Efficient high-pressure centrifugal fan for papermaking

Abstract

The invention discloses an efficient high-pressure centrifugal fan for papermaking, belongs to the technical field of centrifugal fans, and solves the problems of remarkable efficiency attenuation and large pressure fluctuation under the high-pressure working condition in the prior art. The efficient high-pressure centrifugal fan comprises a volute (10), a flow collector (13) is fixedly arranged in the volute (10), and the air outlet end of the flow collector (13) is connected with an impeller (11); a shaft disc (12) is fixedly connected to a shaft core of the impeller (11), the blades (22) are arranged in the impeller (11), the diameter of the front end of each blade (22) is smaller than that of the rear end of each blade (22), and the front end and the rear end of each blade (22) are connected through a curve plane; the vaneless diffuser (31) is arranged on the periphery of the impeller (11) in a protruding mode and used for converting kinetic energy of airflow into static pressure energy, and the technical effect of improving the efficiency and stability of the centrifugal fan is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of centrifugal fan, and particularly relates to a high-efficiency high-pressure centrifugal fan for papermaking. BACKGROUND

[0002] The centrifugal fan is the core equipment of the paper pulp drying and hot air circulation system in the papermaking industry, and needs to continuously transport high-temperature and high-humidity airflow under high pressure. However, the traditional centrifugal fan faces significant challenges under high pressure conditions: the straight blade design leads to aggravated airflow separation and secondary flow loss, and the operating efficiency rapidly decays with the increase of pressure; the volute diffuser structure is not adapted to the high-pressure diffusion demand, the outlet pressure fluctuates greatly, and the drying uniformity is affected; the conventional sealing scheme is difficult to block the leakage of hot and humid gas, and the shaft system failure rate is significantly increased. Although the existing technology attempts to improve the performance through structural complexity or material replacement, it is difficult to be practically used due to high maintenance cost or insufficient aerodynamic efficiency. Therefore, a high-pressure centrifugal fan that takes into account high efficiency, stability and low maintenance is urgently needed to break through the technical bottleneck of high-pressure gas transportation in the papermaking industry. SUMMARY

[0003] In view of the problems of significant efficiency decay and large pressure fluctuation under high pressure conditions in the prior art, the application provides a high-efficiency high-pressure centrifugal fan for papermaking, which aims to improve the efficiency and stability of the centrifugal fan The technical scheme adopted by the application is as follows: A high-efficiency high-pressure centrifugal fan for papermaking, comprising a volute, a flow collector fixedly arranged inside the volute, and an impeller connected to the outlet end of the flow collector, wherein the shaft core of the impeller is fixedly connected with a shaft disc, and further comprising: Blades: a plurality of blades are arranged in the impeller, the front end diameter of the blade is smaller than the rear end diameter, and the front end and the rear end of the blade are connected by a curved surface; Vaneless diffuser section: the vaneless diffuser is protrudingly arranged at the peripheral portion of the impeller, and is used for converting the kinetic energy of the airflow into static pressure energy.

[0004] By the cooperative design of the flow collector, the impeller, the vaneless diffuser section and the volute, the energy conversion and the conveying path of the high-pressure airflow are optimized. The impeller adopts radial blades, the front end diameter of the blade is smaller than the rear end diameter, the inlet angle and the outlet angle are optimized based on the aerodynamic load, and the three-dimensional composite curved line is used to suppress airflow separation and reduce secondary flow loss, so that the total pressure efficiency is improved to 78.58%.

[0005] The impeller comprises: Front end cover: the front end cover is arranged at the front portion of the blade, and the front end cover is attached to the front curve of the blade; Rear end cover: the rear end cover is arranged at the rear portion of the blade; The vaneless diffuser protrudes from the peripheral portion of the front end cover and the rear end cover.

[0006] The vaneless diffuser is of a constant inner diameter structure.

[0007] The volute is of a gradually expanding inner diameter structure.

[0008] The outlet angle of the vane is 90°.

[0009] In the above scheme, the outlet angle of the vane of the curve structure in the top view is 90°, and the vane of this structure can effectively reduce the secondary flow loss of the airflow to ensure the efficiency of the centrifugal fan.

[0010] The shaft disc is fixedly connected with the impeller through rivets.

[0011] A through groove is arranged at the shaft core of the shaft disc, and the driving device is connected to the shaft disc through the through groove.

[0012] The side portion of the collector is of an arc structure, and the distance from the side wall of the collector to the shaft core gradually decreases.

[0013] In the above scheme, the collector of the arc side wall structure can ensure that the high-temperature gas uniformly enters the impeller, and the gradually tapered structure can reduce the loss of inlet turbulence.

[0014] As the above technical scheme is adopted, the present application has the following beneficial effects: 1. The energy conversion and conveying path of the high-pressure airflow are optimized through the collaborative design of the collector, the impeller, the vaneless diffuser and the volute. The impeller adopts radial vanes, the front end diameter of the vane is smaller than the rear end diameter, the flow line type curved surface is smoothly transitioned, the inlet angle and the outlet angle are optimized and designed based on the aerodynamic load, the three-dimensional composite curve line is combined to suppress airflow separation and reduce secondary flow loss, and the total pressure efficiency is improved to 78.58%.

[0015] 2. The outlet angle of the vane of the curve structure in the top view is 90°, and the vane of this structure can effectively reduce the secondary flow loss of the airflow to ensure the efficiency of the centrifugal fan.

[0016] 3. The collector of the arc side wall structure can ensure that the high-temperature gas uniformly enters the impeller, and the gradually tapered structure can reduce the loss of inlet turbulence. BRIEF DESCRIPTION OF DRAWINGS

[0017] The present application will be described by examples and with reference to the accompanying drawings, in which: Figure 1 is a side view structure schematic diagram of the present application; Figure 2 is an impeller side section view of the present application.

[0018] Figure 3 is a schematic view of the internal structure of the impeller from the top view of the present application; Reference numerals: 10-volute; 11-impeller; 12-shaft disc; 13-collector; 14-air outlet; 15-rivets; 16-through slot; 20-front end cover; 21-rear end cover; 22-vane; 31-vaneless diffuser; DETAILED DESCRIPTION

[0019] All features disclosed in this specification, and / or all steps of any methods or processes disclosed in this specification, can be combined in any combination, except combinations where at least some of the features and / or steps are mutually exclusive.

[0020] The following will be described in detail Figures 1-3 with reference to the drawings.

[0021] Example One: A high-efficiency high-pressure centrifugal fan for papermaking comprises a volute 10, a collector 13 fixedly arranged inside the volute 10, and an impeller 11 connected to the air outlet end of the collector 13. The shaft core of the impeller 11 is fixedly connected with a shaft disc 12, and further comprises: A plurality of vanes 22 are arranged in the impeller 11, the front end diameter of the vane 22 is smaller than the rear end diameter, and the front end and the rear end of the vane 22 are connected by a curved plane. A vaneless diffuser 31 is protrudingly arranged at the peripheral portion of the impeller 11, for converting the kinetic energy of the airflow into static pressure energy.

[0022] The impeller 11 comprises: A front end cover 20 is arranged at the front portion of the vane 22, and the front end cover 21 is attached to the front curve of the vane 11. A rear end cover 21 is arranged at the rear portion of the vane 22. The vaneless diffuser 31 is protrudingly arranged at the peripheral portion of the front end cover 20 and the rear end cover 21.

[0023] The vaneless diffuser 31 has a constant inner diameter structure.

[0024] The volute 10 has a gradually expanding inner diameter structure.

[0025] The outlet angle of the vane 22 is 90°.

[0026] The shaft disc 12 is fixedly connected with the impeller 11 by rivets 15.

[0027] A through slot 16 is arranged at the shaft core of the shaft disc 12, and a driving device is connected with the shaft disc 12 through the through slot 16.

[0028] The side portion of the collector 13 has an arc-shaped structure, and the distance from the side wall of the collector 13 to the shaft core gradually decreases.

[0029] The working principle of the present application is as follows: high-temperature gas enters the flow collector 13 from the drying section of the paper machine, uniformly enters the inlet of the impeller 11 after being guided, the impeller 11 rotates at 1730 r / min, the gas is accelerated along the radial direction under the action of centrifugal force, and the flow separation area is reduced when the high-speed airflow flows through the streamlined curved surface; the high-speed airflow enters the vaneless diffuser section 31, and the stable conversion of kinetic energy to static pressure energy is realized through the boundary layer effect in the constant cross-section flow channel, and the static pressure is increased; the airflow then enters the spiral flow channel of the volute 10, the gradual expansion angle design makes the flow velocity uniformly decrease and the turbulent intensity decrease, and finally the airflow is discharged through the high-pressure air outlet 14 with small pressure fluctuation.

[0030] In the present embodiment, the driving device is a motor, the output shaft of the motor is fixedly connected at the through groove 16 of the shaft disc 12, and drives the shaft disc 12 and the impeller 11 to rotate.

[0031] From the optimization of airflow flow characteristics, the unique structure that the front end diameter of the S-shaped blade is smaller than the rear end diameter and is smoothly connected by a curved plane can form precise flow guiding and restraining effect on the high-temperature and high-humidity airflow entering the impeller. When the airflow enters the impeller from the flow collector, it first contacts the arc-shaped curved surface of the front end of the blade. This curved surface design can effectively reduce the impact loss at the inlet of the airflow. The traditional straight plate blade is prone to cause severe turbulent flow and separation phenomenon at the inlet under high-pressure working condition, while the streamlined front end of the S-shaped blade can guide the airflow to smoothly transition along the blade surface, making the airflow velocity gradient distribution more uniform, avoiding the generation of local turbulent vortex, and significantly reducing the area of airflow separation region. With the airflow flowing along the blade curved surface to the rear end, the S-shaped structure with gradually increasing diameter will continuously and stably accelerate the airflow, and under the synergistic action of centrifugal force and blade thrust, the airflow obtains uniformly increasing kinetic energy, ensuring the flow continuity of the airflow in the impeller channel, and greatly reducing the energy loss caused by airflow disturbance.

[0032] In terms of energy conversion efficiency improvement, the curved plane design of the S-shaped blade lays a solid foundation for efficient conversion of kinetic energy to static pressure energy. The smooth curved transition from the front end to the rear end of the blade enables the airflow to maintain a stable velocity field and pressure field during the flow process, avoiding the energy loss concentration phenomenon caused by structural mutation of the traditional blade. In particular, the blade outlet angle is designed to be 90°, which perfectly matches the S-shaped curved surface. When the airflow reaches the blade outlet, it can enter the vaneless diffuser section at the optimal angle, maximizing the transfer of kinetic energy obtained in the impeller to the diffuser for static pressure conversion. Experimental data show that the total pressure efficiency of the centrifugal fan with S-shaped blade is improved to 78.58%, which is much higher than that of the traditional structure fan, which means that under the same driving power, the blade structure can output higher effective air pressure and air volume, significantly reducing the energy consumption per unit air volume, and perfectly adapting to the high-pressure and large-flow working condition requirements of the paper industry.

[0033] From the perspective of enhanced operational stability, S-shaped blades effectively address the technical challenge of large pressure fluctuations in traditional fans under high-pressure conditions. Because S-shaped blades can achieve uniform acceleration and stable flow guidance of the airflow, the pressure pulsation amplitude of the airflow at the fan outlet is significantly reduced. In the pulp drying and hot air circulation systems of papermaking, stable air pressure output is crucial. Excessive pressure fluctuations can lead to uneven distribution of the drying medium, affecting the drying quality and consistency of the paper. By optimizing the flow state of the airflow within the impeller, the S-shaped blades maintain a high degree of consistency in the airflow parameters within each blade channel, avoiding the alternating pressure peaks and valleys caused by airflow disturbances. At the same time, the uniform airflow load distribution also reduces the alternating stress on the blades, reduces the blade vibration amplitude, extends the fatigue life of the blades, and reduces the risk of equipment downtime due to blade failure.

[0034] In terms of wear resistance and adaptability, the streamlined structure of the S-shaped blades reduces the impact wear of impurity particles in the airflow on the blade surface. Conventional straight blades are susceptible to severe localized wear and tear when subjected to high-speed airflow. However, the smooth curve of the S-shaped blades allows particles to flow smoothly along the blade surface, reducing the force and frequency of particle-blade collisions. Experiments have confirmed that even after long-term continuous operation, there is no noticeable wear or scaling on the blade surface. This significantly improves the fan's operational reliability and maintenance intervals in the high-humidity, impurity-laden airflow environments of the papermaking industry.

[0035] Furthermore, the S-shaped blade's seamless fit with the impeller's front and rear covers further enhances its technical effectiveness. The close fit between the front cover and the blade's front curve creates a closed airflow channel, effectively preventing air leakage through the gap between the blade and the cover, reducing energy loss caused by short-circuiting. The supporting function of the rear cover ensures the S-shaped blade's structural stability under high-speed rotation and high-pressure conditions, preventing the degradation of aerodynamic performance caused by blade deformation due to stress. This integrated structural design fully utilizes the aerodynamic advantages of the S-shaped blade, creating a synergistic effect with structures such as the vaneless diffuser and the progressively expanding volute, creating an efficient and stable high-pressure airflow delivery system.

[0036] In summary, the S-shaped blades have many technical advantages, such as optimizing airflow characteristics, improving energy conversion efficiency, enhancing operational stability, and improving wear resistance. They have comprehensively overcome the efficiency degradation and pressure fluctuation problems of traditional centrifugal fans under high-pressure conditions, and provide core equipment performance guarantee for pulp drying and hot air circulation systems in the papermaking industry. The fan is assembled with the impeller 11 as the center, and the driving device drives the impeller 11 to rotate through the transmission shaft. The welding process of the impeller 11 and the front end cover 20 and the rear end cover 21 ensures the structural strength, and the blade tip gap is calibrated by a three-coordinate measuring instrument, and the assembly error is ≤0.1mm. The performance test data is shown in Table 1. Under the standard working condition, the fan volumetric flow is 12548m 3 / h, the total pressure efficiency reaches 78.58% (No. 5), the noise level is 92.8dB(A), and it fully meets the requirements of the papermaking process. The experiment shows that there is no obvious wear or fouling on the surface of the blade 22 during continuous long-time operation. The following table is the centrifugal fan performance data measured in the experiment: Serial number Volumetric flow Fan static pressure Fan pressure Shaft power Impeller power A sound level Fan efficiency qvsg1Gu psfCGu pfCGu PaGu PrGu LAGu ηrC (m 3 / h)]]> (Pa) (Pa) (kW) (kW) [dB(A)] (%) 1 20389.80 2142.5 2589.4 26.640 25.308 100.7 57.58 2 18874.48 2705.5 3097.1 25.707 24.421 97.7 65.92 3 17265.89 3133.1 3471.3 24.447 23.225 96.4 70.96 4 16005.73 4065.0 4381.7 26.349 25.032 95.0 76.79 5 12548.36 3930.1 4140.8 19.089 18.134 92.8 78.58 6 10588.97 4124.8 4292.5 17.325 16.459 91.1 75.72 7 8863.46 4328.3 4466.0 15.369 14.601 90.6 74.31 8 7614.29 4411.0 4527.9 14.021 13.320 90.6 70.96 9 5276.07 4380.2 4457.5 11.556 10.978 92.3 58.85 10 3999.34 4267.7 4324.1 9.732 9.245 91.9 51.48 As Figure 1 shown, the impeller 11 includes a hub, 12 radial blades 22 and a flow guide structure, the center of the impeller 11 is fixedly connected with the driving device through the shaft disc 12, and the flow guide structure is fixed with the rear end of the hub to ensure smooth transition of the airflow. The structure of the centrifugal fan is verified by CFD simulation that the flow field distribution is uniform and the pressure recovery effect is significant.

[0037] The embodiment optimizes the airflow path and component collaborative design, realizes the flow ≥8000m 3 / h, the total pressure efficiency can reach 78.58%, and the pressure fluctuation is small, which meets the requirements of the papermaking industry for high-efficiency and stable airflow delivery.

[0038] The above-described embodiments only express the specific implementation of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the protection scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the technical scheme concept of the present application, a number of modifications and improvements can be made, which are within the protection scope of the present application.

Claims

1. A high-efficiency, high-pressure centrifugal fan for papermaking, comprising a volute (10), a collector (13) fixedly provided inside the volute (10), an impeller (11) connected to the air outlet end of the collector (13), a shaft disc (12) fixedly connected to the shaft core of the impeller (11), characterized in that: Also includes: Blades (22): a plurality of blades (22) are provided in the impeller (11), and the front diameter of the blades (22) is smaller than the rear diameter, and the front and rear ends of the blades (22) are connected by a curved plane; Bladeless diffuser section (31): The bladeless diffuser (31) is protrudingly arranged on the periphery of the impeller (11) and is used to convert the kinetic energy of the airflow into static pressure energy.

2. The high-efficiency and high-pressure centrifugal fan for papermaking according to claim 1, characterized in that: The impeller (11) comprises: Front end cover (20): the front end cover is arranged at the front of the blade (22), and the front end cover (21) is fitted with the front curve of the blade (11); Rear end cover (21): the rear end cover is arranged at the rear of the blade (22); The bladeless diffuser (31) is protrudingly arranged on the periphery of the front end cover (20) and the rear end cover (21).

3. The high-efficiency and high-pressure centrifugal fan for papermaking according to claim 1, characterized in that: The bladeless diffuser section (31) is a structure with a constant inner diameter.

4. The high-efficiency and high-pressure centrifugal fan for papermaking according to claim 1, characterized in that: The volute (10) has a gradually expanding inner diameter structure.

5. The high-efficiency and high-pressure centrifugal fan for papermaking according to claim 1, characterized in that: The outlet angle of the blade (22) is 90°.

6. The high-efficiency and high-pressure centrifugal fan for papermaking according to claim 1, characterized in that: The shaft disc (12) is fixedly connected to the impeller (11) via rivets (15).

7. The high-efficiency and high-pressure centrifugal fan for papermaking according to claim 1, characterized in that: A through slot (16) is provided at the shaft core of the shaft disc (12), and the shaft disc (12) is connected to a driving device via the through slot.

8. The high-efficiency and high-pressure centrifugal fan for papermaking according to claim 1, characterized in that: The side of the current collector (13) is an arc-shaped structure, and the distance from the side wall of the current collector (13) to its axis gradually decreases.

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