In the industrial dust removal system and ventilation system, in order to make the gas in a specific location pass through the centrifugal fan to be discharged from the room smoothly, it is necessary to use the pipeline as the gas transportation carrier. Fan performance has a greater impact.
1)Installation requirements for inlet and outlet pipes of centrifugal fans
1. Installation requirements for air outlet pipes
(1) Diffuser tube: When the centrifugal fan outlet is directly exposed to the atmosphere without a connecting pipe, a diffuser tube with a taper is usually installed at the fan outlet to avoid pressure loss and airflow disturbance. The taper of the diffuser is about 15, the height is equal to 1°, and 1.5 times the width of the fan outlet.
(2) Exhaust elbow: When the elbow is installed at the air outlet of the centrifugal fan, the bending direction of the elbow should be consistent with the rotation direction of the fan blade, and it is recommended to install a circular arc separation at the bending of the pipeline. Plate, which can improve the working conditions of the airflow, thereby reducing the pressure loss of the system.
2. Installation requirements for air inlet pipes
(1) Square air inlet chamber: When the centrifugal fan is installed with a square air inlet chamber, an arc-shaped separation plate should be installed at the bend of the air inlet chamber, a deflector should be installed at the air inlet, and the air chamber should be Make it as large as possible, so as to prevent the airflow from forming a vortex in the air chamber, reduce the pressure loss, and reduce the noise of the system.
(2) Circular intake duct: When a circular duct is installed at the air inlet of a centrifugal fan, the duct should be directly and smoothly connected to the fan, so as to avoid the reduction of the flow area caused by the curved duct , and the resulting turbulent zone and pressure loss, reduce system noise.
3. Other ventilation duct installation specifications
(1) Obstacles at the air outlet: When there are obstacles in the air inlet and outlet of the centrifugal fan, the back resistance will disturb the airflow to the fan, resulting in disturbance of the air flow, thereby increasing the system resistance, reducing the flow rate and increasing the noise. Ensure a distance of at least 1.5 times the diameter of the pipe between the air inlet and outlet and the obstacle.
(2) Pipeline inlet and outlet protection: In order to prevent external sundries from being sucked into the pipeline and causing the pipeline to be blocked, making the entire pipeline system unable to operate normally, safety nets are required to be installed at the pipeline inlet and outlet.
(3) Pipe connection: The pipe network connection of the centrifugal fan and fan should be stable, and the weight of the pipe should not be added to each part of the fan.
(4) Pipeline regulating door: When the regulating door is installed in the pipeline, the air inlet regulating door should be closed before the fan is turned off, the air outlet regulating door should be slightly opened, and the regulating door should be gradually opened after the fan runs normally.
2)the centrifugal fan pipeline layout specification
1. The centrifugal fan used in the dust removal system should not have too many exhaust points in the pipeline arrangement, so as to facilitate the balance of resistance between the branch pipes. If there are many exhaust points, a large-section manifold can be used to connect each branch pipe. The flow velocity in the collecting pipe should not exceed 3m/s, and the lower part of the collecting pipe is equipped with an ash unloading device.
2. The pipes for dust removal should be laid vertically or inclined as much as possible, and the angle between them and the horizontal plane should be greater than 45° as far as possible. If it is necessary to lay horizontally or the inclination angle is less than 30°, measures should be taken, such as increasing the flow rate, setting up a cleaning port, etc.
3. When conveying gas containing steam and mist droplets, the centrifugal fan exhaust pipe should have a slope of not less than 0.005 to remove the accumulated liquid, and a water-sealed drain pipe should be installed at the tight low point of the pipe and the bottom of the fan.
4. In the dust removal system, in order to prevent the centrifugal fan pipeline from being blocked, the diameter of the pipeline varies according to the particle size of the dust. When discharging fine dust, the diameter of the pipeline should not be less than 80mm; when discharging coarse dust (such as sawdust), the diameter of the pipeline should not be less than 80mm. Less than 100mm; when discharging coarse dust (with small objects), the diameter of the pipe should not be less than 130mm.
5. Exclude positive pressure pipes containing highly toxic substances and should not pass through other rooms.
6. Necessary adjustment and measurement devices (such as valves, pressure gauges, thermometers, air volume measuring holes and sampling holes, etc.) should be set on the fan pipeline, or the interface for installing the measuring device should be reserved. Adjusting and measuring devices should be located where they are easy to operate and observe.
7. The piping layout of the centrifugal fan should be straight and avoid complicated local pipe fittings. Pipe fittings such as elbows and tees should be arranged properly, and the connection with the pipeline should be reasonable to reduce resistance and noise.