转化工段大直径换热器管板支撑的设计及其优化

多年前设计转化工段大直径换热器时，根据重力计算下管板厚度并采用六边形梁进行支撑。设备运行情况良好。现经分析比较，提出采用薄管板公式计算下管板厚度，管板下用6根支柱直接支撑。结果表明，设计的管板更薄、更合理。     

GB 151中浮头式换热器管板设计方法的理论依据及其应用

阐述了国家标准GB 151中浮头式换热器设计方法的理论依据。在此基础上,进一步给出了如何应用GB 151中浮头式换热器对应于最小管板设计厚度的公式与曲线,计算实际管板厚度下的管板应力和换热管应力的方法。通过一个实际算例,说明当管板的实际厚度与其最小设计厚度相差较多时,换热管中的应力可以大大降低。     

多管程管壳式换热器隔板槽面积计算

针对换热器设计中转角正三角形排列及转角正方形排列的多管程管壳式换热器管板的隔板槽面积难以精确计算的问题,给出了一种隔板槽面积的计算方法。该方法可以方便地获得多管程管壳式换热器管板的隔板槽面积,从而提高了管板厚度计算的精确性。     

薄管板换热器的拉杆固定结构优化设计

薄管板换热器具有节省材料,加工方便的特点,可有效降低设备造价和缩短订货周期。由于管板自身特点,常规用于厚管板换热器上的拉杆结构已不适用于薄管板换热器。本文提出一种针对《热交换器》GB/T151-2014中拉杆与管板连接结构的优化结构,以适应薄管板换热器的设计要求。     

图解法计算列管换热器的管板厚度

在列管式热交换器设计过程中,为了保证管板有足够的强度,必须对管板所需的最小厚度进行计算。有关的计算公式已由规范作了规定。虽然通过公式计算可以得到精确的数值,但在实际过程中,有时为了估算热交换器管板的大致厚度,以便估计其制造成本,或是在进行几种方案的比较时,不必追求过于精确的计算。这时能否使用更为简便的方法,避免繁琐的计算,快速而又比较直观地知道管板的最小厚度呢?事实证明这是完全可能的。本文介绍三种计算列管式换热器管板最小厚度的计算用图,并结合例题讲解其用法。     

编后记

管板是列管式换热器的主要部件之一,其设计计算方法较多。对我国现行的管板设计计算方法,使用及制造部门通过长期实践普遍反应厚度偏大,管板厚度的不必要的增厚给材料供应、管板制造带来一系列的问题。从引进装置的列管式换热器来看,厚度差异很大,其中以西德进口的按AD规范设计的最薄。总之管板减薄是可能的也是必要的。     

换热器管箱法兰与管板密封问题研究

换热器是一种实现物料之间热量交换的节能设备,它广泛应用于工业各个领域,特别在化工、石油、能源等领域占有主导地位。文中结合我厂一组换热器管箱法兰和管板密封面的泄漏情况,从换热器的设计、制造和安装使用等方面进行泄漏原因的分析,并结合设备日常管理的实际情况,探讨了提高同种换热设备密封性能和解决换热器管箱法兰和管板密封面泄漏的一些方法。     

浮头式热器管板计算问题的讨论

随着工业的发展,换热器成为石油、化工、冶金、电力、轻工等业普遍应用的一种工艺设备.管壳式换热器在工业装置的换热设备中占有相当的比重.管板是管壳式换热器的主要部件,管板的设计是否合理对确保换热器的安全运行,节约材料,降低制造成本及减少加工制造困难是至关重要的.而管板的计算方法又有多种,情况也十分复杂.     

管壳式换热器管板布管数量简易计算

管壳式换热器设计工作中,管板上管孔数量是一个重要的设计数据,它是决定一台换热器的换热面积、管板的计算厚度、壳程壳体计算厚度等许多结果的一个重要参数,必须绝对准确。但计数是一项繁琐的工作。通过在布管限定园内作梯形图及简易公式推导,以简化这项繁琐的工作,提高设计工作效率,缩短设计周期。     

转化系统气体换热器的简捷计算法

介绍一种转化系统常用的管壳式气体换热器的简捷工艺计算方法。这种换热器具有圆缺形折流板，换热管束在管板上为双圆缺形排列。讨论了换热器各参数的选取原则，并作了设计示例，该计算方法为设计型，可快速确定总传热系数和计算出能满足详细设计要求的换热器结构参数。     

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.     

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.     

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.     

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。