High-efficiency centrifugal fan for boiler exhaust gas with inflow distortion

Abstract

The utility model discloses a high -efficient centrifugal ventilator of boiler exhaust gas suitable for inflow distortion, including air inlet tank, air inlet tank one side is provided with anti distortion current collector, and anti distortion current collector one end communicates with air inlet tank, and anti distortion current collector other end is not into volute, and anti distortion current collector is not into volute one end outside and is provided with airfoil impeller. High -efficient centrifugal ventilator of boiler exhaust gas suitable for inflow distortion, through optimizing the airflow import flow state, effectively reduced the internal flow loss of centrifugal ventilator, thereby significantly improved the whole machine operating efficiency, especially in the design working condition vicinity efficiency promotion is more outstanding, provides an effective way for realizing the design of high -efficient energy -conserving centrifugal ventilator.

Description

Technical Field

[0001] This utility model belongs to the field of ventilation equipment technology, and relates to a high-efficiency centrifugal fan for boiler flue gas exhaust that is suitable for inflow distortion. Background Technology

[0002] In the industrial energy consumption structure, boiler systems occupy a core position, while ventilation fans, as key auxiliary equipment, have long suffered from excessively high energy consumption. Statistics show that ventilation systems in traditional coal-fired power plants consume 30%-40% of the plant's electricity. Traditional boiler ventilation fans generally suffer from large design redundancy, low operating efficiency, and poor regulation characteristics; under varying operating conditions, their actual efficiency is often 15%-25% lower than the design value. With the increasing rigidity of "dual carbon" targets, improving the energy efficiency of ventilation fans has become a breakthrough for industrial energy conservation and consumption reduction. Industrial ventilation fans consume approximately 10% of the nation's total electricity annually; improving their energy efficiency has significant positive implications for reducing carbon emissions and alleviating peak-valley pressure on the power grid. Therefore, breaking through the technological bottlenecks of traditional ventilation fans and developing a new generation of high-efficiency, energy-saving ventilation fan models is not only crucial for enterprise economic benefits but also a key support for the national energy strategic transformation.

[0003] Boiler fans often face severe inflow distortion problems during actual operation. Due to factors such as boiler tail flue reversal, limited space layout, and the use of elbows or F-shaped arrangements at the fan inlet, a non-uniform flow field with extremely uneven velocity / pressure distribution is easily generated at the fan inlet section. This distorted inflow leads to impeller flow field separation and vortex structure instability, resulting in a measured efficiency decrease of 8%-15% compared to uniform inflow conditions and a significant increase in energy consumption. Traditional fan designs are based on the assumption of ideal uniform inflow and cannot adapt to real-world complex operating conditions. Therefore, developing a high-efficiency fan model for distorted inflow to improve aerodynamic performance under non-uniform inflow conditions has become one of the core keys to overcoming the dilemma of "high efficiency in the laboratory, low efficiency in the field" in industrial fans.

[0004] In summary, existing technologies suffer from low operating efficiency of boiler fans under inflow distortion. Utility Model Content

[0005] The purpose of this invention is to provide a high-efficiency centrifugal fan for boiler exhaust under inflow distortion, which solves the problem of low operating efficiency of existing boiler fans under inflow distortion.

[0006] The technical solution adopted in this utility model is a high-efficiency centrifugal fan for boiler flue gas with inlet distortion, including an air inlet box, an anti-distortion collector is provided on one side of the air inlet box, one end of the anti-distortion collector is connected to the air inlet box, the other end of the anti-distortion collector is submerged in the volute, and an airfoil impeller is provided on the outside of the end of the anti-distortion collector submerged in the volute.

[0007] The features of this utility model also include: The longitudinal section of the air intake box includes an isosceles trapezoid and two circular arcs. The bottom center of the longitudinal section of the air intake box spreads outward in a petal shape through the two circular arcs and connects with the two sides of the isosceles trapezoid. The two circular arcs are symmetrically arranged and are composed of a large circular arc and a small circular arc respectively.

[0008] The air intake of the air intake box is located at the top of the isosceles trapezoid in the longitudinal section, and the air outlet of the air intake box is located in the middle of the two arcs at the bottom of the isosceles trapezoid.

[0009] The anti-distortion collector includes a converging section and a diffuser section. The converging section has a hollow frustum structure. The larger end of the converging section is connected to the air outlet of the air inlet box, and the smaller end of the converging section is connected to the diffuser section. The outer wall of the smaller end of the converging section is connected to the volute.

[0010] The diffuser section has a trumpet-shaped structure. The smaller end of the diffuser section is connected to the converging section, and the larger end of the diffuser section is connected to the airfoil impeller. The diffuser section is located inside the volute.

[0011] The airfoil impeller includes a front plate and a rear plate arranged opposite each other, with several blades arranged between the front plate and the rear plate. The diameter of the airfoil impeller is D1.

[0012] The length of the top side of the isosceles trapezoid in the longitudinal section of the air intake box is 1.2D1-1.3D1, and the height of the air intake box in the longitudinal section is 1.5D1-1.6D1.

[0013] The radius of the large arc in the longitudinal section of the air intake box is 0.5D1-0.6D1, and the radius of the small arc is 0.09D1-0.1D1.

[0014] In the anti-distortion current collector, the angle between the side of the contraction section and the bottom edge of the larger end face is 64°. The diameter of the larger end face of the contraction section in the anti-distortion current collector is 0.7D1-0.8D1, the diameter of the smaller end face of the contraction section and the smaller diameter of the diffuser end face are 0.5D1-0.6D1, and the larger diameter of the diffuser end face is 0.5D1-0.6D1.

[0015] The circumferential profile of the volute is composed of five segments of circular arcs and straight lines, with the radii of each segment being 0.04D1-0.05D1, 0.5D1-0.6D1, 0.5D1-0.6D1, 0.7D1-0.8D1, and 0.9D1-1D1, respectively.

[0016] The beneficial effects of this utility model are: The overall efficiency is significantly improved and the performance is stable. Under the condition of inflow distortion, the total pressure curve of the optimized fan is consistent with that of the traditional fan. The aerodynamic efficiency under all operating conditions is greatly improved - the efficiency under low flow conditions is increased by 5.58%, the efficiency under the design point conditions is increased by 12.61%, the efficiency under high flow conditions is increased by 1%-14%, and the peak efficiency is more than 10% higher than that of the traditional fan, completely breaking the dilemma of "high efficiency in the laboratory, low efficiency in the field". The flow field uniformity is greatly optimized and the flow loss is reduced. The petal-shaped air inlet box (isosceles trapezoid + two symmetrical arcs) can guide the airflow to the collector in an orderly manner, avoiding the streamline turbulence and vortices of the prototype fan. The anti-distortion collector can rectify the airflow and cancel the inflow distortion. The airfoil impeller and the volute with multiple arcs can match the airflow trajectory, reduce impact and vortices, and reduce flow loss throughout the entire process from inlet to outlet. With outstanding energy efficiency and industry value, this solution addresses the pain point of high energy consumption in traditional fans. The efficiency improvement directly reduces operating energy consumption and carbon emissions, aligning with the "dual carbon" goal and also reducing the electricity costs for enterprises. At the same time, the solution is adaptable to real-world operating conditions such as boiler tail flue reversal and space constraints, requiring no additional modifications and demonstrating strong on-site applicability, providing an effective path for energy-saving upgrades of industrial ventilation fans. Attached Figure Description

[0017] Figure 1 This is a two-dimensional schematic diagram of the axial cross-section of a high-efficiency centrifugal fan with inflow distortion, applicable to this utility model. Figure 2 This is a three-dimensional schematic diagram of the axial cross-section of a high-efficiency centrifugal fan with inflow distortion, applicable to this utility model. Figure 3 This is a two-dimensional longitudinal cross-sectional schematic diagram of the air inlet box of a high-efficiency centrifugal fan with inflow distortion, applicable to this utility model. Figure 4 This is a two-dimensional schematic diagram of the axial cross-section of the air inlet box of the present invention, applicable to high-efficiency centrifugal fans with inflow distortion; Figure 5 This is a three-dimensional schematic diagram of the air inlet box of a high-efficiency centrifugal fan with inflow distortion, which is applicable to the present invention. Figure 6 This is a two-dimensional axial cross-sectional schematic diagram of the anti-distortion collector for high-efficiency centrifugal fans with inflow distortion, applicable to this utility model. Figure 7 This is a two-dimensional schematic diagram of the airfoil impeller of a high-efficiency centrifugal fan with inflow distortion, which is applicable to this utility model. Figure 8 This is a two-dimensional cross-sectional schematic diagram of the circumferential section of the volute casing of a high-efficiency centrifugal fan with inflow distortion, applicable to this utility model. Figure 9 It is a velocity cloud map at the middle section of the prototype wind turbine in the existing technology; Figure 10This is the velocity cloud map at the middle section of the fan after optimization according to this utility model; Figure 11 This is a velocity streamline distribution diagram of the longitudinal section of the air inlet box of a prototype fan in the prior art; Figure 12 This is a velocity streamline distribution diagram of the longitudinal section of the air inlet box of the optimized fan of this utility model; Figure 13 This is a comparison chart of the efficiency of the prototype centrifugal fan in the prior art and the optimized centrifugal fan of this utility model.

[0018] In the diagram, 1 is the air intake box; 2 is the anti-distortion collector; 3 is the volute; and 4 is the airfoil impeller. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] High-efficiency centrifugal fans suitable for boiler flue gas exhaust with inflow distortion, combined with Figure 1 and Figure 2 As shown, it includes an air intake box 1, an anti-distortion collector 2 is provided on one side of the air intake box 1, one end of the anti-distortion collector 2 is connected to the air intake box 1, the other end of the anti-distortion collector 2 is submerged in the volute 3, and an airfoil impeller 4 is provided on the outside of the end of the anti-distortion collector 2 submerged in the volute 3.

[0021] The longitudinal section of the air intake box 1 comprises an isosceles trapezoid and two circular arcs. At the bottom center of the longitudinal section, the two circular arcs radiate outwards in a petal-like shape and connect with the two sides of the isosceles trapezoid. The two circular arcs are symmetrically arranged, each composed of a large arc and a small arc connected together. The apex of the isosceles trapezoid in the longitudinal section of the air intake box 1 is the air inlet, and the air outlet is located at the midpoint of the two circular arcs at the bottom of the isosceles trapezoid.

[0022] The anti-distortion collector 2 includes a converging section and a diffuser section. The converging section is shaped like a hollow frustum. The larger end face of the converging section is connected to the outlet of the inlet box 1, and the smaller end face is connected to the diffuser section. The outer wall of the smaller end face of the converging section is connected to the volute 3. The diffuser section is shaped like a trumpet. The smaller end face of the diffuser section is connected to the converging section, and the larger end face of the diffuser section is connected to the airfoil impeller 4. The diffuser section is located inside the volute 3.

[0023] The airfoil impeller 4 includes a front disc and a rear disc arranged opposite each other, with several blades disposed between the front and rear discs. The diameter of the airfoil impeller 4 is D1. The length of the top side of the isosceles trapezoid in the longitudinal section of the intake box 1 is 1.2D1-1.3D1, and the height of the intake box 1 in the longitudinal section is 1.5D1-1.6D1. The radius of the large arc in the longitudinal section of the intake box 1 is 0.5D1-0.6D1, and the radius of the small arc is 0.09D1-0.1D1. In the anti-distortion collector 2, the angle between the side of the contraction section and the bottom edge of the larger end face is 64°. The diameter of the larger end face of the contraction section in the anti-distortion collector 2 is 0.7D1-0.8D1, the diameter of the smaller end face of the contraction section and the smaller diameter of the diffuser section are both 0.5D1-0.6D1, and the larger diameter of the diffuser section is 0.5D1-0.6D1. The circumferential profile of the volute 3 is composed of five segments of circular arcs and straight lines, with the radii of each segment being 0.04D1-0.05D1, 0.5D1-0.6D1, 0.5D1-0.6D1, 0.7D1-0.8D1, and 0.9D1-1D1, respectively.

[0024] In this invention, an anti-distortion collector 2 is installed downstream of the intake box 1. The downstream of the anti-distortion collector 2 is connected to the airfoil impeller 4. The airflow exiting the airfoil impeller 4 is collected and diffused through the volute 3. The longitudinal section of the intake box 1 is composed of an isosceles trapezoid and two circular arcs, giving it a petal-like overall shape. At the center of the bottom of the intake box 1, the two circular arcs extend outwards in a petal-like shape and connect to the two sides of the isosceles trapezoid. The profile of the anti-distortion collector 2 consists of a contraction section and a diffusion section. The contraction section has a straight cross-section, and the angle between the contraction section and the inlet section of the anti-distortion collector 2 is... =64°; This straight line rotates around the central axis to form a conical structure. The rear end of the converging section of the anti-distortion collector 2 is smoothly connected to the diffuser section by a curved transition. From the circumferential profile of the volute 3, this profile is usually designed as a logarithmic spiral or an approximate spiral form approximated by multiple circular arcs. This kind of geometry can effectively match the fluid motion trajectory thrown out from the airfoil impeller 4, allowing the fluid to enter the volute flow channel with minimal impact and energy loss, thereby suppressing vortex generation, reducing flow losses, and ensuring that the equipment operates smoothly and with low noise in the high-efficiency range. The circumferential profile of the volute is composed of five circular arcs and straight lines connected together. The airfoil impeller 4 profile includes a front disc and a rear disc. The front disc profile of the airfoil impeller 4 has a straight line and a circular arc section, while the rear disc profile is a straight line. The front and rear disc profiles rotate around the central axis to form a disc shape. The diameter of the airfoil impeller 4 is D1. The front and rear disc profiles of the airfoil impeller 4 are smoothly connected by a straight line. The airfoil impeller 4 has several blades evenly arranged along the rotation axis. Each blade is in contact with both the front and rear discs, and the blade outlet installation angle is 60°.

[0025] Example 1 This embodiment proposes a high-efficiency centrifugal fan for boiler flue gas discharge with inflow distortion, including an air inlet box 1, an anti-distortion collector 2 is provided on one side of the air inlet box 1, one end of the anti-distortion collector 2 is connected to the air inlet box 1, the other end of the anti-distortion collector 2 is submerged in the volute 3, and an airfoil impeller 4 is provided on the outside of the end of the anti-distortion collector 2 submerged in the volute 3.

[0026] Example 2 This embodiment proposes a high-efficiency centrifugal fan for boiler flue gas exhaust suitable for inflow distortion, including an inlet box 1. An anti-distortion collector 2 is installed on one side of the inlet box 1. One end of the anti-distortion collector 2 is connected to the inlet box 1, and the other end of the anti-distortion collector 2 is submerged in a volute 3. An airfoil impeller 4 is installed on the outside of the end of the anti-distortion collector 2 submerged in the volute 3. The longitudinal section of the inlet box 1 includes an isosceles trapezoid and two circular arcs. The bottom center of the longitudinal section of the inlet box 1 is diffused outward in a petal shape through the two circular arcs and connected to the two sides of the isosceles trapezoid. The two circular arcs are symmetrically arranged, and each circular arc is composed of a large circular arc and a small circular arc connected together.

[0027] Example 3 This embodiment proposes a high-efficiency centrifugal fan for boiler flue gas discharge with inflow distortion, including an air inlet box 1, an anti-distortion collector 2 is provided on one side of the air inlet box 1, one end of the anti-distortion collector 2 is connected to the air inlet box 1, the other end of the anti-distortion collector 2 is submerged in the volute 3, and an airfoil impeller 4 is provided on the outside of the end of the anti-distortion collector 2 submerged in the volute 3.

[0028] The longitudinal section of the air intake box 1 includes an isosceles trapezoid and two circular arcs. At the bottom center of the longitudinal section, the two circular arcs diffuse outwards in a petal-like shape and connect to the two sides of the isosceles trapezoid. The two circular arcs are symmetrically arranged, each composed of a large arc and a small arc connected together. The apex of the isosceles trapezoid in the longitudinal section of the air intake box 1 is the air inlet, and the air outlet is located in the middle of the two circular arcs at the bottom of the isosceles trapezoid. The anti-distortion collector 2 includes a converging section and a diffuser section. The converging section has a hollow frustum shape. The larger end face of the converging section connects to the air outlet of the air intake box 1, and the smaller end face connects to the diffuser section. The outer wall of the smaller end face of the converging section is connected to the volute 3.

[0029] Example 4 This embodiment proposes a high-efficiency centrifugal fan for boiler flue gas discharge with inflow distortion, including an air inlet box 1, an anti-distortion collector 2 is provided on one side of the air inlet box 1, one end of the anti-distortion collector 2 is connected to the air inlet box 1, the other end of the anti-distortion collector 2 is submerged in the volute 3, and an airfoil impeller 4 is provided on the outside of the end of the anti-distortion collector 2 submerged in the volute 3.

[0030] The longitudinal section of the air intake box 1 comprises an isosceles trapezoid and two circular arcs. At the bottom center of the longitudinal section, the two circular arcs radiate outwards in a petal-like shape and connect with the two sides of the isosceles trapezoid. The two circular arcs are symmetrically arranged, each composed of a large arc and a small arc connected together. The apex of the isosceles trapezoid in the longitudinal section of the air intake box 1 is the air inlet, and the air outlet is located at the midpoint of the two circular arcs at the bottom of the isosceles trapezoid.

[0031] The anti-distortion collector 2 includes a converging section and a diffuser section. The converging section is shaped like a hollow frustum. The larger end face of the converging section is connected to the outlet of the inlet box 1, and the smaller end face is connected to the diffuser section. The outer wall of the smaller end face of the converging section is connected to the volute 3. The diffuser section is shaped like a trumpet. The smaller end face of the diffuser section is connected to the converging section, and the larger end face of the diffuser section is connected to the airfoil impeller 4. The diffuser section is located inside the volute 3. The airfoil impeller 4 includes a front disc and a rear disc arranged opposite each other, with several blades arranged between the front and rear discs. The diameter of the airfoil impeller 4 is D1.

[0032] Example 5 This embodiment proposes a high-efficiency centrifugal fan for boiler flue gas discharge with inflow distortion, including an air inlet box 1, an anti-distortion collector 2 is provided on one side of the air inlet box 1, one end of the anti-distortion collector 2 is connected to the air inlet box 1, the other end of the anti-distortion collector 2 is submerged in the volute 3, and an airfoil impeller 4 is provided on the outside of the end of the anti-distortion collector 2 submerged in the volute 3.

[0033] The longitudinal section of the air intake box 1 includes an isosceles trapezoid and two circular arcs. At the bottom center of the longitudinal section, the two circular arcs diffuse outwards in a petal-like shape and connect to the two sides of the isosceles trapezoid. The two circular arcs are symmetrically arranged, each composed of a large arc and a small arc. The apex of the isosceles trapezoid in the longitudinal section of the air intake box 1 is the air inlet, and the air outlet is located in the middle of the two circular arcs at the bottom of the isosceles trapezoid. The anti-distortion collector 2 includes a converging section and a diffuser section. The converging section is a hollow frustum-shaped structure. The larger end face of the converging section connects to the air outlet of the air intake box 1, and the smaller end face connects to the diffuser section. The outer wall of the smaller end face of the converging section is connected to the volute 3. The diffuser section is trumpet-shaped. The smaller end face of the diffuser section connects to the converging section, and the larger end face connects to the airfoil impeller 4. The diffuser section is located inside the volute 3. The airfoil impeller 4 includes a front disc and a rear disc arranged opposite to each other, with several blades arranged between the front disc and the rear disc. The diameter of the airfoil impeller 4 is D1.

[0034] The length of the top side of the isosceles trapezoid in the longitudinal section of the air intake box 1 is 1.2D1, and the height of the air intake box 1 in the longitudinal section is 1.5D1. The radius of the large arc in the longitudinal section of the air intake box 1 is 0.5D1, and the radius of the small arc is 0.09D1. The angle between the side of the contraction section and the bottom edge of the larger end face in the anti-distortion collector 2 is 64°. The diameter of the larger end face of the contraction section in the anti-distortion collector 2 is 0.7D1, and the diameters of the smaller end face of the contraction section and the smaller end face of the diffuser section are both 0.5D1. The diameter of the larger end face of the diffuser section is 0.5D1. The circumferential profile of the volute 3 is composed of five segments of arcs and straight lines connected together, with the radii of each arc being 0.04D1, 0.5D1, 0.5D1, 0.7D1, and 0.9D1, respectively.

[0035] Example 6 This embodiment proposes a high-efficiency centrifugal fan for boiler flue gas discharge with inflow distortion, including an air inlet box 1, an anti-distortion collector 2 is provided on one side of the air inlet box 1, one end of the anti-distortion collector 2 is connected to the air inlet box 1, the other end of the anti-distortion collector 2 is submerged in the volute 3, and an airfoil impeller 4 is provided on the outside of the end of the anti-distortion collector 2 submerged in the volute 3.

[0036] The longitudinal section of the air intake box 1 includes an isosceles trapezoid and two circular arcs. At the bottom center of the longitudinal section, the two circular arcs diffuse outwards in a petal-like shape and connect to the two sides of the isosceles trapezoid. The two circular arcs are symmetrically arranged, each composed of a large arc and a small arc. The apex of the isosceles trapezoid in the longitudinal section of the air intake box 1 is the air inlet, and the air outlet is located in the middle of the two circular arcs at the bottom of the isosceles trapezoid. The anti-distortion collector 2 includes a converging section and a diffuser section. The converging section is a hollow frustum-shaped structure. The larger end face of the converging section connects to the air outlet of the air intake box 1, and the smaller end face connects to the diffuser section. The outer wall of the smaller end face of the converging section is connected to the volute 3. The diffuser section is trumpet-shaped. The smaller end face of the diffuser section connects to the converging section, and the larger end face connects to the airfoil impeller 4. The diffuser section is located inside the volute 3. The airfoil impeller 4 includes a front disc and a rear disc arranged opposite to each other, with several blades arranged between the front disc and the rear disc. The diameter of the airfoil impeller 4 is D1.

[0037] The length of the top side of the isosceles trapezoid in the longitudinal section of the air intake box 1 is 1.3D1, and the height of the air intake box 1 in the longitudinal section is 1.6D1. The radius of the large arc in the longitudinal section of the air intake box 1 is 0.6D1, and the radius of the small arc is 0.1D1. The angle between the side of the contraction section and the bottom edge of the larger end face in the anti-distortion collector 2 is 64°. The diameter of the larger end face of the contraction section in the anti-distortion collector 2 is 0.8D1, and the diameters of the smaller end face of the contraction section and the smaller end face of the diffuser section are both 0.6D1. The diameter of the larger end face of the diffuser section is 0.6D1. The circumferential profile of the volute 3 is composed of five segments of arcs and straight lines connected together, with the radii of each arc being 0.05D1, 0.6D1, 0.6D1, 0.8D1, and 1D1, respectively.

[0038] Example 7 This embodiment proposes a high-efficiency centrifugal fan for boiler flue gas discharge with inflow distortion, including an air inlet box 1, an anti-distortion collector 2 is provided on one side of the air inlet box 1, one end of the anti-distortion collector 2 is connected to the air inlet box 1, the other end of the anti-distortion collector 2 is submerged in the volute 3, and an airfoil impeller 4 is provided on the outside of the end of the anti-distortion collector 2 submerged in the volute 3.

[0039] The longitudinal section of the air intake box 1 includes an isosceles trapezoid and two circular arcs. At the bottom center of the longitudinal section, the two circular arcs diffuse outwards in a petal-like shape and connect to the two sides of the isosceles trapezoid. The two circular arcs are symmetrically arranged, each composed of a large arc and a small arc. The apex of the isosceles trapezoid in the longitudinal section of the air intake box 1 is the air inlet, and the air outlet is located in the middle of the two circular arcs at the bottom of the isosceles trapezoid. The anti-distortion collector 2 includes a converging section and a diffuser section. The converging section is a hollow frustum-shaped structure. The larger end face of the converging section connects to the air outlet of the air intake box 1, and the smaller end face connects to the diffuser section. The outer wall of the smaller end face of the converging section is connected to the volute 3. The diffuser section is trumpet-shaped. The smaller end face of the diffuser section connects to the converging section, and the larger end face connects to the airfoil impeller 4. The diffuser section is located inside the volute 3. The airfoil impeller 4 includes a front disc and a rear disc arranged opposite to each other, with several blades arranged between the front disc and the rear disc. The diameter of the airfoil impeller 4 is D1.

[0040] The length of the top side of the isosceles trapezoid in the longitudinal section of the air intake box 1 is 1.25D1, and the height of the air intake box 1 in the longitudinal section is 1.55D1. The radius of the large arc in the longitudinal section of the air intake box 1 is 0.55D1, and the radius of the small arc is 0.095D1. The angle between the side of the contraction section and the bottom side of the larger end face in the anti-distortion collector 2 is 64°. The diameter of the larger end face of the contraction section in the anti-distortion collector 2 is 0.75D1, and the diameters of the smaller end face of the contraction section and the smaller end face of the diffuser section are both 0.55D1. The diameter of the larger end face of the diffuser section is 0.55D1. The circumferential profile of the volute 3 is composed of five segments of arcs and straight lines connected together, with the radii of each arc being 0.045D1, 0.55D1, 0.55D1, 0.75D1, and 0.95D1, respectively.

[0041] Figure 1 This is an axial cross-sectional view of the overall wind turbine structure, clearly showing the upstream and downstream connections and relative positions of the four core components: The cross-sectional outline of the inlet box 1 is visible on the left, with its right outlet directly connected to the left inlet of the anti-distortion collector 2; the anti-distortion collector 2 has a two-section cross-sectional shape of "contraction-diffusion," with its right end submerged in the internal flow channel of the volute 3; around the end of the anti-distortion collector 2 submerged in the volute 3, the airfoil impeller 4 is arranged, with the front and rear discs of the impeller forming a ring structure in the cross-section, and the blades evenly distributed between the front and rear discs; the cross-section of the volute 3 exhibits a gradually expanding flow channel shape, corresponding to its "collection and diffusion" function. Through this two-dimensional cross-section, the complete path of airflow entering from the inlet box 1, being rectified by the anti-distortion collector 2, then entering the airfoil impeller 4 to perform work, and finally exiting through the volute 3 can be intuitively understood. Figure 2 In the appendix Figure 1 Based on the two-dimensional cross-section, the three-dimensional structure of the fan is displayed from a three-dimensional perspective, which more clearly shows the spatial adaptation relationship of each component: the "petal-shaped" three-dimensional outline of the air inlet box 1 is presented, and the two arcs at its bottom are not planar structures, but curved surfaces formed by outward diffusion, which together with the side of the isosceles trapezoid form a shell with spatial curvature; the anti-distortion collector 2 extends from the outlet end of the air inlet box 1, in the form of a hollow "frustum-trumpet" combination, smoothly transitioning into the interior of the volute 3, and the spatial fit relationship between its connection part with the volute 3 (outer wall of the small end face of the contraction section) is clearly visible; the airfoil impeller 4 is shown in the three-dimensional perspective as a ring-shaped component surrounding the anti-distortion collector 2, and the three-dimensional disk structure formed by the arc shape of the front disk and the straight shape of the rear disk, as well as the uniform distribution of the blades on the disk, can intuitively reflect the rotational work space of the impeller; the spiral flow channel of the volute 3 shows the gradual diffusion trajectory from the impeller outlet to the total outlet of the fan in the three-dimensional cross-section, which helps to understand how it matches the airflow thrown out by the impeller in space.

[0042] Figure 3The figure shows a two-dimensional cross-section of the air intake box 1 cut longitudinally, a key view for analyzing its "petal-shaped" core structure: the cross-section is clearly composed of two parts—an upper isosceles trapezoid and two symmetrical circular arcs (a large arc and a small arc) at the bottom. The top of the isosceles trapezoid is the air intake of the air intake box 1, and the two sides of the bottom end are smoothly connected to the two circular arcs respectively. The two circular arcs diffuse outward from the center of the bottom of the air intake box 1 in a "petal shape", and finally converge at the middle position to form the air outlet of the air intake box 1 (corresponding to the port connected to the anti-distortion collector 2). The cross-section also marks the dimensionless dimensions based on the diameter D1 of the airfoil impeller 4: the length of the top side of the isosceles trapezoid is 1.26D1, the overall height of the air intake box 1 is 1.51D1, the radius of the large arc is 0.56D1, and the radius of the small arc is 0.097D1. This cross-section allows direct understanding of how the intake box 1 guides airflow through its geometric shape—avoiding the problem of airflow concentrating in the middle of the prototype fan, allowing airflow to flow orderly along the isosceles trapezoidal sidewall and the arc surface to the outlet, reducing vortex generation.

[0043] Figure 4 The two-dimensional cross-section of the intake box 1 cut along the axial direction, and the attached Figure 3 The longitudinal sections complement each other, showcasing the structural features of the air intake box 1 in the axial direction: from the perspective of the cross section, the axial width distribution of the internal flow channel of the air intake box 1 can be clearly seen—from the air inlet to the air outlet, how the axial dimensions of the flow channel adapt to the diffusion requirements of the airflow.

[0044] Figure 5 A complete three-dimensional view of the air intake box 1 is crucial for intuitively understanding its three-dimensional structure. From a three-dimensional perspective, the air intake box 1 is not a simple combination of a trapezoid and an arc, but rather a shell with a complete curved surface. The two sides of the isosceles trapezoid extend in space to form two inclined sides, while the two arcs at the bottom diffuse from the bottom of the two sides towards the center, forming two symmetrical "petal" curved surfaces, ultimately converging at the center of the bottom of the shell to form a circular air outlet. The air inlet is a rectangular or trapezoidal port that matches the top of the isosceles trapezoid, presenting a unique shape that is "wider at the top and narrower at the bottom, with an arc at the bottom." This view clearly demonstrates how the air intake box 1 constructs a uniform flow field space through its three-dimensional geometry, allowing the airflow to naturally diffuse along the curved surface within the three-dimensional shell after entering through the air inlet, rather than being confined to a planar flow channel, thus reducing flow loss in the spatial dimension.

[0045] Figure 6The two-dimensional cross-section of the anti-distortion collector 2, cut along the axial direction, precisely analyzes the structural basis of its "rectification" function: the cross-section clearly divides the collector into two sections—a contraction section on the left and a diffusion section on the right. The contraction section is a hollow frustum shape with a straight cross-section. The angle between the straight line and the inlet cross-section (large end face) of the contraction section is 64°. The diameter of the large end face is 0.71D1 (corresponding to the size of the outlet of the air inlet box 1), and the diameter of the small end face is 0.53D1. The diffusion section is trumpet-shaped, and its small end face has the same size as the small end face of the contraction section (0.53D1). It is connected to the contraction section through a smooth curve. The diameter of the large end face is 0.55D1 (corresponding to the size of the airfoil impeller 4). At the same time, the cross-section also shows that the outer wall of the small end face of the contraction section is tightly connected to the inner wall of the volute 3, ensuring the fixation of the collector within the volute 3. This cross-section reveals the flow rectification logic of the collector: the contraction section accelerates the airflow and initially organizes the flow field through a straight cross-section with a 64° angle, while the diffusion section further homogenizes the airflow through a trumpet-shaped cross-section and a curved transition, ultimately offsetting the inflow distortion and providing a uniform inflow to the impeller.

[0046] Figure 7 The radial two-dimensional cross-section of the airfoil impeller 4 is key to analyzing its working structure: combining Figure 1 As can be seen, the impeller consists of a front disc and a rear disc arranged opposite each other. The profile of the front disc is a combination of a straight line and an arc, while the profile of the rear disc is a single straight line. After rotating around the central axis of the impeller, the two profiles form a disc-shaped structure. The front and rear discs are smoothly connected by a straight line to ensure the integrity of the impeller casing. The diameter of the impeller is uniformly D1, and several blades are evenly arranged along the rotation axis. The two ends of each blade are in close contact with the front and rear discs, respectively, forming a closed working flow channel. The outlet installation angle of all blades is fixed at 60°. This cross-section directly reflects how the impeller matches the airflow of the anti-distortion collector 2—the 60° blade outlet installation angle can accurately match the airflow direction output by the collector, reducing the impact angle between the airflow and the blades; the arc profile of the front disc can reduce the flow resistance of the airflow at the impeller inlet, allowing the airflow to enter the blade flow channel smoothly and improving the working efficiency.

[0047] Figure 8The two-dimensional cross-section of the volute 3 along its circumference is the core view for understanding its "flow collection and diffusion" function: the cross-section shows that the circumferential profile of the volute 3 is not a single curve, but is composed of five circular arcs and multiple straight lines connected sequentially. The radii of each circular arc are based on the diameter D1 of the airfoil impeller 4, and are successively 0.043D1, 0.56D1, 0.56D1, 0.77D1, and 0.93D1, forming an overall profile that approximates a logarithmic spiral. The logic of this profile design is clearly reflected in the cross-section: starting from the position near the outlet of the airfoil impeller 4 (volute inlet), the flow channel gradually expands through the connection of multiple circular arcs and straight lines, perfectly matching the trajectory of the airflow ejected by the high-speed rotation of the impeller. After the airflow enters the volute 3, when it flows along the spiral flow channel, it will not be impacted by the abrupt change in the shape of the flow channel, but will realize the conversion of kinetic energy into pressure energy during the gradual diffusion process, while suppressing the generation of vortices. The cross-section also provides a clear view of the total outlet position of the volute 3, reflecting the complete diffusion path of the airflow from the impeller to the total outlet, explaining how it reduces flow losses and ensures low-noise operation of the fan.

[0048] Figure 9 and Figure 10 The figures show velocity contour maps of the prototype centrifugal fan and the optimized fan at a volute outlet channel width of b=100mm, respectively. As can be seen from the figures, after the gas enters the airfoil impeller 4, both the prototype and optimized fans exhibit high flow velocities, with the optimized fan showing a significantly higher airflow velocity. When the airflow leaves the airfoil impeller 4 and enters the volute section, the airflow velocity in the prototype fan's volute and its outlet region decreases significantly, while the optimized fan maintains a uniform and stable velocity distribution in this region, demonstrating superior flow performance.

[0049] Figure 11 and Figure 12 The streamline diagrams of the prototype and optimized inlet boxes are shown separately. Airflow enters through the inlet of inlet box 1, is guided by the anti-distortion collector 2, and then enters the airfoil impeller 4. Under the centrifugal force generated by the high-speed rotation of the airfoil impeller 4, the airflow is ejected and enters the flow channel of the volute 3, ultimately flowing along the volute structure to the outlet. In the prototype inlet box, airflow is mostly concentrated in the middle region before entering the anti-distortion collector 2, with weaker flow at the bottom. The overall streamline distribution is disordered, exhibiting significant flow separation and vortices. Inlet box 1 significantly improves the internal flow state. The streamlines are closely aligned with the box body profile and guided orderly to the anti-distortion collector 2, resulting in a denser and more uniform overall distribution and a more rational flow structure, effectively reducing flow losses at the inlet section.

[0050] Figure 13The results show the efficiency comparison between the prototype fan and the optimized fan under the same operating conditions. It can be seen that the aerodynamic efficiency of the optimized fan is significantly improved across the entire operating range: efficiency is increased by 5.58% under low flow conditions, by 12.61% under design point conditions, and by 1% to 14% under high flow conditions, indicating that the structure of the air inlet box 1 has a significant effect on improving the fan performance.

[0051] This invention effectively reduces the internal flow loss of a centrifugal fan by optimizing the airflow inlet, thereby significantly improving the overall operating efficiency, especially near the design operating conditions. This structure provides an effective way to design high-efficiency and energy-saving centrifugal fans. Under boiler exhaust inlet distortion conditions, compared with traditional centrifugal fans, the total pressure curve of this invention remains consistent with the original fan, with a significant increase in efficiency, and a peak efficiency increase of more than 10%.

[0052] This invention achieves full-process flow field optimization from airflow inlet to outlet through precise structural design of the air inlet box 1, anti-distortion collector 2, airfoil impeller 4, and volute 3, effectively reducing flow losses. Specifically, the air inlet box 1 adopts a petal-shaped structure with a longitudinal cross-section composed of an isosceles trapezoid and two symmetrical circular arcs (large arc radius 0.56D1, small arc radius 0.097D1). The inlet length of the airfoil impeller 4, after dimensionless calculation of its diameter D1, is 1.26D1, and its height is 1.51D1. This structure allows the airflow, after entering through the inlet, to flow orderly along the box profile towards the anti-distortion collector 2, completely improving the problem of airflow concentration in the middle and weak, turbulent flow at the bottom of the prototype fan's air inlet box. This design avoids significant flow separation and vortex formation, greatly reducing flow losses in the inlet section. The anti-distortion collector 2 is designed as a combination structure of a hollow frustum-shaped contraction section and a trumpet-shaped diffuser section. The angle between the side of the contraction section and the bottom of the large end face is 64°. The diameter of the large end face is 0.71D1, and the diameter of the small end face is 0.53D1. The diameter of the small end face of the diffuser section is 0.53D1, and the diameter of the large end face is 0.55D1. The two sections transition smoothly through a curve, which can accurately rectify the non-uniform airflow exiting the intake box 1, effectively... To counteract the inflow distortion caused by factors such as the boiler tail flue turning and limited space, the airflow enters the airfoil impeller 4 with a uniform velocity and pressure distribution, suppressing impeller flow field separation and vortex instability from the source. The airfoil impeller 4, based on diameter D1, has a front disc profile composed of a straight line and a circular arc, and a rear disc profile that is also a straight line. The front and rear discs are smoothly connected by a straight line. The blades, evenly arranged along the rotation axis, are in close contact with the front and rear discs, and the outlet installation angle is 60°. This structure perfectly matches the airflow direction output by the anti-distortion collector 2. The circumferential profile of the volute 3 is formed by connecting five circular arcs (radii of 0.043D1, 0.56D1, 0.56D1, 0.77D1, and 0.93D1 respectively) with straight lines, which is approximately a logarithmic spiral. This can accurately match the fluid motion trajectory thrown out by the airfoil impeller 4, allowing the airflow to enter the volute flow channel with minimal impact, effectively suppressing vortex generation, and further reducing energy loss of the airflow during the collection and diffusion process.

[0053] Under inflow distortion conditions, this invention achieves a significant improvement in fan efficiency across all operating conditions through the synergistic effect of its core components, without affecting core aerodynamic performance. Actual test data shows that the optimized fan's aerodynamic efficiency is superior to the traditional prototype fan under different flow rates: efficiency increases by 5.58% at low flow rates, reaches a high of 12.61% at the design point, and ranges from 1% to 14% at high flow rates. Peak efficiency is more than 10% higher than traditional centrifugal fans, completely breaking the industry dilemma of "high efficiency in the laboratory, low efficiency in the field" for industrial fans. Simultaneously, the optimized fan's total pressure curve remains consistent with that of the traditional fan, proving that under the premise of a significant efficiency improvement, the fan's pressurization capacity, airflow stability, and other core aerodynamic performance characteristics remain stable, meeting the actual operational requirements of boiler flue gas exhaust. This dual guarantee of efficiency and performance stems from the precise adaptation of the structure of each component—the petal-shaped structure of the air inlet box 1 provides a uniform initial flow field for the airflow, the anti-distortion collector 2 eliminates the influence of inflow distortion on the impeller, the 60° blade outlet installation angle and profile design of the airfoil impeller 4 ensures efficient work of the airflow, and the multi-segment circular arc profile of the volute 3 realizes efficient recovery of airflow energy. The synergy of each link reduces energy loss and ultimately promotes the improvement of the overall machine efficiency.

[0054] This invention addresses the high energy consumption of traditional boiler fans by directly reducing both energy consumption and carbon emissions through efficiency improvements, aligning with the stringent national "dual-carbon" goals. From a business perspective, increased fan operating efficiency translates to reduced power consumption per unit time, effectively lowering plant electricity costs and improving economic efficiency. From an industry application perspective, the structural design of this invention is perfectly suited to the actual operating conditions of boiler exhaust—the combination of the inlet box 1 and the anti-distortion collector 2 can handle inflow distortion caused by boiler tail flue turning and limited space layout, eliminating the need for additional flue modifications or equipment layout adjustments. This significantly reduces the cost and difficulty of on-site application modifications, demonstrating strong practicality. Furthermore, the structural design of the airfoil impeller 4 and volute 3 ensures stable, low-noise operation of the fan within its high-efficiency range, reducing maintenance costs and environmental interference during operation. This provides a practical and feasible technical path for energy-saving upgrades of industrial fans and plays a crucial supporting role in promoting the national energy strategic transformation.

Claims

1. A high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion, characterized in that, It includes an air intake box (1), an anti-distortion collector (2) is provided on one side of the air intake box (1), one end of the anti-distortion collector (2) is connected to the air intake box (1), the other end of the anti-distortion collector (2) is submerged in the volute (3), and an airfoil impeller (4) is provided on the outside of the end of the anti-distortion collector (2) submerged in the volute (3).

2. The high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion as described in claim 1, characterized in that, The longitudinal section of the air intake box (1) includes an isosceles trapezoid and two circular arcs. The bottom center of the longitudinal section of the air intake box (1) spreads outward in a petal shape through the two circular arcs and connects with the two sides of the isosceles trapezoid. The two circular arcs are symmetrically arranged. The two circular arcs are respectively composed of a large circular arc and a small circular arc connected together.

3. The high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion as described in claim 2, characterized in that, The air intake box (1) has an isosceles trapezoidal top in its longitudinal section, which is the air inlet of the air intake box (1). The air outlet of the air intake box (1) is located in the middle of the two arcs at the bottom of the isosceles trapezoid.

4. The high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion as described in claim 3, characterized in that, The anti-distortion collector (2) includes a converging section and a diffuser section. The converging section is in the shape of a hollow frustum. The larger end of the converging section is connected to the outlet of the air inlet box (1), the smaller end of the converging section is connected to the diffuser section, and the outer wall of the smaller end of the converging section is connected to the volute (3).

5. The high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion as described in claim 4, characterized in that, The diffuser section has a trumpet-shaped structure. The smaller end of the diffuser section is connected to the contraction section, and the larger end of the diffuser section is connected to the airfoil impeller (4). The diffuser section is located inside the volute (3).

6. The high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion as described in claim 5, characterized in that, The airfoil impeller (4) includes a front disc and a rear disc arranged opposite to each other, and a number of blades are arranged between the front disc and the rear disc. The diameter of the airfoil impeller (4) is D1.

7. The high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion as described in claim 6, characterized in that, The length of the top side of the isosceles trapezoid in the longitudinal section of the air intake box (1) is 1.2D1-1.3D1, and the height of the air intake box (1) in the longitudinal section is 1.5D1-1.6D1.

8. The high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion according to claim 7, characterized in that, The longitudinal section of the air intake box (1) has a large arc radius of 0.5D1-0.6D1 and a small arc radius of 0.09D1-0.1D1.

9. The high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion as described in claim 8, characterized in that, The angle between the side of the contraction section and the bottom edge of the larger end face of the anti-distortion current collector (2) is 64°. The diameter of the larger end face of the contraction section in the anti-distortion current collector (2) is 0.7D1-0.8D1. The diameter of the smaller end face of the contraction section and the smaller diameter of the smaller end face of the diffusion section are 0.5D1-0.6D1. The larger diameter of the larger end face of the diffusion section is 0.5D1-0.6D1.

10. The high-efficiency centrifugal fan for boiler flue gas exhaust with inflow distortion according to claim 9, characterized in that, The circumferential profile of the volute (3) is composed of five segments of circular arcs and straight lines connected together, with the radii of each segment of circular arcs being 0.04D1-0.05D1, 0.5D1-0.6D1, 0.5D1-0.6D1, 0.7D1-0.8D1, and 0.9D1-1D1, respectively.

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