The Study of Methanol Separation Columns Control

The design, optimization and better control of refinery processes become possible via dynamic simulation. In this article, a methanol distillation unit with three columns has been simulated to separate methanol from its impurities and water in steady and dynamic states, using commercial softwares. Moreover, it investigates, employing simulink/matlab software, the effect of variable changes on purity rate of the product methanol and water flow in the columns. This system has thermal integration property so that the condenser of the second column acts as the reboiler of the third column and these two thermal loads are considered equal in flow sheeting equation section of the commercial softwares employed. In dynamic environment, by installing level pressure controllers, the feed flow rate, product of the three columns and the purity of the product will be controlled. In spite of high number of the trays in the columns and apparently lack of need to install thermal temperature controller, the research findings show that installing temperature controllers for the columns results in high degree of separation of methanol distillation product. The findings also indicate that, with the increase of feed flow rate, the purity rate of methanol products will increase, while the purity rate of water flow will decrease. Further, the increase of feed methanol composition, though ineffective on the purity of methanol flows, it increases the rate of water flow purity. Meanwhile, the increase and reduction of the feed stage position of the first column does not affect the purity of the three product flows.