Facts at your Fingertips: Pneumatic Conveying Flow Patterns
By Scott Jenkins, Chemical Engineering magazine |
Pneumatic conveying is a ubiquitous mode of conveying bulk solids in a wide range of industries, including chemicals, plastics, grain, food, agriculture, mining, power generation and cement, among others. The flow patterns within conveying lines depend on the properties of the materials being moved, the pressure drop across the conveying route and the velocity of the conveying gas. This one-page reference provides information about plotting relationships between these variables.
The relationship between flow pattern (mode of conveying) and key operating variables (such as pressure drop, gas velocity and solids flowrate) for a given conveying layout is best represented by the system state diagram (Figure 1; often called a Zenz plot). Today’s versions of the Zenz diagram typically plot the overall pressure drop against terminal gas velocity on a linear scale. In any pneumatic conveying system, each combination of bulk material characteristics and specific pipe-routing schematics will have its own unique characteristics, hence a system-specific state diagram. Overall pressure drop is used for the ordinate ( y-axis). This diagram is independent of the feeding technology.
In the system state diagram, the lowest curve represents…