Calculation of air volume and pressure for Roots blower pneumatic conveying
The calculation of air volume and pressure of Roots blower in pneumatic conveying is a key step to ensure its performance meets actual needs. The following is the specific calculation method:
1、 Airflow calculation
The air volume refers to the amount of air conveyed by a Roots blower per unit time, commonly measured in cubic meters per minute (m3/min) or cubic meters per hour (m3/h). The calculation method is as follows:
1. Calculation based on displacement:
Airflow (m3/h)=Fan displacement (m3/min) × 60 (min/h)
Among them, the exhaust volume of the fan is generally given in the parameter table of the Roots blower.
2. Standard air volume calculation (considering intake conditions):
Q (standard)=Q (inlet) x (P (inlet gas pressure, Pa)/(P (inlet gas pressure, Pa) - S (relative humidity) x P (water vapor saturation pressure, Pa) x T (thermodynamic temperature of inlet gas K)/273
This formula takes into account the influence of the pressure, relative humidity, and thermodynamic temperature of the intake gas on the air volume.
2、 Wind pressure calculation
Wind pressure refers to the air pressure provided by a Roots blower, measured in pascals (Pa) or kilopascals (kPa). In pneumatic conveying systems, the calculation of wind pressure needs to consider multiple factors, including fan outlet pressure, wind resistance pressure, and pipeline road resistance. The calculation formula is as follows:
*Total system pressure (kPa)=fan outlet pressure (kPa)+wind resistance pressure (kPa)+pipeline road resistance (kPa)
*Among them, the outlet pressure of the fan is related to the air volume, which is generally given in the Roots blower parameter table; Wind resistance pressure is related to wind speed, pipeline length, and friction coefficient inside the pipeline; The resistance of pipeline roads is related to factors such as the bending, branching, and material of the pipeline.
In practical applications, the following points should also be noted:
1. Parameter selection: When choosing a Roots blower, the appropriate air volume and pressure parameters should be selected based on the actual pneumatic conveying requirements (such as conveying distance, material characteristics, etc.).
2. Performance evaluation: By calculating the air volume and pressure parameters, the performance of the Roots blower can be evaluated to determine whether it meets actual requirements. If not met, it is necessary to adjust the fan selection or optimize the pneumatic conveying system.
3. Margin: To ensure the stable operation of the system, a margin is usually added based on the calculated air volume and pressure.
4. Actual testing: Before the Roots blower is put into actual use, performance testing should be conducted to ensure that its performance parameters meet the design requirements.
In summary, the calculation of air volume and pressure for Roots blowers in pneumatic conveying requires consideration of multiple factors, including the exhaust volume of the blower, intake conditions, system pressure, etc. By reasonable calculation and selection, the performance of Roots blower in pneumatic conveying system can be ensured.
