Optimal reaction concept and plant wide optimization of the ethylene oxide process

In this paper, a new method for the identification of the best reaction concept from an overall process point of view is proposed. Using this method the optimal reaction route is determined independent of existing apparatuses and the recycle affecting the reactor is fully considered. The reaction concept and the design parameters of the process are simultaneously optimized. For this purpose, a detailed model of the reaction system including reaction kinetics, thermodynamic relationships, and intrinsic boundaries such as explosion limits as well as a complete model of the downstream process is set up. The potential of different reaction concepts including innovative process intensification alternatives can easily be determined by comparison with an optimized reference case. The example considered in this paper is the oxygen based ethylene oxide process, which is one of the most important chemical bulk processes. Sophisticated cooling in combination with distributed oxygen dosing along the reactor length is identified as best technical reaction concept with a potential of reducing the operating costs of an average sized plant by 1.35 Mio $/a compared to an optimized reference case. In addition, the utility consumption is reduced, especially the consumption of electricity is decreased by 46.3%, and the overall CO2 emissions are cut by 8%. In conclusion, the proposed method enables the predictive determination of the best reaction concept from an overall process point of view taking the full interconnections between the reaction concept and the process into account and considering highly innovative process intensification options. Thereby, this method provides a key stone for the development of more economical and more sustainable chemical reactors and processes of the future. (C) 2012 Published by Elsevier B.V.