The liquid holdup is limited by the physical space of the column and should not be appointed at random. To obtain the design and optimization of liquid holdup on reactive distillation trays, an optimization of tray configuration framework considering hydrodynamic feasibility was proposed. The effect of the liquid holdup on the reaction was studied, and the most optimal liquid holdup was obtained, through simultaneous design of three aspects of the liquid holdup, tray configuration and the hydrodynamic feasibility. Using the synthesis of diphenyl carbonate (DPC) by the transesterification of dimethyl carbonate (DMC) with phenol (PhOH) as an example, the implemented process of this method was described in detail. In the process of implementation, sieve tray was employed as illustrated configuration according to the traditional design method of distillation tray, with the maximum reactants conversion as objective function, weir height and column diameter of tray as decision variable and hydrodynamic feasibility of tray as constraints, a step-by-step simulation and design method was developed to achieve the optimization of liquid holdup on reactive distillation trays. Aspen Plus and Cup-Tower software were used to conduct the process simulation with chemical reaction kinetics and hydraulic computation respectively. The results showed that, the weeping was the main limiting factor to increase the liquid holdup. In the column with a diameter of 0.7 m and 0.06 m weir height, the maximum liquid holdup of 18.5 L was obtained, compared to the basic design an increase of holdup of tray by 1.39 times and PhOH conversion by 33.6% under the condition of satisfying hydraulic feasibility could be obtained. The temperature of the reboiler did not exceed 195℃ with optimizing the liquid holdup. In addition, the reaction rate of PhOH was higher than that of the initial design, which showed the validity of the proposed method for the DPC reactive distillation process.
Zixin LIN Ran AN Weizhong AN Lianxi HUANG Haiyan BIE Jianmin ZHU
. Design and optimization of liquid holdup on reactive distillation tray considering hydraulic feasibility[J]. The Chinese Journal of Process Engineering, 2018
, 18(6)
: 1239
-1244
.
DOI: 10.12034/j.issn.1009-606X.217414
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