射流循环dtb结晶器的水力学模拟与实验化学工程专业论文.docxVIP

射流循环DTB结晶器的水力学模拟与实验CFD 射流循环DTB结晶器的水力学模拟与实验 CFD Simulation and PIV Experiment of Circulation Flow Caused by Jet in DTB Crystallizer Abstract Jet has extensive applications in many fields such as mixing and transmission process． Compare with the conventional impeller，the adjunction of jet nozzle could realize the internal circulation of crystal slurry in the axial propulsive direction for a DTB crystallizer，which could effectively reduce the secondary nucleation caused by collision between stirring paddle and crystal as well as improve granularity of the product．111e optimal structure of dr撒tube and flow field in DTB crystallizer was studied by simulation and experiment．Then the results provide guidance for the design and optimization of jet cycle DTB crystallizer．Specific contents are as follows： Based on the systematical simulation of the single-phase flow field with the configuration of straight draft tube and j et nozzle for the DTB evaporator crystallizer using the RNG k-￡ turbulent model，the optimal draft tube diameter was determined．And then the simulation of the multiphase flow for the novel design DTB crystallizer was also conducted．The simulation results showed that the iet presented an excellent linear expansion in the draft tube and the axial velocity distribution basically meet the Gaussian distribution．For the jet flow at the entrance region of the draR tube．the reciprocal of axis velocity shows a good linearity with the flow distance，and the axial velocity accelerated attenuated．111e area ratio ffl)ofthe annulus between draft tube and the baffle to the cross—section of the draft tube significantly influences the circulation flow ratio()，)．With the increase of屈)，increases at first，and then decreases，there exists an optimal y．Although the particle concentration of crystal slurry decreases along the radial direction in the optimal draft tube．it still has a more even distribution within the optimized crystallizer and a lower circulation flow ratio comparin