Residence time distribution in multiorifice baffled tubes: A numerical study

• Published in: Chemical engineering research & design 2017-02, Vol.118, p.259-269
• Main Authors: González-Juárez, D., Solano, J.P., Herrero-Martín, R., Harvey, A.P.
• Format: Article
• Language: English
• Subjects: CFD; Chemical reactors; Computational fluid dynamics; Configurations; Disks; Dispersion; Dissipation factor; Fluid flow; Friction factor; Mathematical models; Orifice meters; Orifices; Oscillatory baffled columns; Oscillatory baffled reactors; Plates (structural members); Plug flow; Residence time distribution; Residential density; Reynolds number; RTD; Studies; Topology; Transport of species; Tubes
• ISSN: 0263-8762; 1744-3563
• DOI: 10.1016/j.cherd.2016.12.008

[Display omitted] •Chaotic flow structures are described in multiorifice baffled tubes with oscillatory motion.•A numerical model is presented for reproducing the tracer injection test in a reactor tube.•The effect of the number of baffle orifices on the flow pattern and pressure drop is assessed.•Oscillating amplitude is reduced for increasing orifices, as the OBR design decreases baffles separation.•Geometries with higher number of baffle orifices yield lower axial dispersion performance. The fluid flow and the transport of species in an intensified topology of oscillatory baffled reactors is analyzed here by means of CFD. The classic configuration with equidistant single orifice plate baffles has been replaced by multiple-orifice disks, of the same open cross-sectional area. The flow through these disks generates an array of parallel jets downstream and upstream, exhibiting various swirl structures that increase the radial mixing. Time-dependent flow patterns are presented here for configurations of disks with 1, 3, 7, 19 and 43 orifices. The evaluation of their mixing performance has been accomplished by injecting a pulse of a tracer, for a constant oscillatory Reynolds number of Reo=800. The concentration-time profile of the tracer throughout the reactor was analyzed and an axial dispersion coefficient was derived on the basis of a 1D plug flow with dispersion model. It was clear that the quality of plug flow increased with increasing number of holes. Pressure-drop was reported by means of Fanning friction factor and power density dissipation.