撞击流反应器中反应动力学研究

浸没循环撞击流反应器(SCISR)的主要特点是撞击区能显著强化微观混合且存在压力波动.对于若干反应体系例如正丁醇与浓硫酸反应等,SCISR显示出明显优于搅拌反应釜(STR)的反应动力学性能,在相同条件下,浸没循环撞击流反应器中所测的正丁醇与浓硫酸反应速率常数k比搅拌槽反应器高约10%.     

撞击流反应器混合性能研究进展

按照撞击流反应器的研究发展进程,分析了撞击流反应器的混合过程。结合大量学者研究工作,回顾了反应空间、流体流动、喷嘴结构等因素对常见的开放式撞击流反应器、受限撞击流反应器、浸没循环撞击流反应器等反应器混合性能影响的研究。简述了外界激励和其他技术对撞击流反应器混合效果影响的研究进展,并总结了几类反应器的微观混合时间及关联式。同时介绍了一种新型水平三向撞击流反应器,该反应器产生的径向射流不同于两喷嘴径向射流,而为交叉状的伞状射流;通过进一步探究发现当量喷嘴间距L*=2 D~3 D时径向射流偏转角β出现峰值,而且此时的混合时间也最短。最后对撞击流反应器混合性能研究前景进行展望。     

流动结构对化学反应速率的影响

介绍了具有新型流场结构的"空化撞击流"的概念及其提出的背景;阐述了"空化撞击流"的三大特性;分析了空化撞击流技术对反应动力学的促进作用;用实验的方法研究了空化撞击流流场结构对化学反应动力学的影响规律。通过实验验证了关于空化撞击流流场对化学反应速率影响的推断。实验依次在普通喷嘴撞击流反应装置、空化自激脉冲喷嘴空化撞击流反应装置、低速搅拌反应装置和高速搅拌反应装置中进行。由实验结果可见,使用空化撞击流反应器时,反应速率常数分别比使用撞击流反应器、高速搅拌反应器和低速搅拌反应器高出13.42%、27.46%和33.82%,而且空化撞击流反应器的能耗更低。因此,利用空化撞击流技术确实可以有效提高化学反应速率。     

撞击流反应制取“超细”白炭黑

用反应-沉淀法制取超细固体产物最重要的条件之一是高且均匀的过饱和度环境.在有关撞击流性质研究的基础上，研发了浸没循环撞击流反应器(SCISR).它具有全混流-无混合流串联循环的特殊流动结构和撞击区微观混合强烈的特点.后者可以创造高且均匀的过饱和度，产生大量晶核；低过饱和度的无混合区有利于微晶表面稳定和钝化.利用该反应器进行普通沉淀法制取“超细”白炭黑的实验研究，确定了最优操作条件，并与传统的搅拌槽反应器(STR)进行了比较.SCISR可以半间歇或连续操作.制得产品粒径范围0.5～2.0μm，平均粒径1.1～1.6μm，比STR产品细、粒径分布窄.反应产物干燥实验结果表明后处理过程中粒径稳定，不发生微细颗粒并聚.     

撞击流法制备纳米无机粉体新技术

<正>成果简介撞击流(Impinging streams, IS)是一种较新颖的技术方法。其基本原理:两股等量两相流沿同轴相向流动,并在中点处撞击。其结果:在两根加速管之间造成一个高度湍动的撞击区,大大地强化了传质过程。撞击流原理见图1。研发的撞击流反应器可用于反应-沉淀法制取多种超细无机粉体产品,均获得非常好的结果。例如,利用撞击流反应器制备白炭黑的平均粒径为1～2μm,且粒径分布很窄;利用撞击流反应器制备了     

撞击流强化混合特性及用于制备超细粉体研究进展

撞击流以其强化微观混合的优异特性在化学反应、结晶、制备超细粉体等方面有广泛应用。本文在撞击流技术强化混合特性的基础上对近年来几种撞击流反应器制备超细粉体研究进行了综述。简述了流体流动、受限空间、喷嘴形式及结构、外部激励等因素对浸没循环撞击流反应器、受限撞击流反应器、T形撞击流反应器、微小型撞击流反应器、撞击流-旋转填料床反应器混合性能的影响。从结晶、微观混合时间等角度分析了撞击流微观混合特性对化学反应及制备超细粉体的影响。并与常规反应器及方法对比，从超细粉体的粒度大小、形貌、表面、能量、分散性、电性能及稳定性等方面进行评估。提出一种双层对置撞击流反应器用于工业上大规模制取超细粉体的中试研究，并展望了撞击流技术用于制备超细粉体的前景。     

撞击流反应器内涡特性研究进展

撞击流技术具有良好的混合效果,广泛应用于能源、环保、化工等工程领域。由于撞击流反应器流场内存在大量无序的湍流涡结构,使其具有良好的混合效果。本文基于撞击流的混合原理,详细叙述了撞击流反应器内不同混合尺度下的混合过程以及涡的演变对混合的影响。结合实验和数值模拟等研究结果,阐述了不同类型撞击流反应器和撞击流反应器多相流场涡特性,归纳了撞击流反应器流场涡的特点。论述了撞击流反应器涡的产生和脱落机理。着重对圆柱射流、平板射流和撞击流流场内涡特性的本征正交分解（POD）分析进行总结,利用流场能量的角度揭示涡演化和消散规律。最后,对开发新型撞击流反应器、优化分析方法等研究前景进行展望。     

SCISR与STR中微观混合的比较

利用α-萘酚与对氨基苯磺酸重氮盐的偶合反应对浸没循环撞击流反应器与搅拌槽反应器中微观混合性能 进行了比较研究。结果表明,在等比有效输入功率和平均停留时间相同的条件下,浸没循环撞击流反应器具有显著优于 传统搅拌槽反应器的微观混合性能。     

液体连续相撞击流特性及其在超细粉体制备中的应用

20世纪90年代以来撞击流领域研究重点转向以液体为连续相。液体连续相撞击流(US)具有有效促进微观混合和存在压力波动的特性,从而有利于超细粉体的制备。实验结果表明,浸没循环撞击流反应器(SCISR)是反应一沉淀法制取超细粉体的一种优越的反应技术装备。     

立式循环撞击流反应器三维流场的数值模拟

利用Fluent软件对立式循环撞击流反应器三堆流场进行数值模拟和分析.立式循环撞击流反应器内速度场和压力场分布关于撞击面对称,证实了驻面的存在,导流筒外侧和撞击面边缘存在死区;由于导流筒对流体引导作用,撞击区水平面x轴上速度最大的点出现在导流筒近壁面位置;定义了表征不同撞击流初始速度下混合效率无量纲系数k,且k值随撞击...     

撞击流中连续相研究重点的转移

液体和气体性质如密度和黏度等有重大差异，从而显著地影响分别以它们为连续相的撞击流性能。研究发现，液体连续相撞击流(LIS)强化微观混合的性能是撞击流领域研究最重要的进展，因此近十几年来该领域研究的重点明显地转向LIS。通过历史的回顾和连续相性质的比较，阐述这种转移的背景和发展趋势，评价LIS研究的部分成果。     

新型磁性纳米锂离子筛的合成

采用狭道式撞击流反应器,将Fe<,3>O<,4>爆发式成核过程与快速包覆MnCO<,3>+Li<,2>CO<,3>薄膜的过程同步进行,制备出具有核壳结构的纳米Fe<,3>O<,4>/MnCO<,3>+Li<,2>CO<,3>前驱体;然后.通过在450℃下高温焙烧和稀酸酸浸脱锂工艺得到一种组成为Fe<,3>O<,4>/H...     

Preparation and adsorption performance of multi-morphology H1.6Mn1.6O4 for lithium extraction

In this paper, a lithium-ion sieve(LIS) with different morphologies, such as rod-like(LIS-R), spherical(LIS-S),flower-like(LIS-F), and three-dimensional macroporous-mesoporous(LIS-3D), was prepared by hydrothermal synthesis, solid reaction, and hard-template synthesis. The results showed that the LIS with different morphologies presented great differences in specific surface area, pore volume, adsorption selectivity, and structure stability. LIS-3D with highest specific surface area and pore volume displayed the maximum adsorption capacity and adsorption rate, but the stability of LIS-3D was poor because of the manganese dissolution. By comparison, LIS-S has the best structural stability while maintaining a satisfactory adsorption capacity(35.02 mg·g~(-1)) and adsorption rate. The LIS-S remained about 90% of the original adsorption capacity after five cycles of adsorption–desorption process. In addition, in the simulated brine system(the magnesium to lithium ratio of 400), the LIS-S exhibited the highest selectivity(α_(Mg)~(Li)) of 425.14. In sum, the LIS-S with good morphology is a potential adsorbent for lithium extraction from brine.     

Preparation and crystal structure of the recombinant {alpha}1/{alpha}2 catalytic heterodimer of bovine brain platelet-activating factor acetylhydrolase Ib

The intracellular form of mammalian platelet activating factoracetylhydrolase found in brain (PAF-AH Ib) is thought to playa critical role in control in neuronal migration during cortexdevelopment. This oligomeric complex consists of a homodimerof the 45 kDa (ß) LIS1 protein, the product of thecausative gene for type I lissencephaly, and, depending on thedevelopmental stage and species, one of three possible pairsof two homologous ~26 kDa     

Atomic force microscopy based approach to local impedance measurements of grain interiors and grain boundaries of sensitized AISI 304 stainless steel

The paper presents the results of the AFM based approach to local impedance spectroscopy (LIS) measurements performed within the region of austenite grain interiors and the austenite grain boundaries for both sensitized and non-sensitized AISI 304 stainless steel (SS). The local impedance investigations in the AFM contact mode were carried out after standard tests for susceptibility to intergranular corrosion (IGC). Local impedance spectra recorded in the AFM contact mode for both sensitized and non-sensitized AISI 304 stainless steel within the region of the austenite grain interiors and the austenite grain boundaries demonstrated different shapes and characters. Performed researches revealed significant differences in the charge transfer resistance values recorded for the austenite grain interiors and the grain boundaries depending on the sensitization state. Moreover, proposed AFM based approach allows identification of the IGC process even when a double-loop electrochemical potentiokinetic reactivation (DL-EPR) method does not provide evidence of it.     

钛系锂离子筛盐湖提锂的研究进展

随着新能源行业的迅速发展,带动了锂需求量的显著增长,锂提取技术近年来受到广泛关注。中国是盐湖锂资源大国,盐湖锂储量约占全国锂总储量的78%。但是,中国的盐湖锂资源镁含量高,不易分离提取高纯度锂工业产品;因此,研究开发盐湖提锂技术,具有非常重要的应用价值。在众多的盐湖提锂技术当中,锂离子筛吸附提锂,因其选择性好,对镁的分离效果好,适用于镁锂比高的盐湖卤水体系,这对解决盐湖提锂问题有重要指导意义。选择近年来发展比较热的钛系锂离子筛,从提锂机理、制备方法和应用等方面的研究对钛系离子筛进行一个综述,最后对钛系离子筛的未来研究方向进行展望。     

LIS–lnterlink—connecting laboratory information systems to remote primary health–care centres via the Internet

A pilot study was performed to evaluate the feasibility of using the Internet to securely deliver patient laboratory results, and the system has subsequently gone into routine use in Poland. The system went from design to pilot and then to live implementation within a four-month period, resulting in the LIS-Interlink software product. Test results are retrieved at regular intervals from the BioLink^TM LIS (Laboratory Information System), encrypted and transferred to a secure area on the Web server. The primary health-care centres dial into the Internet using a local-cell service provided by Polish Telecom (TP), obtain a TCP/IP address using the TP DHCP server, and perform HTTP ‘get’ and ‘post’ operations to obtain the files by secure handshaking. The data are then automatically inserted into a local SQL database (with optional printing of incoming reports)for cumulative reporting and searching functions. The local database is fully multi-user and can be accessed from different clinics within the centres by a variety of networking protocols.     

Preparation,characterization and properties of Cr-incorporated DLC films on magnesium alloy

Cr-incorporated diamond-like carbon (Cr-DLC) films were deposited on AZ31 magnesium alloy as protective coatings by a hybrid beams deposition system, which consists of a DC magnetron sputtering of Cr target (99.99%) and a linear ion source (LIS) supplied with CH₄ precursor gas. The Cr concentration (from 2.34 to 31.5 at.%) in the films was controlled by varying the flow ratio of Ar/CH₄. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to investigate the microstructure and composition of Cr-DLC films systematically. An electrochemical system and a ball-on-disk tribotester were applied to test the corrosion and tribological properties of the film on the AZ31 substrate, respectively. At low Cr doping (2.34 at.%), the film mainly exhibited the feature of amorphous carbon, while at high doping (31.5 at.%), chromium carbide crystalline phase occurred in the amorphous carbon matrix of the film. In this study, all the prepared Cr-DLC films showed higher adhesion to AZ31 than the DLC film. Especially for the film with low Cr doping (2.34 at.%), it owned the lowest internal stress and the highest adhesion to substrate among all the films. Furthermore, this film could also improve the wear resistance of magnesium alloy effectively. But, none of the films could improve the corrosion resistance of the magnesium alloy in 3.5 wt.% NaCl solution due to the existence of through-thickness defects in the films.     

Centrifuge-aided micromolding of micron- and submicron-sized patterns

Developed from soft lithography, replica molding has been proven to be a good method to prepare micron- and submicron-sized features. However, the fidelity of the features can be compromised by incomplete feature cavity filling and feature shrinkage during the forming process. In this study, centrifuge-aided micromolding is developed to prepare micron- and submicron-sized ZnO features. By introducing a centrifugal force, the shear-thinning behavior of the suspensions is utilized, and the cavity filling process and the diffusion of trapped air out of the features are accelerated. The drying shrinkage is decreased by increasing the density of the wet nanoparticle packing from the centrifugal process. The centrifugal force improves the fidelity of all the designed features. ZnO ridges from 0.4 μm to 2 μm size and rods of 1.6 μm size are prepared successfully. The wide applicability of this strategy has been demonstrated by preparing ZrO₂ features via the same method.