The Synthesis And Design Of Separating Cyclohexene Mixture By The RDC-DRS

Cyclohexene mixture consists of cyclohexene and cyclohexane, which are important chemical raw materials and organic solvents so that they have relatively high economic value. However, because the boiling point of cyclohexene is very similar to that of cyclohexane, it has great difficulty to separate the two by using conventional distillation process. Therefore, a conventional reactive distillation sequence (CRDS) has been proposed, whch can effectively separate cyclohexene and cyclohexane by reactive distillation technology, but the simulation of the process has not been carried out. For energy conservation, this paper presents a new reactive distillation column with double reactive sections (RDC-DRS)——a reactive dividing-wall distillation column with double reactive sections (RDWDC-DRS). The commercial chemical software Aspen Plus is used to conduct the simulation and study of the CRDS and the RDWDC-DRS for the first time.The CRDS is composed of cyclohexene separation column and cyclohexane separation column, which select RadFrac module to conduct the simulation. The total annual cost (TAC) is chosen as the objective function to optimize the structure by using an iterative method, and the optimal structure of the process is obtained. The steady-state process for separating cyclohexene mixture by the optimal CRDS is analyzed through the sensitivity analysis of catalytic amount, reboiler duty and distillation rate, the vapor and liquid flow rates, and the liquid composition distribution.The RDWDC-DRS is simulated in the form of thermal coupling of two columns. The same optimization conditions and methods as the CRDS are used to optimize the structure of RDWDC-DRS and the optimal parameters are gained. Then, the steady-state process of the optimal RDWDC-DRS is also analyzed by the sensitivity analysis of the relevant operating parameters and the liquid composition distribution. Meanwile, the energy consumption, operation costs and investment costs of RDWDC-DRS are compared and analyzed with that of CRDS.The results show that, the RDWDC-DRS could achieve the separation of the cyclohexene mixture; compared with the CRDS, under the same operating comditions and the same product purity, the RDWDC-DRS reduces 4.16% of the investment costs and significantly saves space of equipment.