长输天然气管道水合物生成预测及影响因素分析

在管道输送天然气中,准确预测水合物生成位置及其影响因素分析,对管道安全运行十分重要。为此,基于长输管线温度、压力计算与水合物生成条件预测模型,建立了长输管线水合物生成位置预测程序,并对具体实例进行分析,结果表明,管径越小、输量越大、保温材料导热系数越小、天然气中H2S含量越低、CO2含量越高,水合物生成范围缩小。该程序对长输天然气管道设计、安全管理、天然气脱硫处理提供了技术支持。     

长输天然气管道输损管理探究

长输天然气管道输损是天然气输入总量和管存量输出量之间的差值,出现这种差值的主要原因是长距离的管道输送、输送过程中的多点、多面以及管道输送过程中的环境温度变化和压力差异等多种状况多会造成管道输送损耗。本文主要介绍了天然气管道腐蚀对于管道输损的影响,从而对整个天然气其企业的经济造成影响,因此对其进行研究并找到相应的解决方案就很有必要。     

凝析气田长输管道水合物防治的实践应用

凝析气田长输管道输送介质大多为气液混输,冬季沿程温降过大,极易导致管道内生成天然气水合物,为了防止天然气水合物生成对长输管道的堵塞,降低管道过流面积。有必要弄清楚水合物形成的条件和原因,以便提出有针对性的解决措施。凝析气大多为多相流输送,以饱和烃组分为主,在输送过程中由于沿线温度、压力的变化极易引起凝析和反凝析现象,在气液混输中,气相含烃量很高,冬季气温低时促进了水合物的生成。通过对水合物形成原因、塔里木某凝析气田气相组分和运行工况的综合研究,找出最大的影响因素,结合实际,提出最有效的解决方案。通过HYSYS模拟计算,找到了防止水合物生成的最佳方法。采取降压生产,油气分输的措施,并在生产中实践成功。所以,防止天然气水合物的生成十分重要。     

天然气水合物形成与解堵

天然气水合物是有两种物体形成,分别是碳氢化合物以及通过水一起组成的结晶化合物。天然气长输管道所处环境温度较低且输送压力高,易形成水合物而堵塞管道。本文简述了水合物形成条件、机理和解堵方法。     

浅析天然气长输管道试压

管道试压是管道投产前安全有效运行的前提,是对施工质量、管材性能、管道整体的一次综合检验。管道试压这道工序是确保管道在运行压力下不泄漏,保证管道强度和焊口应力等方面的重要工序。随着近些年我国长输管道建设,如何保证天然气长输管线安全、经济、适宜的进行试压,是各参建单位的关注重点。本文按照规范要求,对天然气管道试压介质进行对比,并以实际施工实例来说明,进一步阐明试压对长输管道的重要性,旨在推动实现试压工作的专业化,保证管道长期运行的安全性。     

长输天然气管道腐蚀的形成与防护措施

随着社会建设工程不断深入,人们对生活环境要求越来越高标准化,长输天然气工程由此得到重点关注。在自然环境中,普通材质的长输天然气管道受外界影响,容易产生管道腐蚀现象,不仅对人们的日常生活造成影响,严重威胁社会安全,造成企业、个人的经济损失。在对长输天然气管道腐蚀问题进行处理时,需要注意管道防腐工作的重要性。本文针对如何对长输天然气管道进行防腐工作进行分析,了解长输天然气管道腐蚀主要原因,并根据问题提出几点管道腐蚀防护措施。     

浅谈如何有效的提高天然气长输管道输气效率

气举采油适用于多种井,具有较强的适用性。本文首先简单的介绍了气举采油的原理并阐述了连续气举和间接气举等两类气举方式,以及从开式管柱、半闭式管柱、闭式管柱等三个方面综述了气举管柱结构。本文笔者主要从两个方面阐述,如何提高管道效率和提高天然气长输管道的输送效率,对于在运行过程中天然气长输管道中既能降低工程的投资也能满足管道需要输气能力。     

天然气长输管道的节能降耗

从管道输送设计方案入手,根据加工工艺方案和机械设备的选用,降低管道输送能耗,强调使用内涂层降低摩擦能耗,选择高压输送明确运输和加工工艺,在可能的情况下,选择合适的压缩机站制冷压缩机推广方案,根据供气变化有效选择压缩机站总数,根据持续改进选择机械设备的方法集气站的处理技术,以降低在输气环节形成的能源消耗。     

管道中天然气水合物的预测

管道中天然气水合物的预测是为了找到天然气水合物生成条件,以便及早的发现水合物的生成,防止水合物聚集堵塞管道,造成不必要的经济损失与安全事故。介绍了图解法、相平衡常数法、热力学统计法、预测模型,并重点介绍了预测模型如VDW-P型天然气水合物预测模型、Chen-Guo预测模型、含抑制剂体系的水合物预测模型等,以期为今后的研究提供参考。     

长输天然气管道腐蚀的形成与防腐保护措施探析

长输管道是当前天然气运输的唯一渠道,因此管道的安全性、防腐程度直接关联到燃气运输工作是否能顺利、稳定开展。因此,加强对天然气管道的腐化预防工作是日常工作的核心关注问题。对天然气管道的腐蚀原因进行了阐述,结合现有技术对管道防腐措施、维护工作提供相关应对策略。     

湿气管道水合物形成概率计算

水合物的生成给湿气管道流动安全带来隐患,管道流动安全评价对于保障安全生产和减少损失具有重要意义。湿气管道内水合物形成概率的计算是湿气管线流动安全评价的基础。选择管道入口参数为随机因素,基于可靠性的极限状态法,选用较高精度的Har-PR预测酸性天然气含水量,在湿气管线水力和热力计算基础上,按Chen-Guo模型计算水合物形成条件,以实际流动温度和水合物形成温度之差建立概率极限状态方程,采用组合概率法计算管线的水合物形成概率。分析环道入口数据认为,入口压力、温度符合正态分布,流量符合最大极值分布。示例计算表明：随机变量的均值和标准差都影响着湿气管道的水合物形成概率;湿气管道的水合物形成概率对不同随机工艺参数的敏感性不同;单随机变量样本数和组合随机变量样本总数同时影响着全线的水合物形成概率。     

Prediction of carbon dioxide gas hydrate formation conditions in aqueous electrolyte solutions

A methodology for predicting the incipient equilibrium conditions for carbon dioxide gas hydrates in the presence of electrolytes such as NaCl, KCl and CaCl₂ is presented. The method utilizes the statistical thermodynamics model of van der Waals and Platteeuw (1959) to describe the solid hydrate phase. Three different models were examined for the representation of the liquid phase: Chen and Evans (1986), Zuo and Guo (1991), and Aasberg-Petersen et al. (1991). It was found that the model of Zuo and Guo (1991) gave the best results for predicting incipient CO₂ gas hydrate conditions in aqueous single salt solutions. The model was then extended for prediction of CO₂ gas hydrates in mixed salts solutions. The predictions agree very well with experimental data.     

长距离浆体管道磨蚀率预测

长距离浆体管道的典型设计寿命通常为15至25年,故管道磨蚀率的确定对管道工程经济效益有较大影响.这里所说的磨蚀是化学腐蚀和物理磨损的综合表征,其中每个因素的影响大小与特定的管道输送工程相关,如细颗粒浆体管道输送工程,化学腐蚀在管道磨蚀中起主导作用,这类管线输送流速一般设计为1.5～2.5 m/s,为高度均质流,其管道底部与顶部磨蚀相差不多,对流速不敏感.但中、粗颗粒如原矿粉及尾矿的管道输送工程,管道的磨蚀方式与细颗粒浆体不同,其主要集中在管道的底部与弯头外弧侧,对流速较为敏感.细颗粒与中、粗颗粒浆体管道沿管线的磨蚀分布规律基本相似.     

Reviews of gas hydrate inhibitors in gas-dominant pipelines and application of kinetic hydrate inhibitors in China

During the development and application of natural gas, hydrate plugging the pipelines is a very important issue to solve. Currently, adding thermodynamic hydrate inhibitors (THIs) and kinetic hydrate inhibitors (KHIs) in gas-dominated pipelines is a main way to prevent hydrate plugging of flow lines. This paper mainly reviews the efforts to develop THIs and KHIs in the past 20 years, compare the role of various THIs, such as methanol, ethylene glycol and electrolyte, and give the tips in using. The direction of KHIs is toward high efficiency, low toxicity, low pollution and low cost. More than a hundred inhibitors, including polymers, natural products and ionic liquids, have been synthesized in the past decade. Some of them have better performance than the current commercial KHIs. However, there are still few problems, such as the complex synthesis process, high cost and low solubility, impeding the commercialization of these inhibitors. The review also summarized some application of KHIs in China. Research of KHIs in China began late. There are no KHIs used in gas pipelines. Only a few field tests have been carried out. In the end of this paper, the field test of self-developed KHIs by China is summarized, and the guidance is given according to the application results.     

油气管道水合物堵塞机理研究进展

国内外对油气管道水合物堵塞机理的实验研究虽然较多,但一直缺少系统的总结归纳。本文根据水合物堵塞实验开展条件的不同,首先将油气管输体系分为油基体系、水基体系（纯水体系及水主导体系）、气主导体系和部分分散体系。文章分析表明,管道水合物堵塞机理众多,具体包括水合物的聚集和沉积、水合物大量聚集阻塞管道流通截面及油水相分离等。其中,水合物的聚集和沉积是油基体系水合物堵塞的主要机理,水合物颗粒的着床沉积是纯水体系水合物堵塞的主要机理,水合物大量聚集阻塞管道流通截面则是气主导体系水合物堵塞的主要机理。水主导体系和部分分散体系的水合物堵塞机理,目前尚无统一定论,有待进一步深入研究。文章指出对环状流液滴分布、油水分散状态、乳状液稳定性及未乳化自由水层等的量化研究则是未来水合物堵塞机理的研究重点。     

Probability distributions of gas hydrate formation

Induction time distributions for gas hydrate formation were measured for gas mixtures of methane + propane at pressures up to 11.3 MPa using a high‐pressure automated lag time apparatus (HP‐ALTA). Measurements were made at subcooling temperatures between 4.3 and 13.5 K and, while isothermal induction times between 0 and 15,000 s were observed, the median isothermal induction times for the distributions ranged from 100 to 4000 s. A hyperbolic relationship between median induction time and subcooling was used to correlate the data. A graphical interpretation is presented that relates the two types of data that can be acquired by using the HP‐ALTA in one of two modes to study hydrate formation: induction time distributions at constant subcooling and formation temperature distributions observed during linear cooling ramps. The equivalence of these two modes provides a robust method for studying the variation of formation phenomena in different hydrate systems. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2640–2646, 2013     

水合物法分离技术研究

从水合物的结构和性能出发,对基于水合物形成和分解的分离过程进行了分析和研究,探讨了基于水合物的分离技术,包括气体分离和水溶液分离或提浓两个方面。综述了近年来水合物法分离的研究现状、相关技术内容和应用领域     

Prediction of induction time for natural gas components during gas hydrate formation in the presence of kinetic hydrate inhibitors in a flow mini‐loop apparatus

The objective of this work is the prediction of induction time (t_i) for simple gas hydrate formation in the presence or absence of kinetic hydrate inhibitors at various conditions based on the Kashchiev and Firoozabadi model in a flow mini‐loop apparatus. For this purpose, the t_i model is developed for simple gas hydrate formation in batch system for natural gas components during hydrate formation in a flow mini‐loop apparatus. A laboratory flow mini‐loop apparatus is designed and built up to measure the t_i for simple gas hydrate formation when a hydrate former (such as C₁, C₃, CO₂ and i‐C₄) is contacted with water in the absence or presence of dissolved inhibitor, such as poly vinylpyrrolidone, PVCap and L ‐tyrosine. In each experiment, a water blend saturated with pure gas is circulated up to a required pressure. Pressure is maintained at a constant value during experimental runs by means of the required gas make‐up. The average absolute deviation (AAD) of the predicted t_i values from the corresponding experimental data are found to be about 11% and 9.4% for gas hydrate formation t_i in the presence or absence of kinetic hydrate inhibitors, respectively. © 2012 Canadian Society for Chemical Engineering     

表面活性剂在瓦斯水合物生成过程中的热力学作用

在实验研究基础上,结合表面活性剂水溶液中瓦斯水合物生成微观机理,提出了表面活性剂改变水合物生成热力学条件物理作用假说,认为表面活性剂胶束对溶于其中的气体分子和吸附于其周围的水分子的束缚作用,相当于降低了体系的温度.利用T40（0.001 mol·L^-1）、T40（0.002 mol·L^-1）、T40/T80（0.001 mol·L^-1）分别组成的3种气 液 煤 水合物反应体系实验测定了水合物生成时的相平衡参数,与同样温度和压力条件下相平衡计算值比较,结果表明,表面活性剂的加入有效地改变了水合物生成的热力学条件.例如,在T40/T80（0.001 mol·L^-1）实验体系中,当压力为22.67 MPa时,水合物生成相平衡温度为22.6℃,比纯水中提高2.1℃.     

Consolidation of sand formation using freon'll gas hydrate

Freon 11 gas hydrate was used to block the pores of four size ranges of sand from 24 mesh to 60 mesh. A 50.8 mm deep bed of sand when thus “frozen” with hydrate could sustain a dfferential water pressure of at least 6895 kPa. A subcooling of about 5 to 6°C below its thermodynamic formation temperature was required to cause the hydrate to form such a plug. Once formed, the hydrate remained stable at temperatures up to its decomposition temperature. The time required for the hydrate crystal to grow to a size large enough to block the pores of the bed was about two hours. The amount of hydrate forming agent required to block the sand pores was found to be approximately that calculated from the ideal composition of the hydrate.