天然气计量技术现状及趋势

天然气流量计量是天然气生产、输送和销售的关键环节,论文分析了发展天然气计量技术的意义;介绍了天然气计量技术的现状,包括:计量标准、孔板流量计、涡轮流量计、超声波气体计量计以及其它新型的天然气计量仪表;结合我国天然气工业发展的需要对天然气计量技术的发展趋势进行了预测。     

天然气输送中流量计计量系统的研究

在天然气输送过程中,应用天然气流量计进行计量,明确输送天然气的量,提高计量的精准度,满足天然气计量的需要。优选最佳的天然气流量计计量系统,能够准确计量天然气的量,达到天然气计量的技术要求。     

天然气计量管理计量仪表与输差控制分析

天然气计量以流量计量为主,围绕流量计量而进行相关量的计量。天然气计量在开采、集输、净化、外输等环节特别重要,几乎每一环节均要计量。天然气作为洁净能源和多用途化工原料,其价值和价格不断上升,流量计量的准确度要求也不断提高,因为流量计量数据是供需双方之间贸易结算的依据。本文主要探讨天然气计量管理计量仪表与输差控制。     

超声波流量计CPU板故障处理分析

近年来,随着国际及我国天然气工业的快速发展,气体超声流量计在高压、大口径天然气流量计量中得以广泛运用,已成为主流流量计。以川气东送管道为例,川气东送管道使用超声波流量计76套,占所有流量计的67%。超声波流量计CPU板是流量计电子的核心部件,本文介绍了daniel超声波流量计CPU板故障处理,更换超声波流量计CPU板步骤及方法。     

天然气超声波计量系统性能的影响因素

超声波流量计量系统应用于天然气流量的计量,为了准确获得天然气的流量数据,加强对计量系统的维护管理。分析影响天然气超声波计量系统性能的因素,采取必要的技术措施,合理解决天然气超声波计量系统存在的问题,提高计量的精准度,满足天然气生产企业的技术要求。     

浅谈减少工厂天然气流量计量系统的误差

综述了工厂天然气流量计量系统管理,从计量公式推导提出补偿计算公式,以及天然气组分和现场仪表对计量的影响。     

天然气组分对流量计计量的影响

本文根据孔板、涡轮和超声波流量计的原理,结合库尔勒天然气分输站的气质现状,逐一分析天然气各组分对孔板、涡轮和超声波流量计量的影响程度,进而找到输送天然气精确计量的有效途径,同时,采用在线色谱分析仪对天然气组分进行实时监测,分析并掌握组分含量对流量计量的影响,实现精准计量和效益最大化。     

浅谈天然气流量计在线检定技术

本文简单说明了天然气流量计的分类及检定技术,包括离线检定和在线检定;在线检定技术中的组合喷嘴式气体流量检定装置的研究,包括装置结构设计、数据采集与处理系统、技术指标等,为从事天然气流量计管理的人员提供一定的参考与借鉴。     

濮城油田天然气计量中存在的问题及对策

在企业生产和经营管理中流量计量是一项日常进行的重要的技术基基础工作。天然气作为一种优质能源和化工原料其计量越来越被人们重视。天然气的准确计量不仅是供需双方贸易结算的重要依据,而且对降低生产成本,提高经济效益有很大帮助。     

气体超声流量计的分析与应用

<正>随着科学技术的发展和天然气流量测量技术研究的深入,近年来超声流量计在天然气贸易计量中得到了广泛的应用。我国于2001年内编制了GB/T 18604《用气体超声波流量计测量天然气流量》的国家标准。该类型教其它流量计有自身有点,因此近些年来除中石油西气东输管线应用超声流     

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。