Optimization Study On Critical Equipment In Potassium Extraction From Seawater

Potash fertilizer is an essential fertilizer in the agricultural production, but the potassium is poor and difficult to exploit in the land. However the total amount of potassium in seawater is very huge. Therefore it has great significance and prospect to study the industrialized technique of extracting potassium from seawater by ion- exchange. Potassium sulfate is a kind of high-quality chloride-free potash fertilizer, so it is confronting with a new round of productivity amplification in the world and the size of potassium sulfate crystal must be large enough for using in agricultural fertilizer. In this work, simulation technology was used to research the flow field distribution in the ion exchange pillar and crystallizer.Calculated the flow field in ion-exchange column and changed the diameter of the ion exchange column, inlet velocity, the diameter of inlet pipe, height of packing and the number of inlet. Flow distribution, velocity vector distribution, histogram of velocity and pressure distribution were analyzed to show the influence of different conditions and ensure the optimum condition: the diameter of the ion exchange column--3m, inlet velocity--0.10m/s, the diameter of inlet pipe--0.8m, height of packing-- 8m,then the results showed that two inlet was conducive to ion exchange process.Researched the flow field distribution of crystallizer after the ion exchange pillar.First of all,completed model validation by contrasting the experimental with simulation results and confirmed the mold flow field simulation is reasonable.Then changed crystal structure, draft tube structure, blade speed, diameter of blade, position of blade, solid particle, diameter of solid and analyzed the influence of flow distribution, turbulence kinetic energy distribution, mixing time, value of nonuniformity and power of blade on above conditions. The simulation results showed that: the baffler in crystallizer changed the fluid flow, reduced the mixing time,increased the mixing efficiency, so it was good for the uniformity of crystal phase. When the diameter of draft tube was 100 cm,and height was 110 cm, the flow field was much more better, the mixing time was short, the mixing efficiency was high,value of nonuniformity was low and stirring power was not large. Changing the stirring paddle speed and diameter made no effect for the streamline and flow in crystallizer. The proposed speed and diameter were chosen as 150 rpm and 90 cm. The optimum position of stirring paddle was H/3 and the value of nonuniformity became larger with the increase of the crystal size.