基于Aspen Adsorption的活性炭吸附溶液中镍离子的模拟研究

利用Aspen Adsorption对活性炭吸附溶液中镍离子的过程进行模拟研究。通过静态吸附实验数据拟合、吸附等温线常数项估算,建立了实验室规模的活性炭吸附溶液中镍离子的单塔吸附模型;在设置的进料流量为0.001m³/s、进料浓度为50mg/m³的初始条件下,模拟计算获得了吸附塔出口液相中镍离子浓度随时间的变化和沿床层轴向的分布,并考察了进料浓度、进料流量和传质系数等对吸附过程和穿透曲线的影响。结果表明:模拟计算结果与实验结果基本吻合,模型假设、参数设置合理,研究条件下吸附床层在15000s后被完全穿透;随进料镍离子浓度、进料流量的增大,吸附床层的穿透曲线均前移,进料流量的影响更为显著,进料镍离子浓度由50mg/m³增大至5000mg/m³时,穿透时间从3500s提前至1500s,而进料量由0.001m³/s提高到0.002m³/s时,穿透时间从3500s即提前至1700s;传质系数≤0.1s^-1时对吸附性能影响显著。模拟研究、计算为放大试验及实际工程应用工艺参数的选择提供了依据。     

液-液喷射器不同进料方式下混合过程的CFD模拟

利用计算流体力学(CFD)软件CFX5对液-液喷射器混合段物料的混合性能进行了模拟,确定了工作流体和引射流体都平行于混合管轴线进料时物料完全混合所需的混合管长度,并分析了三种不同进料方式:(1)工作流体和引射流体都与混合段轴线平行进料;(2)工作流体与混合段轴线平行进料,引射流体与轴线成30°进料;(3)引射流体与混合段轴线平行进料,工作流体与轴线成30°,对混合管内混合过程的影响,结果表明,工作流体和引射流体都与混合段轴线平行进料时混合效果最好。     

双层桨搅拌浸出槽固液两相流场的数值仿真

在石煤提钒搅拌浸出槽的研究中,针对双层桨搅拌浸出槽固液悬浮特性以及混合浸出效果进行了研究.由于实验成本大、操作困难,提出了数值仿真的方法.运用计算流体力学(CFD)软件FLUENT对石煤提钒搅拌浸出槽进行流场仿真,用GAMBIT建立流场实体模型,采用k-ε湍流模型以及多重参考系法(MRF)处理搅拌桨区.探讨了双层桨同向旋转和双层桨异向旋转两种情况下的搅拌效果,结果表明在相同的情况下,双层桨异向旋转时湍动能分布更为合理,并且能够缓解底部沉积,搅拌混合效果更好.仿真结果对于研究搅拌反应容器内部流场规律,进而对搅拌反应容器的结构优化和浸出率的提高具有一定参考价值.     

行星式搅拌釜内固液混合时间的数值计算

行星式搅拌装置内搅拌桨的运动轨迹复杂,对固体颗粒与高黏度聚合物熔体的混合效果较好。混合时间是表征搅拌釜内流体混合状况、评定搅拌釜效率的重要参数之一。利用FLUENT软件数值模拟一种行星式搅拌釜内高黏固液两相混合过程,采用传统混合时间定义方法和体积分数法2种方法计算搅拌桨不同自转转速的混合时间,并将2种方法的计算结果进行比较;采用体积分数法计算搅拌桨不同安装高度时的混合时间。计算中采用欧拉模型,使用动网格技术,利用FLUENT的用户自定义函数确定搅拌桨的速度。数值计算结果表明,采用选取监测点计算混合时间的方法,不同监测点的混合时间有较大差异,为保证全釜内混合均匀,应选取混合时间最长的监测点;选取监测点和体积分数2种混合时间计算方法得到的混合时间基本相同;随着搅拌桨自转转速的提高,混合时间明显缩短;采用釜底加料方式,搅拌桨安装高度从20mm提高到60mm时混合时间缩短。     

基于EMMS曳力的湍动床气固流动CFD模拟

湍动流化床已广泛用于费托合成、FCC催化裂化等工业过程。其主要流动特点是由底部密相鼓泡区与顶部稀相分散区两者构成。由于湍动流化的复杂性,导致目前对该类体系内非均匀结构形成与演化的研究相对较少。近年来,快速发展的计算流体力学方法为深入研究此类流化提供了一种有效的手段,然而传统的双流体模型往往不能成功捕获到湍动流化的复杂结构。为了考虑非均匀结构对曳力的影响,本文提出了一个改进的曳力模型,即将湍动流化床分为3个区域:底部鼓泡区、过渡区和顶部稀相区。其中,底部区采用气泡EMMS曳力模型进行修正,过渡区采用Wen-Yu曳力模型,顶部区采用Schiller-Naumann曳力模型。修正的曳力模型与双流体模型耦合后,再通过FLUENT商业软件平台对湍动流化床内的气固两相流动进行CFD模拟。模拟结果显示,修正的曳力模型可以较好的预测湍动流化床内的流体动力学特征。该曳力模型能够模拟底部密相鼓泡区和顶部稀相分散区的两相共存结构,颗粒浓度在径向分布上为"环-核"结构,模拟的轴向颗粒浓度分布与实验数据吻合较好。     

单级结晶法从混合二氯苯中提取对二氯苯

采用减压蒸馏等方法对氯化苯精馏塔的釜底液混合二氯苯进行预处理,得到了3种不同的原料;设计了梨形夹套式搅拌萃取结晶装置,采用单级结晶法,从3种不同的原料中分别提取高纯度的对二氯苯,对比不同原料的结晶效果;由于温度是结晶过程的主要影响因素,本文重点研究了温度对结晶过程中的对二氯苯的纯度和得率的影响;实验结果表明,采用单级结晶法,选用减压蒸馏和连续精馏处理后的原料,在温度为-5°C的条件下,对二氯苯的纯度可从45.84%提高到98.79%以上,得率达到47.82%.研究结果为多级结晶法提纯对二氯苯进一步研究提供有效数据.     

甲苯歧化进料预热过程的热力学分析与改进

运用流程模拟软件PRO/Ⅱ进行甲苯歧化(TDP)过程模拟,构造新鲜进料和补充进料预热过程的能级-热量(ε-Q)图,对进料预热过程进行热力学分析,发现存在不合理混合、重复冷却升温和大温差换热火用损。应用夹点分析估算2股进料的理论换热终温,确定换热流程优化调整目标,通过热联合及低温余热利用,对冷热物流进行合理匹配,极大减小了过程火用损。分析表明,改造后2股进料混合火用损分别减小54.1%、16.3%,冷热升温火用损减小40.1%,大温差火用损减小25.0%,2股进料换热终温分别提高了9.0℃、22.3℃,加热炉及加热器负荷相应降低,各环节均表现出较大的节能潜力。经济分析表明换热器的投资费用为94639.84$,节能效益约为126750.49$,投资回收期为0.75年,效果明显。     

酯交换合成碳酸二乙酯反应精馏工艺的模拟

碳酸二乙酯是一种性能优良的绿色溶剂,在锂离子电池行业中应用广泛。以碳酸二甲酯和乙醇为原料,采用反应精馏工艺生产碳酸二乙酯是目前的主流工艺。由于该反应分为两步进行,因此如何调节工艺参数来提高反应物转化率和产品收率是工业生产中的重要问题。本文以实验得出的动力学方程、UNIQUAC热力学模型,应用Aspen Plus流程模拟软件实现了工业实际反应精馏工艺流程的模拟,详细讨论了进料位置、回流比、进料配比等因素对反应精馏塔性能的影响。结果表明,模拟值与实验值吻合良好,在回流比为4.5～5,混合进料第20块板,进料醇酯比2.5:1,反应段（2～31）块板,空速小于0.18 hr^-1时,反应精馏塔性能最佳。模拟结果对反应精馏合成碳酸二乙酯的工艺设计和过程优化具有重要指导意义。     

撞击流反应器内气固两相流动的数值模拟

采用标准k-ε湍流模型和颗粒轨道模型模拟了水平撞击流反应器内的气相流场和颗粒运动,实验采用压力计和PV4A光纤速度测量仪测量了整体压力损失和颗粒沿喷嘴轴线的速度变化,模拟得到的规律和实验结果基本吻合。通过模拟还得到了单侧颗粒进料时的颗粒运动特征、颗粒的最大渗透深度和平均飞行时间等信息。结果表明,撞击区域集中在2～3倍喷嘴直径范围之内,气流场的速度和压力呈对称分布,颗粒进入反向气流后速度急剧衰减,最大渗透深度约为喷嘴直径的2倍,颗粒的平均飞行时间在0.7 s～1.8 s之间。随着喷嘴气流速度的增加,颗粒物料更容易被气流带走。     

结晶釜直径对SAS成粒过程影响的CFD研究

为探讨结晶釜直径对SAS(超临界抗溶剂法)过程的影响规律,并确定适宜的结晶釜直径,本文采用计算流体力学(CFD)方法,选用Realizableκ-ε湍动模型对SAS喷射过程建立模型。结晶釜高度为L=190 mm,考察了直径分别为40 mm、30 mm、20 rnm和15 mm时釜内流体迹线、溶剂浓度分布、有效扩散因子分布及湍动强度分布变化规律,尤其是喷嘴出口附近溶液射流区内的流场变化状况。结果表明,随着结晶釜直径的减小,釜内漩涡区逐渐向釜顶缩小,有利于避免釜内颗粒间碰撞造成的粘结;釜内溶剂浓度逐渐减小,而有效扩散因子分布及湍动强度的绝对值逐渐增大但分布范围逐渐向釜顶缩小:喷嘴出口附近溶液射流区内的有效扩散因子与湍动强度逐渐增大,有利于提高成核速率而减小颗粒粒径。较小直径的结晶釜,还会降低流体在釜内的停留时间,减少颗粒生长时间而利于减小颗粒粒径,因此选择小直径结晶釜对SAS过程有利。本文通过CFD模拟研究,揭示了SAS结晶釜直径对SAS成粒过程的影响规律,对SAS结晶釜的优化设计具有一定的理论指导。     

Numerical modeling of polystyrene synthesis in coiled flow inverter

Recent studies show that microfluidic devices are gaining importance as micromixer in chemical and bio-chemical analysis systems. However, little attention has been paid to investigate chemical reactions such as polymerization reaction process in microreactors. In the present study, numerical modeling of the free-radical polymerization of styrene was carried out in novel coiled flow inverter (CFI) microreactor. The concept of CFI is based on the technique developed by Saxena and Nigam (AlChE J 30:363–368, 1984). This device is made up of helical coiled tube which is bent periodically to 90° at equidistant length. The CFD modeling for polymerization reaction taking place in coiled tube reactor was also performed in order to understand the influence of secondary flows on reactor performance for fluid flowing with very low flow rate. Its performance was compared with CFD results obtained in a straight tube reactor having identical length and operating under the same process conditions. The results showed that monomer conversion in the coiled tube reactor was higher than that of the straight tube reactor. Further work was carried out in the novel CFI reactor to study the effect of diffusion coefficient and number of bends on different parameters such as monomer conversion, number-average degree of polymerization (DP _n ), and polydispersity indexes (PDI). It was found that the performance of CFI as reactor increased when the diffusion coefficients of reactants was decreased. Thus, CFI was found to be an efficient microfluidic device for controlling the free-radical polymerization.     

精馏及精馏-膜集成分离乙酸/水

模拟计算考察乙酸／水混合物精馏特性，比较精馏及精馏／膜集成分离过程的能耗特点。塔中部进料，进料级附近出现夹紧点，而塔底部进料时，塔上部出现夹紧点。不同位置的侧线采出通过膜分离后返回塔内对分离效果有影响，且存在一较佳的侧线采出塔级。计算表明通过精馏－－膜集成过程制备无水乙酸可能是一种有应用前景的分离技术。     

Bilayer staggered herringbone micro-mixers with symmetric and asymmetric geometries

Micro-mixing is an important research area for various applications in sensing and diagnostics. In this paper, we present a performance comparison of several different passive micromixer designs based on the idea of staggered herringbone mixers (SHM). The working principle in such designs includes the formation of centers of flow rotation thus leading to multiple laminations with decreasing sizes of the lamellae as the flow passes over staggered structures. We have realized different layout designs of staggered herringbones inside micro-channels and compared their mixing performance. An overall reduction in mixing time and length has been observed as the degree of asymmetry within these structures is increased. The layouts of these staggered structures are based on herringbone bilayers wherein these layers are positioned on the top and bottom walls of a micro-channel. Fluorescence microscopy and computational fluid dynamics (CFD) based modeling have been used to observe the extent of mixing and understand the reasons behind the enhanced mixing effects. We have further varied the degree of asymmetry of the herringbone bilayers and investigated mixing as a function of the asymmetry. We have developed a novel microfabrication strategy to realize these micro-devices using an inexpensive non-photolithographic technique which we call micro-replication by double inversion (MRDI). The paper basically attempts to develop an overall understanding of the mixing process by letting two fluids flow pass over a variety of asymmetric structures.     

基于构件库/工作流的可视化软件开发

在研究构件技术的基础上,结合工作流技术提出了一种新的软件开发模式,即通过将可视化的构件库与可视化的工作流编辑系统全面融合实现零编程的软件搭建平台。构件库包含了多层次和多粒度的可视化软件构件集合。工作流以业务流程为核心来组装各种构件以实现可视化的软件开发。论文提出了软件构件运行与逻辑控制分离的思想,通过构件库不同层次构件为用户提供良好的软件扩展性和移植性,通过工作流引擎的流程控制取代程序流程的过程控制实现面向业务的快速软件搭建,并支持任意流程的实时测试。这种软件开发模式拓展了传统软件工程的过程开发方式,能较好兼容自上而下和自下而上的软件工程方法,并能适用于BS/CS开发模式。该模型已在新一代GIS平台——MapGIS搭建平台中得到成功应用。最后分析了该软件开发方法的优缺点。     

间隔互插式连栋温室的自然通风模拟与优化

从自然通风的特点出发。以计算流体动力学（CFD）理论为基础。运用ANSYS9．0软件，对间隔互插式连栋温室利用风压进行自然通风的情况进行模拟与分析。模拟结果显示当间隔互插式连栋温室的自然通风采用侧窗和肩窗组合通风方式时，在棚室1、2顶部、棚室3的右下端形成回流区，回流区风速接近零风速，温室内部空气混合不均匀，通风效果不好。通过对温室周围气流运动的理论分析和实体仿真模拟，提出了间隔互插式连栋温室通风的优化方式。模拟显示当风向垂直于温室侧窗时，天窗和侧窗组合通风效果优于现行的肩窗和侧窗组合通风方式。     

Control strategies for reactive batch distillation

A batch reactor may be combined directly with a distillation column by distilling off the light component product in order to increase the reactor temperature or to improve the product yield of an equilibrium reaction. The same amount of the light product should be removed as the amount being formed by the reaction at any time. A linearized model has been developed which describes the process behaviour satisfactorily for control analysis purposes. The controllability of a combined batch reactor/batch distillation column is found to depend strongly on the operating conditions and on the time during the run. In general, controlling only the reactor temperature (one-point bottom control) is difficult since the set-point has to be specified below a maximum value in order to avoid break-through of an intermediate component in the ditillate. This maximum value may be difficult to know a priori. For the example considered in this study, control of both reactor temperature and distillate composition (two-point control) is also found to be difficult due to large interactions in the column. As with one-point bottom control, the reactor temperature has to be specified below a maximum value. However, energy can be saved since the heat duty can be decreased with time. Controlling the temperature on a tray in the column (one-point column control) is found to give good performance for the given process with no loss of reactant and a high reactor temperature, although no direct control of the reactor temperature is obtained.     

基于虚拟DCS的电厂烟气脱硫协同仿真系统

介绍新型的电厂烟气脱硫仿真系统,提出采用基于CFD模型及过程模型的协同仿真方法进行建模,硬件系统采用虚拟DCS仿真方式.采用CFD方法建立详尽描述吸收塔特性的CFD模型,同时采用集中参数法对FGD其它设备进行建模,协同仿真方法能充分发挥两种建模方法的优点,更精确地描述FGD系统的特性.采用基于虚拟DCS的激励式仿真方法建立仿真系统,结合了全模拟模式和全激励模式的优点,使用虚拟DCS复现实际DCS的全部功能,具有极高的软件逼真度,同时以软件代替部分硬件,可极大地降低实现成本.基于虚拟DCS的电厂烟气脱硫协同仿真系统对于电厂脱硫系统人员培训、运行分析及系统优化研究具有重要作用.     

室温单电子晶体管制备进展

单电子晶体管由于其纳米级的器件尺寸和超低功耗等优点被广泛认为是当前最有应用前景的纳米电子器件之一,实现室温下的正常工作和器件结构的精确控制是其实用化的关键。室温单电子晶体管的主流制备方法为自顶向下工艺和自底向上工艺。自顶向下工艺便于器件集成,但纳米尺度下的制备工艺误差较大,室温单电子晶体管的性质难以稳定;自底向上工艺能够比较容易地制备出室温单电子晶体管,但同样有耦合结构误差较大的问题。在结合自顶向下工艺和自底向上工艺的基础上,引进纳米结构制备的新技术来提高工艺过程的可控性,是下一步室温单电子晶体管制备的研究重点。     

乙烯裂解炉反应管数学模拟新方法

综述了不同类型的乙烯裂解炉反应管数学模型，分析了各类模型的缺点。为此提出了一种进行反应管数学模拟的新方法。即应用CFD方法对反应管内流体流动、传热、传质及裂解反应过程，不经任何简化直接进行数值求解，得到了管内的流场、温度场和浓度场等详细信息。模拟计算得到了反应管长度方向上的温度、速度、压力和组分浓度的变化规律；在反应管径向上存在着明显的速度和温度分布，而组分浓度变化程度不如速度和温度明显；计算结果为提出结焦抑制方法提供了依据。     

Online genetic-ANFIS temperature control for advanced microwave biodiesel reactor

Biofuels, such as biodiesel, are good for the environment because they add fewer emissions to the atmosphere than petroleum-based fuel. Conventional biodiesel processes are mainly based on use of high power thermal heating to produce biodiesel from pure or waste feedstock such as virgin vegetable oils or waste cooking oils. The development of a novel continuous microwave biodiesel reactor for the conversion of waste oil and fats into biodiesel is reported. This process has the capability to enhance the production of biodiesel in a very short time as compared with conventional methods that require lengthy hours and days. Real time monitoring and control process in microwave biodiesel reactor is necessary to adjust the applied power of microwave reactor under different perturbations for the process temperature control, and full system real time monitoring. The paper focuses on an artificial intelligence technique to design online genetic-ANFIS temperature control based on LabVIEW. The designed controller was compared with error-based Adaptive controller to explore the robustness of the proposed controller in nonlinear real time application.