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Keywords:

  • agitation;
  • mixing;
  • solids suspension;
  • just-suspended speed;
  • solids loading

Abstract

Data taken with six solids at numerous Zwietering loadings ranging from near zero to 67 have been used to determine the just-suspended speed Zwietering loading exponent (Njs ∝ Xn where n is the Zwietering solids loading exponent). When only the loadings range similar to that studied by Zwietering [Zwietering, Chem. Eng. Sci. 1958, 8, 244] is considered (0 < X < 18), the solids loading exponent averaged over all solids is equal to 0.12, essentially the same as the 0.13 reported by Zwietering. However, when the entire loading range is considered (0 < X ≤ 67), a higher average exponent of 0.17 is found and a single power-law correlation does not accurately describe the experimental data. A piecewise fit of the data indicates that the solids loading exponent increases from an average value of 0.097 at low solids loadings (0 < X ≤ 5) to 0.22 at intermediate loadings (5 ≤ X ≤ 25) and 0.34 for the highest loadings (25 ≤ X ≤ 67).