Staged combustion head structure of high-flow fuel incoming flow

Abstract

The invention discloses a staged combustion head structure for high-flow fuel incoming flow, which belongs to the field of combustion chamber heads of gas turbines and comprises a combustion head body, and a fuel nozzle, a main combustion mechanism for high-temperature fuel gas to enter and a pre-combustion mechanism for pre-combustion stage air to enter are sequentially arranged in the combustion head body from the center to the outside. The pre-combustion mechanism comprises a pre-combustion chamber arranged outside the fuel nozzle, the main combustion mechanism comprises a main combustion chamber arranged outside the pre-combustion chamber, and the main combustion chamber comprises a first main combustion chamber and a second main combustion chamber which are sequentially arranged from inside to outside. According to the staged combustion head structure of the large-flow fuel incoming flow, on-duty flames formed by the pre-combustion chamber are matched with strong rotational flow formed by the main combustion chamber to achieve the synergistic effect, the stability of combustion flames of large-flow low-heat-value gas fuel is improved, a diffusion combustion mode of combustion while mixing is adopted, and the backfire risk is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas turbine combustion chamber head, in particular to a staged combustion head structure of large flow fuel flow. BACKGROUND

[0002] The gas turbine is a kind of heat engine that converts fuel chemical energy into impeller kinetic energy, and has a wide range of applications in power generation, ships, gas transmission and other fields. The combustion reaction of the combustion chamber provides an important energy source for the gas turbine, and the combustion chamber head structure needs to withstand large internal and external temperature difference and pressure difference during work.

[0003] In the prior art, the following problems exist for the combustion chamber head low calorific value fuel:

[0004] 1) The low calorific value fuel combustion boundary is narrow, and pre-mixed combustion can ensure stable combustion, but backfire is easy to occur when the fuel end is high-temperature combustible gas;

[0005] 2) The center staged combustion mode forms a duty class flame, which can increase the combustion stability, but the small flow air in the precombustion stage is easy to form a backflow area on the nozzle, and high-temperature backflow is easy to cause nozzle coking;

[0006] 3) For large flow low calorific value gas fuel, direct application in the traditional center staged combustion chamber head will bring the problem of difficulty in mixing small flow air with large flow low calorific value gas fuel. SUMMARY

[0007] The purpose of the present application is to provide a staged combustion head structure of large flow fuel flow, which improves the stability of the combustion flame of large flow low calorific value gas fuel by forming a duty class flame in the precombustion chamber and cooperating with the strong swirl formed by the main combustion chamber, and reduces the risk of backfire by using a diffusion combustion mode of mixing and burning.

[0008] To achieve the above purpose, the present application provides a staged combustion head structure of large flow fuel flow, which comprises a combustion head body, and a fuel nozzle, a main combustion mechanism for high-temperature gas entering and a precombustion mechanism for precombustion stage air entering are sequentially arranged inside the combustion head body from the center to the outside. The precombustion mechanism comprises a precombustion chamber arranged outside the fuel nozzle, the main combustion mechanism comprises a main combustion chamber arranged outside the precombustion chamber, and the main combustion chamber comprises a main combustion chamber one and a main combustion chamber two arranged from inside to outside.

[0009] Preferably, the precombustion chamber, the main combustion chamber one and the main combustion chamber two are sequentially arranged from inside to outside, and the precombustion chamber and the main combustion chamber one, and the main combustion chamber one and the main combustion chamber two are separately arranged.

[0010] Preferably, the precombustion chamber is provided with a precombustion swirler in the inside, the main combustion chamber one is provided with a main combustion swirler one in the inside, and the main combustion chamber two is provided with a main combustion swirler two in the inside.

[0011] Preferably, one end of the combustion head body is a high-temperature gas inlet, and the other end of the combustion head body is a high-temperature gas outlet.

[0012] Preferably, the inside of the combustion head body is provided with a plurality of pre-combustion stage air inlet pipes arranged in an annular array near the high-temperature gas inlet, one end of the pre-combustion stage air inlet pipe is in communication with one end of the pre-combustion chamber near the high-temperature gas inlet, and the other end of the pre-combustion stage air inlet pipe is connected to the combustion head body as a pre-combustion stage air inlet.

[0013] Preferably, the combustion chamber head body is provided with a plurality of main combustion stage air inlets arranged in an annular array near the high-temperature gas outlet.

[0014] Preferably, the combustion chamber head body is provided with a connecting disc for connection and fixation at each end, and the connecting disc near the high-temperature gas outlet of the combustion chamber head body forms a slot with the combustion chamber head body, the slot is connected to a cooling gas hole at an end away from the high-temperature gas outlet, and the cooling gas hole is located between the slot and the main combustion stage air inlet.

[0015] Preferably, the top end of the pre-combustion chamber is provided with a blunt body that is hollow inside, the blunt body is arranged in the inside of the combustion chamber head, the blunt body is located at one end of the combustion chamber head near the main combustion stage air inlet, the side of the blunt body near the pre-combustion chamber is in communication with the pre-combustion chamber through a plurality of cooling gas inlets, and the side of the blunt body away from the pre-combustion chamber is in communication with the inside of the combustion chamber head through a plurality of cooling gas outlets.

[0016] Preferably, the middle of the blunt body is provided with a contraction port for introducing air.

[0017] Preferably, the fuel nozzle is provided with a base at one end near the high-temperature gas inlet.

[0018] Therefore, the present application adopts the above-mentioned structure of a large-flow fuel to flow a staged combustion head structure, which has the following beneficial effects:

[0019] 1. Strong flame stability: the cooperation of the pilot flame formed by the pre-combustion chamber and the strong swirl flow formed by the main combustion chamber improves the combustion stability of high-temperature gas combustion under variable conditions, reduces the risk of flameout or oscillation, and the air in the main combustion chamber enters the horizontal jet flow through the main combustion stage air inlet, the horizontal jet flow of the main combustion chamber and the swirl air of the pre-combustion chamber have a complex effect, which enhances the mixing efficiency of high-temperature gas and supplementary combustion air and improves the combustion efficiency;

[0020] 2. Low risk of backfire: the diffusion combustion method of mixing air with high-temperature gas while burning is adopted to reduce the backfire problem of premixed combustion, which is suitable for high-activity fuel, and the contraction port design of the pre-combustion chamber increases the air momentum and suppresses the formation of a backflow area near the fuel nozzle, further reducing the risk of backfire;

[0021] 3. Flexible combustion organization: the pre-combustion fuel nozzle has the function of selective opening and closing, when the fuel nozzle is closed, the equivalence ratio of high-temperature combustion gas and air is reduced, realizing low-emission working condition, when it is opened, it forms the duty flame, improves the stability of the main combustion stage flame, and adapts to a wide working condition range;

[0022] 4. Efficient mixing and combustion: the main combustion chamber transverse jet is injected from outside to inside, cooperates with the pre-combustion chamber swirl, strengthens the mixing uniformity of high-temperature combustion gas and supplementary combustion air, realizes more precise control of the main combustion chamber high-temperature combustion gas and the main combustion stage air, the pre-combustion stage air and the local proper ratio of fuel.

[0023] The technical solutions of the present application will be further described in detail below through the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a perspective view of the combustion head structure of the embodiment of the present application;

[0025] Figure 2 It is a schematic view of the high-temperature combustion gas inlet structure of the embodiment of the present application;

[0026] Figure 3 It is a schematic view of the high-temperature combustion gas outlet structure of the embodiment of the present application;

[0027] Figure 4 It is a sectional view of the combustion head structure of the embodiment of the present application;

[0028] Figure 5 It is a combustion chamber center section velocity nephogram of the embodiment of the present application;

[0029] Figure 6 It is a combustion chamber 0 velocity line diagram of the embodiment of the present application;

[0030] Figure 7 It is a combustion chamber center section temperature diagram of the embodiment of the present application;

[0031] Figure 8 It is a combustion chamber outlet temperature nephogram of the embodiment of the present application;

[0032] Figure 9 It is a combustion chamber wall surface temperature nephogram of the embodiment of the present application.

[0033] REFERENCE NUMERALS

[0034] 1, combustion head body; 2, fuel nozzle; 3, pre-combustion chamber; 4, main combustion chamber one; 5, main combustion chamber two; 6, pre-combustion swirler; 7, main combustion swirler one; 8, main combustion swirler two; 9, high-temperature gas inlet; 10, high-temperature gas outlet; 11, pre-combustion stage air inlet pipe; 12, pre-combustion stage air inlet; 13, main combustion stage air inlet; 14, connecting disc; 15, slot; 16, cooling hole; 17, bluff body; 18, cooling air inlet; 19, cooling air outlet; 20, base; 21, convergent port. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application are further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present application and should not be used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application. Examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout.

[0036] It should be noted that the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or server comprising a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0037] Similar reference signs and letters in the following drawings represent similar items, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0038] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application.

[0039] In the description of the present application, it is also necessary to explain that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] Embodiment

[0041] As shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 The large-flow fuel flow staged combustion head structure of the present application comprises a combustion head body 1, the inside of the combustion head body 1 is sequentially provided with a fuel nozzle 2, a main combustion mechanism for high-temperature gas entering, and a pre-combustion mechanism for pre-combustion stage air entering from the center to the outside. One end of the combustion head body 1 is a high-temperature gas inlet 9, and the other end of the combustion head body 1 is a high-temperature gas outlet 10.

[0042] The pre-combustion mechanism comprises a pre-combustion chamber 3 arranged outside the fuel nozzle 2, and the main combustion mechanism comprises a main combustion chamber arranged outside the pre-combustion chamber 3, which comprises a main combustion chamber one 4 and a main combustion chamber two 5 arranged from inside to outside. The pre-combustion chamber 3, the main combustion chamber one 4 and the main combustion chamber two 5 are sequentially arranged from inside to outside, and the pre-combustion chamber 3 and the main combustion chamber one 4, and the main combustion chamber one 4 and the main combustion chamber two 5 are separately arranged. The inside of the pre-combustion chamber 3 is provided with a pre-combustion swirler 6, the inside of the main combustion chamber one 4 is provided with a main combustion swirler one 7, and the inside of the main combustion chamber two 5 is provided with a main combustion swirler two 8.

[0043] The inside of the combustion head body 1 is provided with a pre-combustion stage air inlet pipe 11 arranged in an annular array close to one end of the high-temperature gas inlet 9. One end of the pre-combustion stage air inlet pipe 11 is in communication with one end of the pre-combustion chamber 3 close to the high-temperature gas inlet 9, and the other end of the pre-combustion stage air inlet pipe 11 is connected with the combustion head body 1 as a pre-combustion stage air inlet 12.

[0044] The combustion chamber head body 1 is provided with a plurality of main combustion stage air inlets 13 arranged in an annular array close to one end of the high-temperature gas outlet 10. The combustion chamber head body is provided with a connecting disc 14 for connection and fixation at both ends. The connecting disc 14 close to one end of the high-temperature gas outlet 10 of the combustion chamber head body forms a slot 15 with the combustion chamber head body. The end of the slot 15 away from the high-temperature gas outlet 10 is connected with a cooling gas hole 16, and the cooling gas hole 16 is located between the slot 15 and the main combustion stage air inlet 13. Air enters the slot 15 through the cooling gas hole 16 to form an air film to prevent the wall surface of the combustion chamber head from being ablated.

[0045] The top end of the precombustion chamber 3 is provided with an internal hollow blunt body 17 arranged in the interior of the combustion chamber head, and the blunt body 17 is located at one end of the combustion chamber head close to the main combustion stage air inlet 13. The side of the blunt body 17 close to the precombustion chamber 3 is communicated with the precombustion chamber 3 through a plurality of cooling gas inlets 18, and the side of the blunt body 17 away from the precombustion chamber 3 is communicated with the interior of the combustion chamber head through a plurality of cooling gas outlets 19. The fuel nozzle 2 is provided with a base 20 at one end close to the high-temperature gas inlet 9. The middle of the blunt body 17 is provided with a contraction port 21 for introducing air, and the contraction port 21 is used to introduce air, cool the blunt body 17 to prevent ablation, and reduce the weight at the same time. A part of the precombustion stage air enters the cavity of the blunt body 17 through the cooling gas inlet 18 to protect the blunt body 17.

[0046] The present application adopts a central staged combustion structure, the precombustion swirler 6 adopts an axial swirler (swirl number 0.7-0.9) matched with a contraction port 21 throttling design, combined with a fuel nozzle 2 (the fuel nozzle 2 is a centrifugal atomizing nozzle), to realize air-assisted atomization and high-momentum anti-backflow. The main combustion chamber (main combustion chamber one 4, main combustion chamber two 5) forms a strong swirl channel (swirl number 0.7-1) through a main combustion swirler to introduce high-temperature gas, and mixes with transverse jet combustion-supporting air according to a chemical appropriate ratio. The high-temperature gas and the air are controlled through diffusion combustion, the transverse jet of the main combustion stage air inlet 13 and the swirl of the precombustion chamber 3 are compounded and mixed, diffusion combustion is realized, and the risk of backfire of premixed combustion is avoided. The fuel nozzle 2 of the present application is opened when the flame is unstable to form a duty flame, and is closed when it is stable to reduce fuel consumption and form dynamic stable regulation. The transverse jet of the main combustion chamber and the swirl of the precombustion chamber 3 jointly act on the present application to optimize the flow field structure and support high-temperature gas combustion.

[0047] The present application adopts a central staged combustion organization method, the precombustion chamber 3 is provided with a fuel nozzle 2 fuel, the precombustion stage swirler flow passage is provided with precombustion stage air (combustion-supporting air), high-temperature gas and main combustion stage air (combustion-supporting air) enter the flame tube (the outlet of the combustion chamber head structure is connected with the inlet of the flame tube) through the main combustion chamber, wherein the high-temperature gas and the main combustion stage air reach a chemical appropriate ratio, the precombustion stage air and the fuel reach a chemical appropriate ratio, and when the fuel nozzle 2 is not opened, the equivalence ratio of the high-temperature gas and the air is 0.8. The organization method of diffusion combustion is adopted, the high-temperature gas and the combustion-supporting air are mixed and burned at the same time, and the risk of backfire is avoided. The main combustion stage air is mixed with the high-temperature gas in the form of a transverse jet at the outlet of the main combustion chamber, and the mixing effect is ensured. Under this design concept, the transverse jet of the main combustion chamber is injected from the outside to the inside (the combustion-supporting air enters from the main combustion stage air inlet), and the transverse jet of the main combustion chamber and the swirl air jet of the precombustion chamber 3 jointly act to support high-temperature gas combustion. If the main combustion stage flame is unstable, the precombustion stage fuel nozzle 2 is opened to form a precombustion stage duty flame to enhance the stability of the high-temperature gas flame.

[0048] The high-temperature gas directly enters the main combustion chamber swirl channel, and the main combustion stage swirl intensity is 0.7-1. The pre-combustion stage air and the main combustion stage air directly come from the centrifugal compressor. The main combustion stage transverse jet air is injected from the outside to the inside, can be synergized with the pre-combustion chamber 3 swirl transverse jet to act on the main combustion stage high-temperature gas, and strengthens the mixing. The pre-combustion chamber 3 adopts an axial swirler (the swirl number is 0.7-0.9) and a contraction port 21, the pre-combustion stage air has a large momentum through the contraction throttling to prevent the backflow area from being generated at the fuel nozzle 2, and a small flow number centrifugal atomizing nozzle is arranged at the center of the pre-combustion chamber 3, the fuel spray enters the flame tube to stably combust under the atomization of the pre-combustion stage swirl air.

[0049] In the numerical simulation of the combustion chamber, the standard k-ε turbulence model and the flame surface generating manifold (FGM) model are selected for coupled calculation in consideration of the calculation accuracy and efficiency. The standard k-ε model can better predict the high Reynolds number turbulent flow, and has a lower calculation cost, and is suitable for the main flow simulation of the combustion chamber. The FGM model can significantly reduce the calculation amount of complex combustion reaction by pre-generating a low-dimensional manifold containing chemical and thermodynamic information, and can more accurately predict the temperature field and the distribution of key components. The commonly used grid division method in CFD calculation is structured grid and unstructured grid. The calculation model using the structured grid often has higher grid quality, faster calculation speed and less memory. However, the grid drawing process is slow, and it is difficult to apply to complex and variable geometries. In this embodiment, the unstructured grid is selected to adapt to the complex combustion chamber, and the main combustion area is grid-encrypted, with a total of 24.801 million grids.

[0050] ①Velocity

[0051] The velocity cloud chart of the center section of the combustion chamber and the 0 velocity line are shown in Figure 5 , Figure 6 . After checking, the high-temperature gas pressure loss is 3.4%, the air inlet pressure loss is 3.90%, and the pressure loss through the flame tube is 3.11%.

[0052] ②Temperature

[0053] The temperature cloud chart of the center section of the combustion chamber and the outlet temperature cloud chart distribution are shown in Figure 7 , Figure 8 . The average outlet temperature is 1224K, the maximum outlet temperature is 1321K, the OTDF is calculated according to the following formula, and the OTDF of the combustion chamber is 0.15 after calculation.

[0054]

[0055] T 4max : maximum outlet temperature, K; T 4ave : average outlet temperature, K; T 3ave: Inlet average temperature, K

[0056] The assembled test piece was simplified to calculate the wall temperature by fluid-structure coupling, wherein the wall material parameters were referenced to high-temperature alloy. The wall temperature calculation results are shown in Figure 9 As shown in the figure, the maximum wall temperature is not more than 1200K, meeting the requirements of the flame tube.

[0057] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application rather than limiting them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: its still can be modified or equivalent to replace the technical solutions of the present application, and these modifications or equivalent replacements also cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A staged combustion head structure for high flow fuel plumes, characterized by: The combustion head body comprises a fuel nozzle, a main combustion mechanism for high-temperature gas entering, and a pre-combustion mechanism for pre-combustion stage air entering arranged in sequence from the center to the outside of the combustion head body.

2. The staged combustion head structure for high flow fuel coming flow according to claim 1, characterized by: The pre-combustion chamber, the first main combustion chamber and the second main combustion chamber are arranged in sequence from the inside to the outside, and the pre-combustion chamber and the first main combustion chamber and the second main combustion chamber are separately arranged.

3. The staged combustion head structure for high flow fuel coming flow according to claim 2, characterized by: The pre-combustion chamber is provided with a pre-combustion swirler, the first main combustion chamber is provided with a first main combustion swirler, and the second main combustion chamber is provided with a second main combustion swirler.

4. The staged combustion head structure for high flow fuel coming flow according to claim 1, characterized by: One end of the combustion head body is a high-temperature gas inlet, and the other end of the combustion head body is a high-temperature gas outlet.

5. The staged combustion head structure for high flow fuel coming flow according to claim 4, characterized by: The combustion head body is provided with a pre-combustion stage air inlet pipe arranged in an annular array near one end of the high-temperature gas inlet, one end of the pre-combustion stage air inlet pipe is communicated with one end of the pre-combustion chamber near the high-temperature gas inlet, and the other end of the pre-combustion stage air inlet pipe is connected with the combustion head body.

6. The staged combustion head structure for high flow fuel coming flow according to claim 4, characterized by: The combustion head body is provided with a plurality of main combustion stage air inlets arranged in an annular array near one end of the high-temperature gas outlet.

7. The staged combustion head structure for a high-flow fuel coming flow according to claim 6, characterized by: The combustion head body is provided with a connecting disc for connection and fixation at both ends, and the connecting disc near the high-temperature gas outlet of the combustion head body is connected with the combustion head body to form a slot, one end of the slot away from the high-temperature gas outlet is connected with a cooling gas hole, and the cooling gas hole is located between the slot and the main combustion stage air inlet.

8. The staged combustion head structure for a high-flow fuel coming flow according to claim 7, characterized by: The pre-combustion chamber is provided with a blunt body with a hollow interior, the blunt body is arranged in the interior of the combustion head, the blunt body is located near the main combustion stage air inlet of the combustion head, one side of the blunt body near the pre-combustion chamber is communicated with the pre-combustion chamber through a plurality of cooling air inlets, and the other side of the blunt body away from the pre-combustion chamber is communicated with the interior of the combustion head through a plurality of cooling air outlets.

9. The staged combustion head structure for a high-flow fuel coming flow according to claim 8, characterized by: The middle of the blunt body is provided with a contraction port for introducing air.

10. The staged combustion head structure for high flow fuel coming flow according to claim 4, characterized by: The fuel nozzle is provided with a base near one end of the high-temperature gas inlet.

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