空分装置中循环冷却水系统的节能优化研究

针对某30000m^(3)/h空分流程的循环冷却水系统,研究了循环水泵的转速调节和冷却塔风机叶片安装角调节对循环冷却水系统耗功的影响。以实现系统总能耗和冷却水资源节约为目标,利用优化算法,对该系统在不同工况下的运行策略进行了研究,获得了不同工况条件下的优化方案,给出了运行系统的调控策略建议。

Extending the EMMS/bubbling model to fluidization of binary particle mixture: Formulation and steady-state validation

The EMMS/bubbling model originally proposed for fluidization of monodisperse particles is extended to fluidization of binary particle mixture in this study.The dense and dilute phases are considered to comprise of two types of particles differing in size and/or density.Governing equations and the stability condition are then formulated and solved by using an optimization numerical scheme.The effects of bubble diameter are first investigated and a suitable bubble diameter correlation is chosen.Preliminary validation for steady state behavior shows the extended model can fairly capture the overall hydrodynamic behaviors in terms of volume fraction of bubbles and average bed voidage for both monodisperse and binary particle systems.This encourages us to integrate this model with CFD for more validations in the future.

聚硅烷类嵌段共聚物的聚合反应动力学及相分离机理

以聚甲基苯基硅烷为引发剂,在紫外光照下与乙烯基单体聚合形成聚硅烷类嵌段共聚物。基于聚合反应动力学模型,就单体、紫外光强、质量比对反应动力学参数以及嵌段长度的影响进行解析。进一步结合相分离观察的结果,分析了此类共聚物中发生相分离与否的影响因素。结果表明,光聚合后仅1000 s后碳嵌段平均长度就收拢于5~6个碳原子,硅元素嵌段平均长度也降低到2左右,表明此类材料未发生相分离,是适用于光波导领域的理想材料。

Engineered Hybrid Materials with Smart Surfaces for Effective Mitigation of Petroleum-Originated Pollutants

The generation and controlled or uncontrolled release of hydrocarbon-contaminated industrial wastewater effluents to water matrices are a major environmental concern.The contaminated water comes to surface in the form of stable emulsions,which sometimes require different techniques to mitigate or separate effectively.Both the crude emulsions and hydrocarbon-contaminated wastewater effluents contain suspended solids,oil/grease,organic matter,toxic elements,salts,and recalcitrant chemicals.Suitable treatment of crude oil emulsions has been one of the most important challenges due to the complex nature and the substantial amount of generated waste.Moreover,the recovery of oil from waste will help meet the increasing demand for oil and its derivatives.In this context,functional nanostructured materials with smart surfaces and switchable wettability properties have gained increasing attention because of their excellent performance in the separation of oil–water emulsions.Recent improvements in the design,composition,morphology,and fine-tuning of polymeric nanostructured materials have resulted in enhanced demulsification functionalities.Herein,we reviewed the environmental impacts of crude oil emulsions and hydrocarbon-contaminated wastewater effluents.Their effective treatments by smart polymeric nanostructured materials with wettability properties have been stated with suitable examples.The fundamental mechanisms underpinning the efficient separation of oil–water emulsions are discussed with suitable examples along with the future perspectives of smart materials.

甲醇制烯烃流化床内流化特性的多尺度CFD模拟

近些年,我国成功开发了以煤为原料的甲醇制烯烃(Methanol to Olefins,MTO)生产工艺和技术,带动煤制烯烃产业的快速发展,保障了国家能源安全。流化床式反应器是MTO工业生产的核心反应装置,通过计算流体力学(Computational Fluid Dynamics,CFD)方法深入认知MTO流化床内的流化特性规律具有重要的意义,它可以从理论上更加准确地指导MTO流化床的优化与放大。本工作采用基于宏观-亚网格层次的气泡EMMS曳力和传统TFM耦合计算的多尺度CFD方法,对工业尺度MTO流化床内的多相流化行为进行了三维数值模拟。模拟结果表明,该多尺度CFD方法考虑了气泡结构对气-固相间曳力的影响,能较准确地预测MTO流化床内轴向颗粒浓度的"S-型"分布规律,且得到实验数据的验证;所预测的径向颗粒浓度分布呈现出经典的"环-核"分布规律,气体/颗粒的轴向时均速度在径向上的分布也与实际情况相互佐证,表明该多尺度CFD方法显著改善了基于均匀曳力的传统TFM对于宏观流场的预测能力。下一步工作将多尺度CFD方法拓展应用于MTO流化床优化放大及反应特性的研究。

EMMS mixture model with size distribution for two-fluid simulation of riser flows

Further development of an energy-minimization multiscale modeling approach to simulating two-phase flow under turbulent conditions that considers the size distribution of mesoscale structures, i.e. bubbles and clusters, is presented. User-defined values of minimum and maximum cluster or bubble diame- ters were specified. A uniform size distribution was first considered as a test case, in which the drag force comprised contributions from each size group. The mathematical form of the objective function describing the energy for suspension and transport was not altered. The heterogeneity index of this new drag modification was then used to simulate pilot-scale circulating fluidized-bed risers involving Geldart group A particles. The results were validated against available experimental data. The model is capable of capturing both axial and radial profiles of flow-field variables.