Simulation And Optimization Of Butadiene Extractive Distillation Process

Butadiene is an important petrochemical olefin raw material. Since its chemical character is very active, butadiene can be widely used in synthetic rubber, synthetic resin and some organic chemical products. About 92% of the butadiene is separated from the C4 hydrocarbon mixtures by extractive distillation process. According to the different solvents, the process can be divided into ACN process, DMF process and NMP process. Compared with ACN process and DMF process, NMP process has advantage in process integration, equipment investment, three wastes treatment. Besides, it also has mature technology and good adaptation. Due to these advantages, NMP process has attracted more and more attentions and has long-term development potential. In this paper, a byproduct C4 fraction from an ethylene cracking facility is used as raw material to study the NMP butadiene extractive distillation process.NRTL-RK model was chosen to calculate the thermodynamic property of C4-NMP system and checked it with "Date Regression" function. A simulation of NMP butadiene extractive distillation process was performed using Aspen plus software. According to the butadiene separation requirements, took advantage of "Design Spec" and "Sensitivity" to determine the optimum process parameters of distillation columns. Then, analyzed and discussed the simulation results. The results show that the butadiene product of NMP process can meet the separation requirement under the optimal process conditions and the distributions of temperature, pressure, flow rate and components are reasonable. This study provides the theoretical basis for the localization of this technology.In order to reduce the energy consumption of butadiene production process, this article optimized the butadiene refining process using dividing wall column (DWC). Investigated the influences of intraconnection stage, distribution ratio and reflex ratio on the separation effect in DWC, and found the optimal process conditions. The energy consumption of the DWC process and the conventional process was compared at the same separation conditions. It finds that the condenser and reboiler of DWC process can save energy up to 29.36% and 29.19% respectively. Furthermore, the economic evaluation of the two kinds of butadiene refining process was made. It finds that DWC process can save operating cost and capital cost up to 29.21% and 8.96% respectively. As a result, the total annual cost (TAC) can save 26.75%. The DWC process has obvious economic advantage.