Numerical Flow Simulation And Experimental Study Of Mechanical Flocculation Reactor For Extract Of Chinese Herb Medicines

Flocculation technology is a new type of solid-liquid separation technology which utilized the effect of flocculant adsorption, bridging and sweeping, so that the liquid in the original state of stable colloidal particles has been destroyed and gathered into big floc particles and finally settled down. In the process of stewing Traditional Chinese medicine(TCM), there are a large number of inactive ingredients such as protein, tannic acid, pectic and to be colloid shaped, which will influence degree of clarification and stability of the solution. The flocculation technology have applied in the separation and purification of water extract of traditional Chinese medicine, which can remove a large number of inactive ingredients such as protein, tannic acid, pectic, and improve the clarity of solution, and improve the quality of the products of TCM.This paper takes the circular mechanical flocculation reactor as the research object,using standard k-? turbulence model and MRF simulation method to analyze CFD numerical simulation on the flow field in the reactor. Numerical simulation is carried out mainly through the distribution of velocity distribution, turbulent kinetic energy and energy dissipation rate. The flocculation experiment chosen chitosan as a flocculant to deal with suspension of anti-inflammatory antifebrile particles water solution. The retention rate of effective constituents (Aesculetin), protein removal rate, liquid turbidity is used as parameter to evaluate the flocculation effect. Compared the numerical simulation results to experimental results of traditional Chinese medicine flocculation. it will determine the effect of the structure size to the circular flocculation reactor on the flocculation effect of the liquid extraction liquid.The results show that: in the circular flocculation reactor, the impeller installation height is h=0.3H, effective ratio of height to diameter is H/D=0.75, plate width is 0.05D,which can make velocity field, turbulent kinetic energy and the energy dissipation rate distribution better in a circular reactor, And effectively suppress the liquid with impeller to present the circular wall flow phenomenon. Consequently, the flocculant in the stage of rapid stirring uniformly dispersed into the solution. In the slow stirring stage, the impurity particles and floc can involved in double circulation to promote the floc growth, finally obtained the ideal effect of flocculation. Under the condition, the retention rate of the effective components was 86.4%, protein removal rate was 60.1%, the supernatant turbidity was 5.3NTU,after flocculation liquid static 24h turbidity.This research adopts the way of comparison CFD numerical simulation and flocculation experiment to analyze the influence of xiaoyan Tuire Granules raw water extracts flocculation effect of flow field distribution of circular mechanical flocculation reactor, explore efficient flocculation hydraulic conditions, to provide reference for the structure design and operating conditions on flocculation stirring reactor.