Structural optimization of impinging stream mixing chamber through a computational fluid dynamics simulation in a liquid–liquid impinging stream cyclone reactor for isobutane/butene alkylation

A liquid–liquid impinging stream cyclone reactor (LL-ISCR) was proposed for isobutane/butene alkylation. The efficient mixing between heterogeneous phases is realized by the two-stage mixing enhancement induced by impinging flow and shear flow. Meanwhile, the presence of a centrifugal force field also helps to achieve the primary separation of products. In order to investigate the mixing performance in the impinging stream mixing chamber of LL-ISCR, the Eulerian–Eulerian multiphase flow model and Reynolds stress model were adopted to simulate the flow field in LL-ISCR. A parameter, dispersion uniformity of the dispersed phase (kerosene), β, was used to evaluate the dispersion performance of kerosene in the impinging stream mixing chamber. The results show that β increases first and then reduces along the radial direction from the inner to the outer wall at different heights of the impinging stream mixing chamber, which is caused by the non-slip boundary condition. In addition, with the axial section far away from the inlets, β decreases sharply at first, and then more gradually, and finally becomes stable. This can be explained by the fact that kerosene undergoes a reduced amplitude oscillation motion after the impingement between the two phases. Moreover, the influence of the structural parameters of the impinging stream mixing chamber on β was investigated. The results show that almost no change in stable β occurs when the overall height of the impinging stream mixing chamber is greater than 110 mm. And on the premise of fixing the inner and outer diameters of the impinging stream mixing chamber, a two-phase inlet diameter of 8 mm and a kerosene inlet angle of 60°–80° can prompt the mixing induced by the impinging stream to reach the best performance.