Oscillatory baffled reactor Applications

Visualization of dispersions in an oscillatory baffled reactor, ERT applications in, 207-209 Visualization of multi-phase fluids through sudden expansions, PET applications in, 214 V-mixer, 163... 

The chapter on mixers is comparatively short - not because mixers are unimportant, but because mixing is such an integral part of other intensive processes (heat exchange, reactions and crystallisation/precipitation as examples), that the topic is addressed continuously through other equipment and application chapters. The point is well made by Wu et al. (2(X)7) who stresses in their recent review that PI needs to be implemented via increased mixing, as well as heat and mass transfer - hence the success in this area of the spinning disc and the oscillatory baffle reactors. 

The oscillatory baffle reactor/oscillatory flow reactor (OBR/OFR) types are seen as for niche applications, where one wants to convert a long residence time batch process to a continuous one. In the case of biodiesel, Dr Harvey indicates that a conversion could be carried out in 10 minntes, compared to 1-6 hours in continnons indnstrial processes. One variant is shown, by means of a flow diagram, in Figure 10.20, while Figure 10.21 shows components of the OFR. The aim is to make the plant portable so that it will fit into a standard shipping container. The unit could be sold worldwide to, for example, formers to produce their own fuel locally. 

When a water-miscible polymer is to be made via a suspension process, the continuous phase is a water-immiscible fluid, often a hydrocarbon. In such circumstances the adjective inverse is often used to identify the process [118]. The drop phase is often an aqueous monomer solution which contains a water-soluble initiator. Inverse processes that produce very small polymer particles are sometimes referred to as inverse emulsion polymerization but that is often a misnomer because the polymerization mechanism is not always analogous to conventional emulsion polymerization. A more accurate expression is either inverse microsuspension or inverse dispersion polymerization. Here, as with conventional suspension polymerization, the polymerization reaction occurs inside the monomer-containing drops. The drop stabilizers are initially dispersed in the continuous (nonaqueous phase). If particulate solids are used for drop stabilization, the surfaces of the small particles must be rendered hydrophobic. Inverse dispersion polymerization is used to make water-soluble polymers and copolymers from monomers such as acrylic acid, acylamide, and methacrylic acid. These polymers are used in water treatment and as thickening agents for textile applications. Beads of polysaccharides can also be made in inverse suspensions but, in those cases, the polymers are usually preformed before the suspension is created. Physical changes, rather than polymerization reactions, occur in the drops. Conventional stirred reactors are usually used for inverse suspension polymerization and the drop size distribution can be fairly wide. However, Ni et al. [119] found that good control of DSD and PSD could be achieved in the inverse-phase suspension polymerization of acrylamide by using an oscillatory baffled reactor. 

In the time or temporal domain, periodicity in operation is incorporated to realize all four principles of PI. A combination of adsorption-reaction-desorption on catalyst surface by periodic forcing of temperatures and pressures demonstrates the application of first principle. Oscillatory baffled flow reactor enhances uniformity, and illustrates the second PI principle. The application examples for third and fourth PI principles are pulsation of feed in trickle bed reactors enhancing the mass transfer rates, and flow reversal in reversed flow reactors shifting the equilibrium beyond limitations respectively. Switching from batch to continuous processing also result in realization of second and third PI principles. 

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