Axial mixing and scaleup of reciprocating plate columns

AbstractAxial mixing measurements in single phase (water) flow have been taken in open‐type reciprocating plate columns of diameters 25.4 and 508 mm. In the case of the smaller column, two‐phase axial mixing was measured, both in the dispersed phase (water dispersed in n‐heptane) and the continuous phase (with n‐heptane dispersed in water). Pulse injection of a tracer solution of ammonium chloride and methanol in water was used.Under single phase conditions, the axial dispersion coefficients were found to go through a minimum as the agitation level was increased from zero. The coefficients were nearly an order of magnitude higher in the 508 mm column than in the 25,4 mm column. In two phase flow in the 25,4 mm column, the continuous phase axial dispersion coefficients also went through a minimum as agitation was increased. The dispersed phase axial dispersion coefficients decreased monotonically as agitation was increased from zero. The results of this work and previous data are used in modelling the scale‐up of reciprocating plate columns by means of Pratt's simplified technique. The existing empirical scale‐up equation is consistent with an assumption that continuous phase mixing increased with column diameter but dispersed phase mixing remains unchanged.

Axial mixing and scaleup of reciprocating plate columns Journal Articles