Should maximum pressures in ore pipelines be computed out of system startups or power outages?

Abstract

A key aspect of the design of long distance ore concentrate pipelines is the need to properly predict maximum pressures. This is traditionally done by means of transient analysis, thus predicting the possible impact of slurry hammers, which may occur during operation in a potentially uncontrolled manner in case of power outages. In this technical note, it is shown for typical ore slurry and pipeline characteristics, that in long distance systems with routes having inclined sections, the plug formation mechanism may become a dominant factor in system overpressures. A dimensionless number expressed as the ratio of the Joukowski and the plug overpressure value, suggests that a scale for the critical plug length above which maximum pressures are controlled by the plug mechanism rather than the transient flow is between about 150 m and 500 m, or a few percent points of the overall pipeline length in common long distance systems. A critical dependence on the solids initial concentration and the product of the static friction factor and the solids settled concentration is addressed