三相气升式反应器的CFD模拟及分析

CFD simulation and analysis of a three-phase airlift bioreactor

为了研究硅酮母粒对气升式生物反应器流态性能的影响,以气含率和液相流速为评估指标,采用欧拉三相流模型对反应器进行计算流体力学模拟和参数优化。模拟结果表明,反应器气含率和液相流速与进气流速呈正相关,进气量为3 L/min时反应器上升区和下降区气含率分别为17.1%和9.1%,液相流速分别为17.5 cm/s和24.6 cm/s,与实测值误差小于5%,证明了模型的合理性和适用性;硅酮母粒含量(VS)由5%(φ)增至15%(φ)的过程中,反应器中气体分散程度和液相流速整体上有所降低,VS=10%(φ)时反应器内既能实现完全流化又能维持较高的气含率和液相流速;硅酮母粒的粒径与颗粒孔隙率影响三相间的能量传递,最适粒径为1.0 mm,最佳孔隙率为70%。

The model based on Eulerian model was built for computational fluid dynamics simulation and parameter optimization of an airlift bioreactor containing silicone masterbatch.Gas holdup and liquid velocity were investigated to evaluate the bioreactor performance.The results showed that gas holdup and liquid velocity were positively associated with airflow.The gas holdup reached 17.1%and 9.1%respectively while liquid velocity reached 17.5 cm/s and 24.6 cm/s in the riser and downcomer of the reactor under the gas flow rate of 3 L/min,which were basically consistent to experimental results with an error less than 5%and proved the rationality and applicability of numerical simulation.The gas distribution uniformity and liquid velocity declined generally with silicone masterbatch(solid)loading(VS)increased from 5%(φ)to 15%(φ).The reactor achieved full fluidization while kept relatively high gas holdup and liquid velocity at 10%(φ)VS.The particle diameter and porosity affected the energy transfer among the three phases and the simulation results showed the optimal particle diameter and porosity were 1.0 mm and 70%respectively.