A determination of the activity of water in water-alcohol mixtures using mobile order thermodynamics

The non-ergodic theory of mobile order thermodynamics (MOT) is employed to study how the structure of ethylene glycol and several common alcohols influences the activity of water in binary mixtures. Results suggest that alcohol molecules with a smaller alkyl group or a greater number of hydroxyl groups are more effective at lowering the activity of water. The influence of alcohol branching among isomers is examined as well. Calculations are in good agreement with widely used algorithms such as the UNIQAC equation. With more complex alcohols like diethylene and triethylene glycols, the MOT framework requires additional development. Alcohols are known to be thermodynamic inhibitors that hinder the formation of gas hydrates. Since hydrate stability is determined by an equilibrium condition of equal chemical potentials for water in the hydrate and liquid phases, the present study may help clarify the inhibition mechanism for alcohols.     

含水合物沉积物力学-声学联合试验设备的开发和初步应用

为开展天然气水合物沉积物力学、声学特性的试验研究,对高压-温控三轴试验设备的管道线路进行重新规划,并引入GCTS超声波测试系统。为了检验仪器性能,利用福建标准砂和甲烷气体制备不同水合物饱和度的沉积物试样,开展不同有效围压下的三轴排水剪切试验。结果表明：设备能稳定制备含水合物试样并进行力学试验,试验全过程可实时测试试样的压缩波速和剪切波速;波速变化与试样内部密实度、颗粒分布的变化等密切相关,可反映试样体积的变化及剪切初期的剪胀特性;通过固结后的波速计算试样的泊松比,在0.16～0.31之间。     

水合物浆体在水平细管中的流动相变换热

实验测量了质量分数为0~19.2%的TBAB水合物浆体在恒热流条件下在小管径内流动时的流动传热特性。利用数值计算获得管内浆体的沿程温度分布,在此基础上得到水合物浆体在小管径内的强制对流传热特性。结果表明加热功率对小管径管道中的浆体传热特性有较大影响;在层流状态下,流速对传热系数的影响相比紊流时要小。在实验数据基础上总结出了TBAB水合物浆体在小管径管内的对流换热经验关联式。     

柴油加氢尾气中氢气的水合物法回收工业侧线试验

常规氢气回收方法的产品氢气压力偏低,需多级增压后才可被高压加氢装置利用,具有较高的氢气增压成本。水合物法回收加氢尾气具有压降损失小、产品氢气压力高的优点,可降低高压加氢装置的氢气增压成本。为降低高压加氢装置的用氢成本,本文开发了高压尾气的水合物法氢气回收技术。针对高压柴油加氢尾气,在茂名炼油厂建立了一套柴油加氢尾气中氢气水合物法回收的工业侧线试验装置,考察了不同条件下连续搅拌釜法回收柴油加氢尾气中氢气的分离效果。试验结果表明,水合物法可高效脱除CH₄和大部分的H₂S。连续进气工况下,处理脱硫后尾气时可将氢气体积分数从83.76%提高至91.65%,处理含硫尾气时可将H₂S体积分数从0.73%降至0.07%。     

近井储层改造对天然气水合物藏降压开采特性影响的数值模拟研究

本文基于我国第一轮海域天然气水合物试采地质模型,利用Tough+Hydrate对近井储层改造后的水合物藏进行降压开采模拟研究.探究了多孔骨架渗流通道对气/水输送、压降传播、水合物分解等的影响机制,评估了近井储层改造在不同开采层位和整个开采过程中对产能提高的贡献大小.模拟结果表明:多孔骨架渗流通道内气/水流速高,可以起到导流、防砂的作用;近井储层改造可促进压降传播,加快水合物分解,但骨架通道的增产作用随开采时间增加逐渐减弱;近井储层改造在不同开采层位起到的增产效果不同,三相层中的增产效果最明显,但由于模拟改造范围较小、形成的多孔骨架渗流通道渗透性较低,增产效果不明显,多孔骨架渗流通道高度为50 cm时,2年产气量仅提高11.7%.     

DSC技术在天然气水合物研究中的应用

介绍了DSC技术的基本原理,在天然气水合物热力学研究、动力学研究、水合物抑制剂评价中的应用。DSC技术作为一种热分析方法,它具有试样微量化、不用溶剂、适用范围广、快速简便等优点,为探索天然气水合物的特性提供了又一种有效的技术手段。     

DURABILITY OF HARDENED FLY ASH PASTE

The mechanical properties and durability ( mainly frost - resistance and carbonation resistance ) of fly ash-CaO-CaSO4 · 2H2O hardened paste are studied. The relationship among durability of hardened fly ash paste, the quantity and distribution of hydrates and the initial paste texture of hardened fly ash paste is presented.     

天然气的低温处理方法

低温分离,是利用地层本身能量节流降压制冷,用低温分离方法脱除天然气中凝液的处理工艺。其特点是工艺流程及设备简单,运行可靠,维修方便,操作范围弹性大,适用于高压大流量条件,流量和压力易于调节。当地层压力下降过低时,该制冷工艺不适用。     

The effects of capillary forces on the flow properties of glass particle suspensions in mineral oil

The effect of water on the flow behavior of glass microspheres dispersed in mineral oil was investigated for various levels of water, particle volume fractions, and particle sizes. The addition of small amounts of water leads to large increases in viscosity due to the formation of water bridges between particles that give rise to capillary forces between the particles. The capillary forces between the particles also make the flow profile highly shear‐thinning across the range of particle volume fractions that were studied (0.10 to 0.25). The presence of water leads to a significant effect of particle size, and the viscosity of dispersion goes through a maximum as the amount of water is increased. Two hydrophobic surfactants, Span 80 and Arquad 2HT, were found to reduce the viscosity of the dispersions with added water, but the mechanism and extent of viscosity reduction differed. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Nucleation curves of model natural gas hydrates on a quasi‐free water droplet

Heterogeneous nucleation probability distributions of gas hydrates on a water droplet that was supported by inert and immiscible perfluorocarbon oil, perfluorodecalin is studied. The guest gas used was a mixture of 90 mol % methane and 10 mol % propane. The probability distribution was measured using a high pressure automated lag time apparatus under the guest gas pressure range of 6.7–12.5 MPa and the cooling rate range of 0.002–0.02 K/s. Nucleation curves were derived for unit area of water surface. The nucleation rate per unit area of water surface that was contained in a glass sample cell, which differed significantly from that on a quasi‐free water droplet, is also derived. It is concluded that the nucleation curves in the presence of a solid wall should be normalized to the unit length of the three‐phase line at which water, guest gas, and the solid wall meet. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2611–2617, 2015