Numerical Simulation Of Hydrodynamics In Phosphate Reactor With Eccentric Agitators

With the development of the phosphate fertilizer industry andphosphate industry, the demand for phosphate in the industry in increasingrapidly. Rational use of available is particularly important due to the limitedresources of the phosphate. At present, the phosphate reactor design reliesmainly on traditional experience design, this design not only lead to longdesign cycles, and often failed to achieve the optimal use effect of devices,resulting in waste of resources, financial, human and material resources. Theeccentric agitation is a kind of stirring form whose stirring axis is deviatingfrom the center of the stirred tank. It destroys the symmetry structure of theslot flow, so the the chaotic mixing of the fluid in the tank are induced.Comparing with the conventional stirred tank, it doesn’t need to install bafflesand has been widely used in chemical, pharmaceutical, metallurgical andother industries. So far, the eccentric stirring mixed way applies in thephosphoric acid reaction tank never seen in reports.This article is based on the study of a projectφ5000×6500phosphoricacid reactor in the production process of energy-saving optimization problem,after the study, eccentric agitator used in the phosphoric acid reaction tank,the three-dimensional flow field of the phosphoric acid reaction tank weresimulated and analyzed by numerical simulation, focused on the eccentricityand the speed impact on the law of the flow structure, works as follows:(1).The phosphoric acid reaction tank used in project is simplified tothe stirred tank used for the experiment, using water instead of actual workingmedia, using numerical simulation method and PIV experimental research onthe flow field of the eccentric stirred tank, then, to compare the results of theanalysis.(2).The numerical analysis model of the eccentric phosphate reactorwas established, the flow field in eccentric stirred tank was simulated, then, analysis of the change of the eccentric ratio and stirring speed on the law ofthe flow field in tank.(3).The appropriate eccentric ratio and stirring speed of this researchwork were determined.The work was summarized, and gets the following conclusion:(1).The flow field in stirring tank was studied through the FLUENTsoftware and PIV system, after comparing the results; it found that thesimulation results can reflect the real flow field within the range of allowableerror. Thus, the reliability of the FLUENT software predicts the flow field ineccentric tank was verified.(2).The flow field in eccentric stirred tank was asymmetric structure.the flow that from the surface downward movement to the blade is dividedinto two shares of fluid, the one upward along the tank wall; the other dotardalong the tank wall, but turn to at the bottom of tank, then, the flow upward tothe bottom of blade. Therefore, two large circular flows were formed in entiretank.(3).with the increase of eccentricity, the range of the large part of thecircular flow was increased, but not the greater the eccentric ratio, thestronger the flow disturbance. In this work, stirring effect achieve the bestwhen the eccentric ratio of the tank is0.2.(4).As the speed increases, the speed of flow was strengthened,especially the fluid velocity that close to the surface has been strengthened,However, distribution of the slot flow field structure is almost not changedwhen the speed is increased to a value. In this work, the appropriate rotatespeed is160rpm.(5).Eccentric mixing can not only improve the flow structure of thereaction tank, enhance the disturbance of fluid in the tank and improve themixing efficiency, but also save energy.This research work can provide a certain reference value on the phosphoric acid reactor improvements.