Research Of The Application Of SFD-SMTD Drying System In The PVDF Resin Production

SFD-SMTD compound dryer make uniform of SFD dryer and SMTD dryer tactfully.It's suit for the heat-sensitive material drying which need for low moisture,because the SFD will disperse the material and dehydrate most water of them very fast in the first,then the SMTD dehydrate the residual water to get very low moisture by long residence time.What's more,PVDF is a heat-sensitive filtered material because it's intenerating point is 140℃,melting point 170℃,and 60% moisture contained.So,the drying process has considerable influence on the PVDF resin's properties and paint production.In order to study the adaptability of PVDF in the SFD-SMTD process,the influence of the technologic conditions,and find out the optimum technological conditions,the following aspects have be studied:(1) research the fluxion and distribution of the SFD;(2) research the technological conditions of PVDF in SFD-SMTD process.The fluxion and distribution have be studied in theΦ207 SFD. This research has studied the pressure of the SFD when gas-solid suspension passed,the RTD and classification characteristic of material with certain size distribution,and their variation with the gas velocity, the feed flow and stirring.According to the experimental result,there is a biggish axial dispersion in the SFD.The reason for this is that the large size particle has longer residence time than small one.The research of PVDF's technological conditions was worked inΦ207 SFD andΦ400 SMTD compound dryer.This paper find out the optimum technological conditions of PVDF drying process by orthogonal experiment which study the properties of paint making and film test,and also analyzing the influence of the gas velocity,the feed flow and temperature.According to the experimental result,there have three main factors will influence the dispersible and film properties of the PVDF resin, which the flash drying temperature is the most importance,and the gas velocity is the second one.The optimum technological conditions of PVDF drying process in this research are flash temperature 55℃,gas velocity 4.50m·s^-1,feed flow 11.42 g·s^-1.The experimental results are worth to the process equipment design and application in factory.