(86f) Process Integration for Dimethyl Ether Synthesis Via Catalytic Dehydration of Methanol

Distillation is the most widely used separation technique in the process industry. Its main disadvantage is the high consumption of thermal energy: the heat requirements of the distillation columns often represent most part of the total energy cost of the plant. The energy saving in distillation is then an essential field of the chemical engineering research since the early 1970’s; appropriate integration of the distillation columns with the overall process often results in a significant reduction of the energy consumption in many cases.

In this work the concept of the integration with the overall process has been applied by two integrated design approaches:

• Heat-integrated design; where the distillation system of the process will be heat-integrated with the background process (i.e. integration between the distillation columns and the heat exchangers).
• Reactive distillation design; where the reaction and distillation will be accomplished in the same unit operation.

The process of dimethyl ether (DME) synthesis by the catalytic dehydration of methanol has been considered as a case study.

Heat-integrated design of DME process showed a significant total annual cost saving of 41% compared to the conventional process, and the reactive DME distillation column design showed highest saving in total annual cost by 81%.

In addition to the cost saving of the two proposed designs, also the flue gas emissions have been reduced using process integration methodology, where 51% of the total emissions has been reduced by the heat-integrated design and 86% by the reactive distillation column design.