前置式超声速旋流分离器设计与凝结特性分析

针对天然气在长距离管道输送过程中,所含水蒸汽杂质会凝结成液态水的问题,通过运用动力学原理与液滴成核生长理论,开发设计了一种全新的前置式超声速旋流脱水装置。利用CFD中的用户自定义接口建立了含湿天然气的凝结流动模型,数值分析了装置内部的马赫数、过冷度、液滴成核率、液滴半径和湿度等关键凝结参数的变化规律。结果表明:所建立的三维含湿天然气的凝结流动模型可以真实描述超声速旋流分离器中的流动变化规律,为以后装置的工业应用和下一步提高分离效率提供了理论参考。     

超声速气体流动的凝结现象研究综述

超声速气体流动的凝结是一个非常普遍的现象。气体转变为液体的凝结过程,伴随着凝结潜热的释放,急剧改变了流场的热力学性质,流场的改变直接影响了设备的运行状态如汽轮机运行效率降低、风洞偏离设计参数等。本文对超声速气体流动的凝结现象进行了简单的分析,对研究的历史和现状进行了总结．介绍了凝结成核理论、液滴增长模型和相关实验,并对下一步的研究进行了展望。     

旋流分离对天然气水合物除砂提纯的影响

针对固态流化开采方法开采海底天然气水合物含砂量大导致开采效率低的问题,提出原位分离工艺,设计了旋流分离装置,基于该装置利用CFD数值模拟方法研究了固相(砂和水合物颗粒)直径、入口浆体流量及浆体中砂浓度对装置分离性能的影响。结果表明,在研究范围内,砂和水合物分离效率大部分高于60%,最高达98.72%,压降大部分低于0.5 MPa,最低至0.03 MPa。砂粒分离效率随固相粒径增大先增大后趋于平稳,随浆体入口流量增大先增大后减小,随砂浓度增大而降低;水合物分离效率随固相粒径增大先增大后趋于平稳,随浆体入口流量增大先增大后减小,随砂浓度增大而降低。溢流口和底流口压降几乎不随固相粒径变化,随砂浓度和浆体入口流量增大而增大。固相粒径、入口流量、砂浓度对分离性能有较大影响,在砂粒径大于20 ?m、水合物粒径大于40 ?m、浆体入口流量约5 m3/h、入口砂浓度不超过25vol%的条件下分离性能良好。     

天然气跨音速膨胀凝结研究进展

天然气在跨音速膨胀凝结的过程中,水分和重烃的凝结是极其重要且起关键作用的环节,主要包括蒸气的凝结成核和液滴的生长过程。为了探求准确的蒸气成核和生长模型,文中阐述了蒸气成核及液滴生长理论的研究进展,总结了相关实验研究和数值模拟,分析了影响蒸气凝结的因素,并对凝结理论中亟待解决的问题进行了展望。研究结果表明:CNT模型和非等温修正的ICCT模型能较准确地预测单组分凝结过程;修正的双组分成核理论具有较好的准确性。亟待解决的问题有:液滴表面张力模型还不完善,无法准确计算微观表面张力;双组分成核理论的精确度不高;亟待探究多组分成核理论模型,以期为天然气凝结和提高超音速喷管的分离性能打下坚实的理论基础。     

天然气超声速脱二氧化碳技术研究

进行了Laval喷管的结构设计。基于真实气体状态方程和湍流方程,结合凝结成核与液滴生长理论,建立了描述喷管内超声速气体凝结流动的数学模型,进行了CO_2-CH_4气体凝结流动规律研究。研究结果表明:在特定的入口温度与压力条件下可以实现CO_2气体的凝结与脱除,当气体发生凝结后,喷管内形成气、液两相流动,产生的亚微米级微小液滴可随气流运动至喷管出口;CO_2气体成核过程在时间和空间上表现出急剧性,凝结核心形成后,液滴生长过程可维持较长时间和距离,直至液滴到达喷管出口;由于凝结的发生和液滴生长过程释放了大量潜热,喷管内表现出明显的凝结冲波现象,压力下降减缓,温度出现回升。     

旋流分离技术的现状与应用前景

在化工领域旋流分离技术越来越受到重视,其应用程度也随着技术的不断完善而更加普遍,在此通过简述液旋流分离器的基本结构和工作原理及特点的基础上,介绍了旋流分离技术用于化工方面的现状并展望了旋流分离技术在液液分离过程中的应用前景。     

动态旋流分离技术研究进展

在对国内外技术文献广泛分析的基础上,结合研究实际,从动态旋流器的结构形式、结构参数等方面较为深入地论述了动态旋流分离技术的研究进展。并对动态旋流分离技术的发展趋势作了简要分析。     

旋流分离技术研究进展

介绍了旋流分离技术的研究进展,包括水力旋流器的结构形式与结构参数、新结构类型、主要水力学参数、混合液性质及流量稳定性、材料与制造技术、磨损与腐蚀及旋流分离应用技术的研究进展等,还对旋流分离技术的发展趋势作了简要分析。研究表明,随着人们对旋流分离技术的不断开发,其在石油、化工等行业得到了越来越广泛的应用。     

旋流分离技术的现状与应用前景

在简述了液液旋流分离器的基本结构和工作原理及特点的基础上 ,介绍了旋流分离技术用于油污水处理、原油或其他油品脱水、液化气脱胺等方面的研究与发展现状 ,并展望了旋流分离技术在液液分离过程中的应用前景     

基于入口分散相重排序的旋流强化分离研究进展

随着工业化进程的飞速前进,适用于分离多相不互溶介质的旋流分离器已广泛应用于石化、环保等重点行业。为了提高旋流分离器在全粒径范围内分散相的分离效率,涌现出了多种旋流分离过程强化技术。其中,对入口分散相进行重排序的旋流强化技术因具有加工成本及运行费用低、易于实施、强化效果明显等优势,展现出了重要的应用价值及推广前景。本文聚焦于入口分散相重排序的旋流强化技术,对基于惯性力场和离心力场进行分散相重排序的旋流强化原理、排序器结构类型及应用于液-液、固-液、气-固两相的分散相重排序强化技术及研究成果进行了系统的分析和总结。在此基础上,从组织构建分散相重排序后的多股液流,选择促进多股液流间协同高效分离的旋流场入射方案,强化分散相移动过程中的聚并长大和/或惯性碰撞等角度出发,总结了分散相重排序的技术路线并进行研究展望,从而指导旋流器的旋流分离过程强化及优化设计,助力于旋流分离效率的深度提升。     

A new liquefaction method for natural gas by utilizing cold energy and separating power of swirl nozzle

A swirl nozzle with a central body was newly designed to make full use of the cold energy and separating power, and the coupling of swirling flow and condensation was realized based on a condensation model, a droplet surface tension model and a Reynolds stress model turbulence model. The flow and condensation characteristics of methane gas under supersonic swirling flow conditions were studied. The results show that the flow and condensation parameter distribution in the swirl nozzle are similar under varying swirling intensities, but the swirling performance improves with the increase in swirling intensity, and a tangential velocity is beneficial before the gas enters the nozzle. As the inlet temperature decreases or the inlet pressure increases, the liquefaction efficiency increases, and the gas condensation process can be promoted. With the advancement of the initial nucleation position and the increase in the droplet radius, the separation efficiency of the swirl nozzle increases.     

A theoretical analysis of non-chemical separation of hydrogen sulfide from methane by nano-porous membranes using capillary condensation

The potential of a nano-porous membrane to perform non-chemical separation of a gas mixture has been explored theoretically. Separation of hydrogen sulfide from its mixture with methane by capillary condensation has been selected as the model case. Because of its much lower condensation pressure compared to methane, hydrogen sulfide preferentially condenses in the fine pores and get transported by Poiseuille flow. Permeation rate up to 600 gmol/m² s bar has been achieved at a temperature lower than the critical temperature of the permeating species and higher than the critical temperature of the non-permeating species. Since methane has a much lower critical temperature than hydrogen sulfide, it gets physically dissolved in the condensed phase of hydrogen sulfide. An equation of state (EOS) approach ha s been adopted to calculate the fugacity of methane in the gas as well as in the condensed phase-in order to estimate its solubility. Computation of permeation flux of the condensed phase as well as of the separation factor of hydrogen sulfide has been performed over a wide range of temperature, pressure and gas composition. The separation factor which is expectedly a function of these variables, ranged from 700 to 100. The separation technique is expected to have an enhanced attraction since it is clean and does not require a solvent as in the conventional separation of acid gases.     

从超音速蒸汽喷嘴到过冷水直接接触冷凝的数值模拟(英文)

The phenomenon of direct-contact condensation,used in steam driven jet injectors,nuclear reactor emergency core cooling systems and direct-contact heat exchangers,was investigated computationally by introducing a thermal equilibrium model for direct-contact condensation of steam in subcooled water.The condensation model presented was a two resistance model which takes care of the heat transfer process on both sides of the interface and uses a variable steam bubble diameter.The injection of supersonic steam jet in subcooled water tank was simulated using the Euler-Euler multiphase flow model of Fluent 6.3 code with the condensation model incorporated. The findings of the computational fluid dynamics(CFD) simulations were compared with the published experimental data and fairly good agreement was observed between the two,thus validating the condensation model.The results of CFD simulations for dimensionless penetration length of steam plume varies from 2.73-7.33,while the condensation heat transfer coefficient varies from 0.75-0.917 MW·(m 2 ·K) -1 for water temperature in the range of 293-343 K.     

空气分离与天然气液化组合循环

提出了利用空分系统冷量液化天然气的联合流程思想,并介绍了一种采用氮气膨胀循环的空气分离与天然气液化联合方案,在得到液化天然气（LNG）的同时,也生产氮气、氧气等多种产品。通过流程模拟计算并采用有效能分析原理,确定了高、低温膨胀量比对传热温差及有效能损失的影响规律,得到了不同液化量下的优化膨胀量之比。结果表明,基于热负荷总组合曲线的有效能分析原理能够方便、有效地研究整个传热过程的温差分布及有效能损失规律,对实际低温过程系统优化有重要意义。     

Influence of water vapor condensation inside nano-porous 4A adsorbent in adsorption-desorption cyclic process of natural gas dehydration

ABSTRACT

Consequences of water vapor condensation were studied in natural gas dehydration using 4A zeolite. Adsorption-desorption isotherms were studied experimentally and isotherm parameters were predicted using two-site Sips model with maximum 9.6% deviation. Water vapor diffusivity within the adsorbent pores was evaluated and modified by predicting the pore filling pattern. The dehumidification process was modeled employing two assumptions, in the first case, water vapor was assumed to condense within the particles and in the second case no condensation was taken place. After comparison, it was resulted that in the first case, 12% less vapor was absorbed in the bed and 14% more vapor remained inside the adsorbent pores after regeneration.     

A heat transfer relation for swirl flow in a vortex tube

An experimental investigation was made to study the heat transfer behavior of a water-cooled vortex tube with air as the working medium. The vortex flow was generated by leading the compressed air to enter the vortex tube tangentially. The pressures of the inlet air were 300 to 500 kPa gauge. For each of these inlet pressures, the heat transfer performance of the vortex tube was studied at different cold mass flow ratios. New experimental data are presented. An empirical correlation for the prediction of the air-side Nusselt number is established. It was shown that the air-side Nusselt number for the swirl flow in this vortex tube can be up to 30 times higher than that for a flow without swirl in the same tube.     

柔性金属有机骨架材料(MOFs)用于气体吸附分离

柔性金属有机骨架材料(MOFs)具有高度有序的网络结构与可变形的骨架,其骨架结构会对外界的温度、压力及客体分子的刺激产生独特的结构响应。近几年来,柔性MOFs在气体吸附、气体分离、传感等领域显示出巨大的应用潜力。截至目前,研究者们对柔性MOFs的研究仅局限于对其结构形变的机理解释,而缺乏对柔性MOFs应用于相关化工过程的性能研究。本文着重对近年来柔性MOFs在气体吸附分离领域的研究进展进行了综述,并详细地分析了柔性MOFs结构与其气体吸附分离性能之间的构效关系。通过分子模拟结合实验,讨论了柔性MOFs结构对气体分子的平衡吸附与动力学扩散的影响。分析表明,设计合成具有良好吸附选择性与扩散性能的柔性MOFs是其应用于绿色、高效气体分离过程的重要发展方向。     

新型石墨烯防腐涂料在凝露天然气管道的在线施工应用

天然气站场阀室管道涂层在凝露下容易起泡和生锈,漆膜腐蚀和老化现象明显.采用新型石墨烯改性重防腐涂料体系(包括环氧石墨烯防腐底漆和无溶剂水下固化面漆)对其进行修复.室内模拟试验和现场应用试验均表明该石墨烯防腐涂料可在凝露环境中在线施工,涂层平整均匀,附着力强,防腐性能好.     

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