Selection and application of fan performance (I) Description of fan performance: 1. № 10, 12, 16, 20 are converted according to dimensionless performance of № 10 model. 2. № 5, 6, 8 are converted according to dimensionless performance of № 5 model. 3. № 5 and below shall be determined according to the performance of the measured prototype. Note: According to the dimensionless performance curve conversion formula, total pressure H=ρ u2 H (Pa) flow Q=900 π D22 uQ (m3/h) shaft power N=N × D22u3 ρ/4000 (kw), where D2 - impeller outer diameter (m) u - impeller outer edge linear speed (m/s) ρ - gas density (Kg/m3), the required power rate shall be based on shaft power plus mechanical loss and motor reserve. 4. The solid line is № 5 model, and the dotted line is № 10 model. The performance of the fan is expressed by the flow, total pressure, main shaft speed, shaft power, efficiency and other parameters of the fan, and there are certain relationships between the parameters, which are listed in the following table. The relationship of fan performance parameters changes density ρ, speed n changes speed n, atmospheric pressure P, gas temperature t Q1/Q2=n1/n2 H1/H2=(n1/n2) 2 ρ 1/ρ 2 N1/N2=(n1/n2) 3 ρ 1/ρ 2 η 1=η 2 Q1/Q2=n1/n2 H1/H2=(n1/n2) 2 (P1/P2) (273+t2/273+t1) N1/N2=(n1/n2) 3 (P1/P2) (273+t2/273+t1) η 1=η 2 Note: 1. In the middle, Q represents flow (m3/h), H represents total pressure (Pa), N represents shaft power (kw), η represents full pressure efficiency, ρ represents density (kg/m3), t represents temperature (℃), n represents speed (r/min), and P represents atmospheric pressure (Pa). 2. The footnote symbol 2 indicates the known performance and related parameters, and the footnote symbol 1 indicates the required performance and related parameters. （

The selection basis of wet dust collector is as follows. ① customized Dust exhaust centrifugal fan Dust removal efficiency. Whether the efficiency of wet dust collector is high or not is one of the most important performance indicators to be selected. Under certain conditions, the gas flow, specific dust pollutants, and the gas state have a direct impact on the collection efficiency. ② Operational flexibility. Dust exhaust centrifugal fan company Any operating equipment shall consider its negative flow, and the impact on the capture efficiency when the air flow exceeds or is lower than the design value; Similarly, it is necessary to know how to operate when the dust concentration is unstable or continuously higher than the design value. ③ Hydrophobicity. The purification efficiency of wet dust collector for hydrophobic dust is not high, and generally it is not suitable for the operation at the design value. ④ Adhesion. Wet dust collector can purify cohesive dust, but flushing and cleaning shall be considered to prevent blockage, ⑤ corrosiveness. Anticorrosion measures shall be considered when purifying corrosive gas, ⑥ water consumption. How much water is consumed by the dust remover, sewage treatment and anti freezing measures for water in winter. ⑦ Mud treatment. Mud treatment is an inevitable problem for wet dust collectors, and efforts should be made to reduce the harm of pollution. ⑧ Operation and maintenance. Guangzhou Dust exhaust centrifugal fan company Generally, moving or rotating parts inside the dust remover shall be avoided, and it shall be noted that if the gas passes through the channel section too small, it will cause blockage.

The fan is allowed to start at full voltage or at reduced voltage, but it should be noted that the current at full voltage starting is about 5~7 times the rated current, and the reduced voltage starting torque is proportional to the square of the current. When the grid capacity is insufficient, the reduced voltage starting should be used. (When the power is greater than 11KW, it is advisable to adopt the step-down starting.) When the fan is in test run, Dust exhaust centrifugal fan company Carefully read the product manual and check whether the wiring method is consistent with the wiring diagram; Carefully check whether the working voltage of the power supply to the fan meets the requirements, whether the power supply is out of phase or in phase, and whether the capacity of the electrical components provided meets the requirements. During commissioning, the number of people shall not be less than two. One person shall control the power supply and the other person shall observe the operation of the fan. If any abnormality is found, stop the machine immediately for inspection; First, check whether the rotation direction is correct; After the fan starts to run, immediately check whether the running current is balanced and whether the current exceeds the rated current; customized Dust exhaust centrifugal fan If there is no normal phenomenon, stop the machine for inspection. After five minutes of operation, stop the machine to check whether the fan is abnormal, and start the machine again after confirming that there is no abnormal phenomenon. When the two speed fan is tested, start the low speed fan first and check whether the rotation direction is correct; When starting the high-speed train, the fan must be stopped before starting to prevent the switch tripping and motor damage caused by high-speed reverse rotation. When the fan reaches the normal speed, check whether the input current of the fan is normal, and the operating current of the fan cannot exceed its rated current. If the operating current exceeds its rated current, check whether the voltage supplied to the fan is normal. The motor power required by the fan refers to the higher power required for centrifugal fan and fan box when the air inlet is fully open under certain working conditions. If the air inlet is fully opened for operation, the motor may be damaged. During fan commissioning, it is better to close the valve on the inlet or outlet pipeline of the fan, open the valve gradually after operation until the required working condition is reached, and pay attention to whether the operating current of the fan exceeds the rated current

Guangzhou customized Dust exhaust centrifugal fan Fan performance parameters. The performance parameters of fan mainly include flow, pressure, power, efficiency and speed. In addition, the size of noise and vibration is also the main fan design index. Flow, also known as air volume, is expressed by the volume of gas flowing through the fan in unit time; Pressure, also known as wind pressure, refers to the pressure rise value of gas in the fan, including static pressure, dynamic pressure and total pressure; Power refers to the input power of the fan, namely shaft power. The ratio of effective power of fan to shaft power is called efficiency. Dust exhaust centrifugal fan company The total pressure efficiency of fan can reach 90%. Fans are widely used for ventilation, dust discharge and cooling of factories, mines, tunnels, cooling towers, vehicles, ships and buildings; Ventilation and induced draft of boiler and industrial furnace; Cooling and ventilation in air conditioning equipment and household appliances; Drying and selection of grain; Wind source of wind tunnel and inflation and propulsion of hovercraft. The working principle of the fan is basically the same as that of the turbine compressor, but because the gas flow rate is low and the pressure changes little, it is generally unnecessary to consider the change of gas specific volume, that is, treat the gas as an incompressible fluid

2. The influence of the total pressure deviation Δ H of the fan itself was not considered during selection. When the actual total pressure of the fan was positive deviation, the flow increased; When the actual total pressure of the fan is negative deviation, the flow decreases. See (a) below. The relationship between the deviation of the pipe network characteristic curve and the total pressure and the flow can be eliminated by one of the following methods when the fan starts to officially operate after new installation, or when the flow is too large or too small during use. 1. Use the opening and closing of throttling device to adjust the flow. 2. Increase or decrease the flow by increasing or decreasing the fan speed. 3. Use a new fan with higher or lower pressure to increase or decrease the flow. 4. Change the pipe network to reduce the resistance coefficient of the pipe network to increase the flow. It must be pointed out that throttling devices are generally used to regulate the flow. However, when the actual flow is much larger than the required flow, this method wastes too much power and is very uneconomical. If conditions permit, the fan speed is usually reduced or the fan with lower pressure is replaced. When the throttling device is fully open, the flow is still too small. At this time, the throttling device has lost its function, so try to reduce the resistance coefficient of the pipe network to increase the flow, or increase the fan speed and replace the fan with higher pressure. However, the speed of the fans directly connected to the motor and the coupling cannot be changed generally. Only the fan driven by the pulley can increase or decrease the speed by changing the diameter of the pulley, but the speed of the fan cannot exceed the speed max in the performance and selection table.