Reactor oscillatory flow mixing

Formulation of multi-component emulsions and mixtures are of interest in chemical and industrial processes (Vilar, 2008 Vilar et al., 2008). Standard stirred tank reactors (STR) and oscillatory baffled reactors (OBR) are traditional methods for the formulation of liquid-liquid mixtures and liquid-solid emulsions. Compared with STR, oscillatory baffled reactors provide more homogeneous conditions and uniform mixing with a relatively lower shear rate (Gaidhani et al., 2005 Harrison and Mackley, 1992 Ni et al., 2000). Figure 17 is a sketch of a typical oscillatory baffled reactor. It consists of the reactor vessel, orifice plate baffles, and an oscillatory movement part. The orifice plate baffles play an important role in the OBR for the vertex generation in the flow vessels as well as the radial velocities of the emulsions and mixtures. They are equally spaced in the vessel with a free area in the center of each baffle... 

This qualitative explanation for the oscillatory behavior of the particle number density is supported by theory. Assume the system can be modeled as a continuous steady state stirred tank reactor (CSTR) that is, reactants enter and products leave from a perfectly mixed tank with composition equal to that of the products. The set of equations derived in the previous section applies, but a new term must be subtracted from the right-hand side in each case to account for the loss of particles from the CSTR by the flow process. Equation (10.49) for the change in aerosol surface area with time becomes... 

Reactor configurations other than conventional stirred tanks have been proposed for suspension polymerization. Draft tubes, or internal loops , can be used for suspension polymerization [102], but drop size changes can occur [103] and flow patterns may be complicated [104]. Tanaka et al. [105] used a loop reactor for the suspension polymerization of styrene. They employed a double agitation method to control the transient droplet diameter distribution and the final particle size distribution. Ni et al. [106] developed an oscillatory baffled reactor for batch suspension polymerization of methyl methacrylate. Fluid mixing was achieved by eddies that are generated when a fluid passes through a set of equally spaced, stationary, orifice baffles that are located inside a tube. Periodically formed vortices were con-... 

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