Executive Summary
The main aim of this project was to develop the necessary understanding, databases, guidelines and models for the purpose of predicting accurate optimal operating conditions for two modes of dense-phase conveying: low-velocity slug-flow (LVSF) of granules and fluidised dense-phase (FDP) of powders. During the first 3 years of the project, top priority was given initially to LVSF, although some progress also was made with the FDP section of work. The second 3-year period of the project allowed a substantial amount of work to be completed in the FDP section, as well as some interesting investigations emanating from the LVSF work.
Several difficulties were encountered during the course of the project (e.g. unexpected results and phenomena) and these delayed progress in various areas. In some cases, it was not possible to complete certain planned tasks (e.g. testing different pipe wall materials for the LVSF section and also a wide range of bulk solids for the LVSF and FDP sections, further testing and modelling for the FDP section). In other cases, it was necessary to pursue new research activities (e.g. rotary valve air leakage, new pipe wall friction and stress transmission testers, comparisons with other FDP models). However, in terms of achieving the overall goals, there is no doubt that the 6-year project was successful, as measured by the following achievements:
• improved understanding of both LVSF and FDP;
• development of new and comprehensive databases for both LVSF and FDP;
• development of guidelines and new fundamental models for the prediction of LVSF performance (e.g. horizontal pipeline pressure drop, unstable boundaries);
• evaluation of and development of guidelines for FDP performance (e.g. minimum transport conditions, empirical modelling of powder flow frictional properties, scaleup accuracy of new and existing models);
• as well as some new and exciting (additional) developments (e.g. new particle/bulk property testers; novel comparisons of blow tank and high-pressure rotary valve feeder performance for LVSF; new on-line instrumentation to monitor LVSF performance; evaluating the scale-up stability and accuracy of existing FDP models).