旋转填料床精馏性能研究

以乙醇-混合液为物系,对转子内径为60mm,外径为180mm,高40mm的旋转填料床进行精馏实验。结果表明,在低转速区旋转填料床的理论塔板数随气相动能因子F和超重力因子B的增大而增大,传质单元高度为1．09-1．76cm;并建立了传质模型。     

旋转填料床甲醇精馏工艺

以甲醇-水混合液为物系,对转子内径为φ58 mm、外径为φ118 mm、高40 mm的旋转填料床进行精馏实验。结果显示,在低转速区旋转填料床的理论塔板数随气相动能因子F和超重力因子β的增大而增大,传质单元高度为0.9～1.2 cm;并建立了传质模型。     

并流旋转床压降与传质特性的研究

利用水-空气系统对并流旋转床的气相压降进行了研究,并与逆流旋转床气相压降进行了对比。研究结果表明：并流较逆流旋转床的气相压降低;并流旋转床的气相压降随气体流量的增大而增大,随液体流量的增大而减小,随转速的增大明显降低;而逆流旋转床的气相压降随转速的增大明显升高。利用水吸收SO2的实验对并流旋转床的传质特性进行了研究。研究结果表明：并流旋转床填料层内各点的体积传质系数随着气体流量、液体流量和转速的增大而增大;填料层半径由70mm增大至90mm时,并流旋转床的体积传质系数迅速增大,而后并流旋转床的体积传质系数随半径的增大而减小。对并流和逆流旋转床填料层内体积传质系数进行了对比。结果表明：填料层半径由70mm增大至130mm时,并流旋转床的体积传质系数较逆流时大;当半径大于130mm后,逆流旋转床的体积传质系数大于并流旋转床的体积传质系数,且随半径增大而增大。根据研究结果,提出了降低系统压降的设想,即并流与逆流旋转床串联操作。     

精馏过程中转子对旋转填料床传质性能的影响

以甲醇水溶液为介质,在全回流、常压操作条件下,对3种转子的旋转填料床进行精馏实验。结果表明：旋转填料床的理论塔板数随超重力因子、气相动能因子和回流量的增大出现峰值,等板高度最小为9．5mm。转子Ⅲ的传质效率高于转子Ⅰ,低于转子Ⅱ。在实验基础上应用最小二乘法建立了转子Ⅰ的传质关联式。     

用ASPENPLUS软件模拟旋转填料床精馏操作的探讨

运用大型化工流程软件ASPENPLUS对以乙醇-水为体系的旋转填料床精馏工艺进行了模拟,介绍了模拟过程中物流、单元操作模块的选取和灵敏度分析、设计规定的计算方法。模拟结果表明,在低转速区旋转填料床的理论塔板数随气相动能因子F和超重力因子β的增大而增大,传质单元高度为0．9-1．2cm;并建立了传质模型,建立的模型对优化设计具有一定的指导意义。     

蒸馏过程中旋转填料床的传质和流体力学特性

建立了一套完整的精馏实验装置,以甲醇-水溶液为物系,在常压、全回流操作条件下,研究了旋转填料床的传质和流体力学性能. 结果表明,旋转填料床的理论塔板数随超重力因子和气相动能因子的增大出现峰值,理论塔板高度最小为0.0109 m;气相压降随气相动能因子、超重力因子的增大而增大. 在实验基础上应用最小二乘法建立了旋转填料床的传质、压降实验关联式.     

网板填料复合旋转床的传质性能

网板填料复合旋转床(RCB)是一种有别于填料床和折流床的新型旋转床,具有传质效率高和压降小的特点。以乙醇-水溶液为物系,在常压、全回流操作条件下,对同心环网板、同心环网板间径向填充鲍尔环、轴向填充鲍尔环、周向填充鲍尔环的这四种转子进行精馏实验。结果表明:网板填料复合旋转床的等板高度随气相表观动能因子和转速的增大出现最小值,在转速800 r min 1,气相表观动能因子1.3 kg0.5 m 0.5 s 1时,其值为28 mm。鲍尔环的填充有利气液传质,其不同填充方式的气相总体积传质系数由大到小的顺序为:周向填充、轴向填充、径向填充、无填充。     

新型填料结构旋转床传质特性

以CO2-NaOH溶液为工作介质,研究了填料特性、超重力因子、气体流量和液体流量等对不同填料结构旋转床传质特性的影响.结果表明:体积传质系数随液体流量、超重力因子和气体流量的增加而增大;对比六种填料结构的综合性能,不锈钢多孔波纹板和塑料多孔板填料结构较优;在相近的操作条件下,不锈钢多孔波纹板的体积传质系数比文献丝网错流旋转床高0.95～2.10倍、与逆流旋转床相当,比传统气液传质设备高1～2个数量级.对实验数据进行回归分析得出了体积传质系数的关联式,其平均误差小于10%.     

旋转填料床中2种填料压降和传质特性的对比

分别以空气-水和磷酸钠溶液吸收模拟烟气中SO2为实验体系,对装填有θ环和波纹丝网填料的逆流旋转填料床压降和传质特性进行了对比研究,结果表明:在实验操作范围内,逆流旋转填料床的湿床压降随气量、超重力因子的增大而增大,受液量的影响很小;2种填料的湿床压降相差不大,且均低于750 Pa。2种填料的Kya均随喷淋密度、空床气速和超重力因子的增加而增大,当U=6 m3/(m2·h),u=0.73 m/s,β=85及更高的操作范围时,θ环填料的Kya比波纹丝填料高25%以上,说明θ环填料的传质性能明显优于波纹丝填料;最后得到装填θ环和波纹丝填料的旋转床湿床压降和体积传质系数的经验关联式。文中的研究结果对旋转填料床的设计和选型有重要意义。     

三角形螺旋填料旋转床全回流精馏性能研究

为了寻找强化气液传质过程的有效途径,自制了1套小型旋转填料床,床内填充了φ2mm×2mm三角形螺旋填料,以乙醇-水为实验物系,进行全回流精馏实验研究.实验结果表明:三角形螺旋填料旋转床存在一最佳转速nopt=1050r/min,当转速nnopt时,理论板数随液体流量和气体流量的增大而减小,且减小的很快.在nopt=1050r/min、液体流量L=14.7L/h、气体流量V=7.4m3/h时传质效果最好,每米填料相当于88块理论板,在适宜的转速范围内每米填料相当于62～88块理论板.三角形螺旋填料旋转床使传质过程得到极大强化,其传质效果比重力场三角形螺旋填料塔提高1倍左右.     

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。