Experimental and numerical investigation of field conditions associated with the transport of low-conductivity liquids and powders

The generation of static electricity during the transport of low-conductivity materials is a well known phenomenon. Until recently, large-scale experimentation has been the principal means by which the electrostatic conditions associated with the charging of processes have been assessed. Furthermore, the wide range of materials which exhibit differing charging characteristics, together with the various sizes of containers in common use, makes conclusions drawn from one arrangement difficult to apply to others. Consequently, there is an increasing need, at the initial stage of industrial storage facility design, to assess the effect of the electrostatic conditions arising from the transport of these materials. In the paper, mathematical models were developed and numerical solution methods proposed, for typical storage installations. In addition, the results of experiments have been reported which substantiate the methods employed and numerical techniques used. Despite the diversity of materials involved and the widely differing scales of experimentation, the finite-element method is shown to be a feasible and accurate means of assessing these conditions in typical fluid and powder storage situations. Furthermore, because these numerical techniques have been used in a pseudointeractive manner, with ongoing experimentation, they have permitted the process of charging and relaxation mechanisms, which has hitherto been experimentally unobtainable in the practical situations encountered in industry, to be more fully understood.