PRESSURE LOSS CALCULATION MODEL FOR WELL-GRADED SOLID-LIQUID PIPE FLOWS ON THE BASIS OF SYSTEMATIC PILOT PLANT INVESTIGATIONS
If a well granulated bulk solid material is separated into narrow particle fractions by size and the pressure loss curve of each fraction is measured in a given pipe a limit particle size can be determined.
The flow of the smaller fractions and the water can be described as a continuum with own suspension density and rheological properties. This is called fine suspension flow. The pressure loss curve of the coarse fractions and water flow has a minimum point, the continuum model is hard to be applied. This is called coarse mixture flow. In a given pipe only the particle size determines whether the flow is fine suspension or coarse mixture. In case of a coarse mixture flow the particles can be suspended or settled as function of the actual flow rate. When the coarse particles are suspended, this is the case of the many empirical equations, of which the first one was proposed by Durand. Mechanical friction loss of the settled and sliding particles can be correlated by the two-layer model.
On the basis of this point of view a pressure loss calculation method has been developed. The material parameters in the model can be measured by a systematic test by a tube viscometer. A hydraulic test loop and a tube viscometer with three different pipes have been built and experiments were carried out by glass sand from Fehйrvбrcsъrgу and fly-ash from the Power Plant of Mбtra, both located in Hungary.
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