background Art

[0002] In order to protect the earth on which human beings depend for survival and achieve "zero emissions" of carbon, many countries have proposed carbon neutrality goals. At present, carbon dioxide emissions from the global aviation transport industry account for about 2% of the total carbon emissions from human activities that year. If no measures are taken, the industry's carbon emissions will double by 2050. Reducing carbon emissions from aircraft engines has long attracted global attention and is an important part of achieving carbon neutrality. Civil aviation engine pollution emissions mainly include nitrogen oxides (NOx), carbon monoxide (CO), unburned hydrocarbons (UHC), non-volatile particulate matter (nvPM), etc. The International Civil Aviation Organization (ICAO), the Civil Aviation Administration of China (CAAC), etc. have formulated increasingly stringent aviation engine pollutant emission standards. Since the combustion chamber is the main pollutant-producing component of an aircraft engine, the design of the combustion chamber and the combustion conditions inside it directly affect the performance and emissions of the engine. Therefore, low-emission combustion chamber design technology is not only a key technology for aircraft engine product certification, but also an important development technology for achieving carbon neutrality.

[0003] For a typical center-staged lean premixed preevaporative (LPP) combustion chamber, the center precombustion stage is a diffusion flame mode, which mainly works under small operating conditions to ensure reliable engine starting ignition performance and a relatively wide lean flameout margin; the main combustion stage is a lean premixed combustion mode, which mainly works under large operating conditions in combination with the precombustion stage to reduce the generation of CO and NOx. Under small operating conditions, since the precombustion stage is a rich combustion, the NOx emissions are the lowest in the LTO cycle conditions, but the CO, UHC and nvPM emissions are the highest. Therefore, it is particularly important to reduce pollutant emissions in all operating conditions of the LPP combustion chamber, especially under small operating conditions.

[0004] Traditional aircraft engines use aviation kerosene as fuel. On the one hand, fossil energy is facing the risk of shortage due to its non-renewable nature. On the other hand, it is difficult to further develop by enhancing fuel atomization and oil-gas mixing to improve combustion efficiency and reduce emissions. Using new energy as aviation fuel is a technical path to reduce carbon emissions. Hydrogen is clean and renewable, and can effectively solve the problem of carbon emissions. Compared with aviation kerosene, hydrogen has a higher combustion temperature, faster flame propagation speed, and a wider potential for stable operation. The use of pure hydrogen combustion will face new designs such as combustion organization, hydrogen fuel thermal management system, and hydrogen-powered flight integration, which cannot be achieved in the short term. Therefore, blending hydrogen in the combustion chamber of aviation kerosene is a more feasible technical solution in the transition stage to the development of pure hydrogen combustion chambers. Summary of the invention

[0005] The object of the present invention is to provide a combustion chamber for reducing emissions by adding hydrogen to fuel.

[0006] Another object of the present invention is to provide a method for controlling a combustion chamber, which reduces the pollution emission level of the entire combustion chamber by injecting hydrogen to assist combustion.

[0007] According to one aspect of the present invention, a combustion chamber for reducing emissions by adding hydrogen to fuel includes a pre-combustion stage, which includes a venturi, and the venturi is a pre-film forming device for the pre-combustion stage fuel. In the venturi, a hydrogen supply channel is used to receive hydrogen; and a plurality of hydrogen injection holes are arranged circumferentially in the expansion section of the venturi, for injecting hydrogen transported by the hydrogen supply channel.

[0008] In one embodiment, a plurality of the hydrogen injection holes are arranged on the end surface of the expansion section of the venturi tube.

[0009] In one embodiment, a plurality of the hydrogen injection holes are respectively arranged on the outer circumferential surface and the inner circumferential surface of the expansion section of the venturi tube.

[0010] In one embodiment, the hydrogen injection holes on the outer circumferential surface and the inner circumferential surface of the expansion section of the venturi are arranged obliquely relative to the outer surface of the expansion section of the venturi.

[0011] In one embodiment, the hydrogen supply channel includes three-stage hydrogen collecting chambers concentrically arranged in the venturi tube, which are respectively connected to the hydrogen injection holes on the end surface, outer peripheral surface, and inner peripheral surface of the expansion section.

[0012] In one embodiment, the pre-combustion stage further includes a swirler, and a hydrogen inlet passage is provided inside the swirling blades of the swirler, and the hydrogen inlet passage is communicated with the hydrogen supply passage.

[0013] In one embodiment, the combustion chamber further includes a hydrogen supply pipe, and the hydrogen supply pipe is connected to the hydrogen inlet passage.

[0014] According to the control method of the combustion chamber of another aspect of the present invention, when the combustion chamber starts to ignite, only the pre-combustion stage works, so that the pre-combustion stage fuel nozzle sprays fuel, and at the same time, hydrogen is sprayed at the end of the expansion section of the venturi of the pre-combustion stage, so as to assist the combustion by adding hydrogen, reduce the fuel injection ratio, and improve the ignition probability and ignition stability.

[0015] In one embodiment, after successful ignition, when the combustion chamber operates under low-power conditions, only the pre-combustion stage operates, so that the pre-combustion stage fuel nozzle is closed, and hydrogen is sprayed at the expansion section end, outer circumference, and inner circumference of the venturi of the pre-combustion stage.

[0016] In one embodiment, when the combustion chamber operates under a large working condition, the main combustion stage and the pre-combustion stage work together, the main combustion stage injection hole and the pre-combustion stage nozzle both spray fuel, and at the same time, the end and outer peripheral surface of the expansion section of the venturi of the pre-combustion stage spray hydrogen to assist combustion.

[0017] According to an embodiment of the present invention, the pre-combustion stage venturi is used as a hydrogen injection device. The hydrogen injection hole of the expansion section of the venturi allows the hydrogen to be sprayed out from the injection air of the expansion section of the venturi, which can ensure that it is fully premixed with the two-stage swirl air of the pre-combustion stage and then burned. Since the premixing section is short, spontaneous combustion and backfire can be prevented. In addition, such a hydrogen injection device has a simple and compact structure and is easy to install and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0019] Figure 1 It is a schematic diagram of the structure of an aircraft engine;

[0020] Figure 2 is a cross-sectional view of the combustion chamber;

[0021] Figure 3 It is a cross-sectional view of the combustion chamber head;

[0022] Figure 4 It is a stereogram of the pre-combustion stage;

[0023] Figure 5 is a cross-sectional view of the pre-combustion stage;

[0024] Figure 6 is a cross-sectional view of a primary cyclone of a pre-combustion stage;

[0025] Fig. 7A It is a stereogram of the Venturi tube;

[0026] Figure 7B is an end-on view of the venturi tube;

[0027] Fig. 8A is along Figure 7B Cross-sectional view of the middle BB position;

[0028] Figure 8B is along Figure 7B Cross-sectional view at the mid-CC position;

[0029] Figure 8C is along Figure 7B Cross-sectional view at the middle DD position. DETAILED DESCRIPTION

[0030] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the present invention, not to limit the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature illustrated or described as part of one embodiment may be used together with another embodiment to produce yet another embodiment. Therefore, the present invention is intended to cover these modifications and variations within the scope of the appended claims and their equivalents.

[0031] like Figure 1 As shown, the turbofan engine includes a fan 1, a low-pressure compressor 2, a high-pressure compressor 3, a combustion chamber 4, a high-pressure turbine 5, a low-pressure turbine 6 and a casing 7. In the combustion chamber 4, the fuel and air are mixed and burned, and the high-temperature and high-pressure combustion gas formed expands the high-pressure turbine to do work, providing kinetic energy for the engine. The combustion chamber according to the present invention is not limited to Figure 1 The turbofan engine shown is also applicable to other types of aircraft engines or gas turbines.

[0032] Figure 2 It is a cross-sectional view of the combustion chamber structure. The combustion chamber 4 is a central staged combustion chamber (LPP), including a diffuser 8, a combustion chamber casing 9, a combustion chamber casing 10, a combustion chamber outer flame tube 11, a combustion chamber flame tube 12, a pre-combustion stage fuel rod 13, a main combustion stage fuel rod 14, and a combustion chamber head 15. The diffuser 8 is used to decelerate and reduce the pressure of the high-pressure compressor outlet airflow. The combustion chamber casing 9 and the combustion chamber casing 10 are load-bearing structures. The combustion chamber outer flame tube 11 and the inner flame tube 12 are high temperature and high pressure resistant structures. The combustion chamber head 15 adopts a central staged combustion organizational structure, with the center being the pre-combustion stage and the periphery being the main combustion stage. Under the small operating condition where only the pre-combustion stage works in the combustion chamber, the pre-combustion stage is oil-rich combustion, and the nvPM and carbon emissions are very high. Under the large operating condition where the main and pre-combustion stages work together, both the main and pre-combustion stages are oil-lean combustion, and the emissions of various types of pollution are relatively low. In the embodiments described below, in order to further reduce the pollutant emissions of the combustion chamber under various working conditions, a low-emission combustion chamber is provided that injects hydrogen in the pre-combustion stage to assist combustion. The combustion chamber adopts a centrally staged combustion organization mode, the central pre-combustion stage uses fuel (such as aviation kerosene) / hydrogen combustion, and the peripheral main combustion stage uses fuel combustion. By adding hydrogen to the pre-combustion stage to assist combustion, the combustion efficiency and combustion stability can be improved, the lean combustion limit can be widened, and there is great potential for comprehensively reducing pollutant emissions under all working conditions.

[0033] Figure 3It is a cross-sectional view of the combustion chamber head structure. The combustion chamber head 15 includes a main combustion stage 19 and a pre-combustion stage 20. The main combustion stage 19 and the pre-combustion stage 20 are concentrically assembled. The main combustion stage 19 includes an air intake oblique hole 21, an injection pipe 22 and a main combustion stage channel 24. 6 to 24 injection pipes 22 are evenly arranged in the circumferential direction in the main combustion stage channel 24. Each injection pipe 22 is provided with 4 to 10 direct injection holes 23. The main combustion stage fuel rod 14 supplies fuel to the injection pipe 22. The pre-combustion stage fuel rod 13 supplies fuel to the pre-combustion stage fuel nozzle 25.

[0034] Figure 4 2 is a structural stereogram of the pre-combustion stage. The pre-combustion stage 20 includes two stages of tangential swirlers, namely, a primary swirler 26 and a secondary swirler 27. As an example, the pre-combustion stage includes three stages of hydrogen supply pipes, the primary hydrogen supply pipe 16, the secondary hydrogen supply pipe 17, and the tertiary hydrogen supply pipe 18 provide hydrogen for the pre-combustion stage.

[0035] Figure 5 It is a structural cross-sectional view of the pre-combustion stage. The pre-combustion stage 20 also includes a pre-combustion stage fuel nozzle 25, a first-stage swirler 26, a second-stage swirler 27, a sleeve 28 and a venturi 29. The venturi 29 is a pre-film forming device for the pre-combustion stage fuel, and is also a hydrogen injection device. The venturi 29 is a pipeline device that first contracts and then expands. It is usually arranged between the two-stage swirlers of the pre-combustion stage and is mainly used for pre-combustion stage fuel atomization. The fuel forms an oil film on the wall of the venturi. After the oil film is broken by the two-stage swirling air at the end wall of the expansion section of the venturi, fine fuel particles are formed.

[0036] Fig. 7A , Figure 7B , Fig. 8A , Figure 8B as well as Figure 8C : is a schematic diagram of the structure of the venturi 29. The venturi 29 includes three hydrogen supply channels 35, 36, 37, which are exemplified in the figure as three-stage hydrogen gas collecting chambers arranged concentrically. The hydrogen supply channels 35, 36, 37 are used to receive hydrogen. The hydrogen injection holes 38, 39, 40 are arranged circumferentially in the expansion section of the venturi 29, and are used to inject hydrogen transported by the hydrogen supply channels 35, 36, 37. The hydrogen injection holes 38, 39, 40 are arranged at the expansion section of the venturi, and the hydrogen after being sprayed out not only helps the fuel atomization, but also can be fully premixed with the swirl air. The premixing section is short from the pre-combustion stage outlet, which can effectively avoid spontaneous combustion and flashback. In addition, without changing the original configuration of the combustion chamber, a hydrogen inlet duct is provided on the pre-combustion stage swirler blades, and hydrogen supply channels 35, 36, 37 and injection holes 38, 39, 40 are provided inside the venturi, so as to realize the hydrogen-blended combustion function, which has a simple and compact structure and is easy to install and maintain.

[0037] Optionally, a plurality of hydrogen injection holes 39 are arranged on the end face of the expansion section of the venturi 29. When the combustion chamber starts ignition, the pre-combustion stage fuel nozzle sprays fuel, and at the same time, hydrogen is sprayed at the end of the expansion section of the pre-combustion stage venturi. By adding hydrogen to assist combustion, the fuel injection ratio is reduced, and the ignition probability and ignition stability are improved.

[0038] In one embodiment, a plurality of hydrogen injection holes 40 are arranged on the outer circumference of the expansion section of the venturi 29, and a plurality of hydrogen injection holes 38 are arranged on the inner circumference. After ignition is successful, when the combustion chamber works under small working conditions, only the pre-combustion stage works, so that the pre-combustion stage fuel nozzle is closed, and hydrogen is injected at the end, outer circumference and inner circumference of the expansion section of the venturi of the pre-combustion stage. Pure hydrogen is used as fuel, and hydrogen and air are premixed and burned to improve combustion stability and combustion efficiency, and reduce small working conditions nvPM and carbon emissions.

[0039] The hydrogen injection holes 38 and 40 are inclined holes, and the hydrogen injection hole 38 is a straight hole on the end face. In this way, after the hydrogen is ejected from the venturi expansion section, it can be ensured to be fully premixed with the two-stage swirl air of the pre-combustion stage and then burned. Since the premixing section is short, spontaneous combustion and flashback can be prevented.

[0040] The hydrogen supply passages 35, 36, 37 include three-stage hydrogen gas collecting chambers arranged concentrically in the venturi 29, which are respectively connected to the hydrogen injection holes 38, 39, 40. The number of hydrogen injection holes can be adjusted according to the power provided by the combustion chamber, which can be less than three or more than three.

[0041] like Figure 4 , Figure 5 and Figure 6 As shown, the three swirl blades in the first-stage cyclone 26 are respectively provided with hydrogen inlet channels 30, 31 and 32. The hydrogen inlet channels 30, 31 and 32 are respectively connected to the hydrogen inlet holes 33, 34 and 35'. The three blades of the pre-combustion stage first-stage air cyclone are provided with hydrogen inlet pipes, and the integrated design does not affect the pre-combustion stage air intake. The radial distances of the hydrogen inlet holes 33, 34 and 35' are from small to large, and are respectively connected to the hydrogen supply channels 35, 36, 37 or the hydrogen collecting cavity.

[0042] The first-stage hydrogen supply pipe 16, the second-stage hydrogen supply pipe 17, and the third-stage hydrogen supply pipe 18 are connected to the hydrogen inlet channels 30, 31, and 32 in the swirl blades to provide hydrogen for the venturi tube 29. The three hydrogen flow channels inside the pre-combustion stage venturi tube are independently controlled. Different flow channels are opened according to different working conditions to achieve premixed combustion of different amounts of hydrogen under different working conditions, thereby reducing pollution emissions under all working conditions. The end of the expansion section of the venturi tube 29 is provided with 36-60 circumferentially uniformly arranged hydrogen injection straight holes 39, the outer peripheral surface, i.e., the concave surface, is provided with 36-60 circumferentially uniformly arranged hydrogen injection inclined holes 40, and the inner peripheral surface, i.e., the convex surface, is provided with 36-60 circumferentially uniformly arranged hydrogen injection inclined holes 38. The three-stage hydrogen supply channels 35, 36, and 37 arranged concentrically in the venturi tube 29 are connected to the hydrogen injection holes 38, 39, and 40, respectively.

[0043] According to the control method of the present invention, for different working states of the combustion chamber, the injection of hydrogen at different positions and different amounts of hydrogen is adjusted as follows:

[0044] 1) When the combustion chamber starts ignition, only the pre-combustion stage 15 works, and the pre-combustion stage fuel nozzle 24 sprays fuel. At the same time, the hydrogen injection hole 29 at the end of the venturi expansion section sprays hydrogen. By adding hydrogen to assist combustion and reducing the fuel injection ratio, not only the ignition probability but also the ignition stability can be improved.

[0045] 2) After ignition is successful, when the combustion chamber is operating under a small operating condition, including but not limited to coasting, only the pre-combustion stage 15 is operating, the pre-combustion stage fuel nozzle 24 is closed, and the hydrogen injection holes 38, 39 and 40 are all opened to inject hydrogen. Since hydrogen has a higher combustion temperature and has a leaner stable working potential, pure hydrogen combustion can use a lower equivalence ratio to achieve stable combustion, thereby ensuring a significant reduction in nvPM and carbon emissions.

[0046] 3) When the combustion chamber is operating under a large operating condition, which includes but is not limited to take-off and climb, the main combustion stage 18 and the pre-combustion stage 19 work together, the main combustion stage fuel injection hole 23 and the pre-combustion stage nozzle 24 both spray fuel, and at the same time, the hydrogen injection hole 39 at the end of the expansion section of the venturi and the hydrogen injection hole 40 on the outer peripheral surface spray hydrogen to assist combustion, thereby reducing the pre-combustion stage pollution emissions by reducing the pre-combustion stage fuel volume and equivalence ratio, thereby reducing the pollution emission level of the entire combustion chamber.

[0047] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A combustion chamber for reducing emissions by adding hydrogen to fuel, comprising a pre-combustion stage, the pre-combustion stage comprising a venturi, the venturi being a pre-film forming device for the pre-combustion stage fuel, characterized in that: The venturi tube comprises: a hydrogen supply channel for receiving hydrogen; and A plurality of hydrogen injection holes are arranged in a circumferential direction at the expansion section of the venturi tube and are used for injecting hydrogen delivered by the hydrogen supply passage.

2. The combustion chamber according to claim 1, characterized in that A plurality of hydrogen injection holes are arranged on the end surface of the expansion section of the venturi tube.

3. The combustion chamber according to claim 1 or 2, characterized in that A plurality of hydrogen injection holes are respectively arranged on the outer circumferential surface and the inner circumferential surface of the expansion section of the venturi tube.

4. The combustion chamber according to claim 3, characterized in that The hydrogen injection holes on the outer circumferential surface and the inner circumferential surface of the expansion section of the venturi are arranged obliquely relative to the outer surface of the expansion section of the venturi.

5. The combustion chamber according to claim 1, characterized in that The hydrogen supply channel includes three-stage hydrogen gas collecting chambers arranged concentrically in the venturi tube, and are respectively connected to the hydrogen injection holes on the end surface, outer peripheral surface and inner peripheral surface of the expansion section.

6. The combustion chamber according to claim 1, characterized in that The pre-combustion stage further includes a swirler, wherein a hydrogen inlet passage is arranged inside the swirling blades of the swirler, and the hydrogen inlet passage is communicated with the hydrogen supply passage.

7. The combustion chamber according to claim 6, characterized in that The combustion chamber further comprises a hydrogen supply pipe, and the hydrogen supply pipe is communicated with the hydrogen intake passage.

8. A method for controlling a combustion chamber, characterized in that: When the combustion chamber starts ignition, only the pre-combustion stage works, so that the pre-combustion stage fuel nozzle sprays fuel, and at the same time, hydrogen is sprayed at the end of the expansion section of the venturi of the pre-combustion stage. By adding hydrogen to assist combustion, the fuel injection ratio is reduced, and the ignition probability and ignition stability are improved.

9. The control method according to claim 8, characterized in that: After successful ignition, when the combustion chamber works under low operating conditions, only the pre-combustion stage works, so that the pre-combustion stage fuel nozzle is closed, and hydrogen is sprayed at the expansion section end, outer peripheral surface and inner peripheral surface of the venturi of the pre-combustion stage.

10. The control method according to claim 8 or 9, characterized in that: When the combustion chamber operates under high working conditions, the main combustion stage and the pre-combustion stage work together, the main combustion stage injection holes and the pre-combustion stage nozzles both spray fuel, and at the same time, the end and outer peripheral surface of the expansion section of the pre-combustion stage venturi are sprayed with hydrogen to assist combustion.

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