A design programme for dilute phase pneumatic conveyors
A computer programme for the simulation of dilute phase pneumatic conveying of solids is presented. This includes positive pressure and vacuum pneumatic conveying. The characteristic conveying parameters such as the conveying absolute pressure, conveying air density, interstitial and average air velocity, particle velocity and voidage are calculated by integrating five differential equations that govern two-phase flow. The two-phase flow is approximated as one-dimensional along the pipe axis. Density and acceleration effects are accounted for. The integration is carried out by means of the Runge-Kutta-Fehlberg method yielding conveying parameter traces along the length ofthe pipeline. A new method is presented for the determination of the solids friction coefficient from the solids motion equation. This allows for a more accurate determination of the solids velocity in the pipeline when compared to currently used methods. The computer model results are compared to experimental results for cement and ice conveying yielding good correlation for the main output parameters. The theory for the scaling and calculation of Roots blower performance characteristics is presented. This is implemented in a Roots blower selection programme as an integral part of determining the prime air mover for the design of a pneumatic conveyor. The aim of providing a fast, user-friendly interface in terms of pipeline geometry input, simulation and data visualisation has been achieved by using the advantages of object orientated programming and the visual user interface of the DELPHI programming language.