Efficient recovery of high‐purity aniline from aqueous solutions using pervaporation‐fractional condensation system

Selective recovery of valuable minor component with high‐purity form from dilute aqueous solution is an interesting issue in the area of organophilic pervaporation. High‐purity aniline was recovered with a high production rate from dilute aqueous solution by a pervaporation‐fractional condensation (PVFC) coupling system. The effects of downstream pressure and temperature (the first condenser) on the performance of PVFC system were investigated based on experimental measurements and Aspen simulations. Sorption and desorption experiments demonstrated that the sorption selectivity of poly(ether block amide) (PEBA‐2533) membrane to aniline was extremely high, indicating excellent pervaporation performance for aniline/water solutions. The perfect integration of high‐performance PEBA‐2533 membrane with the fractional condensation process yielded high production rate of 1222.5 g/(m² h) as well as high recovery efficiency (86.5%) for recovering high‐purity aniline in the first condenser when feed concentration and temperature were 1 wt % and 80°C, respectively. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4445–4455, 2015     

蒸汽在扁平管内逆流流动凝结实验与理论分析

针对火电机组直接空冷凝汽器扁平管内蒸汽凝结换热过程,设计并搭建了水冷扁平管内可视化流动凝结实验台,开展管内凝结换热研究。建立涵盖壁面薄液膜和圆弧段液池的流动凝结分析模型,得到凝结液膜发展相关方程。特别对于壁面液膜双曲型发展方程,考虑其对流特征和物理守恒特性,提出共轭梯度法-牛顿法-模拟退火相结合的稳态求解算法,避免传统非稳态方法的复杂性。可视化实验结果表明,管内汽液两相分层流动,扁平管圆弧底部形成了液池。对应的理论分析结果更加细致地表明,管内凝结换热为分层流型,液池液膜厚度为1 mm量级,壁面液膜相比液池液膜薄很多,因而具有较高的凝结传热系数。分析结果为判断冬季低温环境运行时管内冻结起始位置提供了依据。     

非共沸制冷剂非完全冷凝现象的假想及判据

为了探讨空调系统中非共沸制冷剂的变工况循环特性,揭示系统循环参数与冷凝器中的换热流体温度和流量之间的关系,进行了大量的实验研究。根据实验数据发现了一种特殊的实验现象,即在换热流体进口温度不变的前提下,系统性能系数（COP）随换热流体流量的逐步增大呈现先升高后降低的特性,为解释此现象提出了制冷剂非完全冷凝的假想。在此基础上,初步建立了非共沸制冷剂非完全冷凝的理论判据,并将该判据推广应用到了15种已商品化的非共沸制冷剂上,预测了这些制冷剂发生非完全冷凝现象的条件。     

冷凝和吸附集成技术回收有机废气

有机废气治理的难度在于石化、石油、化工等领域的工艺不同,导致排放的废气组分及浓度相差很大。根据有机废气的特点,选择合适的工艺进行有效治理并实现资源回收是非常必要的。目前,冷凝和吸附集成工艺回收有机废气成为人们的研究重点。冷凝法回收有机废气应用于高浓度场合,尤其适合应用在集成工艺的前端。吸附法回收技术更适合于低浓度油气吸附,作为集成技术的后端处理。有机废气冷凝和吸附集成技术,既发挥冷凝法在冷凝高浓度油气方面高效的优势,以及吸附法在吸附低浓度油气时可以将油气浓度控制在很低范围的优势,同时又可避免单纯冷凝技术由于低温冷凝而引起的成本及操作费用剧增,以及吸附法由于吸附高浓度油气而产生的安全隐患。通过对冷凝和吸附段的工艺及结构参数进行优化,并选择合适的制冷剂及吸附剂,以期最终达到回收率、设备投资、运行能耗及安全性等综合技术经济指标的最优化。     

专虑(火用)和熵而得到的催化剂粒内活性最优分布

It is generally recognized that the optimal distribution of catalyst activity in a spherical catalyst is a Dirac δ-function. However, catalyst with other alternative distribution may accomplish the same reaction task without necessarily concentrating the catalyst activity in an inside thin layer.Moreover, the alternative with activity on catalyst surface may offer higher reaction rate and better utilization of reaction heat (higher exergy output). Simple cases of first-order exothermal reactions, in particular when the catalyst is limited by the maximum working temperature, are presented to demonstrate the above advantages and to show the importance of studying the optimal activity distribution with the consideration on exergy maximization and entroov oroduction minimization.     

An objective classification of condensation regimes in direct contact condensation

Intensified heat treatment, using direct contact condensation (DCC), is applied in the production of dairy products to ensure a high level of food safety. The key challenge with DCC is the fouling due to the protein reactions that limits operational efficiency and sustainability. Using a condensation regime map can improve operational decision-making. Pilot plant scale experiments were conducted for a wide range of steam mass fluxes and inlet temperatures at high and low channel pressures. High-speed images were recorded and analyzed to obtain penetration lengths and plume area. The experimental data and image analysis supplemented with temperature and pressure measurement, were processed using machine learning (ML) to develop a data driven model to predict the regime maps. The linear discriminant analysis (LDA) was found to be the most suitable model. From the ML models it was also found that the best parameters to make a condensation regime map are the steam pressure, channel pressure, subcooling temperature, water Prandtl number, and the relative velocity ratio between gas and liquid. The condensation outcomes were presented with various two-dimensional regime maps. New regime maps are proposed using the Prandtl number and velocity ratio as dimensionless parameters.     

黄磷生产冷凝收磷原理探讨及操作参数优化

对黄磷生产磷炉气除尘、冷凝收磷原理进行研究探讨,并介绍温度、喷淋水量及停留时间与冷凝的关系。提出生产操作控制要点,指出冷凝过程中1~#冷凝塔是收磷系统的控制重点,必须有充足的热量,避免骤冷;气液两相良好的接触是提高磷收率的保证;使喷淋水pH控制在4~6,并维持水质良好。     

精馏过程中回流比调节方式的讨论

比较了精馏过程中双流量计式、单流量计式、电磁式、机械式等回流比调节系统的应用情况。着重论述了新型机械式回流调节系统。该系统具有计量精确、投资小、操作简便、跑冒滴漏少、应用面广等优点。     

冷凝态下高MFR HDPE注塑专用树脂开发中的问题分析

分析了在气相流化床工艺高负荷冷凝态下开发生产高熔体流动速率(MFR)高密度聚乙烯树脂存在的问题。当氢气摩尔分数超过18%以后,树脂平均粒径大幅下降,聚合反应循环系统细粉的浓度大幅增加,易造成夹带,循环过程中在反应器扩大段部分易沉降粘壁,堵塞反应换热器和分布板。抑制细粉的产生主要采取选择催化剂、控制催化剂活性、控制反应温度等措施。     

制酸熔硫系统乏汽及其凝结水回收装置的优化设计

针对大型硫黄制酸熔硫系统乏汽及其凝结水温度、压力特点,开发一种可操作的乏汽及其凝结水回收方法。介绍需要的设备和工艺流程,对回收难点提出针对性的解决方法,最大限度实现余热的回收再利用。该方法可显著提高余热回收利用量,减少原始新蒸汽的用量,降低熔硫系统生产成本,年产生经济效益900万元以上。     

固液界面能差效应与冷凝传热强化研究进展

综述了固液界面能差效应强化冷凝传热的新机制及其对纯蒸气及含不凝气的蒸气冷凝传热过程影响的理论和实验研究进展.阐述了引入固液界面能差效应后的膜状冷凝、滴状冷凝和过渡状冷凝传热模型,及模型与实验数据的对比结果.介绍了利用固液界面效应强化纯蒸气和含不凝性气体的混合蒸气冷凝传热的强化技术.     

离子液体中缩合反应研究进展

综述了离子液体中Knoevenagel、Aldol、Wittig、Pechmann、Paal-Knorr、Benzoin、Biginelli等各种缩合反应,表明离子液体作为一种新型的绿色溶剂有效地促进了缩合反应的进行,显著地提高了反应的选择性和收率。     

矩形微通道中环状冷凝的三维数值模拟

建立了恒热流边界条件下矩形微通道中环状冷凝过程的三维模型。通过求解气相和弯月面区动量和质量方程及薄液膜厚度方程,得到了弯月面毛细半径分布、冷凝液膜厚度分布,以及传热系数和壁面温度分布。薄液膜区液膜将沿程逐渐增厚,到达一极值后再逐渐变薄。在通道截面中,薄液膜区的传热系数大于弯月面,最大局部传热系数及壁面最高温度皆位于薄液膜区和弯月面的连接处。[JP2]在冷凝起始段,通道横截面平均传热系数沿程急剧减小至一极值;在此之后的很长一段距离内,则基本保持不变;[JP]直至接近环状冷凝终点时又再次沿程减小。     

Visualization study of flow condensation in hydrophobic microchannels

A visualization study on flow condensation in hydrophobic rectangular silicon microchannels with hydraulic diameter of approximately 150 μm is conducted. Thin Au film with thickness of 200 nm is sputtered on channel surfaces to create a hydrophobic surface with an equilibrium contact angle of approximately 96°. In addition to traditional droplet flow, droplet‐annular compound flow, droplet‐injection compound flow, and droplet‐bubble/slug compound flow are also observed. The results indicate that injection location is postponed, and injection frequency increases with increasing inlet vapor Reynolds number and condensate Weber number. An empirical correlation of the injection location and injection frequency are presented and discussed. In particular, for a larger inlet vapor Reynolds number, the injection flow is closer to the channel outlet and the condensation heat transfer is enhanced. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1182–1192, 2014     

Raft-forming polysaccharides for the treatment of gastroesophageal reflux disease (GORD): Systematic review

Gastroesophageal reflux disease (GORD) is a common condition induced by unwarranted reflux of gastric and duodenal contents into the esophagus, and insufficient clearance of refluxate from it. Pharmaceutical formulations possessing raft-forming capability offers an excellent alternative to conventional treatment options to treat uncomplicated GORD. These formulations typically contain a polymer, which performs distinctively upon contact with gastric acid and develops a foam-like structure that can float on gastric contents. This review aims to feature research articles and patents that cover this topic. After undergoing a standardized literature search following preferred reporting items for systematic reviews and meta-analyses guidelines, we have included 38 research articles and 18 patents describing the role of raft-forming polymers in the treatment of GORD. This is a comprehensive review of formulation/testing of raft-forming polymers. As expected, the majority of the studies focused on alginate; however, fewer studies have reported the use of pectin, xanthan gum, and raw psyllium fibers (husk). Moreover, it can be concluded from this comprehensive systematic review that a detailed characterization of raft-forming formulations, type, and concentration of used active and inactive materials and different formulations factors are essential for the development of successful anti-reflux raft-forming formulations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48012.     

激波管中非定常凝结现象的数值分析

引言天然气处理、输运过程中常采用节流制冷工艺,由于节流过程是一个不可逆熵增过程,效率比较低,这会导致压力能的较大浪费。根据已有的研究结果[1]:非定常流动的过程效率高于稳定流动的过程效率。基于非定常、交变流动过程的高效气波     

Reaction steady states and stationary states in modelling semi-batch enzyme hydrolysis

Dimensionless material balance equations describing an uninhibited enzyme hydrolysis process in a semi-batch reactor (i.e. fed-batch reactor) are formulated; numerical solution of these equations provided concentration profiles of the enzyme-substrate complex by using published kinetic parameters. The unrestricted values obtained are compared with estimates based separately on the reaction steady state and stationary state assumptions. Results are discussed in terms of the enzyme/substrate inventory used and it is found that the reaction steady state is a satisfactory approximation only when this ratio is sufficiently small. The stationary state may be a better approximation at other values, particularly when enzyme is added to substrate or when an empty tank is being filled. Reaction yields from semi-batch and batch operations are compared. Processing takes longer in the semi-batch operations and complete conversions are only practical in this mode when enzyme is added to substrate.     

多储罐动态全回流分离方法

多储罐间歇精馏是新型操作方式,目前仅用于多组分混合物分离.为了扩大多储罐间歇精馏塔的应用,将其用于2组分物系的分离,提出了多储罐动态全回流分离方法.其特点是可分为全回流提浓和倒罐采出阶段,这2个阶段交替进行,直到分离结束.建立了该过程的数学模型,并与常规恒回流比方式比较,结果表明:动态全回流方法省时.进一步通过乙酸-水...     

炼油企业供应链管理中实沸点切割点的优化

20世纪90年代以来,国际石油和化工制造业面临新的挑战．企业要想提高竞争力,必须在产品成本、质量及新产品开发能力、生产灵活性以及用户的售后服务等方面取得优势．为此,应将企业整个生产过程放到供应链中去,使整个企业的原料供应→原料运输→仓储→生产制造→产品储存→产品运输→用户需求反馈等形成一个有机联系的系统（图1）．提高整个企业的生产和销售效率,就是提高供应链各环节的效率,对供应链进行动态优化,将所需数量和质量的产品,以最快的速度送到客户的手中．