Numerical Simulation and Process Enhancement of the Hydrolysis of 2-Chlorobenzal Chloride

Abstract

Hydrolysis of 2-Chlorobenzal chloride is the primary production method of 2-chlobrobenzaldehyde in industry, but the reactor technologies and reaction processes of this method are traditional and underdeveloped, in which the dichotomous leaf hydrolysis agitator is commonly used, resulting in low efficiency during the hydrolysis process. In this article, ANSYS software was utilized to enhance the hydrolytic reactors used in industrial production by simulating and analyzing the dispersion characteristics of droplets in the reactor. The particle size distribution of dispersed phase droplets and the Sauter mean diameter (D32) were used to characterize the dispersion effect, and the dispersion characteristics of the dichotomous leaf agitator and the three-bladed back-curved impeller, three-bladed propeller impeller, open turbine impeller, and crescent impeller were compared and studied. The results showed that there was a log-linear relationship between the D32 of the dispersed phase and the stirring speed in different systems; the number of tiny droplets in the three-bladed back-curved impeller system increased remarkably, and the droplets size distribution width decreased significantly, achieving mass transfer enhancement in the hydrolysis reaction system. The reliability of the simulation results was verified by the measurement experiment using the Sauter mean diameter (D32) of dispersed phase droplets. The results showed that the Sauter mean diameter (D32) variation trend is consistent with that of the simulation, and the error between them is less than 10%. A lab-scale hydrolytic reactor was designed and produced based on the scheme of an industrial hydrolytic reactor equipped with a three-bladed back-curved impeller, the effect of the hydrolytic reaction was verified, and the process conditions were strengthened under the same conditions. The results showed that, compared with the case in the reactor using a dichotomous leaf hydrolysis agitator at the same reaction temperature and catalyst conditions, the reaction time of hydrolysis completion reduced to 58.33% at the lab-scale, and to 63.89% at the industrial-scale at the stirring rate of 446 r/min, using a three-bladed back-curved impeller. These results provide a technical scheme and a basis for process strengthening for improving the production efficiency of 2-chlorobenzaldehyde production equipment in industry.