Multi-fuel combustion chamber head and control method for a multi-fuel combustion chamber

Abstract

A multi-fuel combustor head allows hydrogen blending or pure hydrogen combustion in some operating conditions. A control method of a multi-fuel combustor can achieve low pollution and low carbon combustion organization form. The multi-fuel combustor head includes a duty stage, the duty stage includes a first air flow channel and a liquid fuel pipe, the first air flow channel provides air and the liquid fuel pipe provides liquid fuel mixed in a premixing space, and wherein a second air flow channel extends at the outer periphery of the premixing space, and an outlet is located at the downstream side of the premixing space, the second air flow channel cancels a swirler and is provided with an air pressurizing device to accelerate the air to flow out from the outlet; a hydrogen gas distribution pipe includes a plurality of injection holes, the injection holes are set to be transversely injected relative to the air flow direction of the second air flow channel downstream of the outlet of the second air flow channel.

Description

TECHNICAL FIELD

[0001] The present application relates to a combustion chamber, in particular to a combustion chamber head of a gas turbine or an aero-engine and a combustion control method of the combustion chamber. BACKGROUND

[0002] The improvement of environmental awareness makes the reduction of pollutant emissions in the combustion process one of the main challenges in the development of aero-engines. In order to obtain lower NOx emissions, while not increasing the concentration of carbon monoxide and unburned hydrocarbons in the exhaust gas, low-emission combustion forms such as lean premixed pre-vaporization and rich quenching lean combustion have been widely studied and applied in gas turbines and aero-engines. However, with the proposal of carbon neutralization, the exhaust emissions based on hydrocarbon fuels always contain CO2, which cannot meet the requirements of low-carbon combustion. Recently, the combustion organization form based on sustainable fuels and other fuels has been widely studied in aero-engine combustion chambers, and the main purpose is to further reduce carbon emissions while reducing traditional pollutant emissions (such as NOx).

[0003] Hydrogen combustion, as one of the most environmentally friendly combustion organization methods, has the potential to be a low-carbon fuel with no carbon emissions and other combustion pollution problems. However, hydrogen combustion also has problems such as storage difficulties, high transportation cost per unit volume, too fast combustion speed, and high flame temperature, which brings challenges to how to reasonably organize combustion in the aero-engine combustion chamber. At the same time, due to the cost and risk factors of developing a new combustion chamber, traditional liquid fuels and sustainable fuels will still be the main fuels for aero-engines for a long time. Therefore, designing a multi-fuel aero-engine combustion chamber that can simultaneously combust liquid fuel and hydrogen can not only effectively reduce carbon emissions and reduce pollutant products, but also take advantage of the existing mature combustion chamber geometry to reduce the cost and risk of designing a new combustion chamber. SUMMARY

[0004] The purpose of the present application is to provide a multi-fuel combustion chamber head that allows hydrogen-doped or pure hydrogen combustion in some operating conditions.

[0005] Another purpose of the present application is to provide a control method for a multi-fuel combustion chamber to achieve a low-pollution low-carbon combustion organization form.

[0006] According to one aspect of the application, a multi-fuel combustion chamber head comprises a pilot stage, the pilot stage comprising a first air flow channel and a liquid fuel pipe, the first air flow channel providing air and the liquid fuel pipe providing liquid fuel to mix in a premixing space, and wherein a second air flow channel extends around the periphery of the premixing space and an outlet is located on the downstream side of the premixing space, the second air flow channel being devoid of a swirler and being provided with an air pressurizing device to accelerate air to flow out of the outlet; a hydrogen gas distribution pipe comprising a plurality of injection holes arranged to inject hydrogen gas transversely to the direction of air flow of the second air flow channel downstream of the outlet of the second air flow channel.

[0007] In one embodiment, the air pressurizing device comprises a pressurizing section of the second air flow channel, and a plurality of air baffles. The pressurizing section of the second air flow channel extends to the outlet and has a cross-sectional area of the flow channel decreasing in the direction of air flow; the plurality of air baffles are distributed circumferentially in the pressurizing section.

[0008] In one embodiment, the premixing space is defined by the inner surface of a venturi.

[0009] In one embodiment, each of the two air baffles and one injection hole is arranged to accelerate air flow through the corresponding injection hole via the two air baffles.

[0010] In one embodiment, the distance between the injection hole and the end wall facing the flame cavity is 1-5mm.

[0011] In one embodiment, the distance between the injection hole and the end wall of the structure defining the premixing space is 1-5mm.

[0012] In one embodiment, the liquid fuel pipe is connected to a centrifugal nozzle for generating liquid mist from liquid fuel and for impacting the liquid mist on the wall of the premixing space to form a liquid film, and the first air flow channel is provided with a swirler to mix air and atomized liquid fuel sufficiently.

[0013] According to another aspect of the application, a control method of a multi-fuel combustion chamber comprises the following steps:

[0014] A multi-fuel combustion chamber is provided, which comprises any of the multi-fuel combustion chamber heads described above, and further comprises a main combustion stage surrounding the pilot stage;

[0015] When the combustion chamber is ignited, only the pilot stage flame is turned on, and hydrogen-doped or pure hydrogen combustion is used to improve the ignition performance of the combustion chamber;

[0016] When the engine is in a small thrust working condition, only the pilot stage is turned on, and hydrogen-doped or pure hydrogen combustion is used;

[0017] When the engine is in the medium-thrust working condition, the duty class and the main combustion class flames are opened at the same time, the duty class flame adopts pure hydrogen or hydrogen-doped combustion, and the main combustion class flame is pure liquid combustion.

[0018] According to the embodiment of the present application, by introducing hydrogen in the duty class of the combustion chamber, the staged combustion of the duty class hydrogen-doped / pure hydrogen combustion and the main combustion class liquid fuel combustion is realized, and stable combustion with low pollution and low carbon can be formed by flexibly changing the adjustment of the equivalence ratio and the fuel distribution of the combustion chamber. The method is different from the characteristics of the traditional radial staged combustion which is all liquid fuel. By canceling the swirler in the air flow channel where the hydrogen transverse injection flow is located and setting an air baffle, the mixing of hydrogen and air is accelerated, the risk of backfire is reduced, the duty class hydrogen-doped / pure hydrogen combustion is formed, the main combustion class flame is formed by using the existing liquid fuel such as aviation kerosene and other sustainable alternative fuels, and a low-pollution low-carbon combustion organization form is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0019] The above and other features, aspects and advantages of the present application will become more apparent from the following description of the application taken in conjunction with the accompanying drawings, wherein:

[0020] Figure 1 is a schematic view of a multi-fuel combustion chamber.

[0021] Figure 2 is a cross-sectional view of the head of a multi-fuel combustion chamber.

[0022] Figure 3 is a perspective view of the head of a multi-fuel combustion chamber.

[0023] Figure 4 is a perspective view of the duty class of the head of a multi-fuel combustion chamber. DETAILED DESCRIPTION

[0024] Reference will now be made in detail to embodiments of the application, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the application, not limitation of the application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the scope or spirit of the application. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present application covers modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0025] As used herein, the terms "first", "second" and "third" can be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

[0026] The terms "upstream" and "downstream" refer to the relative direction with respect to the fluid flow in a fluid path. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction to which the fluid flows.

[0027] As shown in FIG. 1, the multi-fuel combustion chamber comprises a combustion chamber head 34, which includes a pilot stage in the center and a main combustion stage arranged around the pilot stage to form a radial staged combustion, i.e. a combustion organization form using air or fuel to form sub-regions at different spatial positions in the radial direction. With the staged combustion, the ratio of the fuel in the pilot stage and the main combustion stage can be flexibly adjusted for different operating conditions of the aero-engine. Figure 1

[0028] As shown in FIG. 2, the pilot stage comprises a first air flow channel 11 and a liquid fuel pipe 1, and the air provided by the first air flow channel 11 and the liquid fuel provided by the liquid fuel pipe 1 are mixed in a premixing space 16. The pilot stage further comprises a second air flow channel 12 and a hydrogen distribution pipe 3. The second air flow channel 12 extends around the outer periphery of the premixing space 16, and the outlet of the second air flow channel 12 is located on the downstream side of the premixing space 16. The second air flow channel 12 is free of a swirler and is provided with an air pressurizing device to accelerate the air to flow out of the outlet. The hydrogen distribution pipe 3 is connected to a spray hole 4, which is arranged to spray transversely with respect to the air flow direction of the second air flow channel 12 downstream of the outlet of the second air flow channel 12. In the following description, the air flow channel is in the form of a ring in the combustion chamber head, and the pipe is in the form of an elongated column in the combustion chamber head. Figure 2

[0029] As shown in FIG. 3, after the air 21 enters the combustion chamber through the diffuser, part of the air 24 enters the combustion chamber head to participate in the combustion directly, part of the air 22 flows through the inner annular cavity of the combustion chamber to form cooling air 25, and part of the air 23 flows through the outer annular cavity of the combustion chamber to form cooling air 25. Part of the cooling air 25 enters the inner part of the flame tube to cool the wall surface of the flame tube, and then flows to the downstream high-pressure turbine together with the high-temperature gas 26. As shown in FIG. 4, the cooling air 25 flows through the inner annular cavity of the combustion chamber to form the cooling air 25, and part of the cooling air 25 enters the inner part of the flame tube to cool the wall surface of the flame tube, and then flows to the downstream high-pressure turbine together with the high-temperature gas 26. Figure 1 Figure 2 ​​​As shown, the air 24 entering the head of the combustion chamber is further divided into the duty class air 7 entering the duty class and the main combustion class air 8 entering the main combustion class. The duty class air 7 is divided into two streams, one of which flows through the first air flow channel 11 into the premixing space 16, where it mixes with the fuel supplied by the liquid fuel pipe 1. The other stream of air enters the air flow channel 12 without a swirler, is accelerated by the air booster, and mixes with the hydrogen gas sprayed from the downstream injection hole 4. By removing the swirler in the air flow channel where the hydrogen gas is transversely sprayed, providing the air booster to accelerate the mixing of hydrogen and air, and reducing the risk of backfiring, pure hydrogen combustion can be achieved. In the hydrogen-doped combustion, in the duty class, on the one hand, the hydrogen gas from the hydrogen distribution pipe 3 mixes with the air in the second air flow channel 12 and enters the combustion chamber; on the other hand, the air passing through the swirler 10 mixes with the liquid mist 6 generated by the centrifugal nozzle 32 and enters the combustion chamber. The two mixed gases have a certain mutual mixing relationship between the end face 14 and the end face 15, and further mixing occurs downstream. At this time, the duty class flame is a mixed flame containing a hydrogen transverse injection stream and a liquid fuel centrifugal nozzle, forming a low-carbon duty class flame.

[0030] One embodiment of the air booster includes a booster section of the second air flow channel 12, as shown in Figure 2 The booster section extends upward to the outlet of the second air flow channel 12 and reduces the cross-sectional area of the flow channel in the flow direction. The air booster also includes a plurality of air baffles 33 distributed circumferentially in the booster section. The booster section and the air baffles 33 jointly compress and boost the airflow due to the reduced flow passage cross-sectional area.

[0031] Continuing to refer to Figure 2 The premixing space 16 is defined by the inner surface of the venturi. The effect of the venturi on the fluid, which first compresses and then decompresses, is conducive to the thorough mixing of the liquid fuel and the air.

[0032] In a preferred embodiment, two air baffles 33 and one injection hole 4 are arranged one-to-one so that the airflow passing through the two air baffles 33 accelerates through the corresponding injection hole 4, thereby enhancing the air boosting effect. As shown in Figure 3 and Figure 4 The air baffles 33 and the injection holes 4 are arranged in a ring shape, so the number of air baffles 33 can be the same as that of the injection holes 4, the air baffles 33 are offset by an angle relative to the injection holes 4 in the circumferential direction, or the air baffles 33 are offset from the injection holes 4 in the circumferential direction.

[0033] In one embodiment, the distance between the injection hole 4 and the end wall 15 facing the flame cavity is 1-5 mm.

[0034] In another embodiment, the distance between the injection hole 4 and the end wall of the structure defining the premixing space 16 is 1-5 mm. For example, in Figure 2The distance between the orifice 4 and the end wall 14 of the venturi is 1-5mm.

[0035] In a more specific embodiment, the orifice diameter of the orifice 4 is 0.3-2mm, the number of orifices is 12-60, and the orifices are evenly distributed along the circumference of the end wall 14.

[0036] With reference to the drawings Figure 2 , the liquid fuel pipe 1 is connected to the centrifugal nozzle 32, which is used to generate liquid mist 6 from the liquid fuel and to make the liquid mist 6 impact the end wall 14 of the venturi to form a liquid film. The first air flow channel 11 is provided with a swirler 10 to make the air and the atomized liquid fuel mix well.

[0037] The swirler 10 is preferably a high-swirl number swirler, for example, a swirler with a swirl number greater than 0.7, to form a strong recirculation zone velocity shear to allow the air and the liquid fuel to mix well.

[0038] As shown in Figure 1 , the fuel pipe 29 contains two types of fuel: a liquid fuel delivery pipe 30 and a hydrogen fuel delivery pipe 31. The liquid fuel in the pipe 30 enters the centrifugal nozzle 32 of the pilot stage through the fuel pipe 1 to generate liquid mist 6, which impacts the end wall 14 of the venturi to form a liquid film. The liquid film is subjected to the combined shear of the rotation of the first air flow channel 11 and the air flow of the second air flow channel 12 at the outlet end face 14 of the venturi, and gradually breaks into liquid filaments and then into small droplets. The hydrogen in the pipe 31 enters the hydrogen transverse orifice 4 through the hydrogen distribution pipe 3 to generate a hydrogen transverse jet 18, which further mixes with the droplet group 17 downstream of the pilot stage and enters the combustion chamber to form the pilot stage flame 28.

[0039] The main stage air 8 passes through the main stage swirler 9 and mixes well with the liquid fuel generated by the transverse fuel orifice 5 to enter the combustion chamber. The liquid fuel in the pipe 30 enters the main stage orifice 5 through the fuel pipe 2 to form a transverse jet 19 of liquid mist, which impacts the wall 13 and mixes well with the main stage air in the main stage passage 20 to enter the combustion chamber to form the main stage flame 27. Since the main stage fuel is mixed with the air in the main stage passage through the liquid transverse jet, this is beneficial to the formation of an oil-lean and low-pollution main stage flame.

[0040] In an embodiment, the main stage orifice 5 has a diameter of 0.5-2mm, the number of orifices is 12-24, and the orifices are evenly distributed along the circumference of the main stage air flow channel, with a distance of 5-15mm from the outlet end face 15 of the combustor.

[0041] The pilot stage centrifugal nozzle and the main stage fuel can be traditional aviation kerosene or other sustainable alternative fuels. The hydrogen in the hydrogen distribution pipe 3 can be pure hydrogen or a fuel rich in hydrogen elements.

[0042] As shown in Figure 1 and Figure 2As shown, the standby class flame 27 formed by mixing the standby class hydrogen 18 and the liquid fuel 17 is in the middle of the combustion chamber, and the hydrogen mixing ratio of the standby class flame can be flexibly adjusted according to different working conditions of the combustion chamber, and the standby class can be pure liquid fuel combustion or pure hydrogen combustion. The main combustion class flame 28 formed by the main combustion class fuel 19 is circumferentially around the standby class flame 27. When only the standby class is started, the standby class can be hydrogen mixing and pure hydrogen combustion, and the hydrogen mixing mass ratio adjustment range is 0-100%. When the standby class and the main combustion class flame are started at the same time, the hydrogen mass ratio is less than 25% of the total fuel mass ratio. By flexibly adjusting the hydrogen and liquid fuel ratio, backfire, flameout and combustion oscillation and other phenomena in the combustion chamber are avoided, and stable low-carbon low-pollution combustion is formed.

[0043] In one embodiment, the control method of the multi-fuel combustion chamber flexibly adjusts the ratio of the standby class flame and the main combustion class flame to meet different engine working conditions and emission requirements. When the combustion chamber is ignited, only the standby class flame is started, and hydrogen mixing or pure hydrogen combustion is adopted to improve the ignition performance of the combustion chamber. When the engine is in a small thrust condition, the small condition includes a coasting condition or a condition with a thrust similar to the required thrust, the combustion chamber only starts the standby class, and hydrogen mixing or pure hydrogen combustion can be used. When the engine is in a medium or large thrust condition, the medium or large thrust condition includes take-off, cruising, landing or a condition with a thrust similar to the required thrust, the standby class flame and the main combustion class flame are started at the same time, the standby class flame can use pure hydrogen or hydrogen mixing combustion, and the main combustion class flame is pure liquid combustion.

[0044] Although the present application is disclosed with the preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solution of the present application, falls within the protection scope defined by the claims of the present application.

Claims

1. A multi-fuel combustion chamber head, comprising a control panel, the control panel including a first airflow channel and a liquid fuel line, wherein air supplied by the first airflow channel and liquid fuel supplied by the liquid fuel line are mixed in a premixing space, characterized in that, The duty roster also includes: A second airflow channel extends outward from the premixing space, with its outlet located downstream of the premixing space. The second airflow channel omits swirlers and incorporates an air pressurization device to accelerate the airflow from the outlet. A hydrogen distribution pipe, the hydrogen distribution pipe including a plurality of nozzles, the nozzles being arranged to spray laterally downstream of the outlet of the second air flow channel relative to the air flow direction of the second air flow channel; The air booster device includes: The pressurization section of the second airflow channel extends to the outlet, and the cross-sectional area of ​​the channel decreases along the airflow direction; and Multiple air baffles are circumferentially spaced within the pressurization section.

2. The multi-fuel combustion chamber head as described in claim 1, characterized in that, The premixed space is defined by the inner surface of a venturi tube.

3. The multi-fuel combustion chamber head as described in claim 1, characterized in that, The two air baffles and one nozzle are arranged in a one-to-one correspondence so that the airflow passing through the two air baffles is accelerated through the corresponding nozzle.

4. The multi-fuel combustion chamber head as described in claim 1, characterized in that, The distance between the nozzle and the end wall facing the flame chamber is 1-5 mm.

5. The multi-fuel combustion chamber head as described in claim 1, characterized in that, The distance between the nozzle and the end wall of the structure defining the premixing space is 1-5 mm.

6. The multi-fuel combustion chamber head as described in claim 1, characterized in that, The liquid fuel line is connected to a centrifugal nozzle, which is used to generate liquid mist from the liquid fuel and cause the liquid mist to impact the wall of the premixing space to form a liquid film. The first air channel is equipped with a cyclone separator to ensure that the air and the atomized liquid fuel are fully mixed.

7. A control method for a multi-fuel combustion chamber, characterized in that, include: A multi-fuel combustor is provided, the multi-fuel combustor including a multi-fuel combustor head as described in any one of claims 1 to 6, the multi-fuel combustor head further including a main combustion stage surrounding the duty cell; When igniting in the combustion chamber, only the standby flame is turned on. In order to improve the ignition performance of the combustion chamber, hydrogen-blended or pure hydrogen combustion is adopted. When the engine is in a low thrust condition, it is only operated by the shift worker, using hydrogen-blended or pure hydrogen combustion. When the engine is operating at medium to high thrust, both the duty flame and the main combustion stage flame are activated simultaneously. The duty flame uses pure hydrogen or hydrogen-blended combustion, while the main combustion stage flame uses pure liquid combustion.

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