Dynamic Model And Experimental Study On The Recovery Of Tributyl Phosphate And Kerosene By Distillation Based On MESH Equation

In the spent fuel reprocessing process,the dirty solvent tributyl phosphate（TBP）and kerosene（OK）produced by the PUREX（Plutonium Uranium Reduction Extraction）process are usually disposed of by storage,which is both uneconomical and has certain safety risks.The distillation recovery technology can realize the reuse of TBP and OK under the premise of maintaining a certain extraction efficiency.At the same time,building a real-time simulation model of the reprocessing process can provide a reference for the design of nuclear fuel reprocessing plants.Therefore,the modeling of the distillation process of dirty solvent recovery has some engineering significance.In this thesis,a dynamic model based on MESH equation is constructed for the recovery of foul solvent distillation.This model takes into account both material balance equation and phase balance equation,and combines the molar fraction of liquid phase,temperature distribution,pressure distribution,enthalpy of vapor-liquid phase of each component and enthalpy of mixture for each tower plate number,and relies on Antoine’s equation and hydrodynamic equation of tower plate.The process characteristics are analyzed.The numerical solution of the 30%TBP-OK distillation process was calculated under negative pressure conditions,and the law of the concentration of each component(TBP,C₁₀,C₁₁,C₁₂,C₁₃)at the top of the distillation column and the kettle during the start-up of the dirty solvent recovery section with time was obtained.The calculation results show that under the feeding conditions of 8.078 mol/h,0.2205 TBP,0.0644 C₁₀,0.1993 C₁₁,0.2957 C₁₂ and 0.2201C₁₃,the concentrations of the components at the top of the column leveled off after 20h of operation,and the TBP concentration in the kettle leveled off after 50h of operation.At this time,the TBP tower top concentration was 0.4%and the tower kettle concentration was 96%.Aspen Plus software was used to cross-validate the reasonableness of the model,and the results showed that the dynamic simulation of this model is close to its steady-state simulation results after stabilization,and the error is not higher than 10%,and the calculation confidence is high.Meanwhile,this model can calculate the dynamic response process of tower top and tower kettle concentration after the product content of tower top and tower kettle reaches the steady state,adding the system perturbation and step perturbation of operating variables.In addition,in order to verify the accuracy of the model,the experiments of dirty solvent distillation recovery process are carried out,and the selection method of distillation operation temperature for dynamic experiments is obtained,and the result is the best distillation effect at 150℃of the tower kettle;the experimental data of driving process,system perturbation process and operation variable step perturbation process are obtained.The experimental and model comparison,the dynamic response trend is the same,and the error between the experimental value and the simulated value of TBP content in the tower kettle at the top of the tower at stabilization is less than 5%.