Simulation And Optimization For The Process Of Producing VDF Based On Aspen Plus

Vinylidene fluoride (VDF) is usually used as the precursor to produce PVDF in industry. As known to all, VDF is mainly prepared by thermal dehydrochlorination of1-chloro-1,1-difluoroethane (HCFC-142b). During the process, impurities, such as CH3F, C2H3F,152a (CH3CHF2) and C2H2CIF are simultaneously generated. These impurities could not be simply drawn out from the distillation system efficiently with simple methods. However, it is requested that the purity of VDF should be high enough for the polymerization, and the increasing amount of impurities in the system will make the operation unstable.. Therefore, it is necessary to find a simple way to remove the impurities. Aspen Plus provides a possibility for the simulation of the whole process of producing VDF, based on which the process can be optmizized. In this work, we focused on obtaining an efficient way to remove the impurities. To the best of our knowledge, few similar studies have yet been reported in the literature.In this research, a steady-state simulation model was set up based on the data from the actual process of producing VDF to actually reflect the processand to optimize the process. Two methods of process transformation were first proposed. One could be described as "one colume removed, two columes merged, and the impurities removed in a side line" and another one is "prefractionation followed by distillation". The former method is mainly to to solve the problem of removing impurities and ensure the stability of the operation by slightly modifying the original process. The latter method is very different from the original process, and ultimately can also draw out more than97%of the whole amount of impurities. The purity of the recovered142b is also very high and can be directly used for cracking while the loss of VDF and142b can be neglected.Compared to the results of simulation and the data from previous works, the correct utilization of the NRTL property method was confirmed. The simulation results were consistent with the experimental results. Energy consumption of the merged tower reduced by67%through the sensitivity analysis and optimization of the operating variables, such as Feed location, reflux ratio and D:F.The heat exchange network was analyzed using Aspen Energy Analyzer. A new heat exchange design was proposed. The heat duty reduced by more than25%and the cold duty reduced by more than22%...