Gwyn equation

A lot of attempts have been made to describe the time dependence of the attrition rate in batch fluidized bed processes. Gwyn (1969) studied the degradation of catalysts in a small-scale test apparatus and defined the elutriated particles as the only attrition product. He described the increase of the elutriated mass, Wel, with time, t, based on the initial solid bed mass, Wbed 0, by the now widely known Gwyn equation ... 

For several batches of the same catalyst with quite different mass median diameters, Gwyn found the exponent b to be constant, whereas the attrition constant Ka was found to decrease with mean particle size. Equation (1) is, therefore, valid for a particular size distribution only. Other... 

Figure 23 shows a comparison of the experimental data depicted in Fig. 22 with the calculation from the model equation (27). The required attrition rate constants Cj, K, and Q that describe the materials susceptibility to attrit in the respective regions have been determined by the corresponding attrition tests as described in Sec. 4.3. Cj has been determined from exactly that Gwyn-type test facility that is shown in Fig. 14 and was set to zero in the case of the porous plate distributor has been measured in a 200 mm ID Gwyn-type test apparatus, and Q has been determined from exactly that cyclone attrition-test procedure that is described in Sec. 4.3.4 using the equipment sketched in Fig. 11. The parameters me,in and dpc were measured in the apparatus sketehed in Fig. 21 under the assumption that mc n may be...

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