水合物法天然气脱酸的影响因素

为了促进水合物法分离CO₂在天然气脱酸工艺中的应用,以CH₄+CO₂混合气为例,采用CO₂分离率、CH₄损失率及分离因子作为水合物法脱酸的评价指标,利用自主设计的水合物法气体分离实验装置考察了初始压力、操作温度、四氢呋喃（THF）及实验用水量对水合物法分离CH₄+CO₂混合气的影响。结果表明,随初始压力增大和操作温度降低,平衡时气相CO₂浓度降低,CO₂分离率和CH₄损失率同时增大,分离因子小幅减小;随THF浓度增大,平衡时气相CO₂浓度增加,在THF摩尔分数为1.0%时,体系具有较大的CO₂分离率和分离因子,较低的CH₄损失率;随实验用水量增加,平衡时气相CO₂浓度降低,CO₂分离率增大,CH₄损失率减小,分离因子增大。综合分析,可通过提高初始压力、降低操作温度、增加实验用水量,并添加摩尔分数1.0%THF来促进水合物生成,提高分离效率。     

水合物法分离CO2与N2混合气的实验

与传统的分离方法相比,水合物法分离气体混合物技术具有可降低制冷能耗、简化工艺流程、节省投资成本等优势,但目前该技术还不成熟,尚未形成统一的成套技术。为研究各种因素对分离效果的影响并给出一定配比混合气的最佳分离条件,以摩尔分数59% CO₂+41% N₂混合气为例,利用自行设计的实验装置,系统地进行了温度、初始压力及含水量对分离效果的单值影响实验。分析处理实验数据,得到混合气在温度1.4~5.6 ℃、初始压力4.2~6.8 MPa及含水量160~300 mL范围内的分离效果。实验结果显示：降低温度,升高初始压力都可以提高分离率,但同时也会增大损失率;增加含水量会提高分离率,降低损失率,但含水量超过一定值,对分离率的影响便不再明显。综合考虑,对于一定配比的CO₂+N₂混合气,在允许的损失率及最小气液比下,可以先增大含水量,然后降低温度,最后提高初始压力,以此来达到最佳的分离效果。     

SDS和THF对水合物法捕集模拟烟气中CO2的影响

采用搅拌式反应釜水合物生成实验装置研究动力学促进剂十二烷基硫酸钠(SDS)和热力学促进剂四氢呋喃(THF)对水合物法捕集CO_2的影响,用摩尔分数为25%的CO_2和75%的N_2混合气模拟烟气,分别探究不同浓度的SDS和THF对分离效果的影响;在此基础上,研究了不同初始压力、反应温度对分离效果的影响。结果表明,SDS和THF的存在都能提高CO_2回收率,但同时会降低分离因子。设定初始温度为3.5℃,初始压力为9.2 MPa时,加入质量分数为0.01%的SDS溶液后,CO_2回收率较纯水中增大了4.3%,分离因子较纯水中降低了44.8%;设定初始温度为6.5℃,初始压力为3.7 MPa时,加入摩尔分数为0.5%的THF溶液后,CO_2回收率较纯水中增大了30.4%,分离因子较纯水中降低了72.8%。在实验条件下,适宜的SDS质量分数为0.01%～0.05%,THF摩尔分数为0.5%～2%,初始压力的增加可以有效缩短水合反应的诱导时间,增大储气密度、CO_2回收率和分离因子,降低温度能有效提高分离效果。     

添加剂对CO2水合物生成的影响

以水合物的方式分离/储存CO₂气体是一项具有挑战性的新技术。为了提高水合物的生成速率和储气密度，在小型可视化的水合物反应装置上实验研究了不同种类的添加剂对CO₂水合物生成特性的影响。结果表明，实验用有机硅系列添加剂可以有效降低气-水界面的表面张力，提高水合物的生成速率。CO₂水合物的生成量随着添加剂浓度的增大而增大，但当浓度高于0.1%以后，其生成量增长非常缓慢。单组分添加剂Silwet L-77效果最好，而单组分添加剂THF对CO₂水合物的生成没有任何改善，但将浓度为4%的THF和1%的Silwet L-77混合后却对水合物的生成起到了显著的改善效果，12 h内的气体压降可达到0.27 MPa，是纯水体系的10倍之多，照片显示有大量的水合物生成。研究结果对寻找适合于CO₂水合物快速生成的添加剂，为其应用于高效分离储存CO₂气体技术等方面提供了指导。     

活性炭+THF溶液体系中CO2水合物生成特性研究

水合物法捕集CO₂具有储气量大、生成条件温和等显著优点，应用前景广阔。提高水合物生成速率和CO₂气体消耗量是该方法需解决的关键问题。在活性炭+THF溶液体系中开展了CO₂水合物生成特性研究，探究了THF溶液浓度(物质的量分数，下同)、THF溶液饱和度对CO₂气体消耗量的影响，并通过可视显微实验研究了活性炭+THF溶液体系中CO₂水合物的生长形貌特征。研究结果表明，相比于THF溶液浓度为5.56%的体系，活性炭+THF溶液体系(THF溶液浓度为5.56%、溶液饱和度为100%)的CO₂气体消耗量增加了59%；当THF溶液饱和度为100%时，提高THF溶液浓度可以有效促进水合物生长，在THF溶液浓度为5.56%的条件下，CO₂气体消耗量达到总CO₂气体消耗量90%所需的时间(t90)最短(106.67 min)。活性炭+THF溶液体系中的CO₂水合反应由气体吸附和水合物生长两个阶段组成，水合物最...     

CO2置换法开发不同体系CH4水合物的实验

CO₂置换法引起了许多研究者的注意，该方法能够使CH₄水合物开发和CO₂气体的长期储存同时进行，是一种开发CH₄水合物的新方法。在自行设计的反应装置中考察了3.25 MPa压力下，温度271.2 K、273.2 K和276.0 K时CO₂气体置换十二烷基硫酸钠（SDS）体系和纯水体系CH₄水合物中CH₄的置换过程。实验表明：提高温度有利于置换反应的进行；SDS体系的置换速率比纯水体系的置换速率高。276.0 K、3.25 MPa时，SDS体系和纯水体系100 h的置换效率分别达到6.93% 和14.50%。由于水合物相中静态水的存在，置换反应过程中，CO₂的消耗量与CH₄水合物的分解量并不是1∶1的关系。基于实验结果，简单地分析了CO₂置换CH₄水合物中CH₄的置换机理。     

N2泡沫/CO2复合吞吐提高采收率三维物理模拟试验研究

经CO₂多轮吞吐后,华北某稠油油藏增油效果逐年变差,为进一步改善开发效果,采用N₂泡沫/CO₂复合吞吐提高原油采收率。为明确N₂泡沫/CO₂复合吞吐提高原油采收率机理,通过泡沫体系动、静态性能评价试验,评价了N₂泡沫体系的封堵性能;采用自主研制的三维非均质物理模型开展了N₂泡沫/CO₂复合吞吐室内物理模拟试验,分析了N₂泡沫与CO₂复合提高采收率的效果及其相关机理。试验结果表明,质量分数0.3%的α-烯烃磺酸钠（AOS）和质量分数0.3%的聚丙烯酰胺（HPAM）可形成稳定的泡沫体系,其封堵率达到99.57%,可实现对高渗层的有效封堵。三维试验结果表明,N₂泡沫/CO₂复合吞吐可使采收率提高22.74百分点,吞吐过程中含水率最低可降至2.07%,有效作用期是纯CO₂吞吐的2.5～3.0倍。N₂泡沫/CO₂复合吞吐可有效扩大CO₂和后续水的波及体积,为其后续现场应用提供理论支撑。      

CO2-CH4气体节流及水合物生成特性

CO₂驱采油举升过程中,随着压力的降低,采出液会析出大量伴生气,伴生气中CO₂含量高达50%～90%,相比CH₄气体,气态CO₂节流致冷效应更强,引起的低温可能会生成水合物堵塞管道,威胁集输系统的运行安全。采用高压蓝宝石反应釜研究了CO₂含量对CO₂-CH₄气体节流及水合物生成特性的影响。结果表明：当初始压力为高压(16 MPa)时,相同CO₂占比的混合气体,节流效应系数Di约为1.3～5.4℃/MPa,CH₄的掺入将增强混合气体节流效应,说明高压段主要受CH₄节流效应的影响;当初始压力为低压(5 MPa、4 MPa)时,节流效应系数Di约为3.4～11.9℃/MPa,CH₄的掺入将减弱混合气体节流效应,说明低压段主要受气相CO₂节流效应的影响;相同CO₂含量的CO₂-CH_...     

活性炭的微孔结构对其选择性吸附CH4/N2混合气中CH4的影响

活性炭因其具有较高的选择吸附性和吸附容量已被广泛应用于CH₄/N₂的吸附分离研究,影响活性炭选择吸附性和吸附容量的主要物理参数之一是其微孔结构,准确地表征活性炭的微孔结构并阐明其与活性炭选择性吸附CH₄/N₂混合气中CH₄的内在联系至关重要。为此,结合常温气体吸附法和分子探针技术,采用吸液驱气法表征了6种活性炭的微孔孔径分布,结合动态法测量得到CH₄/N₂分离因子,并借此分析了活性炭的微孔结构对其选择性吸附CH₄/N₂混合气中CH₄的影响。结果表明：①与77 K条件下N₂吸附法测试结果相比,吸液驱气法能够测量到活性炭中更小尺寸的孔;②活性炭样品微孔孔径分布不同,其CH₄/N₂分离因子也不相同;③活性炭孔径小于0.48 nm的微孔对其选择性吸附混合气CH₄/N₂中的CH₄起着非常重要的作用。结论认为,吸液驱气法可为研发吸附分离CH₄/N₂的吸附剂提供更为准确的基础数据。     

高温高压条件下CO2 / 原油和N2 / 原油的界面张力

在油藏温度下,采用ADSA（axisymmetric drop shape analysis）技术测定了不同压力下CO₂/原油和N₂/原油体系的平衡界面张力。实验发现,原油与超临界CO₂接触的初始阶段存在强烈的扩散作用,原油中的轻质组分被超临界CO₂溶解抽提,并且随着压力的增加,这种溶解抽提作用增强;原油与N₂接触时,也存在相互扩散作用,但在本实验所测试的压力范围内（小于36 MPa）并不明显。两种体系的平衡界面张力随着压力的升高逐渐降低,其中CO₂/原油体系的平衡界面张力降低的幅度明显大于N₂/原油体系;N₂/原油体系的平衡界面张力随压力基本呈线性变化。在CO₂/原油体系中,当压力低于17.7MPa时,平衡界面张力下降非常快;当压力大于17. MPa时,CO₂/原油体系的平衡界面张力下降较慢。     

Kinetics of (TBAF + CO2) semi-clathrate hydrate formation in the presence and absence of SDS

In this communication, the impacts of adding SDS (sodium dodecyl sulfate), TBAF (tetra-n-butylammonium fluoride) and the mixture of SDS + TBAF on the main kinetic parameters of CO₂ hydrate formation (induction time, the quantity and rate of gas uptake, and storage capacity) were investigated. The tests were performed under stirring conditions at T = 5 ℃ and P = 3.8 MPa in a 169 cm³ batch reactor. The results show that adding SDS with a concentration of 400 ppm, TBAF with a concentration of 1–5 wt%, and the mixture of SDS + TBAF, would increase the storage capacity of CO₂ hydrate and the quantity of gas uptake, and decrease the induction time of hydrate formation process. The addition of 5 wt% of TBAF and 400 ppm of SDS would increase the CO₂ hydrate storage capacity by 86.1% and 81.6%, respectively, compared to pure water. Investigation of the impact of SDS, TBAF and their mixture on the rate of gas uptake indicates that the mixture of SDS + TBAF does not have a significant effect on the rate of gas uptake during hydrate formation process.     

低温下水合物促进剂SDS及SDBS溶液表面张力研究

由于阴离子表面活性剂十二烷基硫酸钠（SDS）和十二烷基苯磺酸钠（SDBS）能够降低气液界面张力,增大气体溶解度,从而起到促进水合物生成的作用.通过实验室考察SDS和SDBS的表面张力在低温条件下的变化规律,并测定最低表面张力时对应浓度.     

Experimental and Theoretical Investigations on the Enhancement of Methane Gas Hydrate Formation Rate by Using the Kinetic Additives

Effects of the most important influencing parameters on the methane gas hydrate formation kinetics at the onset of hydrate formation in the absence or presence of sodium dodecyl sulfate (SDS) kinetic promoter are investigated. At the SDS concentration of 500 ppm, the maximum methane effective diffusion coefficient and the highest conversion rate are obtained. The methane hydrate-liquid interfacial tension according to the suggested mechanism is about 18.6 mJm^–2 for all cases. The overall average absolute deviations between predicted and measured methane consumption rates are about 0.71% and 0.83% regarding nonpromoted and SDS-promoted gas hydrate formation processes, respectively.     

复合添加剂对二氧化碳水合物生成条件影响的实验研究及动力学模型建立

基于水合物法储存分离二氧化碳具有较广阔的应用前景,通过实验研究了复合添加剂对二氧化碳水合物生成条件的影响,选用十二烷基硫酸钠(SDS)和十二烷基苯磺酸钠(SDBS)以及两者的混合溶液作为实验用溶液,研究发现当采用浓度为265mg/L的SDS和SDBS质量比为1:1的复合添加剂溶液时,二氧化碳水合物的相平衡点最低,最易生成,此时的溶液体系能很好的促进水合物生成,而且比单一的SDS溶液或者SDBS溶液体系下水合物的生成条件都有所降低。建立了考虑复合添加剂促进作用的新型水合物生成动力学模型。     

Experimental Investigation on Promoting Effect of Composite Promoting Agents on Natural Gas Hydrate Formation

An experiment on effects of composite promoting agents composed of surfactants and liquid hydrocarbons on hydrate formation was conducted and the hydrate formation temperature,pressure,induction time and rate in the presence of different composite promoting agent packages were measured.The surfactants used covered sodium dodecyl sulfate(SDS),sodium dodecyl benzene sulfonate(SDBS) and 2-octyl sodium dodecyl sulfate(GC20S),and the liquid hydrocarbon additives utilized included cyclopentane(CP) and methyl cyclohexane(MCH).It appeared that all these combinations of composite promoting agents could promote hydrate formation.The type II hydrate formation conditions using composite promoting agents composed of CP and GC20S were the mildest and the induction time was the shortest;whereas the type H hydrates formation conditions using composite promoting agents composed of MCH and GC20S were the mildest and the induction time was also the shortest.     

化学添加剂对水合物生成和储气的影响

为了研究促进剂对水合物生成的影响,采用自行设计的水合物反应系统,通过恒温定容实验,研究了四氢呋喃(THF)和十二烷基硫酸钠(SDS)对二氧化碳水合物生成的影响。并在实时测量水合物生成过程中系统的温度、压力的基础上,计算得出水合物的生成速率、储气量及表观水合数。结果表明,适宜浓度的SDS能促进气体在液相的溶解,提高水合物的生长速率和储气密度;单独添加THF对水合物生成过程促进效果并不明显;SDS和THF复合添加剂共同作用对水合物促进效果最显著。     

Prediction of carbon dioxide separation from gas mixtures in petroleum industries using the Levenberg–Marquardt algorithm

In this study, two mathematical models for hydrate formation process to separate carbon dioxide by a combination of two different kinds of organic and surfactant promoters are presented. Promoters such as sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, and dodecyl trimethyl ammonium chloride as surfactant promoters; also, tetrahydrofuran, cyclopentane, 1,3-dioxolane, and 2-methyl tetrahydrofuran as organic promoters have been used in recent years. The results showed that a combination of 3000 ppm of surfactant promoters and 4 wt% organic promoters had the highest separation rate of carbon dioxide and; consequently, the investigated models were based on this optimum condition. As a matter of fact, by using these simulations the hydrate formation behavior was predicted with high accuracy; moreover, conducting consuming experiments is not essential anymore. To sum up, in the present research both Vandermonde matrix model and Levenberg-Marquardt algorithm were applied to predict the hydrate formation behavior; in addition, their results were precisely considered and validated with experimental data.     

Experimental study and modeling of the kinetics of gas hydrate formation for acetylene,ethylene, propane and propylene in the presence and absence of SDS

The kinetics of hydrate formation of the hydrocarbons acetylene, ethylene, propane, and propylene were investigated using a fully stirred batch reactor. In relation to hydrate formation, a kinetic model was used to determine the induction time, the rate of hydrate formation, the apparent hydration rate constant, water-to-hydrate conversion associated with hydrate growth as well the storage capacity. This was done for all gases investigated in this study. Experiments were performed in the temperature and pressure ranges of (273.7–280.0) K and (0.5–4.12) MPa, respectively. Furthermore, the effect of sodium dodecyl sulfate (SDS) on the gas hydrate formation rate was examined. A substantial growth in the hydrate nucleation rate was observed in the presence of SDS.     

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文章利用新建立的实验台研究了十二烷基硫酸钠（SDS）和烷基多糖苷（APG）对天然气水合物形成过程的影响。表面活性剂可促进天然气在水中的溶解，从而提高水合物的形成速度。根据表面活性剂对天然气水合物形成耗气量的影响，实验表明十二烷基硫酸钠和烷基多糖苷在水合物形成体系中的临界胶束浓度分别为300 ppm和500 ppm。在临界胶束浓度表面活性剂溶液体系中，实验结果表明微量的表面活性剂减少了水合物形成诱导时间，提高了水合物形成速度和水合物形成的耗气量，并使水合物在静止系统中快速生长。混合表面活性剂可进一步提高水合物的形成速度，但不利于提高水合物形成的耗气量。     

Semicompletion time of carbon dioxide uptake in the process of gas hydrate formation in presence and absence of SDS and silver nanoparticles

Carbon dioxide emission to the atmosphere is one of the main causes of the current global warming. Therefore, capturing this greenhouse gas is very important. The effect of sodium dodecyl sulfate (SDS) and silver nanoparticles on semicompletion time (t_95%) of carbon dioxide uptake in the process of gas hydrate formation is investigated in this communication. The tests were performed at temperatures of 273.65 and 275.65 K and initial pressures of 2 and 3 MPa in a 460 cm³ stirred batch reactor. Experimental measurements show that utilization of SDS and silver nanoparticles decreases the semicompletion time of carbon dioxide uptake considerably. The addition of SDS with concentration of 500 ppm and silver nanoparticles with concentration of 45 μM at p = 2 MPa and T = 275.65 K, respectively, decreases the semicompletion time of carbon dioxide uptake 136.09% and 152.88%, compared to pure water. Investigating the effect of temperature on the amount of t_95% in the presence and absence of tested additives shows that this kinetic parameter decreases by increasing the temperature from 273.65 to 275.65 K.