催化裂化沉降器旋流快分系统分离性能的实验研究与数值模拟

 在FCC沉降器的实验装置上，研究了不同入口处颗粒浓度下旋流快分系统（VQS）分离性能，着重分析入口颗粒浓度对VQS系统内分离效率与压降的影响规律。结果表明，随着入口颗粒浓度的增加，VQS系统的分离效率随之增加，而压降随之减小。采用Fluent软件对VQS系统内气、固两相流进行了数值模拟，并由此估算了不同入口颗粒浓度下VQS系统的压降、颗粒分级分离效率以及总分离效率，计算结果与实验结果吻合情况较好。入口颗粒浓度越高，气相被颗粒相消耗的能量越多，切向速度衰减越明显，从而导致系统压降的降低。同时，入口颗粒浓度的增加导致单位体积内颗粒质量流率增加，重力沉降作用增大，故上行流轴向速度减小，下行流轴向速度增加，有利于颗粒下行分离。此外，颗粒相的存在可有效抑制湍流，降低系统内的湍流强度，这有利于改善颗粒返混，提高系统对中细颗粒的捕集能力，从而提高系统的分离效率。

EXPERIMENTS AND NUMERICAL SIMULATION OF THE SEPARATION PERFORMANCE IN VORTEX QUICK SEPARATION SYSTEM FOR FCC DISENGAGER

Vortex Quick Separation system (VQS) is a novel FCC riser termination device developed by China University of Petroleum (Beijing), China. Through experimental study, the effects of inlet particle concentration on the separation performances of VQS were investigated. According to the experimental results, the separation efficiency increases and the pressure drop decreases with the increase of inlet particle concentration. The causes of above effects were analyzed by numerical simulation. The gas-solid flow field in VQS was numerically simulated by the use of Reynolds Stress Model (RSM) and Discrete Particle Model (DPM) on the Fluent 6.1 platform. The simulated results are in good agreement with the experimental results, which show the validity of the CFD model. The simulated results show that the gas tangential velocity in outer vortex area decreases with the increase of inlet particle concentrations，which indicates that the particles weaken the vortex energy and swirl intensity of gas phase, and consequently cause the decrease of pressure drop. At the same time, particle sedimentation is strengthened with the increase of inlet particle concentrations, so the upward axial velocity of particle entrainment in inner vortex area becomes lower and the downward axial velocity in outer vortex area becomes higher, which are help to improve the separation efficiency of system. In addition, the turbulent intensity decreases obviously with the increase of inlet particle concentrations and it is help to diminish the particle entrainment and improve the grade efficiency of fine particles in VQS.