Study On The Characteristic Of Mixing In The New Type Of Exterior Circulative Impinging Stream Reactor

Exterior circulative impinging stream reactor (ECISR)，which hadbeen researched by She Qiming with liquid-continous impinging streamshas the excellent features of enhancing micro-mixing. In this paper, basedon the ECISR, impinging area has been improved. The macro-mixing andmicro-mixing in the reactor by one hundred and thirty-two litres involume was studied experimentally in cold. The influences of impingingvelocity and nozzle sparation on the mixing were discussed.In the macro-mixing experiment, the characteristics of fluid mixingtime in exterior circulative impinging stream reactorhave been studied byconductance measurement. The residence time distribution weresimulated by tanks-in-series model for calculating the exit concentrationof the impinging area in the reactor.The calculated results showed that themodel could finely describe the residence time distribution and the exitconcentration every well.The experimental resulted indicate that numberof tanks and the mean residence time decreased with decrease of thenozzle distance,increased with increase of impinging velocity.The flow inthe reactor was almost mixed flow when impinging velocity at2.0m/s.The macro-mixing process in the reactor was improved obviouslywhen the impinging velocity was added. When nozzle distance at120mm,the mixing time reached the minimum. The cycle time did not change atdifferent nozzle sparation, but decreaed with the increase of impingingvelocity. In this experiment, the iodide-iodate parallel compering reactionsystem was used to characterize micromixing in this reactor. The factorsof acid feed-in time, nozzle distance, impinging velocity affecting themicromixing were experimentally studied, determining the concentrationof ion of three iodine in product by UV spectrophotometer obtainedsegregation index for analyzing the micro-mixing efficient. The resultsshowed that the increasing in acid feed-in time promoted micromixing.But the acid feed-in time limited impact for the segregation index andexited critical value. The segregation index become steady while acidfeed-in time was up to this critical value; it could eliminate themacromixing influence for micromixing when the acid feed-in time wasthirty minutes in this experiment. Reducing the nozzle distance andincreasing impinging velocity could intensify micromixing efficiently.The characteristic micro-mixing time t_m calculated by the model oftheory was7ms~60ms, much shorter than that in the stirred tank reactor.The micro-mixing time was related to the segregation index, the relationship was liner, which was in good agreement with those in the literature.When a=120mm，υ=2.0、2.8m/s, t_m＜t_R，the segregation index was thesmallest, and the reaction was almost not limited by micro-mixing.Reserch results showed that impinging streams reactor had a goodmicro-mixing performance and was useful for fast reactions．...