Molerus diagram

The value of ratio 14 is then calculated from the Molerus diagram (Figure 5-10). The values of Xand APJL are then calculated from Equations 5-59 and 5-60. This step may be repeated for each range of particle size and summed up with other particle sizes to get an overall pressure drop for solids. However for Non-Newtonian mixtures additional procedures are needed. 

FIGURE 5-10 Molerus diagram. (From R. Darby, 2000. Reproduced by permission of Chemical Engineering)... 

Molerus (1993) developed a state diagram that shows a correlation between these dimensionless groups based on an extremely wide range of data covering 25 < D < 315 mm, 12 < d < 5200/am, and 1270 < ps < 5250 kg/m3 for both hydraulic and pneumatic transport. This state diagram is shown in Fig. 15-3 in the form... 

Figure 15-3 State diagram for suspension transport. (From Molerus, 1993.)...

Modifications to the Geldart (1973) fluidization diagram have been proposed by Molerus (1982) and Zenz (1984), but are not considered here as they require some knowledge or measurement of particle adhesion forces and bulk surface tension, respectively. That is, detailed investigations into evaluating and/or developing such fluidization diagrams are beyond the present scope of work. 

Figure 3. Geldart diagram (boundaries according to Molerus [24]).

A criterion for the prediction of minimum stirrer rotation speeds for the suspension of coarse-grain particles (Archimedes number > 40) is derived by Molerus and Latzel (1987). They showed that the minimum stirrer rotation speeds can be predicted by the evaluation of two diagrams the drag of fluidized particles as a function of concentration, and the pressure-head volumetric flow-rate characteristics of the agitated vessel. The latter can be obtained using the similarity of fluid-kinetic machines and can be expressed as lAav = /([Pg.48]

Obviously, concerning the formulation of failure conditions at the particle contacts we can follow the Molerus theory [8, 9], but here with a general supplement for the particle contact constitutive model Eq.( 2). It should be paid attention that the stressing pre-history of a cohesive powder flow is stationary (steady-state) and delivers significantly a cohesive stationary yield locus in radius-centre-stresses of a Mohr circle or in a t-a-diagram [28], see Fig. 2,... 

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