| Intensification of the mass transfer of extraction process is important research focus of process intensification technology.The results of the previous studies show that microstructure equipment or gas-agitated technology has its unique advantages in intensifying mass transfer,shortening residence time and controlling fluid mixing.However,the application and mechanism of gas-agitated technology in microstructure equipment to enhance the extraction process is still uncommon and poorly understood.Therefore,this research designs and implements a gas / liquid / liquid micro-dispersive extraction system,which is applied for process intensification of extraction with high phase ratio in the traditional extractor.Hexanoic acid/water/n-octanol system was selected as the model system,and gas introduced was nitrogen.The main content could be divided into the following three parts:(1)The T-tube was used to simulate the dispersion structure and mass transfer of the traditional liquid-liquid extractors.It shows that the Murphree efficiency does not exceed 35%even when the residence time is above 10 s.Then,the microstructure extractor with stainless steel microfiltration membrane(average pore diameter is 5 μm)as the dispersion medium was used to intensify the extraction process,indicating that the residence time in 6 s or more,the Murphree efficiency can reach 60%,but still takes a long time to reach 90%.(2)Six different gas-agitated modes were achieved through a double microstructure extractor,and the results show the Murphree efficiency increased with the increase of the gas flow rate.The most efficient and stable mode was recommended,with which the overall volumetric mass transfer coefficient ranges in 7.88-41.34 s-1,about 40 times greater than liquid-liquid system.Furthermore,the Murray efficiency of the six modes could reach 90%in 0.5 s under certain conditions.Taking into account the energy loss and intensify effect of different extraction modes,the most suitable dispersion mode for industrial applications was given,with an energy loss of about 0.6 J / s.(3)The influence of various factors on mass transfer performance was further analyzed,and the mathematical model was established for the extraction and mass transfer process of the corresponding dispersion mode with different dispersion structure.After gas-agitated in extraction process,the effects of increasing the turbulence of aqueous phase and adjusting the ratio of continuous phase and dispersed phase on mass transfer in different dispersion modes were discussed. |
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