Flow guide silencing device for air outlet pipe of large fan

Abstract

The invention discloses a flow guide silencer for an air outlet pipe of a large fan, which comprises a plurality of hollow cylinders with openings at two ends, the plurality of cylinders are nested according to the size, two adjacent cylinders are connected by a plurality of connecting rib plates to form an air outlet channel, and the connecting rib plates are as long as or slightly shorter than the inner length of the cylinders; the barrel bodies comprise a sound absorption and insulation barrel located on the outermost layer, an inner sound absorption barrel located on the innermost layer and N middle sound absorption barrels arranged between the sound absorption and insulation barrel and the inner sound absorption barrel; the sectional area S defined by the two adjacent connecting rib plates and the wall of the connected cylinder meets the condition that S is larger than or equal to 0.1 m < 2 > and smaller than or equal to 0.25 m < 2 >; and air guide heads are arranged at one ends, facing the air inlet side, of the middle sound absorption cylinder, the inner sound absorption cylinder and the connecting rib plates. The sectional area defined by the two adjacent connecting rib plates and the wall of the connected cylinder is controlled, the air outlet effect is guaranteed, and the noise reduction performance can be guaranteed; and the semicircular air guide head, the circular barrel and the connecting rib plates form a sector-shaped section structure to guide air into the corresponding section, so that the noise reduction effect is very obvious.

Description

Technical Field

[0001] The invention relates to a flow guiding and silencing device for an air outlet pipe of a large fan, belonging to the technical field of noise control equipment. Background Art

[0002] Large fans, such as the primary fans in thermal power plants, primarily draw air from the atmosphere and provide energy to move it through equipment like the preheater, ultimately transporting pulverized coal into the furnace for combustion. Primary fans are divided into hot and cold primary air. The hot primary air is used to dry the pulverized coal and deliver it to the boiler burner, while the cold primary air mixes with the hot primary air to regulate the inlet and outlet temperatures of the coal mill. Because the primary fan's air duct noise exceeds standards, seriously affecting the health of production personnel and surrounding residents, noise reduction is necessary. To address this issue, we searched existing technologies and identified some solutions.

[0003] For example, CN202023288962.1 discloses that the primary fan array silencer adopts a spring shock-absorbing array structure, which has a complex structure, and the spring shock absorption of the silencer is essentially ineffective. The vibration noise of the primary fan cannot be solved by an external silencer.

[0004] Another example is CN202022972032.1, which describes a silencer that effectively reduces primary fan noise. The silencer is fixed to one side of the flue air inlet and comprises a rectangular frame with multiple vertically fixed silencer panels facing the air outlet. Silencer panels are also evenly fixed to the inner wall of the flue between the primary fan and the silencer, and the outer circumference of the flue is also wrapped with silencer cotton. This technical solution targets the air inlet, not the outlet, and uses a square frame structure with silencer panels, making it unsuitable for outlet structures.

[0005] For example, CN201721216301.3 describes a comprehensive fan noise reduction system, which includes a detachable lightweight flexible noise reduction system 7, a duct acoustic wrapping system 8, a microporous rock muffler 9, and a soundproofing cover 10, respectively, to control the noise from the axial fan body 1, the air duct 2, the air inlet 6 of the air inlet duct 4, and the motor 3. However, for outlet duct noise, only the duct acoustic wrapping system 8 is used. This technology ensures the air outlet effect, but it cannot solve the problem of excessive outlet duct noise.

[0006] Another example is CN201610387317.4, a method for controlling fan noise in a thermal power plant, which decomposes the fan noise into at least the following four parts for control: First, an air inlet silencer is set at the air inlet of the fan, and a sound-absorbing and insulating structure is covered on the air inlet duct between the air inlet and the fan; Second, an air outlet silencer is set at the air outlet, and a sound-absorbing and insulating structure is covered on the air outlet duct between the air outlet and the fan; Third, a sound-absorbing and insulating chamber is made, and the fan body is placed in the sound-absorbing and insulating chamber; Fourth, a sound-absorbing and insulating room is made, and the motor is placed in the sound-absorbing and insulating room, and the sound-absorbing and insulating room is provided with an air inlet directly opposite to the motor heat dissipation fan and on the connecting surfaces on both sides of the directly opposite side, an air inlet silencer is set on the air inlet, an air outlet and a forced air outlet are set on the top surface of the sound-absorbing and insulating room on the output side of the motor shaft, and an air outlet silencer is set on the air outlet and the forced air outlet.

[0007] A search revealed that existing noise reduction and flow diversion structures typically involve installing deflector plates (sheets) within the muffler. For large fans, this structure presents a problem when simultaneously achieving both flow diversion and noise reduction: while noise reduction is achieved, it impacts the flow of primary air, thus hindering the drying and transport of pulverized coal, which is unacceptable. However, while primary air flow is maintained, noise reduction is insufficient, making it impossible to achieve standard emissions. Summary of the Invention

[0008] According to the customer's technical requirements and in view of the above-mentioned problems in the existing technology, our company organized R&D personnel to tackle the problems and finally came up with a diversion and silencer device for the air outlet duct of large fans, which can solve the problems of diversion and noise reduction at the same time.

[0009] The present invention aims to solve the above-mentioned problems in the prior art and provides a flow guide and silencer device for the air outlet duct of a large fan, comprising a plurality of hollow cylinders with openings at both ends, wherein the plurality of cylinders are nested according to size, and two adjacent cylinders are connected by a plurality of connecting ribs to form an air outlet channel, wherein the connecting ribs are equal to or slightly shorter than the length of the cylinder interior; the plurality of cylinders include a sound-absorbing and isolating cylinder located in the outermost layer, an inner sound-absorbing cylinder located in the innermost layer, and N intermediate sound-absorbing cylinders (N≥1) arranged between the sound-absorbing and isolating cylinders and the inner sound-absorbing cylinders; the cross-sectional area S enclosed by two adjacent connecting ribs and the walls of the connected cylinders satisfies 0.1m 2 ≤S≤0.25m 2 Air guides are installed on the middle and inner sound-absorbing tubes, as well as on the air inlet side of the connecting ribs. To achieve the primary fan's function of drying and conveying pulverized coal into the furnace, it is necessary to ensure both air volume and pressure while meeting noise reduction requirements. The silencer structure must ensure effective ventilation. Therefore, a structure with nested hollow cylinders and controlled ribs defining the cross-sectional area is adopted to maximize the sound-absorbing area while reducing wind resistance, thus simultaneously solving the challenges of air diversion and noise reduction.

[0010] Furthermore, the air guide is semicircular in shape. The function of the semicircular air guide is to allow the incoming air to better bypass obstacles in an arc and be dispersed into the sound absorption channel, which does not hinder the passage of airflow and helps reduce noise.

[0011] Furthermore, the hollow cylinder is a hollow cylinder, and the cross-sectional area S of the inner sound-absorbing cylinder is 内 Meet 0.125m 2 ≤S 内 ≤0.25m 2 .

[0012] Furthermore, the connecting ribs between two adjacent cylinders are evenly distributed with the cylinder center as the center, forming a fan-shaped cross-section structure with the circular cylinder. The even distribution can better achieve even dispersion of the airflow.

[0013] Furthermore, the connecting rib plate is made of two aluminum alloy perforated plates, sound absorbing material is filled between the two perforated plates, the two ends of the two perforated plates are connected by non-porous end plates, and the two sides of the two perforated plates are connected to the corresponding hollow cylinders.

[0014] Furthermore, the inner sound absorbing tube and the middle sound absorbing tube both include an inner aluminum alloy perforated plate and an outer aluminum alloy perforated plate, as well as sound absorbing material filled between the inner aluminum alloy perforated plate and the outer aluminum alloy perforated plate, and both ends of the inner aluminum alloy perforated plate and the outer aluminum alloy perforated plate are connected by non-porous end plates.

[0015] Furthermore, the sound-absorbing and insulating tube includes an outer sound insulation board and an inner aluminum alloy perforated board, and a sound-absorbing material filled between the inner aluminum alloy perforated board and the outer sound insulation board.

[0016] Furthermore, the length of the hollow cylinder is greater than the outer diameter of the sound-absorbing and isolating cylinder. It is necessary to consider the comprehensive requirements of the silencing area, exhaust volume and air pressure at the same time.

[0017] Furthermore, the length of the hollow cylinder is 1.5 to 3 times the diameter of the outer wall of the sound-absorbing and insulating cylinder.

[0018] The beneficial effects of the present invention compared to the prior art are: 1. Control the cross-sectional area enclosed by the two adjacent connecting ribs and the connected cylinder wall to ensure both the air outlet effect and the noise reduction performance; 2. A semicircular air guide head is used to form a fan-shaped cross-section structure with the circular cylinder and the connecting rib plate. Adjacent air guide heads guide the wind into the corresponding cross-sections and influence each other, so that the sound waves enter the sound-absorbing material from the sound-absorbing perforated plate and obtain sufficient energy consumption, and the noise reduction effect is very obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of Example 1 of the present invention; Figure 2 This is a schematic diagram of the connecting ribs and wind guide structure of Example 1 of the present invention; In the figure: 1. Sound-absorbing tube, 2. Connecting ribs, 3. Middle sound-absorbing tube, 4. Inner sound-absorbing tube, 5. Wind guide. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Example

[0021] like Figure 1 、 2 The device is shown as a flow guide and silencer for a large fan outlet duct. The device comprises four hollow cylinders with openings at both ends. The four cylindrical hollow cylinders are nested according to size, and two adjacent cylinders are connected by a plurality of connecting ribs 2 to form an outlet channel. The four cylindrical hollow cylinders include a sound-absorbing and isolating cylinder 1 located in the outermost layer, an inner sound-absorbing cylinder 4 located in the innermost layer, and two intermediate sound-absorbing cylinders 3 disposed between the sound-absorbing and isolating cylinders 1 and the inner sound-absorbing cylinders 4. The cross-sectional area enclosed by two adjacent connecting ribs 2 and the walls of the connected cylinders is 0.24 m2. 2 The wind guide 5 is set at the middle sound absorbing tube 3, the inner sound absorbing tube 4, and the end of the connecting rib 2 facing the air inlet side. The wind guide 5 is semicircular, and the cross-sectional area of ​​the inner sound absorbing tube is 0.25m 2 The connecting ribs (2) between two adjacent cylinders are evenly spaced about the center of the cylinder, forming a fan-shaped cross-section. The length of the hollow cylinder is twice the outer diameter of the sound-absorbing and sound-isolating cylinder. The length of the hollow cylinder and the outer diameter of the sound-absorbing and sound-isolating cylinder ensure ventilation volume and wind pressure, while also providing sufficient sound-absorbing length and space to ensure effective sound absorption.

[0022] The connecting rib plate 2 is made of two aluminum alloy perforated plates, the space between the two perforated plates is filled with sound absorbing material, the two ends of the two perforated plates are connected by non-porous end plates, and the two sides of the two perforated plates are connected to the corresponding hollow cylinders.

[0023] The inner sound absorbing tube 4 and the middle sound absorbing tube 3 both include an inner aluminum alloy perforated plate and an outer aluminum alloy perforated plate, as well as sound absorbing material filled between the inner aluminum alloy perforated plate and the outer aluminum alloy perforated plate. Both ends of the inner aluminum alloy perforated plate and the outer aluminum alloy perforated plate are connected by non-porous end plates.

[0024] The sound-absorbing tube 1 includes an outer sound insulation board and an inner aluminum alloy perforated board, as well as a sound-absorbing material filled between the inner aluminum alloy perforated board and the outer sound insulation board. A keel connection can be provided between the outer sound insulation board and the inner aluminum alloy perforated board according to strength requirements.

[0025] The above embodiments are merely explanations and illustrations of the technical solution of the present invention and are not intended to limit the scope of protection of the technical solution of the present invention. All simple variations based on this solution fall within the scope of protection of the present invention.

Claims

1. A flow guide and silencer device for a large fan outlet duct, characterized by: It includes a number of hollow cylinders with openings at both ends, which are nested according to their sizes. Two adjacent cylinders are connected by a number of connecting ribs to form an air outlet channel. The connecting ribs are equal to or slightly shorter than the length of the cylinder. The cylinders include a sound-absorbing and isolating cylinder located in the outermost layer and an inner sound-absorbing cylinder located in the innermost layer, as well as N intermediate sound-absorbing cylinders (N≥1) arranged between the sound-absorbing and isolating cylinders and the inner sound-absorbing cylinders. The cross-sectional area S enclosed by two adjacent connecting ribs and the connected cylinder wall meets the requirement of 0.1m 2 ≤S≤0.25m 2 ; An air guide is provided on the middle sound absorbing tube, the inner sound absorbing tube, and the end of the connecting rib facing the air inlet side.

2. The flow guide and silencer device for the air outlet duct of a large fan according to claim 1, characterized in that: The air guide head is semicircular.

3. The flow guide and silencer device for the air outlet duct of a large fan according to claim 1, characterized in that: The hollow cylinder is a hollow cylinder, and the cross-sectional area S of the inner sound-absorbing cylinder is 内 Meet 0.125m 2 ≤S 内 ≤0.25m 2 .

4. The flow guide and silencer device for the air outlet duct of a large fan according to claim 3, characterized in that: The connecting ribs between two adjacent cylinders are evenly distributed with the center of the cylinder as the center, forming a fan-shaped cross-section structure with the circular cylinder.

5. The flow guide and silencer device for the air outlet duct of a large fan according to claim 1, characterized in that: The connecting rib plate is made of two aluminum alloy perforated plates, the space between the two perforated plates is filled with sound absorbing material, the two ends of the two perforated plates are connected by non-porous end plates, and the two sides of the two perforated plates are connected to the corresponding hollow cylinders.

6. The flow guide and silencer device for the air outlet duct of a large fan according to claim 1, characterized in that: The inner sound absorbing tube and the middle sound absorbing tube both include an inner aluminum alloy perforated plate and an outer aluminum alloy perforated plate, as well as sound absorbing material filled between the inner aluminum alloy perforated plate and the outer aluminum alloy perforated plate. Both ends of the inner aluminum alloy perforated plate and the outer aluminum alloy perforated plate are connected by non-porous end plates.

7. The flow guide and silencer device for the air outlet duct of a large fan according to claim 1, characterized in that: The sound-absorbing and insulating tube comprises an outer sound insulation board, an inner aluminum alloy perforated board, and a sound-absorbing material filled between the inner aluminum alloy perforated board and the outer sound insulation board.

8. The flow guide and silencer device for the air outlet duct of a large fan according to claim 1, characterized in that: The length of the hollow cylinder is greater than the outer wall diameter of the sound-absorbing and sound-isolating cylinder.

9. The flow guide and silencer device for the air outlet duct of a large fan according to claim 8, characterized in that: The length of the hollow cylinder is 1.5 to 3 times the diameter of the outer wall of the sound-absorbing and sound-insulating cylinder.

Images