Dear Scott,

Questions keep this forum alive.

If melting because of friction is the cause of the material sticking to the wall can be determined by the remnants found in the pipe.

Electrostatic phenomena can also be a reason for sticky behavior.

Determining the maximum filling pressure is a pneumatic conveying calculation.

A higher pressure causes lower velocities in the pipeline and decreases the amount of energy losses in friction.

Again:

To investigate the cause of the behavior of the system, it is necessary to know the product characteristics s.a. particle size, material density, suspension velocity and the exact pipe geometry and filter data and compressor data.

best regards

teus ■

Interparticle friction seems unlikely because in most tanker unloading operations the rise starts just after the connection point. There hasn't been enough travel for the particles to shoulder charge each other. (Assuming some agglomeration, its Monday morning please, at the first bend).

As Teus says its questions that keep the forums alive, especially ones like this.

Is the material hygroscopic? I hope I've spelled it right. I appreciate the air will be hot..but. ■

Melting it is then; by interparticle friction as well. So, if the melt solidifies on the bends, can you heat the bends & then lag the heat in throughout the unloading?

Its going to be one or t'other; cooled air or hot bends. I don't think using peened pipe will keep it off the walls altogether, not in the bends anyway. My thinking is that any melt which impinges on the hot bend will remain fluid, won't stick & will soon get swept away by folowing airflow, hopefully as drobules (something between droplets & globules).

If its already melted what's the beef about keeping it melted tills its cleared the bends? Wadayathink? ■

Build-up in pneumatic conveying bends for certain materials is very common and there are different causes for it which I won’t go in details. I am very surprised no one has given the solution for this simple problem! Probably free advice is not free anymore………

Search in this forum and you will get the answer, I am sure this problem been discussed previously. ■

Wax pellets are one of the most challenging materials to handle. Many of the screw conveyor and pneumatics companies bow out when faced with the application.

While I doubt it will help your application, the only reliable method I have found to convey wax pellets is a bucket elevator.

Regards, Delmar Schmidt

Melfi Technologies Houston

www.melfitechnologies.com ■

Is there not a case for expanding the pipe diameter before the bend to reduce the impact and sliding velocity. It may even be worth while exploring a more exotic solution of converting the bend to a flat slot of greater cross section, backed by a PTFE surface. In principle, the combination of particle inertia and elutriation, rather than conventional pneumatic conveying velocities, should be adequate to move the particles round the bend with minimum wall contact pressure and velocity. The basic problem is that it is not commercially attractive for a manufacturer to develop a special geometry and construction for an individual application. ■