Study On Hydrodynamics Of Moving-bed Column Of Ion Exchanger And Dynamics Of Drying Process In The System Of Cesium-removing From Highly Radioactive Solution

For the cesium-removing process using potassium titanium hexacyanoferrate(KTiFC) as ion exchanger in the Chinese total partitioning process for highlevel liquid waste, the particles transport velocity and influencing factors forФ280 moving-bed column, which is possibly used in industry for removing¹³⁷Cs ions from the highly radioactive solution, are investigated firstly in thisthesis. Experimental results show that the feeding rate of liquid into themoving-bed column, the liquid rising velocity of the riser and the height ofparticles in the moving-bed column have dominant influence on the particlestransport velocity, and the reason has been analyzed by the pressure balanceof system. Based on these results, the dimensionless correlation for theparticles transport velocity and an empirical hydrodynamic model for the ionexchange system are presented. Experimental results also show that theleakage rate of liquid through the solid-return pipe remains constant and itsdirection of the liquid leakage is from the riser to the downer due to therestively thin and long solid-return pipe.Secondly, the drying process of the ion exchanger which came from themoving-bed has also been investigated. The real ion exchanger was used inthe experiment and the appropriate temperature range, the velocity of drynessand the factors which can effect the velocity have been investigated at thesame time. Experimental results show that the appropriate temperature of thereactor should be under 120℃ so that the ion exchanger will not decomposeto discharge (CN)₂, and the process need be heated. The drying processincludes three phases: the adjustment phase, the constant rate phase and thetwo types of underspeed phase. If the other experimental conditions areunchanged, the critical moisture content X_C of the ion exchanger reduceswhen the gas velocity increases and another critical moisture content X_Dbetween the two types of underspeed phase, linearly depends on the values ofXC. Finally, Based on the data, an empirical dynamical correlation for thedrying process is presented. These results will be applied in the disposal ofnuclear industry.