Analysis On Flow Field Of Stirred Tank Used To Produce B-Carotene By Fermentation Method

This paper used FLUENT to simulate the three dimension flow field of200t β-carotene fermentation tank, analyzed the flow pattern and turbulence intensity distribution within the fermentation tank, calculated the stirring power, and discussed the mix of the fermentation tank. Simulation results show that:Inside the tank there is a crowd ring, most fermentation broth are in a large cycle; The distribution of turbulent intensity indicates that the turbulence intensity at the end of BTD is the biggest, and the effect of mixing and shearing is the best; method of calculating by simulating the stirring power provides references for the design of the fermentation tank; The mixing time is related to the feeding position, but the mixing time is similar with the different location of the blade; Loading in the same position, mixing time of diverse monitoring position is different, and when the monitoring stations close to the surface, the mixing time is the biggest.Based on different blades submerged depth LO (N1:LO/dj=2.33; N2:LO/dj=3; N3: LO/dj=3.67) of the fermentation tank for three dimensional flow field simulation, analyzed the effects of the blade span and the blade submerged depth on the flow field, turbulence intensity and mix time, The results show that the flow pattern within the fermentation tank is the most symmetry when the blender close to the surface, and the toroidal velocity of fluid would be more bigger when the fluid on the top of blade nearer to blade; Turbulence intensity is used to characterize the mixed conditions in the fermentation tank, the average turbulence intensity between N1and N2is similar, which can be thought as that the effect of two kinds of hybrid working condition is quite, and the average turbulence intensity of N3is minimum, and the mixing effect is less effective. From the concentration of the tracer diffusion and mixing of the monitoring time, it can be seen that tracer diffusion velocity of N1is fastest, and the required mixing time is minimum; The stirring power of three blade distribution is basically the same, which can show that the stirrer of span have little impact on the power. As for the overall effect, the blade distribution of N1can be thought as the most reasonable.