Research On Stripping Free Formaldehyde From Urea Formaldehyde Resin In Rotating Packed Bed

According to the development of polymer devolatilization, the work presented in this paper focuses on several aspect of following:summaring the application of the polymer devolatilization,the polymer devolatilization equipment and rotating packed bed(RPB) in polymer devolatilization,describing the possess of devolatilization by RPB,concluding the advantage of RPB in devolatilization,establishing the model of polymer devolatilizatiom. Free formaldehyde contained in urea formaldehyde resin(UF),used in the plate industry is usually over standard. The purpose of this paper is to investigate the effect of tempreture, high gravity factors,gas liquid factors and the first content of free formaldehyde on the removal officiency,and to find out the applied content of free formaldehyde in UF and The optimized conditions.The method used in our study is known as air-stripping,combine with the method of reducing the free formaldehyde and the release technology.The subject selected in this paper is called liquid UF. We conclude that RPB speed is the key factor for free formaldehyde removal efficiency by orthogonal experiment.The calculate values from mathematical model accord with the experimental velues well. The free formaldehyde stripping ratio come to the best 55﹪, in following conditions: with the normal atmospheric pressure, feed tempreture= 80℃,high gravity factors=100,gas-liquid ratio=1100～1300, the content of free formaldehyde=1﹪. The content of free formaldehyde in UF accord to national criterion(<0.3﹪). After two cyclic process,content of formaldehyde can't continue to reduce for high content.In this paper we analyse the reason and carry on its verification.In the end,we draw a conclusion as follow:UF containing high content of free formaldehyde is not fit to be devolatilized in RPB.About polymer devolatilization, RPB has special advantage: gas liquid contact uplifted, fast surface renewal speed,decrease apparent viscosity of subject ,assist bubble braking,low time consumption, simple technological process, simple operation. The techniques of polymer devolatilization in RPB has broad developing space.