Dispersion Characteristics Of Liquid-Liquid Heterogeneous System In Helical Tube Reactor And Its Application

Dispersed phase size has great influence on the reaction rate, masstransfer rate and product quality in liquid liquid reaction/dispersion orpolymerization. The regulation of dispersed phase size plays an important rolein polymerization reaction, synthesis of nanoparticle, preparation of emulsionliquid and nitration or sulfonation of aromatic compounds.In this work, the novel helical tube reactor (HTR) consisted of a chargingcomponent and helical tube. According to different operating conditions ofvolumetric flow ratio, two types of charging component were designed. Thedispersion characteristics of liquid liquid system in helical tube reactor wasinvestigated by using caster oil (containing1mol·L1acetic anhydride) wateras the working system; Then benzene nitration process was employed toexplore nitration reaction in Helical tube reactor. Main research contents andresults are as follow:1. The dispersion characteristics in HTR were investigated by usingcaster oil (containing1mol·L1acetic anhydride) water as the working system. The main results are as follow:(1) The experimental results with large volumetric flow ratio chargingcomponent indicated,dV AM,vertical<dV AM,parallel. V type charging componentshowed better pre dispersion performance than P type charging component.Experimental results with small volumetric flow ratio charging componentindicated, four hole Vertical type charging component showed betterpre dispersion performance than three hole vertical and one hole parallel typecharging component.(2) Under the same Re and continuous volumetric flow,d VAMdecreasedwith the increase of volumetric flow ratio of continuous phase to dispersedphase.(3) In large volumetric flow ratio charging component, when chargingposition was set from position1to position6,d VAMdecreased continuously.In small volumetric flow ratio charging component,d VAMreached minimumat position3. Larger velocity of continuous phase lead to decrease ofdV AM.(4) By comparison,d VAMin the helical tube were all smaller than that inthe straight tube with similar diameter and length, helical tube shown betterdispersion effect than straight tube.2. Benzene nitration reaction was employed as working system to explorenitration reaction in HTR. Nitration processes in HTR were conducted incirculation process and continuous process respectively. The results show that:(1) In circulation process, selectivity of nitrobenzene increased and the conversion of benzene decreased with the increase of circulating volumeflowrate of benzene or reaction temperature. The increase of mixed acidvolume flowrate or the molar ratio of sulfuric acid to nitric acid resulted in theincrease of conversion of benzene and the decrease of selectivity ofnitrobenzene. The conversion of benzene and selectivity of nitrobenzene in thehelical tube were higher than that in the straight tube with similar diameter andlength.(2) In continuous process, longer residence time resulted in a higherconversion of benzene from15.6%to94.5%, and lower selectivity ofnitrobenzene from96.5%to80%. With the molar ratio of sulfuric acid tonitric acid increased from1to5, conversion of benzene increased by36%, andselectivity of nitrobenzene decreased by17%. When reaction temperatureraised from50℃to70℃, conversion of benzene increased by20%, andselectivity of nitrobenzene decreased by5%.