单效热压缩蒸馏海水淡化热力过程数值模拟

建立了单效热压缩蒸馏海水淡化系统的热力学模型。分析了蒸发温度、压缩比和主动蒸汽压力等主要设计参数对系统造水比、单位造水换热面积和单位造水冷却水量的影响。结果表明,降低蒸发温度、减小压缩比和提高主动蒸汽压力将提高系统造水比,而单位产水换热面积将随蒸发温度和压缩比的减小而增加;提高蒸发温度和减小压缩比可以减小单位产水冷却水量;主动蒸汽压力对单位产水面积和冷却水量影响较小。研究成果将对系统优化设计提供有益的参考。     

罗茨压缩机驱动MVR热泵系统的节点分析

通过温熵图和焓熵图结合工艺流程图对MVR系统进行了深度剖析,在Aspen Plus软件的辅助计算下,以水为蒸发工质,忽略系统的一切热量损失,对系统中的各个操作单元进行了理论上的分析,并结合工艺要求给出了最佳的操作条件:原料进入蒸发室前需要预热到蒸发压强下的饱和温度或者处于微过热状态;在设备条件允许的条件下,尽量控制在较高的真空度下蒸发;罗茨压缩机对二次蒸汽压缩时,压缩比控制在2左右最佳,既能保证有效的传热温差,又能拥有很高的能效比;冷凝液可以作为补充水源来消除压缩蒸汽的过热度,使过热蒸汽饱和化或处于微过热状态;蒸汽冷凝液应在饱和液体状态下引出,然后去预热原料和充当补充水;真空系统的处理应由真空泵抽吸不凝性气体和少量的二次蒸汽,为了维持MVR系统的能量平衡,应适时的补充少量新鲜蒸汽。     

机械蒸汽再压缩蒸发系统的性能分析

机械蒸汽再压缩（MVR）蒸发系统是一种新型高效节能蒸发技术。它有多个单元设备组成,每个操作节点的控制都对系统运行的稳定性和节能效率至关重要,其中包括进料温度、蒸发压强、蒸汽压缩比、冷凝液温度等。若操作条件不当,不仅会大大降低蒸发效率而且会对设备和管路造成损害。本文建立了一套充分利用能源的MVR蒸发工艺流程,并通过理论分析对每个操作节点进行了质量和能量衡算,同时利用Aspen Plus模拟软件建立了系统的流程模拟图。通过对操作单元的变量控制,研究了循环蒸汽量、补充水的量与进料温度、冷凝液温度、蒸汽压缩比以及蒸发压强等之间的变化关系。由数据分析可得：原料在饱和液体时进料最佳,冷凝液的温度应保持与蒸发温度的有效温差在5～8 ℃时较好,压缩机的蒸汽压缩比控制在1.8～2.2较为合理。同时可利用冷凝液和浓缩液的余热对原料预热,补充水也可从冷凝液中直接取用。     

中药热泵低温蒸发过程模拟与实验研究

通过对中药药液ZY-3的低温蒸发过程的Aspen模拟,以模块化的方式先后确定了中药药液的露点温度,使中药药液蒸发和使溶剂蒸气冷凝所需的热量和冷量,通过其热量和冷量的计算匹配出相应的热泵系统,最终得出蒸发操作的适宜条件,即在0.01 MPa(绝压)的压力下蒸发,溶剂冷凝到20℃。随后组建实验设备,以实验的方法来验证Aspen模拟的可能性,通过对实验数据和模拟数据的采集、计算与分析,结果表明,选定的压缩机在正常工作条件下,其冷量和热量可以很好地与中药ZY-3药液蒸发所需热量和蒸气冷凝所需冷量相匹配;在操作压力为0.01 MPa(绝压)、操作温度为25℃的操作条件下,ZY-3药液的进料量为10.62 kg/h,可以蒸发9.94 kg/h溶剂,产品含溶剂质量分数约为26%,远远好于厂家对于产品指标的要求。     

高沸点升溶液蒸发系统的设计与分析

针对高沸点升溶液蒸发过程的特点,结合蒸汽压缩机提升二次蒸汽压力和温度的实际能力,提出一种分级压缩的机械蒸汽再压缩(MVR)蒸发系统,建立了分级压缩和多级压缩MVR蒸发系统的数学模型,考察了溶液沸点升高、压缩机压缩比和一级排出液浓度等运行参数对蒸发系统能耗、蒸发器换热面积、设备成本和系统总费用的综合影响.结果表明,分级压缩MVR蒸发系统适用于沸点升在15℃以上的物料,NaOH溶液浓缩的最优操作工况为压缩机压缩比2.0、一级排出液浓度23%(w).相同蒸发水量下,分级压缩MVR蒸发系统可节约47.83%的系统能耗和28.75%的设备成本,比多级压缩MVR蒸发系统节能效果好.     

蒸发在丙烯腈行业中的应用

阐述蒸发操作在丙烯腈行业中的利用—蒸发结晶和四效蒸发。丙烯腈生产过程会形成稀硫铵溶液和含CN-1的重组分溶液等副产物,稀硫铵溶液采用蒸发结晶的工艺生产化肥级硫铵,重组分溶液采用四效蒸发,提浓原溶液,减少后续工序的处理量;同时,两种工况产生的二次蒸汽被利用或冷却,其凝液再次补充到工艺用水系统中。本文通过几套装置的设计参数,计算出回收的水量。     

水力喷射冷凝器在硝铵生产工艺上的应用

蒸发工序是硝铵生产工艺的重要组成部份。按原定型设计,我厂系用 PMK—4型水环式真空泵抽吸不凝缩性气体,用气压式冷凝器冷凝二段二次蒸汽,负压450～500mmHg 操作。流程如图。气压式冷凝器冷凝二段二次蒸汽流程复杂,设备庞大,配管长,耗钢材多;冷凝器内隔板之间易被水垢堵塞,冷却效率差;检修频繁而困难;真空度波动大,操作不稳,稍有不当,数十吨半成品硝铵就会由气压式冷凝器带走,排至水封槽而流入地沟。     

热泵闪蒸汽提脱氨生产固体硫酸铵过程的能量利用

研究了蒸发结晶和闪蒸汽提脱氨技术集成生产固体硫酸铵系统中的各种热量利用效果;蒸发结晶和闪蒸汽提脱氨技术集成生产固体硫酸铵与直接生产硫酸铵溶液总蒸汽耗量基本一致;蒸发结晶和闪蒸汽提脱氨技术集成生产固体硫酸铵时,保证过程能耗不增加,达到节能目的;随着废水中氨氮含量的增加,系统整体的蒸汽耗量增加,但补充蒸汽用量降低,且到一定含量时,不需要补充蒸汽,甚至需排放过多蒸汽。     

蒸发冷却空调试验室冷凝热回收系统实验研究

回收冷凝热对流经蒸发器的空气再热,减少电加热器耗能,是降低蒸发冷却空调试验室能耗的有效方法.为研究试验室环境温度、冷凝温度对蒸发冷却空调试验室冷凝热回收系统性能的影响,在不同试验室环境温度、冷凝温度工况下进行实验.结果表明:冷凝热回收系统的制冷量随着环境室温度的升高而增大,当试验室环境温度由27℃增至35℃,冷凝热回收...     

确定多效蒸发最佳效数的捷径

在化工厂中，为了最低限度降低能耗和冷却水用量，常采用多效蒸发。在多效蒸发系统中，几个蒸发器，用管道连接，使蒸汽从一效连续地进入下一效。这样，向第一效蒸发器提供的热量用于蒸发其中的水分，所产生的蒸汽，依次进入下一效，直至最终，供给未效蒸汽热量传递给冷凝器。这种安装净结果是热量多次重复使用及蒸发系统的经济性明显提高。蒸发经济性定义为蒸发的总水量与供给第一效的水蒸汽量之比。效数的增加意味着蒸发经济性提高。将效数乘以0．8可得到蒸发经济性粗略估算值。当效数增加的时候，除了节省水蒸汽用量外，还节省冷凝器冷却…     

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.     

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.