STATIONARY DEPOSITS AND SLIDING BEDS IN PIPES TRANSPORTING SOLIDS

To improve the predictions of the limit of deposition and the pressure drop characteristics of dredge lines, or other pipes transporting solids, it is necessary to analyse the physical mechanisms involved. This analysis shows that the limit of the stationary-deposit zone occurs when the driving force is sufficient to overcome the mechanical friction of the grains against the pipe wall. The results are displayed on a dimensionless co-ordinate system which, for any specific case, can be reduced to the usual j-V axes by simple transforms. With increasing in situ concentration it is found that the velocity for the limit of deposition passes through a maximum and then decreases. This behaviour, which has been verified experimentally, supports the conclusion that Durand's F sub L correlation fails to take all factors into account. The force balance equations can be extended to the case of stratified flow, i.e. flow with a sliding bed, and the calculated pressure drop curves are found to be more realistic than those predicted by Newitt's correlation for this case. An example of the use of the calculated values for a specific application indicated that the optimum transport efficiency occurs at very high concentration and relatively low velocity. This prediction suggests a promising field for future development.

  • Supplemental Notes:
    • Paper C-3 from BHRA Fluid Engineering Symposium, University of Kent, Canterbury, England.
  • Corporate Authors:

    British Hydromechanics Research Association

    Cranfield MK43 0AJ, Bedfordshire,   England 
  • Authors:
    • Wilson, K C
  • Publication Date: 1975-9

Subject/Index Terms

Filing Info

  • Accession Number: 00128422
  • Record Type: Publication
  • Source Agency: British Hydrodynamics Research Association
  • Files: TRIS
  • Created Date: Jan 14 1976 12:00AM