用于微生物石油脱蜡的新型气升环流反应器

本文报导了一种新型气升环流反应器,对反应器中液相流型、气含率与操作条件之间的关系进行了实验考察。利用气升环流反应器强化传质和混合的原理,将一个100m^3鼓泡塔反应器改造成三管循环的气升环流反应器,发酵试验结果表明气升环流反应器微生物脱蜡周期比原鼓泡反应器缩短4倍,气升环流反应器能耗比鼓泡反应器降低约30％。     

鼓泡塔气液两相流内部流场的流体力学特性

采用计算流体力学CFD软件对鼓泡塔内部4种表观气速下内部流场的流体力学行为进行模拟。分析了鼓泡塔内部整体气含率及轴截面处（X=0）液相速度随时间的变化情况;并且对比了在不同表观气速下局部气含率和液相速度在不同高度处的径向分布情况。模拟结果表明,随着时间的增大,整体气含率增大速度比较快,到达稳定时间,整体气含率不再增大。在同一高度处局部气含率随着表观气速的增大而增大。H/D<3时,液相循环流动表现为单相循环流;当H/D=3时,表现为双循环流,流型较单相复杂。     

基于声发射信号递归分析的气固流化床流型转变

利用声发射技术采集不同流化气速下流化床内颗粒与壁面碰撞的声信号,结合声能量及递归分析法研究不同流型下颗粒运动特征,得到鼓泡流态化到湍动流态化的临界转变速度及流型转变规律。特别是针对声能量分析无法准确区分不同床层高度处流型转变的不足,利用递归分析可有效预测系统周期性的特点,将声信号进行递归分析,研究了流化床不同位置的流型转变性质。结果表明,鼓泡流态化下颗粒运动的周期性较湍动流态化强,并能够清晰地检测到由鼓泡流态化向湍动流态化的流型转变速度,而且床层较低处的流型转变速度比床层较高处大。由此获得了一种便捷灵敏、安全环保的非侵入式流化床流型转变速度的测量技术,可用于对整个流化床内不同位置流型转变过程的实时在线监控。     

基于声发射信号递归分析的气固流化床流型转变

利用声发射技术采集不同流化气速下流化床内颗粒与壁面碰撞的声信号,结合声能量及递归分析法研究不同流型下颗粒运动特征,得到鼓泡流态化到湍动流态化的临界转变速度及流型转变规律。特别是针对声能量分析无法准确区分不同床层高度处流型转变的不足,利用递归分析可有效预测系统周期性的特点,将声信号进行递归分析,研究了流化床不同位置的流型转变性质。结果表明,鼓泡流态化下颗粒运动的周期性较湍动流态化强,并能够清晰地检测到由鼓泡流态化向湍动流态化的流型转变速度,而且床层较低处的流型转变速度比床层较高处大。由此获得了一种便捷灵敏、安全环保的非侵入式流化床流型转变速度的测量技术,可用于对整个流化床内不同位置流型转变过程的实时在线监控。     

矩形鼓泡塔流体动力学数值模拟

鼓泡塔反应器内流体动力学特性预测对于鼓泡塔的设计和发展具有重要意义。文中应用CFX4.4商业软件,采用k-ε模型中气泡诱发湍流模型,对较高鼓泡塔中湍流弥散力影响和Tomiyama模型的作用进行了数值模拟。研究发现,目前通用的湍流弥散力对所研究的气泡流体动力学影响很小,引入带有气泡诱发湍流模型的Tomiyama模型能获得较好的速度分布。在这种情况下,Pfleger&Becker的模型要优于Troshko&Hassan模型,原因在于后者高估气泡诱发湍流时间尺度。     

SEBS高黏度溶液气液鼓泡塔的流体力学研究

针对SBS加氢反应器开发与设计,以SEBS-1650己烷溶液为液相,采用差压法和床层塌落法研究了气液鼓泡塔中高黏度溶液的流体力学行为,考察了黏度对低表面张力溶液的气含率、大小气泡气含率、大小气泡上升速度和比表面积等因素的影响。结果表明,随黏度增加,大气泡增多,气含率明显降低,塔内流型处于湍流区;由床层塌落曲线确定鼓泡塔内存在三种类型的气泡：大气泡、小气泡及细小气泡,随黏度增加,小气泡与细小气泡逐渐减少;黏度对大小气泡的上升速度略有影响,比表面积随黏度增加而明显降低。根据实验结果给出了大小气泡气含率与平均气含率的计算公式。     

环流反应器参数测量和流型识别的研究进展

环流反应器结构简单,传热传质能力高,功率消耗小,对细胞的损害极微,作为化工、环保和生化反应器,有着广泛的应用前景。本文综述了环流反应器中气含率和循环液速的测量方法,归纳了均匀鼓泡区和非均匀鼓泡区两种流型识别的最新方法,提出了今后研究工作的方向。     

气液鼓泡塔液体流动状态的声发射检测

提出一种基于声发射气液鼓泡塔液相流动状态检测方法,将多通道声发射传感器等距地置于鼓泡塔轴向壁面,提取不同表观气速下的各通道声发射信号,对其做经验模态分解(EMD),根据每个imf的Hurst指数值,提取和重构相应的imf,求其每个信号的平均能量。实验结果表明:鼓泡塔壁处液体轴向流速随着表观气速的增加而增大,当表观气速为14 m/min时,塔壁处液体轴向环流速度最大,当表观气速大于18 m/min时,液体轴向完全变为湍流,出现严重返混。声发射检测法能够有效检测出液体流动状态。     

国内外化学工程文献摘要

<正> 89062 气液并流双管式鼓泡塔中的滞气量和液体循环速度——都田昌之等人,化学工学论文集(日),14,[5],593(1988)。 在大范围的操作条件下,测定了在装有气浓喷嘴的鼓泡塔中的平均滞气量和环流液体循环速度,并观察了流型变化。在较低的液速范围内,平均滞气量随气速的增大而增加,与液速无关。而在高液速范围内,平均滞气量随气速和液速的增大而增加。当液体流速大于临界喷射速度时,液体喷嘴所产生的气泡相对地比较均一。还关联了平均滞气量的计算方程式。环流液体循环速度随液速的增加     

气体分布器结构对气升式环流反应器内气液两相流动的影响

使用欧拉两流体模型研究气体分布器结构对气升式环流反应器内气液两相流动的影响,预测了环己烷氧化反应器内单环结构、三环结构、五环结构的气体分布器时反应器内液相速度分布、气含率分布、液相循环速度以及液相微观混合特性.模拟结果表明,在等量的进气流量下,气体分布器环数增加,液相速度分布和气含率分布更趋均匀;气体分布器环数增加,液相推动力增加,从而使得液相循环速度增加,液相的宏观混合效果增强;气体分布器环数增加,导流筒内外的平均气含率增加.随机游走模型模拟结果表明,气升式环流反应器与普通鼓泡床反应器对气体分布器结构要求不同.     

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。