工业结晶器内流体流动过程的数值模拟  

Numerical Simulation of Mixing Process in Industry Crystallizer

作　　者：张梦华[1] 李小松[1,2] 罗妍[1] 宋兴福[1] 于建国[1] 

机构地区：[1]华东理工大学国家盐湖资源综合利用工程技术研究中心,上海200237 [2]青海盐湖工业集团股份有限公司,青海格尔木816000

出　　处：《华东理工大学学报（自然科学版）》2010年第1期14-19,共6页Journal of East China University of Science and Technology

基　　金：青海省2006年度重大科技攻关项目(2006-G-161);上海市重点学科建设项目(B506);教育部新世纪优秀人才计划项目(NCET-08-0776)

摘　　要：对某无机盐工业结晶反应器中的流体流动过程进行了三维数值模拟，采用多重参考系法（MRF）及标准k-ε模型，分析了桨型、转速、桨的安装高度对结晶器流场的影响情况。计算结果表明：速度分布主要集中于内导流筒内部以及内、外导流筒之间的区域，相应地，结晶器被粗略地划分为对反应结晶过程具有不同作用的两个区域——内导流筒内速度较大的循环区和外导流筒外速度较小的沉降区。通过对循环区和沉降区的速度分布比较，认为推进式搅拌桨的流体流场速度云分布均一性要好于其他型式的搅拌桨，其最佳安装高度为3．5～5．7m。在合适的搅拌速率下，结晶器沉降区的流体流动速率具有均匀向上的特点，可以有效带出部分小粒子，有利于获得大粒度产品。通过流动过程的数值模拟获得详细的流场分布及操作参数，为结晶器结构和操作参数优化提供了理论指导。实践表明：优化后的产品粒度显著提高，产品中大于0．2mm的粒子从优化前的不足50％提高到优化后的90％以上，干燥产品的天然气消耗从优化前的22m^3／t降低到优化后的15m^3／t，节能降耗效果显著。Stirred tanks are widely used in many industrial processes. In this paper, the mixing process of industry crystallizer was simulated three dimensionally by computational fluid dynamics （CFD）. The multi-reference frame （MRF） and standard k-ε turbulent model were used in the simulation to analyze the effect of the propeller structure, rotational speed and the distance of impeller location on the flow field in the crystallizer. The simulation results show that the velocity distributes mainly on the area in the interior draft tube and between the interior and exterior draft tube. Therefore, according to the notable difference of velocity at different areas, the crystallizer can be divided into approximately two zones based on the different effects in the flow processes of crystallization： the cycle zone with high velocity speed inside the draft tube and the sedimentation zone with low velocity speed outside the draft tube. Through comparison of velocity contour between cycle zone and sedimentation zone, propeller is proved to be more suitable than others, and the best distance of impeller location in the system is from 3. 5 m to 5. 7 m. The uniform velocity rate of fluid flow upward at the sedimentation zone engendered through the appropriate rotational speed can bring out the small crystals and is favorable for large particle size products. The detailed flow field in the stirred tank and different operation parameters can provide theoretical guidance to optimize the structure and operation parameter in the industrial scale. The industrial results show that the product particle size has been significantly increased, and the proportion of particles more than 0.2 mm increases from less than 50% to more than 90%. Natural gas consumption for drying products is decreased from 22 m^3/t to 15 m^3/t. The energy is remarkable saved.

关 键 词：数值模拟 搅拌桨 导流筒 结晶器 

分 类 号：TQ027[化学工程]