气体水合物分解原理的研究

气体水合物作为清洁能源,具有良好的利用前景,而且由于气体水合物资源量大,能量密度高,可作为理想传统化石燃料的替代品,因此受到各国相关领域专家和政府的高度关注。基于此,主要探讨几种典型气体水合物的分解行为,包括甲烷水合物,二氧化碳水合物,氢气水合物,并总结分析不同种类气体水合物的分解原理及实现过程,以期实现天然气水合物的大规模安全开采。     

气体水合物平衡生成条件的测定及预测

建立了一套气体水合物实验测定装置，采用该装置在温度２６２．６－２８５．２Ｋ范围内分别测定了甲烷，二氧化碳和一种合成天然气在纯水、电解质水溶液以甲醇水溶液中水合物的平衡生成压力，共计９个体系，７８个数据点。     

H型气体水合物结构稳定性的分子动力学模拟

采用分子动力学模拟方法首次对H型气体水合物的晶体结构及稳定性进行了研究,得到H型气体水合物中各分子（原子）作用点之间的径向分布函数．在此基础上,通过计算水合物晶格上水分子的平动均方置换、取向均方置换以及取向自关联函数,考察了温度和客体分子对H型气体水合物结构稳定性的影响．结果表明：在水合物生成条件下,水合物晶体结构的稳定性依赖于晶体胞腔空穴中的客体分子;而对温度的变化则不太敏感．     

水基钻井液中天然气水合物形成的研究进展

依据水基钻井液中天然气水合物生成的相关研究,结合理论与实践,介绍了一些钻井液处理剂对水合物生成的影响,重点概述了水基钻井液对天然气水合物生成的抑制效应,并简要说明了水合物抑制剂在钻井液中应用的相关研究。     

天然气水合物试采监测井技术研究进展

天然气水合物在海域和冻土分布广,资源量大,能量密度高,是重要的潜在高效清洁油气接替能源。但水合物储层开采过程中压力、温度时空演化规律复杂,合理的监测井布设不仅能够监测开采过程中物理参数的时空演化,还能够对周围环境的影响进行评估。本文通过对国内外水合物试采监测井的相关案例分析,得到监测井的主要监测参数包括温度、压力、井口流出物及海床扰动等,监测井与生产井之间的方向部署需要依据实际的储层环境,监测井位置设计要能够对储层压力、温度等主要参数变化做出及时响应,监测井数通常为1～2口。本文能够对天然气水合物试采监测井部署提供指导。     

活性炭复配氨基酸强化的甲烷水合物动力学

基于吸附与水合的活性炭湿储甲烷技术具有较高的储气能力，而随着反应压力降低和预吸附水量增加，水合性能大幅降低。为了克服该技术难题，文中研究在活性炭体系中引入环境友好的L-甲硫氨酸与L-亮氨酸，评价了活性炭复配氨基酸体系中水合物生长动力学，探究了氨基酸浓度、反应压力以及液炭比的影响。结果表明：当将质量分数0.2%的L-甲硫氨酸与0.5%的L-亮氨酸引入活性炭体系时，其在低反应压力和高液炭比下对水合物生长动力学表现出优异的促进作用。并且，与L-亮氨酸相比，L-甲硫氨酸具有更优异的促进作用，在低反应压力(5 MPa)和高液炭比(1.4)下，甲烷储量分别增加3.57%和5.26%,水合物诱导时间降低41.14%。该发现为活性炭湿储甲烷技术的应用与推广提供了理论支撑。     

天然气水合物的生成机理与防治研究

概述了天然气水合物的分子结构,分析了天然气水合物的生成条件,总结了天然气水合物生成的概念模型,研究了天然气水合物的防治方法:物理方法和化学方法。其中物理方法包括:加热法,脱水法,降压法,清管法;化学方法包括:添加热力学抑制,动力学抑制剂以及水合物浆输送技术。提出了今后的研究重点和方向。     

天然气水合物储运技术

天然气水合物(NGH)的研究是当今世界能源开发的热点。本文了介绍了天然气水合物储运方法的研究背景,总结了然气水合物储运方法的特点。分析总结了天然气水合物储运方法,关键技术及待解决的技术难点,并对天然气水合物储运技术的展望。     

天然气水合物储运技术综述

在能源危机日益严峻的21世纪,天然气水合物被公认为是具有良好前景的重要后续能源。其储运技术在近年来也得到了大力的发展。本文介绍了天然气水合物的特性、目前天然气主要的储运方式以及国内外水合物储运技术的应用前景。     

甲烷水合物分解实验

在体积10 L的静态反应器中研究了水合物分解动力学,考察了储存温度和水合物量等因素对水合物分解的影响。实验结果表明,水合物在273.15 K以下时存在一种异常的自我保护效应,其在268.05 K时分解速度最慢;而水合物的储运压力与储罐中的水合物量有关,当储罐容积一定时,分解压力随着储罐中水合物量的增加而增加,但水合物的分解百分比随着水合物量的增加而减少;最后提出了在一定压力下储运水合物的方法。以期为水合物法固态储存气体技术的工业化应用提供实验数据和理论依据。     

甲烷水合物在纯水中的生成动力学

引言一些低分子量气体,如石油和天然气中C_1～C_4轻烃、氮气、硫化氢、二氧化碳和惰性气体等,在一定压力和温度的条件下可与水形成一类笼形结构的冰状晶体,即所谓的气体水合物．气体水合物是一类较为特殊的包络化合物：主体水分子通过氢键相互结合形成一种内含空隙的笼形框架,客体分子则被笼罩于这些空隙中．主、客体分子之间的作用力为vanderWaals力．水合物晶体最为常见的两种结构分别称为结构I（体心立方构型）和结构Ⅱ（金刚石构型）．甲烷和水形成结构I水合物．文献阐述了开展水合物生成动力学研究的重要意义．但由于水合物生成…     

0℃以下含SDS的甲烷水合物生成方式及过程对其分解速率的影响

The dissociation rates of methane hydrates formed with and without the presence of sodium dodecyl sulfate(methane-SDS hydrates),were measured under atmospheric pressure and temperatures below ice point to investigate the influence of the hydrate production conditions and manners upon its dissociation kinetic behavior.The experimental results demonstrated that the dissociation rate of methane hydrate below ice point is strongly dependent on the manners of hydrate formation and processing.The dissociation rate of hydrate formed quiescently was lower than that of hydrate formed with stirring;the dissociation rate of hydrate formed at lower pressure was higher than that of hydrate formed at higher pressure;the compaction of hydrate after its formation lowered its stability,i.e.,increased its dissociation rate.The stability of hydrate could be increased by prolonging the time period for which hydrate was held at formation temperature and pressure before it was cooled down,or by prolonging the time period for which hydrate was held at dissociation temperature and formation pressure before it was depressurized to atmospheric pressure.It was found that the dissociation rate of methane hydrate varied with the temperature(ranging from 245.2 to 272.2 K) anomalously as reported on the dissociation of methane hydrate without the presence of surfactant as kinetic promoter.The dissociation rate at 268 K was found to be the lowest when the manners and conditions at which hydrates were formed and processed were fixed.     

Kinetics of carbon dioxide and methane hydrate formation

Experimental data on the kinetics of carbon dioxide hydrate formation and its solubility in distilled water are reported. The experiments were carried out in a semi-batch stirred tank reactor at nominal temperatures of 274, 276 and 278 K and at pressure ranging from 1.59 to 2.79 MPa for the kinetics experiments and at pressure ranging from 0.89 to 2.09 MPa for the solubility experiments. A minor inconsistency in the kinetic model developed by Englezos et al. (1987a) was removed and the model was modified to determine the intrinsic kinetic rate constant for carbon dioxide hydrate formation. The same model was also used to re-determine the intrinsic kinetic rate constant for methane hydrate formation. The model is based on the crystallization theory coupled with the two-film theory for gas absorption in the liquid phase. The Henry's constant (H) and apparent dissolution rate constant (K_La) required in the model were determined using the experimental solubility data. The kinetic model describes the experimental data very well. The kinetic rate constant obtained for the carbon dioxide hydrate formation was found to be higher than that for methane.     

甲烷+氨水体系水合物生成条件实验测定及计算

甲烷在氨水体系中生成水合物的实验数据对于开发水合法回收合成氨驰放气工艺以及操作条件的确定具有重要意义。本文测定了氨摩尔分数为1.018、3.171、5.278氨水溶液中甲烷气体水合物的生成条件。结果表明：氨的加入对甲烷水合物的生成起着明显抑制作用,而且随着氨浓度的增加,生成压力越高。采用Chen-Guo模型对甲烷在氨水中生成水合物的数据进行了计算,得到了较为满意的计算结果,平均误差为2.71%,说明Chen-Guo模型能够较好地预测该类体系的水合物的生成条件。     

Methane hydrate formation and dissociation behaviors in montmorillonite

The methane hydrate formation and the methane hydrate dissociation behaviors in montmorillonite are experimentally studied. Through the analyses of the microstructure characteristic, the study obtains the porous characteristic of montmorillonite. It is indicated that methane hydrate in montmorillonite forms the structure I(sI) crystal.Meanwhile, molecular dynamics simulation is carried out to study the processes of the methane hydrate formation and the methane hydrate dissociation in montmorillonite. The microstructure and microscopic properties are analyzed. The methane hydrate formation and methane hydrate dissociation mechanisms in the montmorillonite nanopore and on the montmorillonite surface are expounded. Combining the experimental and simulating analyses,the results indicate the methane hydrate formation and methane hydrate dissociation processes have little influence upon the crystal structure of porous media from either micro-or macro-analysis. It is beneficial to the fundamental researches on the exploitation and security control technologies of natural gas hydrate in deep-sea sediments.     

Kinetic and Phase Behaviors of Catalytic Cracking Dry Gas Hydrate in Water-in-Oil Emulsion

The systematic experimental studies were performed on the hydrate formation kinetics and gas-hydrate equilibrium for a simulated catalytic cracking gas in the water-in-oil emulsion. The effect of temperature, pressure and initial gas-liquid ratio on the hydrate formation was studied, respectively. The data were obtained at pressures ranging from 3.5 to 5 MPa and temperatures from 274.15 to 277.15 K. The results showed that hydrogen and methane can be separated from the C₂₊ fraction by forming hydrate at around 273.15 K which is much higher temperature than that of the cryogenic separation method, and the hydrate formation rate can be enhanced in the water-in-oil emulsion compared to pure water. The experiments provided the basic data for designing the industrial process, and setting the suitable operational conditions. The measured data of gas-hydrate equilibria were compared with the predictions by using the Chen-Guo hydrate thermodynamic model.     

A water droplet size distribution dependent modeling of hydrate formation in water/oil emulsion

Experimental data on chord length distributions and growth rate during methane hydrate formation in water‐in‐oil emulsions were obtained in a high pressure stirring reactor using focused beam reflectance measurement and particle video microscope. The experiments were carried out at 274.2 K for 10–30% water cuts and agitation rates ranging from 200 to 500 rpm initially at 7.72 MPa. Rapid growth was accompanied by gradually decrease in rate. Free water was observed to become depleted during rapid growth while some water remained encapsulated inside hydrate layers constituting a mass transfer barrier. The apparent kinetic constants of methane hydrate formation and free‐water fractions were determined using a newly developed kinetic model independent of the dissolution rate at the gas–oil interface. It was illustrated that continued growth depends on distribution and transfer of water in oil‐dominated systems. This perception accords with observations of hydrate film growth on suspended water droplet in oil and clarifies transfer limits in kinetics. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1010–1023, 2017     

石英砂中甲烷溶解运移体系水合物生成与聚集实验分析

建立了可模拟海底天然气水合物形成环境的大型三维成藏实验模拟装置,其主体高压反应釜内径500 mm,高1000 mm。在此基础上,采用填砂模型,进行了甲烷溶解运移体系下甲烷水合物生成与聚集过程的实验模拟分析。实验流程为：甲烷溶解于NaCl溶液中,再泵送进入高压反应釜,在沉积层中渗流并生成甲烷水合物。通过30个电阻率传感器监测甲烷水合物的生成和聚集过程。实验结果表明,甲烷溶解运移体系下甲烷水合物生成之后首先分散在溶液中,当溶液的总甲烷浓度（溶解的甲烷及水合物分散相中的甲烷）达到操作条件下盐溶液体系甲烷饱和溶解度后,甲烷水合物从溶液中析出。电阻率分布实验结果表明,析出甲烷水合物的聚集区域受溶液流动控制。     

Dual Effect of Low‐Dosage Poly(Ethylene Oxides) on Methane Hydrate Formation

Time‐dependent isochoric formation of methane hydrate was investigated in the presence of low‐dose poly(ethylene oxides) (PEOs). The effect of different molecular weights of PEO on methane hydrate nucleation time and storage capacity was studied and compared. Kinetic measurements revealed a dual effect of PEO, including inhibition and stabilization effects, on methane hydrate formation. The nature and type of the effect arises from the difference in molecular weights and concentration ranges of PEOs. These parameters directly affect the nucleation time and storage capacity of methane hydrate. Generally, in comparison with pure water, PEO improved the storage capacity of methane hydrate. PEO (1000 kD) at a concentration of 0.5 wt % exhibits a significant kinetic inhibitory performance. However, it was an efficient low‐dosage hydrate stabilizer at a concentration of 0.25 wt %, along with producing gas‐rich methane hydrate suitable for gas fuel storage and transportation.     

低温常压条件下水合物法储存甲烷的实验研究

利用水合物法实现对天然气的工业储运,需要提高水合物的储气量并解决水合物的分解速度问题。为此,文章研究了在十二烷基硫酸钠（SDS）体系中,甲烷水合物的储气量和在冰点以下的常压分解规律。研究发现,SDS浓度为650 mg/L时甲烷水合物储气量达到最高值,约为170 V/V。分解温度为268.2~272.2 K区域内,甲烷水合物的分解速率随温度的降低而降低;在268.2 K时,甲烷水合物分解速率最低。