Parameters Used in Dense Phase Conveying

Posted in: , on 29. Sep. 2011 - 13:12

Dear All,

Going through a literature study for my project, I seek some more clarity on the following terms used in Dense Phase Conveying,

1.Particle Velocity

2.Minimum conveying velocity vs gas velocity (can the terms be used interchangeably ?)

And the interrelation of the above two.

3.Temperature considerations for air property calculations( If it refers to solids temp or any intermediate temp between solids and ambient)

Thanks in advance,


Re: Parameters Used In Dense Phase Conveying

Posted on 29. Sep. 2011 - 03:35

Dear vandana,

1)particle velocity.

A conveyed particle travels with a certain (changing) velocity through the pipeline (particle velocity). This particle velocity is a result of the accelerating forces and decelerating forces acting on the particles by the moving carrying gas (mostly air) and resistances and gravity.

2)The gas velocity minus the particle velocity generates the driving force on the particle according the general formula F =1/2 * Cd * gas density * (v-gas – v-particle)^2 * A-particle

The minimum conveying velocity is the gas velocity, whereby the particles are just kept in suspension. The gas velocity must be higher to prevent sedimentation. Gas velocity and minimum conveying velocity are not the same.

3)The air temperature is influenced by the material temperature. The heat exchange between particles and air has to be calculated to a common temperature (Mixture temperature).

In addition, the temperature changes due to expansion and heat radiation through the conveying pipeline are also to be considered. (A hot conveying pipe is cooler at the end than at the beginning)

have a nice day