Scaleup flow regime

Flow regime General scaleup factors Series scaleup Geometric similarity Constant pressure scaleup... 

Prior to discussing scaleup, the factors that affect tray efficiency need to be addressed. These factors are addressed in Secs. 7.3.1 to 7.3.3. Considerations relevant to the effect of flow regime were previously discussed in Secs. 6.4.4 and 6.4.5. 

The flow regime plays a very important role in reactor scaleup. If the data obtained in the pilot-scale reactor are to be useful for a larger-scale reactor, the flow regime in these two reactors must be the same. The flow regimes in a variety of fixed-bed operations are described in Chaps. 6 to 8. 

Since gas causes most of the mixing in three-phase reactors, its distribution is, of course, very important. For small-diameter columns, the nature of a gas distributor is known to have a significant effect on RTD. Similar information on large-diameter columns is presently unavailable. For reactor scaleup purposes, such information is desirable. Studies should consider various reactor configurations and flow regimes. 

Various factors should be considered during the scaleup of slurry reactors such as flow regime, backmixing in the different phases, temperature control, controlling regime of the overall reaction, etc. Details of the effects of various factors on scaleup are available in the literature (1,11,21,30,34). In this section, some of the factors which influence the scaleup of slurry reactors as applied to coal technology are briefly mentioned. 

When scaling the process, the model and prototype must have Reynolds numbers in the same regime (i.e., laminar or turbulent flow) in order to achieve similar results. Ideally, the two reactors would have nearly identical or identical Reynolds numbers. In order to satisfy this requirement for scaleup, the model and prototype must be similar to each other with respect to reactor design, fluid flow, and physical dimensions. According to the principle of similarity, for every process condition and point in the model, there must be a corresponding condition and point in the prototype.This principle is applied to the scaling process by observing similar requirements for several other dimensionless ratios or variables that must be treated in a similar fashion. 

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