1. jack_archer Guest

I have had a long standing question....

How does one calculate the saturation carrying capacity of a pneumatic conveying system ?

Let me explain further. It is easy to calculate the saltation velocity for given set of conditions (pipe size, conveying rate, particle size, particle density, gas density). However, there would still be an upper limit on the conveying rate (for a given pipe size) beyond which the gas would not be able to maintain a stable gas-solid suspension regardless. Sort of upper limit on solids loading for dilute phase conveying.

We have rule of thumb .... solids loading (mass) of 5 - 7 & so on. However, does any one know of any mathematical expression which can be used to calculate this term ? References ?

Jack

2. Dennis Hauch - Freeport, TX, USA Guest

Jack,

There is no reliable mathematical expression for maximum solids loading, per se.

There is no getting around the fact that, like saltation, solids loading is the result of a specific set of conveying conditions.

Dennis Hauch

3. Equations for maximum solids to gas ratio can be derived from Dr. Klinzing's book "Pneumatic Conveying of Solids". Refer to Section 4.11, Voidage and Slip Velocity. Voidage decreases with increase in solids loading. This then affects the slip velocity.
Slip is the difference between the gas velocity and the solids velocity. Greater the slip, lower is the solids velocity. Eventually, solids salt out due to low voidage at maximum solids loading.

Regards,

Amrit Agarqwal (Tim)
Pneumatic Conveying Consultants
www.powderandbulk/pcc.com
polypcc@aol.com