管廊上蒸汽管道布置及应力分析计算

蒸汽是石油化工生产装置中重要的公用工程物料,如何做好石油化工生产装置各类蒸汽管道设计,使蒸汽管道既安全可靠又经济尤为重要。本文以某化工装置中管廊上超高压蒸汽管道设计为例,介绍了蒸汽总管布置特点及蒸汽总管应力分析与计算。     

硫化机蒸汽管道分析

介绍国内普遍使用的硫化机蒸汽管道输送方式,分析高压蒸汽低压使用的优点及在高低压转换过程中存在的系统问题和对轮胎硫化质量的影响。为保证蒸汽压力稳定,不产生水锤等问题,在管道布置和设计安装时应注意管道口径匹配、长距离管道的坡度、正确布置疏水器、低压总管和高压总管的连接方式、调节阀的安装位置,同时还要在管道上安装汽水分离器、过滤器和蒸汽排空气阀。     

中压蒸汽管道设计

以中压蒸汽管道设计为出发点,重点分析了中压蒸汽管道设计过程中补偿器的设置、固定支架设置、推力计算以及管道应力分析等技术问题,并阐述了管径及管材的选择、疏水器设置及保温材料的选择原则。     

尼龙66盐蒸汽系统存在问题及解决措施

针对河南神马尼龙化工有限公司蒸汽系统存在的己二胺装置精制工序真空波动、中压蒸汽外供不足、硝酸低压蒸汽易波动及蒸汽管道膨胀节泄漏等问题,提出解决措施,保证了公司蒸汽系统的稳定运行和长周期生产.     

直埋蒸汽管安装的要点

直埋蒸汽管是最近几年在蒸汽管道安装使用的一种组合材料,其由蒸汽管、保护钢管、保温层、蒸汽管固定架及防腐层等组合而成,与管廊蒸汽管、架空蒸汽管相比具有不占空间、不占用地、不易受损、不影响环境等优点。本文介绍了直埋蒸汽管的施工程序,从材料进货检验,蒸汽管道焊接、保护管道焊接、蒸汽管蒸汽吹扫及管道回填等施工过程中的要点、施工方法及应该注意事项,严格整个过程控制。     

一起直埋蒸汽管道泄漏案例的探讨

直埋蒸汽管道以保温效率高,节能效益显著,占地少且维护费用低而被广泛应用.但相比与传统的地上敷设和管沟敷设其技术难度要大得多,若处理不好,将会对安全运行带来一定的隐患.文中以一起直埋蒸汽管道泄漏案例探讨其设计、施工及运行管理的问题.     

浅谈蒸汽疏水器存在问题及选用方法

分析我厂蒸汽疏水器工作原理及使用现状,提出了存在的问题及选用方法,并探讨在生产中合理管理应用蒸汽疏水器,发挥节能潜力的方法。     

关于工业蒸汽管道的吹扫

以500 kt/a合成氨项目中蒸汽管道的吹扫为例,阐述了工业蒸汽管道吹扫的步骤及重要参数的选择,并讨论了蒸汽流量、吹扫压力对蒸汽管道吹扫的影响。     

大型蒸汽透平蒸汽入口管道的支吊架合理设置

针对进口大型蒸汽透平机蒸汽入口管道与法兰连接位移量太大,不满足安装偏差要求的问题,以应力分析为参考,通过对整个管系支吊架系统改造,解决了这一工程难题。蒸汽机组蒸汽管道经过了三年多的平稳运行考核,汽轮机运行稳定,有力保证了生产和经营各项目标的顺利完成。     

化工装置内高压蒸汽主管道设计

结合某化工项目主装置内高压蒸汽系统管道设计经验,讨论高压蒸汽管道设计中的管道材质选择及管道壁厚的计算、管道应力计算及分析、结合管架形式合理选择隔热管托、确定保温层结构及保温层厚度等高压蒸汽管道设计中所涉及的问题。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。