Gwyn-type test

Both devices described above were developed in order to test the friability of FCC catalysts. Nowadays the application of these or similar tests is a common procedure in the development of fluidized bed catalysts. Contractor et al. (1989), for example, used a submerged-jet test to compare the attrition resistance of newly developed VPO catalysts. In fact, such tests can be applied to any type of fluidized bed processes. Sometimes they have to be slightly modified to adapt them to the process under consideration. The drilled plate may, for example, be substituted by a porous plate if only attrition in the bed is of interest. Even temperature and pressure can be adapted. Vaux and Fellers (1981) investigated for example the friability of limestone sorbent that is used for fluidized bed combustion. By surrounding a Gwyn-type test facility with a heating system, they took thermal shock and reaction into account. 

The investigation of the gas distributor and the bubbling bed attrition were both almost exclusively carried out in various derivations from the Gwyn-type test facility. Hence the material loss is the only attrition result considered, and the derived model approaches thus exclusively deal with the production of elutriable fines. There is consequently a lack of direct information on the role of attrition in the adjustment of the bed particle size distribution. 

Figure 14 Gwyn-type test apparatus suggested by Werther and Xi (1993) to investigate the jet-induced attrition separately from the bubble-induced attrition.

More recently, Werther and Reppenhagen (1999) correlated their bubbling bed attrition test results obtained under pure abrasion conditions in a 200 mm ID Gwyn-type test plant even to the excess gas velocity raised to a power of 3 (Fig. 18), which indicates that the bubbling bed attrition is linearly increasing with the excess kinetic energy supplied to the system ... 

Figure 18 Bubbling bed attrition test results obtained by Werther and Reppenhagen (1999) in a 200 mm diameter Gwyn-type test plant under pure abrasion conditions with fresh FCC catalyst.

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...

It should be noted here that the quantitative results obtained in a Gwyn-type attrition apparatus will in general depend not only on the cut size of the gravity separator but also on the entrainment and elutriation conditions in the main column. Werther and Xi (1993) compared, for example, attrition test results of the same catalyst obtained from three differently sized Gwyn-type units, one with column A having 50 mm ID and 500 mm height, one with column B having... 

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