Rotatable self-adjusting flow guide device for flue gas and air pipeline elbow and design method of rotatable self-adjusting flow guide device

Abstract

The invention provides a rotatable self-adjusting flow guide device for a flue gas and air pipeline elbow and a design method thereof.The rotatable self-adjusting flow guide device comprises the elbow, a flow guide piece set is arranged in the elbow and comprises a plurality of flow guide pieces sequentially arranged in the airflow direction, and the flow guide pieces are arranged in the elbow. The end, close to the air inlet end of the elbow, of each flow deflector is connected with the elbow through a rotatable connecting rod, and the axis of the connecting rod is coplanar with the corresponding flow deflector. The method can effectively solve the common problems of instability and non-uniform abrasion of a flow field in a high-dust-content flue gas and air pipeline elbow area, and is particularly suitable for high-dust-content flow velocity dynamic change working conditions such as flue gas and air conveying of thermal power plants, metallurgical high-temperature flue gas treatment and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluid transportation engineering, and relates to a diversion regulation method and a diversion device, in particular to a rotatable self-adjusting diversion device for a smoke and air duct elbow and its design method. Background Art

[0002] Under the background of the energy structure transformation, coal-fired thermal power generation remains the core support of the power supply system. As a key gas transportation carrier of coal-fired units, the smoke and air duct system undertakes the important function of transporting multiphase flow media such as high-temperature flue gas, cold air, and hot primary air. Limited by the site space, the smoke and air duct system generally needs to avoid civil structures and the air flow direction changes frequently, resulting in a large number of elbow sections (especially 90° standard elbows) in its pipeline system, which has become the key bottleneck restricting the system energy efficiency and directly affects the operating energy consumption of induced draft fans / blower fans.

[0003] When the air flow passes through the elbow pipe fitting, the flow direction changes. When the gas-solid two-phase flow containing dust gas carrying particles (the particulate matter concentration is as high as 200 g / Nm³ under typical working conditions) passes through the elbow, significant secondary flow effects and particle phase segregation phenomena will occur. The specific manifestations of this flow state deflection are as follows: 1) Air flow separation leads to a sharp increase in local turbulence intensity, triggering high-frequency aerodynamic noise and pipeline vibration; 2) Solid particles collide with the elbow during the air flow deflection process, forming a concentrated erosion wear area on the outer arc surface of the elbow, resulting in a significantly higher wear rate of the elbow than that of the straight pipe section; 3) Due to the deflection phenomenon of the flow state in the elbow, the velocity field and concentration field distributions in the straight pipe section downstream of the elbow are severely uneven. The velocity in the inner area of the elbow decreases and local eddies appear, aggravating the ash accumulation and hardening in the tail flue. In the current engineering practice, the static deflector arrangement scheme can effectively improve the flow field uniformity, but the deflector cannot be adjusted after installation, and the static deflector is only effective for a specific range of flow parameters. Limited by the fixed geometric parameters of the static deflector, it is difficult to adapt to the dynamic changes of flow parameters such as flow velocity, working temperature, and load, resulting in the lack of dynamic adjustment ability of the smoke and air duct system. Summary of the Invention

[0004] Aiming at the problems of the mismatch between the static diversion structure and the dynamically changing flow field in the current smoke and air duct elbows and the separation of the anti-wear protection and flow field regulation functions, the present invention proposes a rotatable self-adjusting diversion device for a smoke and air duct elbow and its design method, which effectively solves the common problems of flow field instability and non-uniform wear in the elbow area of the smoke and air duct under high dust conditions, and is particularly suitable for the flow rate dynamic change conditions with high dust content such as smoke and air transportation in thermal power plants and metallurgical high-temperature flue gas treatment.

[0005] The present invention is realized through the following technical solutions: In a first aspect, the present invention provides a rotatable self-adjusting flow guiding device for a smoke and air duct elbow, comprising: an elbow, wherein a set of flow guiding vanes is arranged inside the elbow, the set of flow guiding vanes includes a plurality of flow guiding vanes arranged in sequence along the air flow direction, one end of each flow guiding vane close to the air inlet end of the elbow is respectively connected to the elbow through a rotatable connecting rod, and the axis of the connecting rod is coplanar with the corresponding flow guiding vane.

[0006] Preferably, the connecting rod passes through the center line of the elbow and is perpendicular to the center line of the elbow.

[0007] Furthermore, the included angle between the connecting rod and the plane where the center line of the elbow is located is 45° - 90°.

[0008] Furthermore, the included angle between the connecting rod and the plane where the center line of the elbow is located satisfies that: the connecting rod installed according to the included angle divides the inlet surface of the elbow into two semi-circular inlet surfaces, satisfying the following formula:

[0009] wherein, V x is the component of the air flow velocity at the inlet of the elbow in the direction perpendicular to the inlet of the elbow, and are respectively the areas of the two semi-circular inlet surfaces.

[0010] Furthermore, the elbow is formed by welding a plurality of straight pipe segments, and a flow guiding vane and a connecting rod are correspondingly arranged inside each straight pipe segment, and the connecting rod passes through the midpoint of the center line of the corresponding straight pipe segment.

[0011] Furthermore, the shape of the flow guiding vane is semi-elliptical, the long axis of the flow guiding vane is arranged along the air flow direction, and the short axis of the flow guiding vane is arranged along the length direction of the connecting rod and is connected to the connecting rod.

[0012] Furthermore, the diameter of the elbow is Φ, the length of the long axis of the flow guiding vane is Φ / 2 + a, and the length of the short axis is Φ - b, wherein 50mm ≤ a ≤ 150mm, 100mm ≤ b ≤ 300mm.

[0013] Preferably, a sleeve is arranged on the outer surface of the elbow, and both ends of the connecting rod are rotatably inserted into the sleeve.

[0014] Furthermore, the sleeve includes an inner sleeve, an outer sleeve and a cover; one end of the inner sleeve is connected to the elbow; one end of the outer sleeve is connected to the cover, and the other end is threadedly connected to the inner sleeve.

[0015] Furthermore, the bending angle of the elbow is 22.5° - 90°.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention constructs a flow guiding device, which includes a flow guiding vane and a connecting rod located inside an elbow. The flow guiding vane has the characteristic of being rotatable. When the air flow passes through the elbow, the flow velocity near the inner side of the elbow increases, while the flow velocity on the outer side of the straight pipe section behind the elbow is large, and the air flow presents a state of deflecting flow. By installing the flow guiding device of the present invention to guide the deflecting flow inside the elbow, the flow guiding vane is simultaneously affected by the acting force of the deflecting air flow, and the flow guiding vane can rotate around the connecting rod. When the forces on both sides of the flow guiding vane are balanced, the flow guiding device maintains a dynamic balance, and this balance will be broken with the change of the deflecting flow, and the flow guiding vane starts to rotate until the acting forces on both sides of the flow guiding vane are equal again. At this time, the flow guiding vane maintains a dynamic balance at a new position. This rotatable flow guiding vane has the ability to adapt to the dynamic flow field. Through the self-adjusting process, it can guide the changing flow field, reconstruct the flow field behind the elbow, effectively improve the hydrodynamic performance of the regions before and after the elbow, improve the uniformity of the flue gas flow field, reduce the resistance of the flue gas and air system, and thus reduce the operating cost. After installing the flow guiding device of the present invention, the particulate matter carried by the air flow will first erode the flow guiding vane due to the biasing effect, which can reduce the erosion of the particulate matter carried by the air flow on the elbow body. The flow guiding device of the present invention can be quickly installed at the elbow of the flue gas and air pipeline. For the elbow of the pipeline that has been put into operation, the flow guiding device of the present invention can also be installed after simple transformation to optimize the flow field. The flow guiding device of the present invention can be adapted to various pipe diameter specifications from DN800 to DN2000, shorten the transformation construction period, and is especially suitable for the technical transformation of in-service pipelines.

[0017] Further, each flow guiding vane is installed in the air flow direction. The shape of the flow guiding vane is a semi-elliptical arc (symmetrically divided based on the minor axis of the ellipse). The major axis of the ellipse is greater than the diameter Φ of the elbow, so as to ensure that the flow guiding vane always maintains the air flow direction. The minor axis of the elliptical flow guiding vane is welded to the connecting rod.

[0018] Further, both ends of the connecting rod pass through the sleeve and can rotate inside the sleeve to realize the function of the rotation of the flow guiding vane. The sleeve is fixed on the elbow. The end of the connecting rod can rotate inside the sleeve. The sleeve is composed of an inner sleeve and an outer sleeve, and the inner and outer sleeves are connected by threads and can be disassembled, which is convenient for maintaining the flow guiding vane and the connecting rod without damaging the elbow structure. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 Schematic diagram of the elbow in Embodiment 1 of the present invention; Figure 2Schematic installation diagram of the rotatable self-adjusting flow guiding device according to Embodiment 1 of the present invention; Figure 3 Schematic diagram of the size and installation of the flow guiding plate according to Embodiment 1 of the present invention; Figure 4 Schematic structural diagram of the sleeve of the present invention; Figure 5 Schematic installation diagram of the elbow and the rotatable self-adjusting flow guiding device according to Embodiment 2 of the present invention; Figure 6 Schematic installation diagram of the elbow and the rotatable self-adjusting flow guiding device according to Embodiment 3 of the present invention; Figure 7 Velocity contour and velocity vector diagrams of the centerline cross-section before and after installing the flow guiding vanes on the elbow of Embodiment 1.

[0021] Among them, each reference numeral in the figure represents the following meanings respectively: 1, elbow; 2, sleeve; 2-1, inner sleeve; 2-2, outer sleeve; 2-3, cover; 3, connecting rod; 4, flow guiding vane. Specific embodiments

[0022] The following specific examples are used to illustrate the embodiments of the present invention. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0023] The rotatable self-adjusting flow guiding device of the present invention for the elbow of the flue gas and air duct includes: an elbow 1, a set of flow guiding vane groups are arranged inside the elbow 1, the flow guiding vane groups include a plurality of flow guiding vanes 4 arranged in sequence along the air flow direction, one end of each flow guiding vane 4 close to the air inlet end of the elbow 1 is respectively connected to the elbow 1 through a rotatable connecting rod 3, and the axis of the connecting rod 3 is coplanar with the corresponding flow guiding vane 4.

[0024] In the flow guiding device of the present invention, the flow guiding vane 4 can rotate around the connecting rod 3. When one side of the flow guiding vane 4 is washed by the deflected flow, the force on the other side of the flow guiding vane is unbalanced, and the deflected flow will push the flow guiding vane to rotate around the connecting rod 3. Therefore, the angle between the plane formed by the flow guiding vane 4 and the plane formed by the perpendicular air flow direction at the air inlet end of the elbow can be automatically adjusted according to the deflection degree of the air flow organization inside the elbow to achieve dynamic balance on both sides of the flow guiding vane 4. When the deflected flow enters the elbow and washes the first flow guiding vane to reach balance, the flow guiding vane also changes the air flow direction to guide the air flow to wash the next flow guiding vane, causing the second flow guiding vane to rotate and be in force balance, and finally all the flow guiding vanes reach a balanced state.

[0025] In some embodiments of the present invention, the connecting rod 3 passes through the center line of the elbow 1 and is perpendicular to the center line of the elbow 1. More preferably, the included angle between the connecting rod 3 and the plane where the center line of the elbow 1 is located is 45° - 90°, and this angle can be designed according to different flow conditions. When the straight pipe section before the elbow is short and the air flow direction has been deflected by another elbow, the two elbows in the pipeline system deflect the air flow in two different directions. The flow state of the deflected flow in the latter elbow does not conform to the characteristic of high flow velocity inside the elbow, but shows the characteristic of high flow velocity on the left or right side of the elbow. The installation method where the connecting rod 3 passes through the center line of the elbow 1 and is perpendicular to the center line of the elbow 1 is not applicable, and it is necessary to adjust the included angle between the connecting rod 3 and the plane where the center line of the elbow 1 is located. The connecting rod 3 can evenly divide the oncoming flow and guide the flow in the subsequent flow, so as to maintain the flow stability after the air flow flows out of the elbow.

[0026] In some embodiments of the present invention, the elbow 1 is a welded elbow formed by welding multiple straight pipe sections. The pipeline diameter using such a welded elbow is generally large, and there are many application scenarios, such as being used in the flue gas and air pipelines of thermal power plants. A set of guide vanes 4 and a connecting rod 3 are correspondingly arranged in each straight pipe section. The connecting rod 3 passes through the midpoint of the center line of the corresponding straight pipe section, and the sleeve can be avoided from the elbow weld.

[0027] The included angle formed by the plane perpendicular to the air flow direction at the intake end of the welded elbow and the plane perpendicular to the air flow direction at the outlet end is 22.5° - 90°, for example, it can be 22.5°, 33.75°, 45°, 56.25°, 67.5°, 78.75°, 90°. The welded elbow can be spliced by n (n = 2 - 8) straight pipe sections of 11.25°. At this time, the number of guide vanes 4 is the same as the number of straight pipe sections, that is, the number of guide vanes 4 is n.

[0028] In some embodiments of the present invention, the shape of the guide vane 4 is semi-elliptical, and the elliptical curve is the sectional curve of the straight pipe section of the elbow at different angles, which can enable the guide vane to rotate to the maximum extent inside the elbow, enhance the range of the guide vane deflecting and guiding the air flow. The long axis of the guide vane 4 is arranged along the air flow direction, and the short axis of the guide vane 4 is arranged along the length direction of the connecting rod 3 and is connected to the connecting rod 3.

[0029] In some embodiments of the present invention, the diameter of the elbow is Φ (for example, 219mm ≤ Φ ≤ 4020mm), the length of the long axis of the guide vane 4 is Φ / 2 + a, and the length of the short axis is Φ - b, where 50mm ≤ a ≤ 150mm and 100mm ≤ b ≤ 300mm. The length of the long axis of the guide vane 4 is greater than the radius of the elbow, which can ensure that the guide vane 4 does not deviate towards the reverse air flow direction and makes its long axis always arranged along the air flow direction. More preferably, the guide vane 4 is symmetric about the center line of the elbow.

[0030] In some embodiments of the present invention, the connecting rod 3 is connected to the elbow 1 through a sleeve 2. Specifically, a plurality of sleeves 2 are arranged on the outer surfaces of both sides of the elbow 1, and both ends of the connecting rod 3 are rotatably inserted into the corresponding sleeves 2. The axes of the two sleeves 2 connecting the same connecting rod 3 are collinear. Here, the "both sides" refers to the two sides with the plane where the center line of the elbow 1 is located as the symmetry plane.

[0031] As a more preferred method, the sleeve 2 includes an inner sleeve 2-1, an outer sleeve 2-2 and a cover 2-3; one end of the inner sleeve 2-1 is connected to the elbow 1; one end of the outer sleeve 2-2 is connected to the cover 2-3, and the other end is hermetically sleeved outside the inner sleeve 2-1, and both ends of the connecting rod 3 are rotatably inserted into the inner sleeve 2-1. For example, the other end of the outer sleeve 2-2 is threadedly connected to the inner sleeve 2-1 to ensure that the medium flowing in the elbow does not leak.

[0032] In the present invention, both ends of the connecting rod 3 are concentric with the inner sleeve 2-1, the inner diameter of the inner sleeve 2-1 is larger than the outer diameter of the connecting rod 3, and the connecting rod 3 can rotate along the axis of the connecting rod 3 inside the inner sleeve 2-1.

[0033] To better illustrate the actual application scenarios of the present invention, three embodiments are selected to illustrate the present invention.

[0034] Embodiment 1 Taking the design of a flue gas pipeline elbow in a thermal power plant as an example, the bending angle of the elbow is 90°, the nominal diameter DN1000, the outer diameter Φ is 1020 mm, the wall thickness is 6 mm, the design temperature is 150 °C, and the design pressure is -10 kPa. The diversion device of the present invention is applied to this elbow.

[0035] The elbow 1 is composed of n = 5 straight pipe sections. After the bevel cutting of each straight pipe section, they are welded and spliced. The combination form is as shown in Figure 1 (a), and a 90° elbow 1 is formed after splicing. Sleeves 2 are symmetrically installed on the upper and lower sides of the elbow 1, and sleeves 2 are installed on the projection center line of each straight pipe section and the inlet and outlet interfaces of the elbow 1, as shown in Figure 1 (b). The sleeve 2 is composed of an inner sleeve 2-1, an outer sleeve 2-2 and a cover 2-3. Among them, the outer sleeve 2-2 and the cover 2-3 are fully penetrated and welded, and the outer sleeve 2-2 and the inner sleeve 2-1 are hermetically connected by threads. The inner sleeve 2-1 is welded to the elbow 1. Specifically, the bottom of the inner sleeve 2-1 is connected to the wall surface of the elbow 1 by full penetration welding, as shown in Figure 4 . Sleeves 2 need to be installed on each straight pipe section of the elbow 1, and the size of the sleeve 2 needs to be determined according to the specifications and lengths of the connecting rods 3. A total of 5 groups (10 pieces) of sleeves 2 are installed in this embodiment. Each group of sleeves 2 is symmetric up and down and the axes are collinear. After the connection is completed, it forms as shown in Figure 1 (c).

[0036] The internal flow guiding device of the elbow 1 consists of a flow guiding vane 4 and a connecting rod 3. The flow guiding vane 4 is semi-elliptical, and its minor axis is welded to the connecting rod 3, as Figure 3 (a) shows. In this embodiment, the outer diameter Dw of the elbow 1 is 1020 mm, and the dimensions of the flow guiding vane 4 adapted to it are: the major axis dimension of the semi-ellipse = Φ / 2 + 50 mm = 560 mm, and the minor axis dimension of the semi-ellipse = Φ - 100 mm = 920 mm. After selecting the flow guiding vane 4, according to the dimensions of the elbow 1 and the installation requirements of the sleeve 2, a connecting rod 3 with a length of Φ+150 mm = 1170 mm is selected. According to the length of the connecting rod 3, a suitable connecting rod specification of Φ76×8 is selected. After determining the dimensions of the connecting rod 3, an inner sleeve 2-1 with a specification of Φ89×6 and an outer sleeve 2-2 with a specification of Φ108×10 are selected according to the specification of the connecting rod 3. According to the length of the connecting rod 3, the height H of the inner sleeve 2-1 is selected as 80 mm. After selecting the flow guiding vane 4 and the connecting rod 3, they are connected, and both ends of the connecting rod 3 are installed into the sleeve 2. The medium flow first passes through the connecting rod 3 and then through the flow guiding vane 4. The installation section is as Figure 3 shown in (b). In this embodiment, a total of n = 5 flow guiding vanes 4 are installed to form a flow guiding vane group. The flow guiding vane group is installed in the elbow and installed in the direction of the air flow, and the installation method is as Figure 2 shown.

[0037] The numerical simulation method is used to model the embodiment model. To ensure that the flow of the medium is fully developed before entering the elbow, the straight pipe section before the elbow is 10Dw. The air flow deflects when passing through the elbow. To avoid the influence of the insufficient length of the downstream pipe on the flow, the length of the downstream straight pipe section is 20Dw. The inlet of the pipe is a velocity inlet, the inlet velocity is 12 m / s, the inlet turbulence intensity is 5%, and the inlet hydraulic diameter is 1.02 m. The outlet is a free outflow, and the wall is a non-slip wall. In this simulation, the thermal buoyancy effect accounts for a relatively small proportion, and the heat exchange between the air flow and the pipe wall is ignored.

[0038] The simulation results are as Figure 7 shown, Figure 7 (a) is the velocity contour map without installing the flow guiding vane, Figure 7 (b) is the velocity vector map without installing the flow guiding vane, Figure 7 (c) is the velocity contour map after installing the flow guiding vane, Figure 7 (d) is the velocity vector map after installing the flow guiding vane. The flow velocity of the air flow is relatively average before entering the elbow. When passing through the elbow, there is an accelerating effect of the wall-attached flow and accompanied by air flow separation. After the air flow passes through the elbow, an obvious recirculation area appears. After installing the flow guiding device of the present invention, the air flow deflects after entering the elbow and the air flow is relatively uniform when flowing out of the elbow.

[0039] Embodiment 2 As Figure 5As shown, on the basis of Embodiment 1, the bending angle of the elbow is changed from 90° to 45°. In this embodiment, the number of the flow guiding vanes 4 is three, and the dimensions of the flow guiding vanes 4, the connecting rods 3, and the sleeves 2 are the same as those in Embodiment 1.

[0040] Embodiment 3 During the implementation process of the present invention, the layout of the pipeline system is limited by the site layout, and the flow state inside the elbow is also affected by the upstream pipe fittings. If there is a long straight pipe section upstream of the elbow, the air flow velocity before the inlet of the elbow is relatively uniform. At this time, the installation method of the flow guiding vanes in Embodiment 1 can be used. If there is only a very short straight pipe section upstream of the elbow, the inlet velocity distribution of the elbow is uneven. If the installation method of the flow guiding vanes in Embodiment 1 is used at this time, it will cause the flow rate distribution on both sides of the flow guiding vanes to be different, and the guiding effect is poor. To meet the guiding requirements under different flow conditions, it is necessary to adjust the inclination angle of the flow guiding vanes according to the velocity deflection characteristics at the inlet of the elbow. This adjustment method and implementation process are introduced in this embodiment.

[0041] As Figure 6 shown, on the basis of Embodiment 1, the installation angle of the flow guiding vanes inside the elbow is rotated. The angle β needs to be calculated according to the velocity at the inlet of the elbow, so that the integral of the velocity V x in the cross-sectional area perpendicular to the inlet direction of the elbow on both sides of the flow guiding vanes is approximately equal, satisfying the following formula:

[0042] In the formula: V x is the component of the air flow velocity at the inlet of the elbow in the direction perpendicular to the inlet direction of the elbow, and A1 and A2 are the areas of the two semi-circular inlet surfaces divided by the connecting rod 3 respectively; In engineering applications, this formula is simplified, and the approximate equality of the average velocities on both sides is used as the judgment condition . After calculating the rotation angle β that satisfies the formula, the flow guiding vanes are rotated around the center line of the elbow. Taking the rotation angle β = 45° as an example, the subsequent flow guiding vanes are adjusted according to β = 45° in turn, as Figure 6 shown.

Claims

1. A rotatable self - adjusting flow - guiding device for the elbow of a flue gas and air duct, characterized in that, Comprising: An elbow (1), a set of flow guiding vane groups are arranged inside the elbow (1), the flow guiding vane groups include a plurality of flow guiding vanes (4) arranged in sequence along the air flow direction, one ends of the flow guiding vanes (4) close to the air inlet end of the elbow (1) are respectively connected with the elbow (1) through rotatable connecting rods (3), and the axis of the connecting rod (3) is coplanar with the corresponding flow guiding vane (4).

2. The rotatable self-adjusting flow guiding device for the elbow of the flue gas duct according to claim 1, wherein The connecting rod (3) passes through the center line of the elbow (1) and is perpendicular to the center line of the elbow (1).

3. The rotatable self-adjusting flow guiding device for the elbow of the smoke and air duct according to claim 2, characterized in that, The included angle between the connecting rod (3) and the plane where the center line of the elbow (1) is located is 45° - 90°.

4. The rotatable self-adjusting flow guiding device for the elbow of the flue gas and air duct according to claim 3, characterized in that, The included angle between the connecting rod (3) and the plane where the center line of the elbow (1) is located satisfies that the connecting rod (3) installed according to the included angle divides the inlet surface of the elbow (1) into two semi-circular inlet surfaces, and satisfies the following formula: Wherein, V x is the component of the inlet airflow velocity of the elbow in the direction perpendicular to the inlet direction of the elbow (1), and are the areas of two semi-circular inlet surfaces respectively.

5. The rotatable self-adjusting flow guiding device for the elbow of the flue gas and air duct according to claim (2), characterized in that, The elbow (1) is welded by a plurality of straight pipe segments, a flow guiding vane (4) and a connecting rod (3) are correspondingly arranged in each straight pipe segment, and the connecting rod (3) passes through the midpoint of the center line of the corresponding straight pipe segment.

6. The rotatable self-adjusting flow guiding device for the elbow of the flue gas and air duct according to claim 2, wherein The shape of the flow guiding vane (4) is semi-elliptical, the long axis of the flow guiding vane (4) is arranged along the air flow direction, and the short axis of the flow guiding vane (4) is arranged along the length direction of the connecting rod (3) and is connected with the connecting rod (3).

7. The rotatable self-adjusting flow guiding device for the elbow of the flue gas duct according to claim 6, wherein The diameter of the elbow (1) is Φ, the length of the long axis of the flow guiding vane (4) is Φ / 2 + a, and the length of the short axis is Φ - b, where 50mm ≤ a ≤ 150mm and 100mm ≤ b ≤ 300mm.

8. The rotatable self-adjusting flow guiding device for the elbow of the smoke and air duct according to claim 1, wherein, A sleeve (2) is arranged on the outer surface of the elbow (1), and both ends of the connecting rod (3) are rotatably inserted into the sleeve (2).

9. The rotatable self-adjusting flow guiding device for the elbow of the flue gas duct according to claim 8, characterized in that, The sleeve (2) includes an inner sleeve (2-1), an outer sleeve (2-2) and a cover (2-3); one end of the inner sleeve (2-1) is connected with the elbow (1); one end of the outer sleeve (2-2) is connected with the cover (2-3), and the other end is threadedly connected with the inner sleeve (2-1).

10. The rotatable self-adjusting flow guiding device for the elbow of the flue gas and air duct according to claim 7, characterized in that, The bending angle of the elbow (1) is 22.5° - 90°.

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