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乙烯精馏塔运行状况的好坏与乙烯产品的质量及产量息息相关。中韩石化乙烯装置乙烯精馏塔经过110万t/a脱瓶颈改造后,出现了塔压差增高、塔顶产品不合格、塔釜乙烯损失增多等生产问题。文中从乙烯精馏塔实际运行状况着手,分析影响乙烯精馏塔正常运行的原因并提出优化措施。通过将乙烯精馏塔气相进料部分转至液相进料来降低精馏塔整体负荷;优化裂解原料组成;降低中沸、增加底沸热负荷等优化措施,消除了塔压差高的影响,降低塔顶乙烷含量及塔釜乙烯损失,让乙烯精馏塔能安全稳定运行,保证乙烯产品质量合格。 相似文献
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提出在乙烯精馏塔DCS控制中采用24位A/D转换器代替原16位A/D转换器的改进措施,并通过动态仿真实验证明该措施使温度测量精度由0.03℃提高到0.000 1℃,温度与产品质量之间的信息丢失量降低,可以用温度表征相应的产品质量,温度可以形成闭环反馈控制回路,满足实际乙烯精馏塔质量控制要求。 相似文献
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针对具有3个换热器结构的外部热耦合双精馏塔(S-EHIDDiC),提出了一种新型的控制与优化策略。顶部与底部换热器的热负荷能够改变高压精馏塔的回流量和低压精馏塔的上升汽量,因而可以用来控制高压精馏塔塔顶和低压精馏塔塔底的产品质量。这种控制方法与常规精馏塔的LV控制结构相似。S-EHIDDiC还有多余的决策变量(如进料分流比,高压精馏塔塔压和中间换热器的热负荷),可以对稳态操作进行优化。闭环仿真证明了这种控制结构的可行性,稳态优化也提高了系统的热力学效率。 相似文献
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通过Aspen Plus软件模拟计算了某乙烯装置1 100 kt/a改扩建前、后乙烯精馏塔系统,针对生产中乙烯精馏塔塔釜乙烯损失较大的问题,从工艺角度分析中沸和再沸换热器热负荷,从设备角度分析乙烯精馏塔的水力学模型。结合现场实际情况提出工艺优化措施,通过降低中沸,提高再沸解决精馏段液泛问题;通过降低冷凝罐(D-410)取液点、或适当提高乙烯制冷压缩机四段出口压力或通过适当降低热流股温度强化相变传热来增加热流股流量,最终满足所需热负荷。 相似文献
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精馏塔是化工过程经常用到的一种分离设备,操作条件不当,易使精馏塔进入异常工况.正常工况时,出料温度随回流量增大而降低,模型增益为负;回流量继续增大,导致板效率下降,出料温度开始上升,模型增益变为正,精馏塔进入异常工况.针对此情况提出一种基于最小二乘法的乙烯精馏塔模型增益在线辨识方法,在线实时辨识出模型增益符号,根据辨识结果,判断乙烯精馏塔是否进入异常工况.建立正常与异常工况的乙烯精馏塔控制系统,根据模型增益辨识结果,由负反馈原理确定正常与异常工况中控制器正反作用,使得回流量和出料温度均控制在正常工况允许范围内,保证乙烯精馏塔在正常工况工作,实现乙烯精馏塔正常与异常工况控制. 相似文献
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《化学工程》2017,(1)
反应体系中混合物的相对挥发度排序对整个反应精馏过程的设计和控制都有很大的影响,针对拥有最不利相对挥发度排序的棕榈酸异丙酯(IPP)反应精馏塔的特点,建立合理的稳态模型,并设计常规的温度控制TC方案以及新颖的温差控制TDC方案来控制出料产品的纯度。通过Aspen Dynamics软件进行模拟仿真实验。在系统中引入3种干扰(操作压力,进料流量和进料组分)用于评估2种控制方案的性能。仿真结果表明:2种控制方案最终都能很好地控制出料产品的纯度,这突显了稳态模型设计的合理性。但TDC方案明显具有更好的鲁棒性,保证了产品纯度的同时还使系统能够快速的稳定,且超调量较小,这为今后反应精馏过程的设计与控制提供了一种新思路。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
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. 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
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. 相似文献
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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. 相似文献
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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. 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
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. 相似文献
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
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。 相似文献