Flow Field Characterisation And Structural Optimisation Of A Multi-orifice-impinging Liquid-liquid Efficiency Mixer

The mixing reaction between liquid-liquid phases in pharmaceutical and fine chemical production is widespread,such as the mixing of ammonium diazodisulphonate solution and sulphuric acid solution in the preparation of pyrazolone,and the difficulty in this mixing process is how to achieve efficient mixing of one liquid with a relatively large flow rate and another with a small flow rate.In order to solve this problem,this paper explores a multi-orifice-impinging liquid-liquid efficient mixer,and carries out experimental and numerical simulation research on it,in order to provide ideas and reference for the development of equipment to realize the mixing of two liquids with large differences in flow rate.Firstly,an experimental study was conducted on the effect of different operating parameters on the mixing effect of the multi-orifice-impinging liquid-liquid efficient mixer.The feasibility of the multi-orifice-impinging liquid-liquid efficient mixer was investigated using red ink and hexane as the primary and secondary fluids respectively,and the colour uniformity of the images of the straight pipe section taken by a high-speed camera was used as the evaluation index,and the optimum primary fluid flow rate of 11.4 m~3/h was obtained.Secondly,the numerical simulation model of the multi-orifice-impinging liquid-liquid efficient mixer was established by using Solid Works software,and the mesh division was carried out by using Fluent meshing,and different mesh numbers were selected to verify the mesh irrelevance,and the maximum variation of flow velocity was found to be 5.3%;meanwhile,the obtained flow velocity of straight pipe section was compared with the experimental results,and the maximum error between the simulated and experimental values was found to be 8.42%.Again,numerical simulation was used to investigate the effects of operating and structural parameters on the mixing effect of the multi-orifice-impinging liquid-liquid efficient mixer,and the optimal operating parameters were obtained:the primary fluid flow rate was 11.4 m~3/h,the secondary fluid flow rate was 0.7 m~3/h;the optimal structural parameters were obtained:the number of transverse orifice was 4,the transverse orifice diameter was 1 mm,the neck section diameter was 10 mm,the neck section length was 40 mm,the diffusing section angle is 8,and the diffusing section length is 40 mm.Finally,MATLAB software was used for binarization to explore the relationship between the ratio of the area of secondary fluid flow through the neck in the transverse orifice section to the whole neck area and the mixing uniformity index.The results show that the two trends are basically the same,proving that the ratio of the area of secondary fluid flow through the neck in the transverse orifice section to the whole neck area affects the mixing effect of the multi-orifice-impinging liquid-liquid efficient mixer,and after some parameter adjustment,the area share is close to 100%.