二氧化碳水合物分解动力学研究

油气在生产、储运过程中易形成二氧化碳水合物 ,而二氧化碳水合物的合理利用又可以解决如温室效应等的环境问题。为了考察二氧化碳水合物的分解动力学性质 ,采用改进的气体水合物静力学实验装置 ,测定了二氧化碳水合物在不同温度、压力下的分解动力学数据。将水合物分解反应看作一级反应 ,建立了分解动力学模型 ,计算了二氧化碳水合物的分解速率 ,较好地拟合了所测得的实验数据 ,模型的平均误差为 8.0 %。实验数据验证了二氧化碳水合物的分解速率与压力推动力有关 ,水合物表观分解速率常数与压力推动力成正比。将分解速率常数k以Arrhenius方程描述 ,计算出的二氧化碳水合物分解活化能为 71.4kJ/mol,与文献值相近     

二氧化碳水合物分解动力学研究

油气在生产,储运过程中易形成二氧化碳水合物,而二氧化碳水保物的合理利用又可以解决如温室效应等的环境问题,为了考察二氧化碳水合物的分解动力学性质,采用改进的气体水合物静力学实验装置,测定了二氧化碳水合物的不同温度,压力下的分解动力学数据,将水合物分解反应看作一级反应,建立了分解动力学模型,计算了二氧化碳水合物的分解速率,较好地拟合了所测得的实验数据,模拟的平均误差为8．0％,实验数据验证了二氧化碳水合物的分解速率与压力推动力有关,水合物表观分解速率常数与压力推动力成正比。将分解速率常数k以Arrhenius方程描述,计算出的二氧化碳水合物分解活化能为71．4kJ/mol,与文献值相近。     

蔗糖对四氢呋喃水合物分解平衡温度影响的实验研究

随着油气资源的开采趋于深海,对促进水合物分解的研究在管道解堵和水合物开采方面都具有重要的意义。实验测试得到蔗糖的质量分数分别为0.05%、0.5%、2.4%、9.1%、20.0%、33.3%和39.4%。实验结果表明体系中蔗糖的存在对THF水合物的分解有促进作用,能降低THF水合物的分解平衡温度且分解平衡温度随着蔗糖含量的增加而降低;当蔗糖的质量分数大于27.7%时,THF水合物的分解平衡温度降至冰点以下。热力学模型以液-水合物-气三相逸度平衡为起始点,根据THF水合物的特点对传统的逸度计算模型进行了适当的简化,用基团贡献法计算得到了实验体系下水的活度系数,并利用实验数据拟合得到了模型中用于计算Langmuir常数的两个重要参数,最后选定适用于其他参数的经验公式。用该模型预测得到的水合物分解平衡温度与实验得到的数据相吻合,说明该模型可用于预测常压下的THF+水+蔗糖体系水合物分解平衡温度。本文建立的模型对不同客体水合物的热力学模型的建立也具有指导意义。     

煤层气水合物合成与分解实验研究

天然气水合物储气技术(NGH)是正在研究开发的天然气储存新技术,它比液化方式(LNG)节能并降低成本。为了揭示煤层气水合物生成与分解过程规律,利用实验室大型水合物实验装置研究了表面活性剂(SDS)水溶液体系中煤层气水合物的生成过程以及在水浴条件下分解时的特点。实验结果表明,煤层气在一定温度、压力下与水及表面活性剂(SDS)能够快速生成固态气体水合物,其分解受温度影响明显。这种新方式有助于利用水合物技术储运与加工煤层气,促进煤层气开发与利用。     

南海沉积物中甲烷水合物定压分解特性

在定压条件下,实验研究了我国南海神狐海域沉积物中甲烷水合物的分解特性,所使用的沉积物平均孔径为12.178 nm,总孔容为4.997×10~(-2)mL/g,比表面积为16.412 m~2/g.所用沉积物样品含水量为40%,实验的温度范围为274.15–281.15 K,分解压力范围为3.0–5.0 MPa.实验结果表明,海底沉积物中甲烷水合物在降压过程中就开始迅速分解,分解过程造成体系温度迅速下降,最低温度远低于冰点温度.水合物的分解速率随着分解压力的降低而增大,总的分解产气量以及水合物分解率也随着分解压力的降低而增大.在不同温度的实验中,产气速率随着实验温度的升高而增大,总的分解产气量与初始的水合物量有关.当分解压力低于实验温度下纯水的甲烷水合物平衡分解压力时,水合物可以完全分解.     

大气常压等离子体弧清洗反应动力学模型和参数的研究

针对大气常压等离子体弧清洗金属表面的工艺,从反应动力学角度提出了一种新的研究方法.通过分析金属表面大气常压等离子体弧清洗的基本原理和清洗界面随时间移动的显著特点,根据清洗界面上的能量平衡条件,建立清洗界面的运动控制方程.在此基础上,采用四阶RUNGE-KUTLA法求出不同热流密度下清除界面位移规律,间接求得不同时刻所对应的清除百分比,进而结合反应动力学理论建立相关反应动力学数学模型以及计算活化能和反应频率因子相应反应动力学参数.以清洗金属表面润滑油污为例,建立了反应动力学模型,并采用称重法对其进行实验验证.结果表明:该模型不同时刻关于油污去除百分比的预测值与实验测量值相吻合;此外,清洗率与清洗界面处的氛围温度密切相关,随氛围温度的升高而增加.过高的氛围温度容易对基体造成损伤,存在一个理想的氛围温度阈值,该值介于分解温度与基体损伤温度之间.     

含水合物地层井壁力学状态的弹塑性解析分析

含水合物地层钻井引发井壁周边温度和渗流压力变化,可能导致水合物分解,对井壁安全产生不利影响。基于Mohrp-Coulomb准则、理想弹塑性模型以及非关联流动法则,针对含水合物地层中井壁力学分析, 建立了稳态轴对称平面应变模型,考虑水合物分解对地层温度、渗流和力学特性的影响,得到了欠压和过压钻井条件下井周应力及位移的解析解答,与相同假定下有限元模型、复杂数值模型的结果吻合较好。结果表明一定范围内水合物分解范围的增大会引起塑性区显著扩展。水合物分解引起的弹性模量劣化在欠压条件下将引起塑性区范围减小,在过压条件下则引起塑性区范围增大。     

多孔介质中天然气水合物注热盐水分解实验研究

利用自制的一维天然气水合物开采模拟实验系统,模拟海洋地质条件,在填砂模型中生成天然气水合物,并通过注入热盐水进行热力开采的物理模拟实验,分析多孔介质中天然气水合物注热盐水分解动态过程及注热参数对热力开采能量效率的影响.结果表明:注热盐水可有效地促进水合物的分解,水合物分解时局部电阻率明显升高;通过正交设计实验对注热参数进行敏感性分析,在相同的初始温度、压力及水合物饱和度条件下,注热水温度对注热分解的能量效率影响最大,然后依次是注热水速度、注热水时间.实验条件下,注热盐水分解可达到最大能量效率的注热参数为注热水温度60℃、注热水速率为12 mL/min、注热水时间100 min,此时能量效率为3.86.     

不同剪切作用下VC-713水溶液水合物抑制性研究

VC-713是一种抑制能力强、应用成熟的水合物动力学抑制剂,其水合物抑制性及抑制机理一直是各国学者研究的热点.通过600 rpm和12 000 rpm的搅拌剪切作用促使加质量分数为0.5%的VC-713不同程度地溶解分散于溶液中,进而结合THF水合物形成模拟实验(实验条件为常压、温度由5.0℃逐渐降至0.5℃)、VC-713浓度变化监测实验及实时记录的反应釜内实验现象探明了不同剪切作用下各组VC-713水溶液的水合物抑制性,并对其内在影响机理进行分析.结果表明:VC-713可通过吸附、包裹作用抑制水合物成核及生长,且相对更好地溶解分散于溶液内的VC-713能够更为有效地抑制水合物的形成.     

多孔介质中天然气水合物降压分解有限元模拟

基于多孔介质中水合物分解动力学、传热及气、水两相流理论,同时考虑水合物分解引起的渗透率及有效孔隙度变化,建立水合物、气、水三相的天然气水合物降压分解模型,并进行有限元程序开发及验证.利用此模型模拟水合物分解过程中压力、温度、水合物饱和度、有效孔隙度及气、水相渗流速度等物理量的空间分布及随时间的变化特征,分解前缘位置及累积产气量随时间的变化规律.结果表明:水合物分解使有效孔隙度和渗透率大幅度提高;水合物分解为吸热过程,分解前缘处温度降低明显;环境温度提高则水合物分解速率和产气速率提高,但压力增加,产气速率下降;温度和出口端压力是影响水合物降压分解的两个重要因素.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that