| The recycling of industrial waste oil is of great significance in protecting the environment,saving energy,improving quality and efficiency.It is a very important way to alleviate the dilemma of energy shortage in China.Demulsification and dewatering is a key process in the resource utilization of waste oil emulsion.For emulsions with complex components and high water content,the purpose of demulsification and dewatering cannot be achieved by a single process method.Therefore,the high-voltage electric field is embedded in the swirl centrifugal device to build a double-field coupling separation device,which can effectively realize the efficient dehydration and purification treatment of emulsion under the action of double-field coupling.The cone structure of the double field coupling device has an important influence on its separation performance.In view of this,through the design and optimization of the cone structure of the device,three new double field coupling demulsification and dewatering devices are proposed,the double field coupling numerical calculation models under different cone structures are established,and the internal flow field distribution and separation performance of the devices with different cone structures under the action of double field coupling are investigated.It provides guidance for the design and development of high-performance emulsion double field coupling device.Firstly,the separation characteristics of the coupling device are investigated by establishing a numerical model of demulsification and dewatering with double field coupling.According to the flow field characteristics of oil and water coexistence in the dual-field coupling device,the Mixture model is used to simulate the oil-water two-phase flow,the RSM turbulence model is selected to simulate the high-speed rotating flow of emulsion,and the PBM model is used to obtain the droplet size distribution in emulsion.Considering the influence of electric field on droplet coalescing and breaking,the coupling of electric field equation,droplet coalescing and breaking model with flow field control equation and population balance equation is realized by using user-defined function method,and the numerical calculation model was established.The effects of different operating parameters on the flow field and separation efficiency of the coupling device were studied.Secondly,the structures of the two-field coupling devices with double spherical tangent cone,double elliptic tangent cone and compound curved cone are optimized by enumeration method and response surface method.Box-Behnken method is used to design the parameter combination,and simulation calculation are carried out.The separation efficiency response model of the dual-field coupling device under different structural parameters is established,and the structural parameter combination under the optimal separation efficiency condition is obtained.At the same time,the flow field distribution and separation characteristics of the coupling device under the optimal combination of structural parameters are investigated through numerical calculation,and the accuracy of the response model in predicting the optimal combination of structural parameters is compared and verified.In addition,the internal flow field distribution and separation efficiency of three different structures under the condition of optimal structural parameters are compared and analyzed,and the coupling device with the best separation performance is obtained.Finally,the rationality of the numerical analysis results is verified by the double field coupling demulsification and dewatering experiment.By designing and manufacturing a straight face double cone section double field coupling demulsification and dehydration device,a double field coupling demulsification and dehydration experimental platform was built,and the effects of different operating parameters on separation efficiency were compared and analyzed through experiments.The results show that the numerical results are basically consistent with the experimental results.The model established in this paper is reasonable and suitable for the study of the internal flow field and separation characteristics of the two field coupling device. |
