摘要
在刮膜式分子蒸馏器中,可以通过液体的停留时间分布反映物料蒸发分离特性,研究其规律对改进蒸馏器内的流场结构、优化操作参数和装置的设计都具有重要意义。今采用计算流体力学的方法,建立三维CFD模型,研究了进料速率和转子转速对停留时间分布规律的影响,并且与实验值进行对比验证;对蒸馏器壁面进行了优化,包括水平圆环、倾斜圆环和网状圆环三种优化壁面,并且对其分别进行模拟计算和实验验证。模拟结果显示出与实验结果相同的规律。结果表明,在研究范围内,停留时间随着进料速率的增大而减小;随着转子转速的增大,停留时间先增大,达到一定转速后,停留时间反而减小。经过壁面优化以后,在相同的进料速率和转子转速下,水平圆环壁面和网状圆环壁面的停留时间得到延长,倾斜圆环壁面的停留时间适当缩短;壁面湍动程度增大,有利于传质传热,提高了分离效率。
The residence time distribution（RTD） is a key parameter for reflecting the material flow and separation performance in wiped film molecular distillation. Therefore, the investigation of liquid RTD is of significance for comprehending and optimizing the wiped film molecular distillation apparatus. In this paper, a 3-D CFD model was established and employed to study the influences of inlet liquid velocity and rotor rotating speed on liquid RTD. Three different optimized wall structures were presented in this paper： the horizontal annulus wall, the inclined annulus wall and the webbed annulus wall. The simulation results of RTD agree with the experimental data reasonably. The results indicate that the mean residence time decreases with the increase of the inlet liquid velocity. As the inlet liquid velocity increased, the mixing degree is enhanced. In the beginning, the mean residence time increases with the increase of rotating speed; however, it decreases after the rotating speed reaches a certain speed. Under the same inlet liquid velocity and roating speed, the liquid residence time in the wiped film molecular distillator（WFMD） with horizontal annulus wall or webbed annulus wall is longer than that in the WFMD with smooth wall, while the liquid residence time in WFMD with inclined annulus wall is shorter. The turbulence intensity on the optimized wall is effectively promoted, thus enhancing heat transfer and improving separation efficiency.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2015年第2期277-283,共7页
Journal of Chemical Engineering of Chinese Universities
基金
国家自然科学基金(20976118
21176170)
关键词
刮膜式分子蒸馏
停留时间分布
计算流体力学
壁面优化
wiped film molecular distillation
residence time distribution
CFD
optimized wall structure
