Conveying speed / air velocity
Recommended values in pneumatic conveying
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# Types of pneumatic transport
# Conveying phases
# Dilute Phase transport
# Dense Phase transport
# Air mover
# Roots Blower
# Roots Blower performance curve
# After Cooler
# Airlock Rotary Valve
# Product inlet / Injector
# Choking velocity
# Conveying speed / velocity
# Air volumetric and mass flowrate
# Pipe Equivalent Length
# Solids particle velocity in pipe
# Solids Breakage
#Pipe Diameter or Bore
# Selecting dilute or dense phase
The conveying air velocity is the speed at which air circulates in the conveying pipe of a pneumatic conveying line. Air velocity is changing all along the conveying line, thus one must always refer to a reference position (beginning or end of the line) when calculating the air velocity. The air velocity is sometimes called conveying speed.
The air velocity in the pipes is calculated by dividing the air volumetric flowrate (m3/s) by the passing section of the pipe (m2).
Equation 1 : calculation of the air velocity in a conveying pipe of diameter D
With :- uair = air velocity in conveying pipe of diameter D (m/s)
- Qair = air volumetric flow rate (m3/s)
- D = pipe diameter (m)
Note the following : the air volumetric flowrate is changing with the pressure and temperature, along the conveying line pressure is decreasing thus air expands, which makes the volumetric flowrate higher and thus the conveying air velocity higher (at constant D). To counter this phenomena, it is possible to change the diameter of the pipe, thus D may not be constant all along a same pipe.
3. Usual values for dilute and dense phase conveying
Every conveying line is unique and will have its specific air velocity, however, some orders of magnitudes can be given for both dilute and dense phase.
Table 1 : Reference end of
line velocity for dilute and dense phase conveying
Note that the actual velocity of the product conveyed is lower than the conveying air velocity.
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