| The static mixers have the excellent properties of mixing the two immiscible phases and have been widely used in industrial production.But it is not good for small dispersed phase concentration and has the questions of using too much extraction liquor or incomplete separation.It is of great practical value to design a mixer with good mixing effect under the small dispersed phase condition.In this paper,a diameter-varied micro-mixer is designed based on the principle and structural characteristics of static mixing and ejector mixing.Using simulation and experimental method,the influence of the stage number,channel number,convergent section angle,spiral blade guide and the spiral blade length on the internal flow field and mixing effect was studied.The structural parameters of the diameter-varied micro-mixer were optimized,and the distribution characteristics of droplet size were compared with two conventional mixers,and it was used in the development of the new technology of on-line desalting and deacidification in overhead circulation system of atmospheric tower.Research shows that:(1)The variable diameter structure and helical blade structure make the inner flow field superpose secondary vortexes in the main stream,and the radial mixing is strengthened,so the mixing effect of the mixer is greatly improved.(2)The optimal structure parameters for the diameter-varied micro-mixer is the stage number n = 3,channel number m = 3,convergent section angle α= 6 °,spiral blade guide S=12.5 mm and the spiral blade length L2=44 mm.After optimization,the appropriate flow rate of the diameter-varied micro-mixer was 0.82m/s～1.36m/s,and the optimal working flow rate was 0.82m/s when considering the energy loss.(3)The oil droplets size distribution mixed by the diameter-varied micro-mixer mixing all showed a trend of logarithmic normal distribution,and to reach the best mixing effect under the concentration of the dispersed phase when flow rate up to 800L/h.Three mixer mixing effect is in turn:the diameter-varied micro-mixer>SV static mixer>ejector mixing.(4)The new technology of on-line desalting and deacidification in overhead circulation system of atmospheric tower uses the diameter-varied micro-mixer as mixing cell and fiber coalescing separator as separating element.The salt and acid corrosive medium have been efficiently eluted in the diameter-varied micro-mixer,so the new technology can effectively reduce the operation cost and safety problem caused by equipment corrosion. |
