Kinetics, Mass Transfer, and Reactor Scaling Up in Production of Direct Dimethyl Ether

A two-phase model was developed for scaling up bubbling fluidized bed reactors for dimethyl ether production. Kinetic model correlations for the reactions were developed from fixed-bed experimental data. In addition, the mass transfer coefficient between the bubble and emulsion phases in a bubbling fluidized bed was estimated from experimental data, and the Sherwood number correlation was reported. Finally, scaling up of a bubbling fluidized bed reactor from laboratory to industrial scale was carried out using three similarity criteria: hydrodynamic, residence time, and performance. The hydrodynamic similarity criterion was shown to be inadequate due to low mass transfer and residence time on a large scale. The criteria of similarities in performance and residence time provide the same dimethyl ether yield in all scales. The two-phase models, combined with correlations developed for kinetic and mass transfer parameters, are useful for analysis of laboratory and industrial-scale reactors, and provide information on scaling up.