We are executing a dense phase pneumatic conveyor for an Aluminium paste plant project in India (site temperature is 50°C, relative humidity is 83% at 26°C) for handling dry fines of petroleum coke and recycled carbon fines.

The system uses dry compressed air for conveying the material at a rate of 2 tons per hour through a steel pipe of 80 nominal bore (pipe thickness is 4.5 mm). The working pressure of compressed air is 5 bar(g) and the conveying velocity is 5 m/s.

The conveying material has following properties:
• Particle size is 0 to 1 mm.
• Condition of material: dry & abrasive.
• Angle of sliding friction between petroleum coke & steel pipe: 21 to 30°
• Hard groove index: 33 to 42 (HGI)
• Design Specific gravity: 0.7 tons/cu.metre
• Angle of repose: 33 to 36°
• Internal angle of friction: 34 to 37°

As per contract, we are not allowed to do ground piping. Hence, we are utilizing the gallery portion of adjacent belt conveyor for supporting this pipe. At the starting point, the gallery has an inclination of 12° on its climb and therefore the material is lifted up through this pipe along the inclined portion. The overall conveying distance is 356 metres (of which, horizontal distance is 340m while the vertical distance is 36 metres). Due to long distance conveying, we have introduced an additional booster air supply of 5 bar(g) pressure after 150 metres conveying distance from the starting point.

The inclined pipe has a long radius bend (bend radius=10 times the pipe diameter) at the entry point and a slightly inclined pipe at the termination point.

The vendor for this pneumatic conveyor system has confirmed that the system shall be satisfactory for pipe inclination upto 15°. However, since the vendor has less experience in such design; we would appreciate your feedback for following points:
1) “Whether the pneumatic conveying can be done through inclined piping, having inclination upto 15°.”
2) Should the conveying be always restricted to horizontal or vertical piping.

Your feedback for above shall be highly appreciated.

Our email id is mukmbd@vsnl.com, while fax no. is 91-22-5330029 or 5348179.

Regards,

Mahesh Thota,
Mukand Limited, Mumbai, India