Structure Optimization And Property Research Of Cage Aeration Stirred Bioreactor

With the continuous development of animal cell culture technology, it is possible to obtain significant medical value of biological products in vitro. In order to meet the growing demand for biological products, researching and developing more efficient animal cell bioreactor has become imperative. Cage aeration stirred bioreactor is a kind of widely used in animal cell culture bioreactor. The reactor consists of a lifting stirrer and an aeration cage, which has not only gentle stirring progress and good mixing performance, but also separates the aeration area and cell culture area through the screen to reduce the shear forces in the reaction liquid greatly. But the shortcoming of the reactor is also very prominent. Since the scope of the mass transfer is limited, the oxygen transfer rate in the reactor is low. So it can’t meet the demand of oxygen in large-scale cell cultivation.In this paper, the structure of the lifting stirrer is improved, which adds a spiral blade inside the lifting tube to increase the amount of circulation in the reactor through the blade work and to accelerate the fluid exchange inside and outside the screen, so as to enhance the oxygen transfer rate. CFD is carried out on the optimization of the blade structure. The numerical analysis model is established, which consists of dividing grids using ICEM, processing the area of the stirrer with the Multi-reference Frame and simulating the stirring progress with the standard k-s turbulent model. By analyzing the effect of the blade inner diameter, the blade laps, the blade angle and the blade numbers on the flux of the lifting tube, the best geometric parameters of the spiral blade are determined.The cycling performance of the reactor flow field before and after adding the blade is analyzed through CFD simulation. The results show that the velocity after adding the blade is obviously improved and the flux in the lifting tube is significantly increased. The flux increases by 27.5% at the speed of 200rpm. PIV testing technology is used to research the flow field and obtain the local velocity, which shows that the velocity is evidently increased after adding the blade. The comparison between experiment results and simulation results shows that the simulation results are consistent with the experiment results well. The flow constructions are similar, the variation tendency of the local velocities is equal and the changes of the velocities are reasonable. The accuracy of the simulation results is verified.On the basis of the numerical simulation, the method of sulfite oxidation is used to research the oxygen dissolving performance of cage aeration stirred bioreactor. The results show that the volumetric oxygen transfer coefficient KLa of the reactor after adding the blade increased by 23.3% at the speed of 200rpm. After measuring KLa of different operating conditions, the results show that the improvement of the rotating speed and the ventilation rate can both increase the oxygen transfer rate of the reactor.