In high-temperature workplaces, in order to timely and effectively ventilate the workplace, high-temperature fan equipment must be installed, and in the face of different plant forms and gases in the workplace, the selection of high-temperature fans is also different, but generally According to the actual conditions, refer to the main parameters of the fan to select the type, so what parameters are the main parameters for the selection of the high-temperature fan?
1)Main parameters of high temperature fan selection
1. Air volume: The number of cubic air delivered by the fan per minute, unit: m³/h.
2. Total pressure: The total energy of the gas is equal to dynamic pressure + static pressure, unit: Pa.
3. Dynamic pressure: The pressure required to accelerate the gas from zero speed to a certain speed, unit: Pa.
4. Static pressure: The difference between the pressure at a certain point of the fluid and the atmospheric pressure, unit: Pa.
5. Fan speed: The number of revolutions per minute of the fan impeller, unit: RPM.
6. Shaft power: The actual power transmitted to the fan shaft after the internal loss factors are removed by the motor is generally considered to be the actual power required by the fan, unit: KW.
7. Noise: The noise formed by the superposition of aerodynamic noise and mechanical noise during the normal operation of the fan; most manufacturers publish A-weighted noise (dBA), at 1.5m, unit: dBA.
8. Total pressure efficiency: Air volume X total pressure/shaft power/1000/3600*100%.
9. Power supply: 380/50/3, 220/50/1, 220/50/3, 690/50/3, etc.
10. Exit wind speed: The wind speed of the cross-sectional area of the fan outlet. Controlling the outlet wind speed can indirectly control the noise, unit: m/s.
2)Calculation and formula for high temperature fan selection
1. Air volume calculation of high temperature fan
The air volume of a high-temperature fan is actually the product of the wind speed V and the cross-sectional area F of the air duct. Since the large-scale high-temperature fan can accurately measure the wind speed with an anemometer, the calculation of the air volume is also very simple, and the air volume can be calculated directly with the formula Q=VF.
2. Calculation of the required quantity of high temperature fans
The determination of the number of high-temperature fans needs to calculate the total air volume required by the plant according to the number of air changes in the selected room, and then calculate the number of fans. The calculation formula is as follows:
N=V×n/Q
Among them:
N——the number of fans (units);
V——site volume (m³);
n——Number of air changes (times/hour);
Q——the single air volume of the selected fan model (m³/h).
3. Calculation of wind pressure of high temperature fan
The wind pressure of a high-temperature fan refers to the resistance to be overcome during the air volume delivery process, and refers to the pressure rise. The total pressure of the fan minus the resistance of each processing section of the fan cabinet is the residual pressure outside the machine. The resistance of the return air duct is generally calculated at 7~8Pa/m, and the resistance of the 90-degree elbow is calculated at 10Pa/each. The empirical formula is:
External residual pressure = fan total pressure – resistance of each treatment section fan power (W) = air volume (L/S) * wind pressure (Kpa) / efficiency (75%) / force rate (75%) total pressure = Static pressure + dynamic pressure
Fan motor power (W)=fan power (W)*130%=air volume (L/S)*wind pressure (Kpa)/efficiency (75%)/force rate (75%)</strong >*130%
