Control volume pelletized solid

Prefer monolithic confignration for intensification with surface area/volume usually 1.5 to 4 times greater than traditional pellets. Excellent for mass transfer controlled reactions. For gas reacting with solid nsnally heat transfer controlled, because these are highly exothermic or endothermic reactions. Particle size and size distribution are critical. These reactions may follow different patterns ... 

In continuous centrifugation, the centrifugal force and flow rate must be controlled to provide sufficient time for solid or denser liquids to sediment before being carried out with the supernatant but not so long as to underutilize the rotor-throughput capacity. With information on liquid volume within the rotor and assuming laminar flow, the maximum flow rate can be determined from eqn [8]. Alternatively, if the rotor i -factor and the particle sedimentation coefficient are known, the minimum residence time required for pelleting can be calculated from eqn [11],... 

Another important feature of Fig. 4.10 is that a linear relationship between QpJ X) and time is observed in all cases for < 1, that is, before the external layer is completely reacted. For the systems with Fg = 1, this is expected since the rate of reaction per unit volume of the pellet remains constant during the reaction until the solid reactant is completely consumed. The analytical solution indicates this feature, as can be seen in Eqs. (4.3.41) and (4.3.60). For the systems with Fg > 1, the reason for the linear relationship is not so obvious, although a qualitative explanation can be put forward. The linear relationship persists up to a high conversion value, even for values of a as large as 1, that is, when chemical reaction and diffusion are of comparable importance. This indicates that the existence of a linear relationship between gp (X) and time does not necessarily mean that the system is controlled by chemical reaction even when there is a substantial effect of intrapellet diffusion, one may observe a linear relationship. 

---