萃取精馏的计算传质学模拟与实验验证

提出了萃取精馏过程模拟的计算传质学方法,并针对以N-甲基吡咯烷酮(NMP)为溶剂分离苯和噻吩的萃取精馏过程进行了模拟计算。在散堆填料实验塔内进行了相同的萃取精馏实验,得到了萃取精馏塔内浓度分布。将模拟计算结果与实验结果进行比较表明,提出的计算传质学方法能够有效预测萃取精馏塔内浓度和速度分布,为萃取精馏过程设计提供依据。     

基于CFD数值模拟的汽车排气系统结构分析

采用台架试验与计算流体力学（CFD）数值模拟相结合的方法,对某款汽车排气系统进行结构优化,以降低其排气背压.根据台架试验结果,划分了原排气系统中紧耦合催化转化器、二级催化转化器、主消声器和副消声器等各部件对整个排气背压的贡献量.通过CFD数值计算,详细分析了原排气系统中的流动特性,找到各部分排气背压的产生原因.结合台架试验和CFD的分析结果,对原始方案进行了针对性的结构优化.优化方案的排气背压比原始方案的排气背压平均下降了40%左右,最大排气背压由原来的90 kPa下降到改进后的51 kPa左右,达到了设计要求.     

精馏塔板液相流场三维模拟

The liquid flow on a single-pass sieve distillation tray is simulated with a three-dimensionM computational fluid dynamics (CFD) program with the K-e turbulence model. In the model, a source term SMi is formulated in the Navier-Stokes equations to represent the interfacial momentum transfer and another term Sc is added to the mass transfer equation as the source of interfacial mass transfer. The simulation provides the detailed information of the three-dimensionM distribution of liquid velocity on the tray, the circulation area and the concentration profile along the height of liquid layer.     

塔板液相三维流场的研究(Ⅰ)试验测量

本文针对热膜流速仪元件的工作原理提出了在平面旋转测量液体三维流速的方法,并测量了大型精馏塔板液相单相三维流场。为计算流体力学对塔板模拟提供了实验验证。测量结果发现在塔板的回流区、出口堰和塔壁附近流速的垂直分量是不可忽略的,有的地方流速的垂直分量的大小与其水平分量数量级相同。     

一个用于精馏塔模拟的新模型

A new computational mass transfer model is proposed for simulating the distillation process by solving the fluctuating mass flux for the closure of turbulent mass transfer equation in order to obtain the concentration profile and the separation efficiency of distillation column. The feather of the proposed model is to abandon the conventional way of introducing the turbulent mass transfer diffusivity (dispersion coefficient) to the turbulent mass transfer equation. To verify the validity of the proposed model, a commercial scale packed column and a sieve tray column were simulated and compared with published experimental data. The simulated results were satisfactorily confirmed in both concentration distribution and separation efficiency.     

界面传质中Rayleigh对流的格子Boltzmann模拟和实验验证(英文)

Concentration gradient induced Rayleigh convection can influence effectively interfacial mass transfer processes, but the convection phenomena are known as mesoscopic and complex. In order to investigate this phe-nomenon, a two-equation Lattice Boltzmann Method (LBM) is proposed to simulate the velocity and the concentra-tion distributions of Rayleigh convection generated in the CO2 absorption into ethanol liquid. The simulated results on velocity distributions are experimentally verified by PIV (particle image velocimetry technique) measurements. In order to simplify the analysis, the convection in the simulation as well as in the experiment, the Rayleigh convec-tion was manipulated into a single down flow pattern. The simulated results show that the concentration contours agree qualitatively with the schlieren images in the literature. The experimental and simulated results show that the Rayleigh convection under investigation is dominated by the flow in the downward direction and impels exchange of the liquid between the interfacial vicinity and the liquid bulk promoting the renewal of interfacial liquid, and hence enhances mass transfer. The comparison between the simulated and experimental results demonstrated that the proposed LBM is a promising alternative for simulating mass transfer induced Rayleigh convection.     

规整填料塔中氨水吸收CO2的体积总传质系数

目前,CO₂排放问题已经成为世界各国可持续发展面临的重要挑战。以化学溶剂吸收法工艺为基础的燃烧后脱碳是当前比较成熟的已进入工业规模实验的技术路线。而氨水作为一种新的吸收剂受到广泛关注。以气相体积传质系数（K_Ga_e）作为表征,对规整填料塔中氨水吸收CO₂的传质性能进行了研究,探索了气速、CO₂分压、液速和氨水浓度对K_Ga_e的影响。实验结果表明,在本文的工况条件下,K_Ga_e随液速和氨水浓度的增大而增大,随CO₂分压的增大有所减小,气速对K_Ga_e的影响不大。实验结果对今后填料塔的设计工作的经济性和合理性有一定指导作用。     

分子模拟评价萃取精馏萃取剂的新方法

萃取精馏是强化分离的有效方法,选用不同的萃取剂对萃取精馏过程的可行性和经济性有很大影响。探索性地使用分子模拟软件Material Studio 计算二元物系的混合能来作为萃取剂优劣的判据。以苯和环己烷为待分离物系,选择多种溶剂作为萃取剂,计算萃取剂分子与苯分子之间的混合能以及萃取剂分子与环己烷分子之间的混合能,并计算2个混合能的差值。以文献报导的选择性和以热力学NRTL方程计算无限稀释活度系数得到的选择性为标准来验证使用混合能差值评价萃取剂优劣的合理性。验证结果表明混合能差值基本随选择性的增加而增大,这一结论为进一步深入理论研究和新的萃取剂选择方法的开发打下了基础。     

不同方法合成金属有机骨架材料MOF-5的比较研究

针对金属有机骨架材料MOF-5的制备,采用了水热合成法、直接加入法以及在直接法中额外滴加H₂O₂的3种方法分别合成MOF-5晶体。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、傅里叶红外光谱仪（FTIR）以及热重分析仪（TG）等仪器对MOF-5晶体进行了表征。研究了不同合成方法对其结构、形貌及热稳定性等性质的影响。结果表明：3种方法所制备的晶体XRD衍射峰与文献中MOF-5晶体的特征峰相符,即均可合成MOF-5晶体。但SEM、FTIR以及TG结果表明：水热法合成的晶体具有粒径较小和结构规则的特点,但热稳定性较差;其余2种方法合成的产物为微米级无规则聚集状晶体,与水热法相比晶体性质有一定差异。此外,滴加H₂O₂有助于晶粒的快速形成以及晶粒分散。     

钙钛矿La_(1-x)Ce_xMnO_3在三元催化剂中的应用

开发研制出一种以钙钛矿La0.6Ce0.4MnO3和贵金属Pt、Pd为主要活性成分的汽车尾气净化三元催化剂,催化剂配方大大降低了贵金属用量。小试评价试验表明,新配方催化剂活性比目前市场上的催化剂催化活性更强。