In pneumatic conveying installations, the gas velocity is normally the lowest at the beginning of a pipe section of a certain diameter.

Therefore, sedimentation and the chance of choking starts always at the intake of a pipeline or right after a diameter increase, stepped pipelines)

As

v(gaswall )/vsuspension

is a parameter for the occurrence of sedimentation and choking, and as this ratio is velocity and pressure dependent, the local pressure and velocity in a pneumatic conveying pipeline must both match to prevent sedimentation and/or choking.

Using the equation:

v(gaswall )/vsuspension massflowgas/√(1+∆p)

Increasing the gas mass flow or reducing the conveying pressure always increases the ratio v(gaswall )/vsuspension and thereby reduces the chance of sedimentation and choking.

The occurrence of sedimentation, related to a too high pressure is investigated by the calculation of the Capacity – Pressure curve.

The occurrence of sedimentation, related to a too low gas mass flow is investigated by the calculation of the Zenz curve. ■