天然气-凝析液管道研究进展

湿天然气与干天然气不同,是多元组分的气体混合物,成分以饱和烃组分为主。由于输送过程中沿线温度、压力的变化,凝析和反凝析现象显著,使得天然气-凝析液的管道输送不同于气体或液体的单相输送,其实质是气液混输[1]。国内的一些凝析气田或油田,伴生气从联合站或平台分离器和原油稳定装置生产出来后,接着输送至天然气处理厂。随着压力、温度的降低,在联合站或者平台分离器到天然气处理厂的富气管线内,会有液体凝析,导致此处管段处于多相流动状态。我国早期开发的位于四川地区的气田,虽然在井口处设置了分离器,但仍有液体凝析,其部分管线仍处于多相流动状态。     

含液天然气管输减阻剂的研究进展

介绍了含液天然气管道的阻力成因,从减阻技术对管壁粗糙度、持液率、水合物的控制三方面阐述了其减阻降耗机理,对国内外目前已开发的天然气管输减阻剂的结构类型分析总结,得出Gemini型表面活性剂和高聚物减阻剂之间的有效复配是未来主要的研究方向。     

天然气液烃输送管道沸腾气泡起飞直径计算模型

提出了一种改进的气泡起飞直径计算方法,用以表征天然气液烃在管道输送过程中流动沸腾的气液相间传热传质速率。考虑作用在气泡上的不稳定阻力、剪切升力、浮升力以及管道倾角等因素,基于受力平衡原理和气泡脱离壁面的临界条件,建立了新的气泡起飞直径模型,在此基础上分析了管道倾角对气泡起飞直径的影响情况。结果表明:文中模型计算的水平、垂直管道中气泡起飞直径与实验值的平均相对偏差分别为10. 07%和5. 1%,精度优于目前常用的Fritz,Cole,Kocamustaf,Farajisarir,Golorin,Kirichenko和Borinshansky-Fokin(B-F)模型。该模型还弥补了现有方法不能计算倾斜管道气泡起飞直径的不足。     

榆林气田天然气凝析液管道工艺设计方法研究

本文在分析了榆林气田天然气凝析液混输管线原设计的基础上,结合这条气液混输管线的现场运行状况,对天然气凝析液两相混输管路的工艺设计方法,进行了分析研究。通过横向对比榆林天然气凝析液管线的具体设计数据,纵向对比管线设计数据与现场运行数据的差异,并采用当前较为先进的OLGA工艺设计计算软件对之进行核算,结合以往的工艺设计经验,对目前所采用的天然气凝析液混输管道工艺设计方法提出一些可供参考的新建议和想法。     

凝析天然气海管旁通清管技术

针对凝析天然气海管清管段塞影响油气田正常生产的问题,介绍了常用的解决方法,重点研究了旁通清管技术。以乐东22-1气田海底登陆管道为例,利用当前国际上先进的OLGA瞬态流动模拟软件,对旁通清管器在凝析天然气管道中的运动过程进行模拟,研究旁通清管器不同于常规清管器的运动特性、压力和流量等关键参数的变化规律以及旁通清管对清管段塞的抑制效果,以期为今后旁通清管器在凝析天然气海管中的现场应用提供理论指导。     

汽-液-液三相流流体力学的模型与求解

以直接接触换热器为研究对象,从基本的一维两流体模型出发,在全面地考虑了该换热器中汽体的膨胀、水蒸汽的蒸发、界面张力的作用以及汽液两相的相互作用和滑移等因素影响的基础上,建立了换热器的一维流动模型,并进行了数值求解,模型的结果与实验数据符合较好。     

浅谈天然气化工的发展

天然气化工的发展具有下述特点：①从天然气出发的大宗化工产品,如氮肥、甲醇及其加工产品（甲醛、醋酸等）发展速坟较快;②在烯烃的生产中,美国扩大了天然气原料的使用量,中东和南美国家将计划大力发展天然气制烯烃工业,从而提高世界烯烃生产中天然气原料所占比例;③以节能为中心的研究开发工作十分活跃;④新工艺相继出现,特别是以合成气为基础的碳一化学更为突出。     

水平管气液两相弹状流液弹频率的水动力学新模型

The prediction of slug frequency has important significance on gas-liquid two-phase flow. A hydrodynamic model was put forward to evaluate slug frequency for horizontal two-phase flow, based on the dependence of slug frequency on the frequency of unstable interfacial wave. Using air and water, experimental verification of the model was carried out in a large range of flow parameters. Six electrical probes were installed at different positions of a horizontal plexiglass pipe to detect slug frequency development. The pipe is 30 m long and its inner diameter is 24 ram. It is observed experimentally that the interracial wave frequency at the inlet is about i to 3 times the frequency of stable slug. The slug frequencies predicted by the model fit well with Tronconi (1990) model and the experimental data. The combination of the hydrodynamic model and the experimental data results in a conclusion that the frequency of equilibrium liquid slug is approximately half the minimum frequency of interfacial wave.     

萃取柱内液-液两相流CFD-PBM模拟研究进展

对萃取柱内CFD-PBM模拟研究进行了较详细的综述,包括其基本理论、不同的求解方法及模拟研究现状等. CFD-PBM模拟的基本方程包括流动方程和群体平衡方程,其相互耦合,群体平衡方程涉及破碎与聚并2个关键模型. 群体平衡模型的求解方法包括直接离散化方法、矩量法、正交矩量法、直接正交矩量法、分段正交矩量法等,对这些方法的原理、优点和缺点进行了综述. 目前国际上关于萃取柱内CFD模拟采用较多的是简单的欧拉-欧拉两相流模拟,考虑液滴尺寸分布和进一步的浓度分布的群体平衡模型应用较少. 完善伴随传质的液-液分散体系的群体平衡模型,并将其应用于不同类型的萃取柱中,是萃取分离学科的重要任务.     

微通道内液-液两相流研究进展

从流型、传质和应用3个方面,介绍了近年来微通道内液-液两相流的研究进展。液-液两相流型研究内容主要有两部分,即流型的观察、流型谱图的绘制以及考察多种因素对流型的影响,但是具有普适性的流型谱图和流型转变线仍未提出。液-液两相传质研究方法包括实验研究和数值模拟两种,主要研究在液滴流、弹状流和平行流3种稳定流型下的传质过程;且相对于定性研究,定量的传质研究较少。对于微通道内液-液两相流应用研究,主要体现在萃取、材料合成、生物结晶等方面。此外,对今后微通道内液-液两相的流型、传质和应用研究进行了展望,指出需从实验与模拟计算相结合以及拓展微通道内液-液两相流的应用研究两个方面进行深入研究,推进其工业化进程。     

Modeling flow distribution and pressure drop in redox flow batteries

The combination of interdigitated flow fields (IDFF) with porous electrodes offers lower pressure drop and better performance than conventional flow‐through porous electrodes in redox flow batteries. Comprehensive three‐dimensional and simplified one‐dimensional + two‐dimensional models describing flow uniformity and pressure losses within flow through, parallel, and interdigitated flow fields were developed and used to demonstrate the benefits of IDFF. Analytical solutions for IDFF that compare favorably with computational fluid dynamics quantify the trade between pressure loss and velocity maldistribution both along the channels and within the electrode. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3746–3755, 2018     

大直径地下敷设管道高压水射流清洗工艺的研究

介绍了直径为７２０ ｍ ｍ 、井口间距２００ ｍ 的地下敷设管道内壁用高压水射流清洗除垢,并将清下的锈垢吹扫到井口、提升到地面上来的新工艺．现场试验表明：该工艺对其他工况类似的管道清洗具有一定意义     

Liquid‐liquid flow patterns in reduced dimension based on energy minimization approach

Study of liquid‐liquid flow patterns in reduced dimensions is relevant under the current trends to miniaturize process equipment. The phase distribution results from interplay of surface (dominant in microchannels) and gravity forces (dominant in larger dimensions). The proposed analysis, based on minimization of total system energy comprising of kinetic, surface, and potential energy, unravels the influence of wetting properties and predicts the range of existence of annular and plug flow as well as the onset of stratification with increasing conduit dimension. Unlike existing models marking abrupt transitions, the proposed methodology can predict zones of transition where interfacial distributions gradually evolve with change of operating conditions—the predictions agreeing closely to experimental and literature data. The analysis illustrates the coupled effect of diameter, contact angle, and inlet composition on flow distribution and defines the transition from macrodomain to microdomain (millichannels) in terms of Bond number as 0.1 < Bo < 10. © 2015 American Institute of Chemical Engineers AIChE J, 62: 287–294, 2016     

Modeling of dry pressure drop for fully developed gas flow in structured packing using CFD simulations

Dry pressure drop in columns equipped with structured packings is considered to involve two components: drag force due to the direction changes near the column walls and in the transition region between two packing layers rotated to each other by 90°, and friction force between the different gas flows inside the crossing triangular channels and with the packing solid walls. It is believed that in a packed bed with compact sheet density and large packing surface area (above 250 m²/m³), the major contribution of the pressure drop is generated by the friction component.In this paper, a model is proposed to determine the dry pressure drop friction component. The gas is assumed to establish a fully developed turbulent flow inside the structured packing channels. The structured packing geometry consists of a combination of periodic elements. It is shown that the reproduction of one periodic element aerodynamics leads to determine the gas distribution and pressure drop inside the packed bed. Therefore, modeling the dry pressure drop through one periodic element is a meaningful representation of the dry pressure drop over the packing.CFD simulations are carried out on periodic elements using different turbulence models: RNG k−ε, realizable k−ε, and SST k−ω. The best results that agree with the experimental data in the literature are obtained with the SST k−ω model. The CFD model proposed is used to study the impact of packing geometry variations on the dry pressure drop and to bring up a correlation for the pressure drop with respect to changes of packing geometry: channel height dimension, channel opening angle, and corrugation angle.     

混流式粮食干燥机性能的模拟和参数分析

在中国农业大学的谷物干燥研究领域中，重点是数学模型和计算机模拟。从1985年至今，顺流式、逆流式、横流式以及混流式谷物干燥机的研究已经取得了成功。分析和讨论了空气温度、流速、风道中的风道尺寸对混流谷物干燥机的影响。发展了混流干燥机的模拟程序，着重提出了混流谷物干燥机中风道的设计，给出了最佳参数。     

水平管段塞流气弹区液膜特性研究

为了研究气液段塞流相界面的结构特征,采用了双平行电导探针技术对水平管内段塞流气弹区的液膜特性进行了实验测量,并基于一维双流体模型导出液膜厚度的控制方程,该方程对液膜厚度的预测结果与实验结果吻合良好。结合液膜厚度计算模型提出了计算段塞流的机理模型,该段塞流机理模型的计算结果表明对于液相表观速度较高而气相表观速度较低的段塞流,机理模型中忽略液膜非平衡性时得到的平均液膜厚度和气弹区长度明显偏低。     

油水混合物在水平管中的二相流动特性研究

对内径40mm的钢管和有机玻璃管内油水二相水平流动时的流型、摩擦压降特性进行了详细的实验研究,结果表明:油包水向水包油的转变发生在含水体积分数约0. 4时。随含水体积分数的增大,油水二相流的摩擦压降先是急剧减小,其后在含水体积分数大于0. 4时压降变化趋于平缓。油水二相流的摩擦压降受含水体积分数、管壁润湿特性、管壁粗糙度以及混合物流速的影响,当二相流体处于水包油状态时,钢管内的摩擦压降比有机玻璃管内的大;而当处于油包水时,有机玻璃管内的摩擦压降则比钢管内的摩擦压降大。     

高压高过冷度下过冷流动沸腾数值模拟

采用双流体模型对高压高过冷度下垂直圆管中水的过冷流动沸腾进行了数值模拟。通过对比不同气泡直径模型,揭示了气泡直径对于壁面传热方式的影响,确定了适合高压工况的气泡直径模型。考察了压力及壁面热通量对流动及传热特性的影响。计算结果表明,压力增加气泡脱离直径减小,单相对流传热所占比例增加,表面传热系数减小。高压高过冷度特征决定了气泡相分布极不均匀,随着热通量的增加,壁面附近容易形成气泡的密集,对过冷流动沸腾中的传热特性有重要影响。     

Slip flow of coal water slurries in pipelines

Experiments were carried out on a pilot scale slurry transport apparatus to investigate slip flow behavior of coal water slurries (CWSs) in pipes with various diameters (25, 32, 40 and 50 mm). The effects of volume concentration, particle size and slurry temperature on wall slip behavior (wall slip velocity, critical wall shear stress and slippage contribution) were investigated. A numerical technique based on Tikhonov regularization was applied to determine the wall slip behavior. As the slurry temperature or the particle size increased, the critical wall shear stress was observed to decrease and the wall slip velocity was observed to increase significantly, while when the solid concentration was very close to the maximum packing fraction, a slight increase in volume concentration would lead to a rapid decrease in wall slip velocity and a sharp increase in critical wall shear stress. The temperature influence on critical wall shear stress and yield stress increased as volume concentration increased. At low wall shear stress, the slippage contribution was mainly dependent on the difference between yield stress and critical shear stress. While at high wall shear stress, it was dependent on both of the shear viscosity of the bulk slurries and the wall slip velocity.