Simulation Calculation And Optimization Of Methanol Distillation Process And Research On Novel Process

Methanol is an important organic chemical raw material. The energy consumption of crude methanol production is one of the key factors which affects the cost of methanol production. The process of methanol distillation includes single-column process, tow-column process, three-column process and four-column process which is based on Lurgi three-column double-effect methanol distillation and is most widely used in the present large-scale methanol distillation. With the development of economy and the growing tension of energy, people become increasingly demanding on energy saving in the chemical production. Therefore, research and development on more energy-saving methanol distillation process have become one of the most important subject in the development of methanol distillation process. This paper is based on the existing methanol distillation process, the writer used the chemical process simulation software PRO/Ⅱ to simulate and analyse the existing process. The results show that, in the condition of the purified methanol meets the related quality requirements, the simulation results and production data reported in the literature is consistent, the selected simulation method is correct, and the results are accurate and reliable.Five-column process is a new multi-effect methanol distillation process which is based on four-colunm process. It adds one medium-pressure column after the original higher-pressure column so that purified methanol product can be obtained as the overhead products with an appropriate proporation from higher-pressure column, medium-pressure column, atmospheric column and recovery column accordingly in the new scheme. Raise the operating pressure of recovery column, thus a multi-effect distillation model with three groups heat integration between higher-pressure and medium-pressure columns, atmospheric and recovery columns, recovery and pre-run columns is created. Steady-state process simulation results indicate that temperature differences at tow sides of each heat exchanger are appropriate, allowing effective heat transfer. Economic analysis shows that the energy consumption of the five-column scheme can be reduced by23.33%compared to the four-column scheme. Significant savings in operating costs can therefore be achieved. And the writer also did research on the factors which could affect the new five-column scheme from the operating pressure, theory plate number, feed position and reflux ratio. Finally the best operating data are proposed.This work also propose a five-column multi-effect methanol distillation process in the reverse order on the basis of the new process mentioned before. After the simulation, the results shows that the reverse order process is feasible, the energy consumption can be reduced by27.28%compared to the four-column scheme, by5.18%compared to the five-column scheme, and this kind of scheme is more energy saving.In a word, the energy-saving effect of the new five-column methanol distillation process is very significant. Especially for large-scale methanol production process, it has a very good economic and application prospects. Results of this research can provide important reference on further research on dynamic performance and technology package design.