I have 12mm Aluminium pellets (assume to be spherical) with a particle density of 2700kg/m3 and bulk density of 1500kg/m3. The pellets are specified as being 5mm -12mm but I want to assume the worst case scenario,12mm.

I am trying to design the system to convey these pellets in a lean phase.

Maximum flowrate of Aluminium pellets is to be 630kg/hr. Air will flow at the flowrate of 770m3/hr. Discharge air pressure is 140kpa absolute and the discharge temperature of the air is to be 89oC.

Selected internal diameter of the pipe is 77.9mm carbon steel.

I have performed all pneumatic sizing calculations.

The last hurdle that I have is selection of the appropriate set up to feed the Aluminium pellets out of the hopper into the moving air stream.

There is an existing hopper (pressure vessel) on site with the pinch valve on the outlet. As far as I know Pinch Valve is an absolute no in pneumatic conveying as its rubber seats will get damaged very quickly and the valve does not allow dosing.

We have considered installing a rotary valve but concern is that the pellets are rather large (12mm) and will cause blockages.

Another option we are considering is MATCON valve but our production department is not keen on it because this is something "new" and there are concerns regarding the maintenance (when hopper is full) and also need to redesign the feed hopper in order to integrate it

Is anyone able to help?

Regards and thanks ■