Abstract
The aim of this work is to present a model of a reaction tube with cross structures in order to improve ethyl acetate production and microwave heating uniformity. A commercial finite element software, COMSOL Multiphysics 4.3a (Newton, MA, USA), is used to build the proposed model for a BJ-22 rectangular waveguide system. Maxwell’s equations, the heat conduction equation, reaction kinetics equation and Navier-Stokes equation are combined to describe the continuous flow process. The electric field intensity, the temperature, the concentration of water, the coefficient of variation (COV) and the mean temperature at different initial velocities are compared to obtain the best flow rate. Four different initial velocities are employed to discuss the effect of flow velocity on the heating uniformity and heating efficiency. The point temperatures are measured by optical fibers to verify the simulated results. The results show the electric field intensity distributions at different initial velocities have little difference, which means the initial velocity will have the decisive influence on the heating process. At lower velocity, the COV will be smaller, which means better heating uniformity. Meanwhile, the distance between each cross structure has great influence on the heating uniformity and heating efficiency, while the angle has little. The proposed model can be applied to large-scale production of microwave-assisted ethyl acetate production.
Highlights
As an important industrial product, ethyl acetate has been widely used as solvent and intermediate [1]
The esterification reaction is selected since the kinetics of the chemical reaction is well investigated and this process is easy to simulate in the COMSOL Multiphysics
The tube with cross structures can obviously improve the heating uniformity and mean temperature compared to the tube without cross structures, due to the 10 K higher mean temperature and about
Summary
As an important industrial product, ethyl acetate has been widely used as solvent and intermediate [1]. Ethyl acetate is produced through the Fischer esterification reaction of acetic acid [2], the Tishchenko reaction of two acetaldehyde molecules [3] and the addition of acetic acid to ethylene [4] by conventional heating, which has the limitations of energy loss and being unfriendly to the environment [5,6,7]. The combination traditional means of drying with microwave technology can reduce processing time and produce higher quality foods in the food industry [8,9]. Microwave sintering could reduce time and energy during sintering process and improve mechanical properties and microstructure of products compared to conventional sintering process [10,11]. During the large-scale industrial application, non-uniform heating always happens, which may lead to the burning of samples [14,15]
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