Flow Investigation in Ordinary Baffled Columns Using Numerical Methods - Capstone Project Example

In recent times CFD has been finding extensive use around various flow related problems including bio-engineering applications, reactor designs, automobile engineering, aerospace engineering, etc.This particular research will be looking into flow-related phenomena resulting from the manipulation of ordinary baffled columns (OBCs) in order to promote better mixing and reaction characteristics. The use of OBCs is a relatively new phenomenon but it is taking up strong ground given the relatively small size and energy consumption of OBCs compared to conventional reactors and mixers.

This paper will proceed by introducing and detailing flow behaviours for OBCs followed by detailed numerical investigations. The essential idea behind this research is to utilise existing experimental techniques in order to create and apply fitting numerical models for investigating flow inside OBCs. Once these models are available, these can be used with a high degree of reliability to investigate other nuances in flow characteristics given variations in key parameters.The typical ordinary baffled column (OBC) can be understood as a simple cylindrical tube or column that has periodically spaced baffles attached inside the column.

These baffles are in the shape of single orifice plates. It is essential for the orifice to be concentric to the overall baffle. Moreover, the spacing between baffles is typically kept constant to ensure reproducible flow characteristics. The fluid or multiphase mixture inside an OBC is oscillated in the axial direction through the use of diaphragms, pistons, or bellows either at one end or both ends of the cylinder. When batch operations are being carried out the OBCs are run vertically. The mixing mechanism at work in an OBC can be delineated better using the diagram below.

The sharp edges of the baffles are placed transverse to the direction of flow which is oscillating and fully reversing. The interaction between the baffles and the oscillating flow tends to create eddies downstream of the baffles.