The Simulation And Design Of 200 Kt/a Isobutane Distillation And Its Energy-Saving Optimization

The distillation process is the main part of the total energy consumption in the Chemical unit operations, and it is considered energy-intense. So it is of great significance to analysis the energy utilization of this process. As we all know, the heat pump distillation is a kind of energy saving technology which can effectively increase the thermodynamic efficiency of the distillation process, and can reduce energy consumption and achieve greater economic benefits. The non-equilibrium thermodynamics analysis can analysis the position, potential and cause of the separation process, therefore there is a wider use of this theory in the distillation process these years.The technological process was simulated and the process parameters were using the HYSYS ASPEN PLUS, and the tower was designed with the software CUP-Tower. We concentrated mainly on optimization the process, operating parameters, distillation way and the main equipments by using these software. The main works were summarized as follows.The optimization of operating parameters:By analyzing the process, determining process scheme of three columns. From the optimization of the process parameters, the optimal conditions were determined under the plates, feed stage, reflux ratio. The results show that optimization conditions were the distillation columns plates of 45、60、93, the quality of the reflux ratio of 100、 7、5.The optimization of distillation way:To solve this problem, this research was committed to minimize the energy consumption in the isobutene/n-butane separation. The simulated results of the process showed that the optimal energy-efficient was obtained at 7×105 Pa at the top and 7.5×105 Pa at the bottom, the circle working flow of 3055.13kmol/h and the compression ratio of 2.286. A thermodynamic analysis for the heat pump system was performed, and compared with conventional process. The results suggested that the new process was able to decrease the energy consumption from 68.16 GJ/t to 45.87 GJ/t. The utility cost can save 1.1587 million each year beyond the expectations.A general thermodynamic and kinetics model was presented by analyzing this process. The model was capable of both simulating industrial distillation processes and analyzing energy consumptions of the processes, which was assumed in a non-equilibrium thermodynamic state and entropy generation rate of each plate. The C₃-C₄ multivariate distillation was selected as the model system to test the model. Under the premise of meeting the production requirement, the process was thoroughly analyzed. The results show that compared with the exergy analysis, the distribution tendencies of the exergy were consistent, but varies with different parts of the rectifying column. For analyzing the exergy flow of the heat and mass transfer, put forward variable temperature difference and chemical potential difference to improve the energy transfer and conversion process. The model can reveal the dynamic hierarchy of the exergy loss.