Mixing residence time

Wet Oxidation Reactor Design. Several types of reactor designs have been employed for wet oxidation processes. Zimpro, the largest manufacturer of wet oxidation systems, typically uses a tower reactor system. The reactor is a bubble tower where air is introduced at the bottom to achieve plug flow with controlled back-mixing. Residence time is typically under one hour. A horizontal, stirred tank reactor system, known as the Wetox process, was initially developed by Barber-Cohnan, and is also offered by Zimpro. 

Coagulation/flocculation Size of coagulation and flocculation basins and proper mixing (residence time) Dose of coagulants (alum)... 

Generally speaking, the design of TBR requires knowledge of hydrodynamics and flow regimes, pressure-drop, hold-ups of the phases, interfacial areas and mass-transfer resistances, heat transfer, dispersion and back-mixing, residence time distribution, and segregation of the phases. 

Further details of the mass transfer enhancement techniques in membrane separation processes are reported by Belfort and Al-Bastaki and Abbas. In this entry, the focus is on the flow instabilities produced by Dean vortices in curved and coiled tubes because of their advantages over the other techniques, viz., lower axial dispersion, better radial mixing, residence time distribution closer to plug flow, higher mass... 

Pressure Velocity Strain Viscosity Density Acceleration Gradients Tensor Volume Flow Force Melting Deformation Mixing Residence Time Distribution... 

The other continuous reactor processes listed earlier will, in terms of mixing, residence time distributions and kinetic models, fall between the PFT and the ideal CSTR. The PFT, as mentioned earlier, is an ideal reactor that should be... 

Working capacity is 50 to 60 % of total internal volume. Mixing residence times are 3 to 10 min. Mixing time increases with (particle diameter) . Rpm 20 to 100 rpm. 

Fig. 4.22. Airlift mixer-settler stage with long mixing residence time. (Jamrack,...

Flow regimes, pressure drop, phase holdup, liquid distribution, mixing, residence time distribution, heat and mass transfer, interfacial areas... 

A deaning chamber is substantiaiiy iess weii mixed than perfect - at least because the racked parts block fluid flow and cause the flow patterns to be non-uniform. And the chamber shape, while often radially symmetrical, is not longitudinally symmetrical. So, the less than perfectly mixed vessel will retain a fluid component longer than would be expected from the assumption of perfect mixing. Deviation from the well-mixed residence time will be different for every vessel shape and loading of parts, and will be specifically unpredictable (Chapter 2.13.1). 

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