Catalytic Rectification Adopted in DME Production for the First Time

Catalytic Rectification Adopted in DME Production for the First Time

The new technology for manufacture of dimethyl ether (DME) via catalytic recti fi cation of methanol completed by the Kerry Environmental Science and Technology Company, Ltd. has passed the review and appraisal organized by the Hebei Provincial Science and Technology Department. The experts attending the appraisal meeting have unanimously recognized that the said technology was a fi rst innovative one in China, with its overall technical performance reaching the internationally advanced level to play a demonstrative role.

The catalytic recti fi cation technique has been for the fi rst time introduced in China during the DME production. Inside the catalytic rectification tower the etherification reaction and product separation can proceed concurrently to break down the reaction equilibrium in order to shift the reaction towards DME formation, resulting in a methanol conversion of more than 99.5%. The DME product with a purity of exceeding 99.5% is delivered from the tower overhead to meet the standard for aerosol agent purity without further separation and purification. The wastewater delivered from the tower bottom contains less than 300 ppm of methanol at most and can be routed to the wastewater treatment plant without any need to recover methanol. This technology features shorter process fl ow scheme, lower reaction temperature, no needs for vaporization of feedstock, absence of side reactions, lower energy consumption and high product purity. This technology has grappled with the problems of traditional gas phase process, such as the long process fl ow diagram, the high reaction temperature, the high energy consumption, the needs for methanol vaporization, the low methanol conversion rate, the needs for purification and recovery of methanol as well as the needs for puri fi cation of DME product.

In comparison with the traditional gas phase process (calculated on the basis of a 200 kt/a DME unit) the new process accounts for about 60% of energy consumed by the traditional process, while its investment cost is equal to 90% of the traditional process. The operating cost of the new process can be reduced by 70 RMB on each ton of DME produced to signi fi cantly enhance the competitive edge and pro fi tability of the DME producing enterprise.