(137c) Optimization of Cyclone Separators in Series Based on Computational Fluid Dynamics

Cyclone separators, simply known as cyclones, are commonly used equipment in the industry with the main purpose of gas-solid separation. There are also examples of them being used for other functions, such as heat transfer or as reactors. Cyclones are frequently employed in parallel or series configurations to better conform to process requirements. In serial configuration for gas-solid separation, the gas cleaned in one cyclone is fed into the next cyclone, to try to further collect the remaining particles. In order to find the best possible performance for this equipment, optimization procedures are conducted with mathematical models. Studies which employ optimization techniques to cyclones have demonstrated the existence of geometries with better characteristics than those with classical dimensions, such as the Lapple or Stairmand geometries. Although there are several geometry optimization studies of single cyclone configurations, to the best of our knowledge no paper explores multiple cyclones in series. In addition, in spite of the better predictions provided by phenomenological models such as those used in computational fluid dynamics (CFD), authors mostly use lower fidelity models due to their lower computational resources requirement. This paper therefore describes the optimization of three cyclones in series based on high fidelity CFD cyclone modeling. For this purpose, a methodology on how to solve this problem is evaluated, with the COBYLA optimization method and an Eulerian-Eulerian six-phase two-way gas-solid CFD approach, solved using an axisymmetric approach with an in-house developed code. The optimization of three cyclones in series had as objective the efficiency maximization. Results indicate that the optimized trios of cyclones outperform the classical high efficiency Stairmand trio of geometries with 30 times less solids emitted. We show that the optimization of cyclones in series delivers excellent results and is highly feasible in industrial time without compromising the fidelity of the mathematical cyclone model used.