Interface Tracking and Multi-Fluid Simulation of Bubbly Flows in Bubble Columns

Fischer-Tropsch bubble column reactors are being utilized in a GTL (Gas-To-Liquid) plant for the synthesis of liquid fuels such as diesel oil and kerosene from the syngas made from natural gas. The bubbly flow in the column is highly complicated because of a high void fraction of poly-dispersed bubbles, a high volume concentration of fine catalytic particles and complex mass transfer, adsorption-desorption and chemical reaction processes. Since the degree of conversion of the syngas to liquid fuels inevitably depends on the bubbly flow structure in the column, reliable CMFD (Computational Multi Fluid Dynamics) tools for gaining insights on the flow inside the column would be of great use when designing the bubble column. We, therefore, have improved our hybrid CMFD, which is a combination of an interface tracking method, an Euler-Lagrange method and a multi-fluid model so as to be applicable to bubble column reactors. Some of the improvements will be introduced in the talk, i.e. (1) a new interface tracking method for predicting mass transfer from high Schmidt number and high Reynolds number bubbles, (2) that for predicting the effects of surfactant on the motion of deformable bubbles and (3) a multi-fluid model which can deal with bubble coalescence and breakup encountered in a poly-dispersed gas-liquid-solid three-phase flow with a high void fraction and a high particle concentration.