活塞式压缩机压力脉动与管道振动的消减

活塞式压缩机管运振动是由于气流压力脉动过大引起的。该文主要介绍了管系气柱固有频率的计算以及配管设计中为消减压力脉动而采取的诸如安装缓冲器、孔板和盲管的多种措施。将之实践用于湘江氮肥厂4号循环压缩机的配管设计中,装置投产后运行平稳。     

往复式压缩机管道振动案例设计探讨

介绍了MD-267/81型往复式压缩机现场振动情况,对振动原因进行分析,并阐述了往复式压缩机机组及其附属设备的布置原则。分析了往复式压缩机设计段间管道支吊架布置的注意事项以及支吊架选择的合理性。在脉动激振力不大及管道静力分析通过的条件下,首先通过调整管道的固有频率来避免管道系统的振动,即通过简化管道走向,增加限位架、导向架、固定架等方式来增加管道系统的刚度,以此提高其固有频率,避免管道振动。     

往复式压缩机管道内压力脉动的测试与分析

通过对管道内压力脉动的实验测试及测点信号的时域分析和频域分析 ,计算出了压力不均匀度。测试结果证实 ,往复式压缩机管道内压力脉动总是存在的 ,其特征频率为压缩机激发基频的倍频 ;对测试的压力脉动值与有限元理论计算值比较 ,其结果是相当吻合的     

往复式压缩机管路振动与疲劳分析及减振方案研究

运用管路气柱分析软件Bently PLUS对某往复式压缩机管路系统的气柱进行声学模拟,应用管路应力分析软件CAESARII对管路进行静态分析和疲劳应力分析。研究发现,该管路系统不满足管道振动和疲劳强度要求,为此,用支架或缓冲罐等对其进行减振,分析后发现管路支架可以改变管系的固有频率、减小振动位移和降低动态疲劳应力;而添加缓冲罐可以改变管路气柱的模态,使管路气柱共振频率避开激振的共振频率范围,从而有效减小压力脉动,降低管路振动水平。     

往复式压缩机管道的振动分析及防振设计

对往复式压缩机管道振动原因分析可知,活塞在汽缸中进行周期性的往复运动,所引起的压力脉动是管道产生振动的主要原因。管道振动的第二个原因是管道系统的固有频率与机器的激振频率相等时,管道发生机械共振。根据API618规定,确定采用何种分析方法,提出在工程设计中应采取的合理防振措施。通过减振实例解决往复式压缩机管道的振动问题。     

氢压缩机管道强烈振动的消除

本文针对一往复式氢气压缩机管道振动十分强烈的情况，分析了管系的结构自振频率、气柱固有频率和气流脉动，采取了改变管系结构频率和气柱固有频率的减振措施，经实践证明获得了较为理想的减振效果。     

变工况双级压缩中间压力及其对系统性能的影响

基于质量与能量守恒方程,以转子压缩机几何模型为基础,建立反映中间压力形成过程的变容量双级压缩系统压缩机动态耦合模型,并利用实验对模型进行了校核。基于模拟和实验结果,分析了中间压力随时间的变化及其变工况特性。结果表明,中间压力具有脉动特性,但脉动幅值相对于时均值较小;在影响中间压力的因素中,低高压压缩机理论输气量比的影响最为显著,冷凝温度的影响明显小于蒸发温度的影响;系统制热量随中间压力的升高近似呈线性增加,而系统制热COP随中间压力升高具有先升高后降低的趋势,且存在最优值。     

往复式压缩机进气管路气流压力脉动分析

使用Bentley PULS软件对往复式压缩机进气管路进行气流压力脉动分析,设计进气缓冲罐,计算管道系统中各节点的脉动压力。根据计算结果在管路中增设孔板对超标的气流压力脉动幅值进行抑制,使得进气管路内的气流脉动满足API618标准的要求,保证了装置的安全运行。     

往复式压缩机管道的减振设计

往复式压缩机进出口管道产生振动的主要原因是压力脉动和共振。管道设计完成后需要对管系进行脉动分析和振动分析,将压力脉动控制在合理的范围内,同时避免管系发生共振。介绍了某石化公司液相加氢新氢压缩机的分析实例,并提出了工程设计中减轻管道振动的一些措施。     

往复式压缩机的配管设计研究

往复式压缩机配管设计的工作难题是,将流体压力脉动和配管系统的有害振荡控制在合理的范围内,尽量使往复式压缩机的配管达到一个理想的工作状态。因此,本文以往复式压缩机的配管设计作为研究的重点,在提出设计建议的同时还给予了改善振动的措施。     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料，介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比，介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序，对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Some Large Wood-Boring Beetles in Southeastern USA

Ethanol and α-pinene were tested as attractants for large wood-boring pine beetles in Alabama, Florida, Georgia, North Carolina, and South Carolina in 2002–2004. Multiple-funnel traps baited with (−)-α-pinene (released at about 2 g/d at 25–28°C) were attractive to the following Cerambycidae: Acanthocinus nodosus, A. obsoletus, Arhopalus rusticus nubilus, Asemum striatum, Monochamus titillator, Prionus pocularis, Xylotrechus integer, and X. sagittatus sagittatus. Buprestis lineata (Buprestidae), Alaus myops (Elateridae), and Hylobius pales and Pachylobius picivorus (Curculionidae) were also attracted to traps baited with (−)-α-pinene. In many locations, ethanol synergized attraction of the cerambycids Acanthocinus nodosus, A. obsoletus, Arhopalus r. nubilus, Monochamus titillator, and Xylotrechus s. sagittatus (but not Asemum striatum, Prionus pocularis, or Xylotrechus integer) to traps baited with (−)-α-pinene. Similarly, attraction of Alaus myops, Hylobius pales, and Pachylobius picivorus (but not Buprestis lineata) to traps baited with (−)-α-pinene was synergized by ethanol. These results provide support for the use of traps baited with ethanol and (−)-α-pinene to detect and monitor common large wood-boring beetles from the southeastern region of the USA at ports-of-entry in other countries, as well as forested areas in the USA.