Study On Heat Integration Of The Dimethyl Carbonate Production Proces

Dimethyl Carbonate (DMC) is a "green" chemical. It is considered to be an environmentally friendly product because of its negligible ecotoxicity and biodegradability. It is widely used in coating, medicine, pesticides, additives, and other industries due to its versatile chemical properties. It can replace highly ecotoxicity materials in traditional process, and be used as gasoline additive and solvent in organic synthesis industry. At present, the transesterification method and urea method is widely used for the synthesis of DMC at home and abroad. In our country, the transesterification method used propylene carbonate and methanol is the most common methed. At this paper, the production process of dimethyl carbonate in a chemical plant was improved in order to saving more energy. The dynamic behavior of the new process was studied and heat exchange network of the whole plant was optimized. The research content mainly includes the following several aspects:(1) The steady-state simulation of the process is performed with Aspen Plus. During the simulation, the suitable thermodynamic model UNIQUAC-RK should be used in this work. The binary interaction parameters of the physical model are obtained based on the experiment data in previous literature. The result of the steady-state simulation shows that the proposed new process is feasible and preferable for the synthesis of DMC. Therefore, the model can estimate the improved effect accurately in the subsequent optimization study.(2) The integrated optimization of the reactive distillation and the pressure-swing distillation is researched. Basing on the original process, a novel process is put forward based on the traditional pressure-swing distillation. For the purpose of saving energy, the simulation and the partially heat integration of the new process are performed. The simulation result shows that the novel procedure can simplify the process and reduce energy consumption. Compared with the traditional processes, the new procedure can save energy costs and the new procedure with heat integration.(3) The dynamic behavior of the new process is Studied. First, the two kinds of control scheme are designed according to the characteristics of the process, and the control parameters are setting. The dynamic behaviors of the system are studied at the disturbance of feed rate and composition of the reaction distillation column by Aspen Dynamics. Results shows that the control structure 2 is more effectively maintain the system. Second, the dynamic behaviors of the system with heat integration are studied at the same disturbance, and it shows that control structure control process effectively.(4) Using Aspen Energy Analyzer, the design of the heat exchange network for the dimethyl carbonate production process was accessed basing on pinch technology. The design should satisfied the requirement of heat exchange and energy saving. The heat exchange network of the optimized process is evaluated and improved by a comprehensive evaluation model. Finally, we got a technological process with less operation cost and investment cost.