弯头直角管道顺序输送混油特性的数值模拟

通过多相流模型对成品油管道进行数值模拟,以汽油和柴油作为顺序输送对象,分别就直角弯管向上、直角弯管向下两种工况时研究输送顺序、重力、管径、粘滞力对混油的影响,研究结果表面:当直角弯管向上时前行柴油的混油量小于前行汽油的混油量,当油品运行到竖直管道时,前行柴油比前行汽油油品运行的缓慢,前行柴油混油的倾斜角度大于前行汽油混油的倾斜角度;当直角弯管向下时前行汽油的混油量小于前行柴油的混油量,前行汽油混油的倾斜角度大于前行柴油混油的倾斜角度。通过对比可以看出:直角弯管向上前行柴油时混油运行的最为缓慢。无论是前行汽油还是前行柴油管径越大混油量越小,当管径相等时前行柴油比前行汽油的混油长。该数值模拟与管道实际结果相一致。     

邻苯二酚技术进展与市场分析

邻苯二酚是一种重要的精细化工中间体。世界上邻苯二酚生产能力约为3．8万t／a，2004年产量约为3．1万t。2004年我国邻苯二酚产量约为1500吨，表观消费量达到7287吨；2005年产量约为2800t，表观消费量达到9077吨。目前国内仅有连云港三吉利化工有限公司生产邻苯二酚，产能3000t。预计2008年我国邻苯二酚的需求量将达到1138万吨。     

面向对象技术应用于嵌入式控制系统的可行性及实现研究

针对控制系统开发工程师普遍认为采用面向对象语言开发的代码效率低、不稳定的观点,论述了在面向对象编程中,在掌握编程语言的基础上同样能开发经济高效的代码,并通过试验比较目前最常用的C 和C语言开发出的代码的执行效率证实了这一点.抽象出了控制系统中常用的类,并以硬件类为例进行了详细说明.运用面向对象技术开发了高产梳棉机控制软件,软件运行可靠,证明在嵌入式控制系统中应用面向对象技术是可行的.     

差示分光光度法测定废水中间甲酚的含量

对间甲苯胺经重氮化水解制备间甲酚中所产生的废水,采用差示分光光度法测定其中间甲酚的含量,以间甲酚水溶液为参比,在波长237 nm处对间甲酚的NaOH溶液扫描,测得差示吸光度(△A),从而得出废水中间甲酚的含量。同时进行了加标回收率实验,平均回收率为100.3%,相对标准偏差为2.1%。并与4-氨基安替比林分光光度法比较,废水中间甲酚含量非常接近。结果表明,此方法是简单、快速、准确的测定方法。     

新绛威顿1000t/d生产线的生产调试

在新绛威顿水泥有限公司1000t／d熟料生产线调试期间，因燃煤及原料等原因，造成一系列工艺问题。通过采取一系列对应措施，收到了良好的效果。如针对进场原煤挥发分偏低，煤粉燃绕速度慢的问题，采取了提高煤粉细度指标，增设放风旁路等技术措施；针对传统投料方案操作难度大等问题，及时调整了投料方案，简化了操作过程，提高了生产效率；通过调整配料，优化操作，加强管理，解决了因原料及煤粉中Cl^-含量偏高导致预热器系统频繁堵料的问题；通过优化操作，有效地减少了因窑内产生长厚窑皮、结圈造成的停窑次数，提高了系统运转率。     

聚丙烯酰胺对氨水中有机悬浮物絮凝作用的研究

对氨水中的有机悬浮物采用聚丙烯酰胺(PAM)进行絮凝。通过絮团特征、清液特征、絮团聚集程度以及氨水中絮团体积的变化率同絮凝时间的关系,比较了不同添加量、不同种类的PAM絮凝效果。结果表明,采用阴离子型聚丙烯酰胺和阳离子型聚丙烯酰胺相结合的絮凝方式,能较好地絮凝氨水中的有机悬浮物。较好的絮凝方式是:在140 r/m in搅拌中,往氨水中加入分子量为1100万、浓度为1‰的阴离子型聚丙烯酰胺15 mL/L,搅拌1 m in;调转速为60 r/m in,加入离子度为20%~25%、浓度为1‰的阳离子型聚丙烯酰胺5 mL/L,搅拌5 m in,静止1 h。     

Metals in commercial catalysts: 1. Molybdenum and tungsten

Information on the production and consumption of molybdenum and tungsten in the world and in Russia is provided. The lowering of domestic consumption of these metals in the Russian industry is demonstrated. The use of these metals in catalysts manufacturing in Russia is considered. The assortment of domestic molybdenum- and tungsten-containing catalysts is discussed, and their consumption is estimated. The current demand for molybdenum and tungsten in catalyst manufacturing is small because of the high impact of imported catalysts and low level in the development of chemical catalytic processes. Certain applications of molybdenum- and tungsten-containing catalysts are considered. It is shown that the consumption of molybdenum and tungsten in the manufacturing of high-added value products (catalysts) may grow at the expense of the replacement of imported catalysts by competitive domestic molybdenum- and tungsten-containing catalysts and their use in new processes.     

硼在玉米中的分布特征及化学形态的研究

对施硼肥和不施硼肥的土壤上种植的玉米中硼的分布及化学形态进行了研究 ,结果表明 ,靠近根部的玉米叶子中含硼最多 ,中部和上部叶子中含硼量依次递减 ,玉米种子中的含硼量低于叶子中的含硼量。通过研究不同溶剂对玉米叶子和种子中硼的浸提能力 ,探明了以 10 %醋酸浸提下来的硼最多 ,其次是用 0 .0 1mol/LEDTA浸提下来的硼 ,用水浸提下来的硼的含量最少。     

如何正确处理和防止氧气瓶泄漏

氧气瓶是移动式压力容器,在工业和医疗系统中广泛使用。因其充装压力高(15 Mpa),密封材料长时间与纯氧接触,容易氧化、老化。使用时瓶阀开关经常转动,使密封材料摩损减薄。因此,氧气瓶漏气十分普遍,既浪费能源,又给安全生产带来隐患,如果处理不好,引发气瓶爆炸,将会造成严重的经济损失。本文就处理和防止氧气瓶泄漏提出一些方法,供气瓶检验同行参考。     

吖啶橙受溶液pH和浓度变化的光谱研究

利用荧光光谱分析仪研究吖啶橙受溶液pH和浓度变化的吸收光谱和荧光光谱的变化。实验表明,当改变吖啶橙溶液pH和浓度时,它的吸收光谱和荧光光谱发生位移。吖啶橙为1×10-6mol/L时,不同pH的吖啶橙溶液均在(490±3)nm出现一个强吸收峰,pH=6.5,吸收光谱的λm ax=430 nm,发生蓝移;而荧光光谱的λm ax随pH增大发生红移,荧光强度减弱。在浓吖啶橙溶液中,不同pH的吖啶橙溶液的吸收光谱的形状基本相同,出现两个吸收峰,λm ax1分别为(455±3)nm和(430±3)nm,λm ax2分别为(505±4)nm和(510±2)nm,吸收光谱红移;荧光光谱的λm ax均为(535±2)nm,荧光强度荧光很弱。pH相同或相近时,吖啶橙溶液的吸收光谱蓝移和荧光光谱红移,浓度越大,荧光强度越弱。还探讨了吖啶橙在水溶液中的赋存状态,结果表明,在稀溶液中,吖啶橙主要以单体的形式存在;在高浓度吖啶橙溶液中则以吖啶橙单体、二聚体,甚至多聚体形式存在。这说明溶液pH主要影响到吖啶橙分子基态的质子化和氢键的形成能力,使得分子的基态与激发态之间的能量间隔发生了变化,吖啶橙被质子化,则引起发光光谱向短波方向移动,而离解作用,则引起发光光谱向长波方向移动;吖啶橙浓度变化影响吖啶橙在水溶液赋存状态,引起吸收光谱向短波方向移动或向长波方向移动。     

蒸发-凝结流动的边界层现象及热短路效应

热管是一种高效传热元件,为了降低理论研究的复杂性,对其做出简化是必要的。针对一些基本假设的适用性,本文建立了一维蒸发-凝结流动传热模型。通过初积分,对控制方程进行了化简和数值计算。结果表明,温度、流速以及压力场,在蒸发和凝结相界面上明显存在着边界层,其中蒸发侧尤为明显,速度、压力梯度较大;在雷诺数很大的情况下,温度梯度也较大。由边界层现象推出了蒸发-凝结流动传热的热短路效应：汽相工质的最终趋势是达到均匀的温度场和饱和状态,汽相热阻为零。     

中国西北地区肥料使用和生产现状及问题

利用统计资料和农户调查资料综合分析了中国西北地区肥料使用和生产现状及问题。结果表明,西北地区虽然可耕地面积小,耕地质量差,仍是全国重要的农产品生产基地之一;各省(区)土地利用状况各具特色,可利用潜力较大;近年来西北地区肥料用量增长减缓,单质氮、磷肥基本稳定,钾肥和复合肥在增加;各省(区)施用肥料的结构以氮肥为主,复合肥次之,钾肥比例很低;单位种植面积施肥量低于全国水平;西北地区主要作物施肥量差别很大,其中蔬菜、棉花施肥量最多,小麦、玉米居中,豆类、薯类和油料类较少。多年来化肥生产量一直低于消费量,但氮肥发展为供大于求。综合分析认为,作物生产用肥量尚有进一步增长的可能性,需进一步研究草地用肥的可能性。应注意土地合理利用、施肥效果、施肥量和草地施肥等问题。     

Photoinduced oxygen release and persistent photoconductivity in ZnO nanowires

Photoconductivity is studied in individual ZnO nanowires. Under ultraviolet (UV) illumination, the induced photocurrents are observed to persist both in air and in vacuum. Their dependence on UV intensity in air is explained by means of photoinduced surface depletion depth decrease caused by oxygen desorption induced by photogenerated holes. The observed photoresponse is much greater in vacuum and proceeds beyond the air photoresponse at a much slower rate of increase. After reaching a maximum, it typically persists indefinitely, as long as good vacuum is maintained. Once vacuum is broken and air is let in, the photocurrent quickly decays down to the typical air-photoresponse values. The extra photoconductivity in vacuum is explained by desorption of adsorbed surface oxygen which is readily pumped out, followed by a further slower desorption of lattice oxygen, resulting in a Zn-rich surface of increased conductivity. The adsorption-desorption balance is fully recovered after the ZnO surface is exposed to air, which suggests that under UV illumination, the ZnO surface is actively "breathing" oxygen, a process that is further enhanced in nanowires by their high surface to volume ratio.     

Self-Diffusion of Beryllium in Polycrystalline Beryllium Oxide

The self-diffusion of beryllium in polycrystalline beryllium oxide was measured from 1330° to 2135°C with the ⁷Be tracer. Results are compared with the findings of other investigators, and it is concluded that the differences reported are due to variations in impurity and porosity contents. Diffusion has been shown to be via a vacancy mechanism, with such impurities as aluminum and silicon being the principal contributors of vacancies. A roll-over in the plot of log D versus 1/ T , where D is the diffusion coefficient and T is absolute temperature, was found in this study as in some others. Above about 1500°C the activation energy is no higher than 62 kcal, whereas it is 92 kcal at lower temperatures. It is suggested that this roll-over is due to aluminum impurity. There appears to be a temperature-independent anisotropy of diffusion, with the rate in the 〈 c 〉 direction being 30% higher than that in the 〈 a 〉 direction. It is concluded that for this and other investigations the diffusion coefficient of beryllium in beryllium oxide above the rollover temperature is governed by impurities and in this region it is given by the formula

where F_p is the fraction of porosity and N_v is the molar fraction of vacancies introduced by impurities. There is sufficient scatter in individual 〈 a 〉 and 〈 c 〉 diffusion values so that there is no value in discriminating between directions in this formula.     

连续氧化还原滴定法测定玻璃澄清剂中的砷和锑

介绍了一种氧化还原滴定法连续、快速测定玻璃澄清剂中的砷和锑的方法。试样经硫酸-硫酸钾分解,滤纸片将试样中全部的五价锑和五价砷定量还原为三价。采用硫酸铈和溴酸钾作为氧化滴定剂,将三价的砷和锑定量氧化为五价。通过精密度和准确度实验表明,该方法标准偏差小于0.1,回收率为96%～105%。测试方法稳定,数据结果可靠。     

乙醇重结晶法精制含酚亚硫酸钠

以工业酒精作为亚硫酸钠的重结晶剂,使含酚亚钠中的苯酚溶于乙醇中,亚硫酸钠结晶析出,从而有效地降低亚钠中的含酚量,减少亚钠在造纸行业中使用而造成的含酚废水的污染。讨论了乙醇用量,精制温度及精制次数对亚钠精制效果的影响,并对结晶工艺和进一步处理进行了讨论。结果表明,采用乙醇重结晶法精制含酚亚硫酸钠,工艺路线可行,效果显著,对环保有重要意义。     

Verarbeitung von PVC auf kalandern. Formgebung im walzenspalt

Shaping in the nip of the calender is characterized by the presence of a spindle-shaped bead of superfluous melt, i.e. bank, front of the nip. The melt transported to the nip by the drag set up by the rolls is then subjected to partial change in flow. The rerouted melt flows into the bank and is replaced by melt transported from the bank into the nip. The currents at the interior of the bank are also governed by its outer movement, a rotating movement, which is superimposed by a spiral undulation, and this decisively affects the quality of the film. The bank is formed by the melt which is severely sheared in the nip and high temperatures are correspondingly displayed. The length of time the melt remains in the bank is thus decisive for thermal loading during calendering. With the Luvitherm process, in which no true melt is present in the calender sheared material is collected in the nip in flake form before the nip and is again drawn through the nip in irregular sequence. Here also, calendering is governed by the flow conditions at the entrance to the nip.     

以石油替代为目标的我国新型煤化工

我国油气资源比较匮乏,而煤炭资源相对丰富,新型煤化工是以煤为原料生产洁净能源和可替代石油原料的化工产品为目标。简要介绍了我国新型煤化工制油、烯烃、天然气、乙二醇在建和在运项目,提出我国新型煤化工要创造技术核心竞争力,实现与石油路线经济效益竞争的优势,具有特殊战略意义的观点。同时,指出企业延长产业链、提高产品附加值,并不一定能够获得较好的投资回报。     

The toughness of copolymers of polypropylene

A series of fracture mechanics tests of a set of random and impact copolymers of polypropylene, in which the ethylene content was varied, is described. The plane strain toughness is found to change from the homopolymer value, but thereafter to be independent of ethylene content. The yield stress of the impact copolymers decreases markedly with ethylene content, while that for random copolymers increases only slightly. This is reflected in toughness values in tension. A comparison with the behavior of other rubber-modified materials is made and it is concluded that crazing is an important mechanism in polypropylene and is perhaps more rate and temperature sensitive than in acrylonitrile-butadiene-styrene (ABS).     

Coarsening in molten quiescent polymer blends: The role of the initial morphology

Coarsening of the phase dimensions in polymer blends under quiescent conditions is studied in blends of different morphologies; the dependence of the rate and extent of coarsening on the initial morphology is demonstrated. In blends with a droplet/matrix structure, coarsening via coalescence is found only above the percolation threshold for spherical particles (16 vol%). The rate of coalescence in the droplet/matrix structure is shown to obey the theory of Fortelny and Zivny for coalescence of droplets in quiescent media, and no constant level of the phase dimensions is reached. Below a volume fraction of 0.16 limited coarsening is found only for fibrillar and co-continuous morphologies. This coarsening is in fact the result of a restructuring because retraction and breakup occur, leading to a droplet/matrix morphology in which the droplet diameter is approximately twice the diameter of the original fiber. Breakup and retraction are completed in a short time relative to coalescence. At higher volume fractions in co-continuous structures (>30 vol%), these structures do not break up, and coarsening is found to take place by retraction only. No constant level of the phase dimensions is reached in the latter case.