Conveying speed / air velocity
Types of pneumatic transport
Dilute Phase transport
Dense Phase transport
Airlock Rotary Valve
Product inlet / Injector
Conveying speed / velocity
Air volumetric and mass flowrate
Pipe Equivalent Length
Solids velocity in pipe
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.
|Do you want to
know more ?
www.powderprocess.net is covering all aspects of solids and powder processing and handling
The pages below will probably interest you !
Answers ALL your questions on solids and powder mixing
of MIX / MEASURING DEGREE OF MIXING
All you need to know about measuring the degree of mixing (Coefficient of Variation) of a dry mix
OF POWDERS / DEMIXING
All on the physical phenomena causing segregation of particles and how to avoid them
All on main size reduction processes, key equipement, design consideration..etc..
All on powder key physical characteristics, among others : flowability, density...etc..
All equipment found in bulk solids handling industries, explained, with design tips...
|You can find much more through the menus at the top of the page !|