A process integration approach to the design of the two- and three-column methanol distillation schemes

A thermal and economic comparison of two- and three-column methanol distillation schemes for the purification of crude methanol is presented. The schemes investigated include the conventional two-column scheme involving a topping column and a refining column, two different enrichment cascade three-column schemes and a double-effect three-column scheme. Three different reforming process technologies are considered for the front-end process. Heat integration methodologies are used to determine the optimum column pressure settings. The benefits of enhanced heat integration with the background process are assessed through a determination of the respective capital, operating and investment costs.