水溶液全循环法尿素装置配套联产三聚氰胺技术改造

水溶液全循环法尿素装置为配套联产三聚氰胺,需消化吸收三聚氰胺装置副产的尾气,打破了尿素装置原有生产的水平衡,导致系统水碳比高、存在尿素合成塔处理能力不足,需提高生产能力的问题.从尿素合成转化率、系统热平衡等方面分析了该尿素装置的处理能力,提出解决水平衡的办法.通过双尿素合成塔并联操作,提高尿素合成转化率,中压系统分解、吸收能力的改造等措施,解决了上述问题.结果表明,改造后顺利实现尿素与三聚氰胺联产,尿素装置在高水碳摩尔比下生产运行良好,消化吸收了46 t/d三聚氰胺装置来的全部的甲铵液,装置生产能力达到750 t/d,尿素消耗降低,氨耗等与CO2汽提法尿素工艺相当.     

节资降耗的尿素生产工艺实现突破

四川金象化工集团对传统水溶液全循环尿素生产工艺进行了改进：尿素合成采用液相换热合成塔,提高了CO2转化率和安全系数,同时可杜绝尿素合成塔发生化学爆炸事故;中压分解采用预精馏和组合加热方式,提高了中压分解率,减少了投资;中压回收采用低水碳比和多段吸收,氨冷凝采用蒸发式氨冷器,尾气采用精洗,降低了消耗并避免了尾气爆炸的可能性;     

关于改进型CO_2汽提法尿素装置尿素合成塔的腐蚀与控制

尿素合成塔是改进型CO2汽提法尿素装置的4大重要高压设备之一。介绍了34万t/a尿素合成塔的基本结构;阐述了尿素合成塔的腐蚀机理;从温度、氨碳比、水碳比、甲铵液浓度、氧含量等方面等论述了尿素合成塔产生腐蚀的影响因素;提出了正常运行、开车、停车、封塔停车以及低负荷运行期间减缓尿素合成塔腐蚀的控制方法。     

高压法三聚氰胺装置尾气回收新技术

论述了高压法三聚氰胺装置尾气用于联产尿素的尾气回收新技术;介绍了该技术的工艺流程、技术特点、技术原理,以及氨碳比、水碳比、CO2转化率的确定原则;对实际生产运行数据进行了分析和总结.     

尿素合成塔的水碳比控制

1 概述 1987年,我们用TDCS-2000基本控制器完成了尿素合成塔的氨碳比,氧碳比等系统的控制。进一步研究的课题就是如何实现水溶液全循环尿素生产装置合成塔的水碳比控制,这也是中氮尿素厂同行所关心的课题。结合我厂尿素生产装置特点,我们用     

氨汽提尿素装置节能改造

我公司尿素装置采用意大利斯拉姆氨汽提尿素工艺,从1991年建成投产到现在,已生产尿素100多万t。近10年的生产实践证明,该技术具有消耗低、操作弹性大、热能利用充分,操作易控制等特点。但由于原设计中存在的不足,导致尿素的能耗指标未能达到工艺的保证值。十年来我公司通过对工艺、设备进行技术改造和工艺参数的优化控制,取得了良好的节能效果。1　高压系统1.1　合成塔适当降低氨碳比、水碳比操作设计合成塔氨碳比3.4～3.6,水碳比0.6～0.9,二氧化碳转化率65%,但实际生产中CO2转化率一般只有59%～61%,低于设计值。这样就造成汽提塔的负荷加…     

低压尿素深度水解装置运行总结

山东阿斯德化工有限公司对尿素装置高压系统、中压分解吸收系统改造后,生产运行过程中的主要问题：由于二段分解吸收时解吸气相带液,造成二循一冷吸收负荷加重,经常出现连续性漫液,致使二循二冷氨水中CO2含量严重超标,二段经常超压,直接影响一段吸收塔的稳定运行。解吸废液中氨质量分数最高为3．6％（平均为0．8％）,废液中尿素质量分数平均为1．3％,氨及尿素损失都比较严重,生产成本上升。     

CO_2汽提法尿素装置提高CO_2转化率的措施

尿素工业装置中工艺优化与设备改进的核心目标之一是提高尿素合成塔的CO_2转化率。结合阳煤丰喜肥业(集团)有限责任公司多套CO_2汽提法尿素装置的实际运行情况,总结分析影响尿素合成塔CO_2转化率的因素,采用半经验公式推导CO_2转化率以利于指导工艺操作,并就尿素合成塔的设计及生产强度控制、水碳比控制、氨碳比控制、合成系统压力与温度控制、原料液氨与CO_2纯度控制、开好回收及解吸水解系统等提出优化措施,以利提高尿素合成塔的CO_2转化率,达到节能降耗的目的。     

运用BP网络分析尿素合成塔CO2转化率

采用BP神经网络模型预测尿素合成塔CO2转化率，分析了氨碳比和水碳比与转化率之间的关系。详细介绍了建模过程并对隐含层神经元数和迭代次数对网络性能的影响进行了讨论。分析结果表明：所建模型能准确地对CO2转化率进行预测，平均相对误差在1．0％以内；CO2转化率随氨碳比的增大而显著增加，水碳比的影响则相对较小。     

小尿素系统降氨耗措施浅析

衡量一个尿素装置经济运行的关键指标是一段分解吸收负荷与二段分解吸收负荷的分配比例。如果尿素合成塔的转化率下降1％,则一段分解吸收负荷将上升10％;如一段分解负荷下降1％,二段分解吸收负荷将上升10％。因此,在实际生产中也要遵循这个原则,把分解吸收负荷尽量增加在一段分解吸收系统,尽量减少二段分解吸收负荷。这样才能使二段负荷降低,二段吸收加水量就少,返回一段的水量也就会减少,最终尿素合成塔的水碳比也会降低,合成塔转化率就会高,系统会趋于良性循环。     

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。