摘要
为深入研究对二甲苯悬浮结晶过程与晶体流动分布特性,明确影响结晶的关键因素,将欧拉-欧拉多相流模型与粒数衡算方程(PBM)耦合,关联晶体成核速率和生长速率方程,模拟求解了对二甲苯的结晶与分布情况。结果表明:随着流动时间的增加,结晶器内的混合程度逐渐增加,30 s后流场基本保持稳定。流体在结晶器内主要为内循环流动与局部涡流并存,各区域温度差异很小,晶体在涡流区域的体积分数大于涡流区域附近的体积分数。粒度分布最大位置位于结晶器下挡板以及底部,随着区域流速的增大,晶体体积分数逐渐减小,流速大于1.40 m/s时不利于晶体生长,在工业生产时应避免结晶器内流速大于1.40 m/s。结晶器内0.01 mm晶体的不均匀度为0.0007,随着晶体粒径增大,大粒径晶体不均匀度逐渐增加;晶体粒度分布整体呈正态分布,其中0.03~0.05 mm粒径的晶体数量最多,占晶体总量的44.5%。本文实现了复杂流场下的结晶过程模拟仿真,所得结果揭示了结晶器内对二甲苯的成核生长规律,为优化创新对二甲苯结晶分离提供了依据和理论指导。
In order to further study the suspended crystallization process and crystal flow distribution characteristics of p-xylene,and to clarify the key factors affecting crystallization,the Euler-Euler multiphase flow model is coupled with Population Balance Model(PBM)to correlate the crystal nucleation rate equation and growth rate equation,and the crystallization and distribution of p-xylene are simulated and solved.The results show that the mixing degree in the crystallizer increases gradually with the increase of flow time,and the flow field is basically stable after 30 s.The crystal flow in the crystallizer is mainly in an internal circulation and local vortex.The temperature difference in each zone is very small,and the volume fraction of crystals in the vortex area is greater than that near the vortex area.The maximum particle size distribution is located in the lower baffle and bottom of the crystallizer.With the increase of the regional flow rate,the crystal volume fraction gradually decreases.When the flow rate is greater than 1.40 m/s,it is not conducive to crystal growth.In industrial production,the fluid velocity in cryatllizer should not be greater than 1.40 m/s.The non-uniformity of the 0.01 mm crystal in the crystallizer is 0.0007,and with the increase of the crystal size,the non-uniformity of large-size crystal increases gradually.The particle size distribution of crystals is basically normal,and the number of crystals with size of 0.03~0.05 mm is the largest,accounting for 44.5%of the total crystals.This paper has realized the crystallization simulation under complex flow field,the conclusions obtained reveal the nucleation and growth law of p-xylene in the crystallizer,and provide the basis and theoretical guidance for the optimization and innovation of p-xylene crystallization separation.
作者
董佳宇
任智宏
彭小成
陈强
王斯民
DONG Jiayu;REN Zhihong;PENG Xiaocheng;CHEN Qiang;WANG Simin(School of Chemical Engineering and Technology,Xi’an Jiaotong University,Xi’an 710049,China;SINOPEC Guangzhou Engineering Co.Ltd.,Guangzhou 510620,China;Luoyang R&D Center of Technology,SINOPEC Engineering(Group)Co.Ltd.,Luoyang,Henan 471003,China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2022年第2期26-34,共9页
Journal of Xi'an Jiaotong University
基金
国家自然科学基金资助项目(51676146)。
关键词
多相流
悬浮结晶
数值模拟
对二甲苯
粒度分布
multiphase flow
suspension crystallization
numerical simulation
paraxylene
particle size distribution
