悬垂水滴表面天然气水合物的生长特性

针对天然气水合物的喷雾法制备,设计并搭建了悬垂水滴显微实验装置,研究了不同温度和压力条件下天然气水合物在悬垂水滴表面的生长形态,建立了水滴表面水合物膜的生长模型,并通过实验研究了驱动力、过冷度、水合反应速率、气体扩散速率及十二烷基硫酸钠(SDS)浓度对水合物膜生长的影响. 结果表明,水合物膜的生长速率随过冷度的增加而增加,实验条件下测得水滴表面水合物膜的生长率为0.24~0.39 mm/s. 水滴表面水合物膜的生长为内扩散控制,水合物的活化能为13.01 kJ/mol. 当SDS浓度为550 mg/L时,界面反应速率常数有最大值0.0027 m/s.     

喷雾反应器中甲烷水合物生长动力学模型

提出了喷雾反应器中甲烷水合物的形成机理,并引入传质对水合反应影响的有效因子等参数,得到了喷雾法生成水合物的改进动力学方程.通过实验验证,实验数据与模型计算数据基本吻合,平均误差为4.63%.方程回归得出甲烷水合物表观活化能(Ea)为54.25 kJ/mol,根据文献结果,说明喷雾反应器中甲烷水合物生长过程由表面反应所控制.     

一种喷雾强化制备二氧化碳水合物的实验系统

为了更直观地研究喷雾强化制备二氧化碳水合物的方法,设计了一套喷雾强化制备二氧化碳水合物的实验装置,并考察了生成过程中系统的温度和压力的影响,以及二氧化碳气体的消耗量,初步研究了二氧化碳水合物的生成驱动力问题.结果表明:在水合反应系统压力越高、温度越低的情况下,二氧化碳水合物的生成驱动力数值的绝对值越大;温度为275.15 K时,随着压力的增加,二氧化碳水合物的生成驱动力不是呈现简单的线性增加,而是从快到慢渐趋于平缓的变化.该系统能很好地应用于气体水合物制备过程中特性和工艺的研究.     

XNC-98催化剂甲醇合成本征动力学

在等温积分反应器中研究了XNC-98催化剂上甲醇合成反应本征动力学.实验压力为4~8MPa,空速7000~13000h-1,反应温度200~260℃.实验采用粒度为0.154~0.198mm的细颗粒催化剂.选取以各组分逸度表示的CO、CO2加氢合成甲醇的Langmuir-Hinshelwood本征动力学模型.采用正交实验设计,实验测定了25组数据,用全局通用算法结合马夸特算法确定动力学模型参数.残差分析和统计检验表明,动力学模型是适宜的.随温度升高,反应器出口甲醇浓度、CO和CO2转化率先增加后降低,在4~8MPa下,230~245℃为较佳反应温度范围:随着反应压力的提高,反应器出口甲醇浓度、CO和CO2转化率都有显著增加,提高反应压力能够有效提高反应器的生产能力.     

TBAB水合物晶体生长过程的实验研究

通过对常压下9%(w) TBAB溶液降温生成水合物晶体的过程进行观察,以过冷度作为生长驱动力,研究了TBAB水合物晶体的生长特性. TBAB水合物刚形成时,晶体呈高透光度及规则柱体外形,随晶体继续生长逐渐变得不规则,透光度下降. 当恒温浴的过冷度分别为6.0, 8.1和9.6 K时,水合物晶体长度/宽度方向生长时间依次为183 min/140 min, 85 min/65 min, 70 min/37 min,同时反应前的等待时间即生成时间分别为83, 53和55 min. 生长时间和生成时间随过冷度增加逐渐降低,幅度逐渐减小,表明过冷度增加能有效减少水合反应时间,促进水合物的快速生成. 过冷度增加会增加TBAB水合物晶体成核数量,因此晶体与溶液的总体接触面积增加,有利于水合物的快速形成.     

海底沉积物层CO2封存中水合物研究进展

海底沉积物层内CO2封存被认为是缓解全球气候变暖的有效途径,本文介绍了CO2封存时水合物自封机理、水合物形成条件和水合物稳定带范围,描述了水合物生成动力学研究现状,包括成核动力学、生长动力学以及水合物结晶过程驱动力,水合物的成核模型有成簇成核模型、成簇成核扩展模型、界面成核模型、Chen-Guo模型,水合物生长动力学模型有Englezos、Kvamme生长模型、指数增长模型、流体流动模型以及LB模型,水合驱动力有化学势差、温差、吉布斯自由能差、浓度差、压差或逸度差。总结了多孔介质渗透率和孔隙度随水合物成核和生长的演化关系,有KC模型、NR模型、平行毛细管束模型、渗透率下降模型和Morisdis相对渗透率模型,最后介绍了CO2水合实验情况,展望了CO2海底沉积物层内封存与水合物相关的科学问题。     

初始压力对冰冻石英砂中CO2水合物生成特性的影响

利用冰冻石英砂模拟冻土水合物的赋存条件，研究了压力对二氧化碳水合物生成特性的影响，在300 mL高压水合物反应釜中于271 K下进行了多组CO2液化压力以上及以下的霰状冰粉包裹的石英砂中水合物生成实验。结果表明，充入的CO2未液化时，初始压力越大，水合反应速率越快，压力越早达稳定状态；充入压力达液化压力后，注入的CO2越多，水合反应速率越快。压力作为水合反应的驱动力，压力越高水合物生成越多，冰的最终转化率越高。采用CO2置换冻土区中甲烷水合物时，控制压力低于液化压力或注入过量的CO2，置换效果更好。     

高压低温下H2O-H2O2-CO2三元体系CO2气体水合物的分解动力学

研究了非纯水体系H2O-H2O2-CO2中CO2气体水合物分解的动力学,测定了高压低温条件下CO2气体水合物分解过程的液相组成. 依据实验数据建立了CO2气体水合物分解动力学模型,模型计算值与实验值吻合良好. 确定了3个温度下气体水合物分解的速率常数,计算得出CO2气体水合物分解的活化能为97.17 kJ/mol.     

通气量和CO2对Nannochloropsis sp.在光生物反应器中的生长和EPA合成的影响

实验考察了在气升式内环流光生物反应器中通气量、CO2含量等培养条件对Nannochloropsis sp.生长及EPA合成的影响. 结果表明,在气升式内环流光生物反应器中培养,Nannochloropsis sp.生长速率显著提高. 培养8 d,Nannochloropsis sp.生物量(干重)可达857 mg/L,是摇床培养的2倍. 在一定范围内,Nannochloropsis sp.的生长速率随通气量的增加而增加,在本实验条件下,通气量为500 mL/min时生长最快,而过高的通气量则对Nannochloropsis sp.的生长没有促进作用. 在通气中含1%(j) CO2时,可加快藻细胞的生长,最大生长速率可达不配加CO2时的1.8倍. 通气量和CO2对Nannochloropsis sp.细胞内总脂肪酸及EPA的积累有显著影响. 在通气量为400 mL/min及CO2含量为0.5%时,培养液中EPA产量最高,达到39.0 mg/L.     

双流化床生物质气化动力学建模与分析

为进一步研究双流化床生物质气化器中合成气含量分布,将气化器鼓泡床层分为气泡相和乳化相,依据动力学反应分别进行各相质量和热量衡算,计算结果与实验值吻合较好. 随气化温度升高,CO含量增加,而H2和CO2含量降低;蒸汽与生物质质量比(S/B)增加促进水蒸汽变换和重整反应,消耗CO和CH4,生成H2和CO2,当S/B从0变化到1.2时,CO/H2变化44%,说明S/B增加主要促进了水蒸汽变换反应. 气化温度870℃及S/B=0.75条件下,当气化器高度为0~0.5 m时,H2O含量急剧下降,H2含量急剧上升,CO与CO2含量逐渐上升,当该高度大于0.5 m后,气化反应基本完成.     

环戊烷/水乳化液水合法捕获烟道气中CO_2(英文)

Capture of CO2 by hydrate is one of the attractive technologies for reducing greenhouse effect.The primary challenges are the large energy consumption,low hydrate formation rate and separation efficiency.This work presents a new method for capture of CO2 from simulated flue gasCO2(16.60%,by mole) /N2 binary mixture by formation of cyclopentane(CP) hydrates at initial temperature of 8.1°C with the feed pressures from 2.49 to 3.95 MPa.The effect of cyclopentane and cyclopentane/water emulsion on the hydrate formation rate and CO2 separation efficiency was studied in a 1000 ml stirred reactor.The results showed the hydrate formation rate could be increased remarkably with cyclopentane/water emulsion.CO2 could be enriched to 43.97%(by mole) and 35.29%(by mole) from simulated flue gas with cyclopentane and cyclopentane/water(O/W) emulsion,respectively,by one stage hydrate separation under low feed pressure.CO2 separation factor with cyclopentane was 6.18,higher than that with cyclopentane/water emulsion(4.01) ,in the range of the feed pressure.The results demonstrated that cyclopentane/water emulsion is a good additive for efficient hydrate capture of CO2.     

Evaluation on the natural gas hydrate formation process

Gas hydrates have endowed with great potential in gas storage, and rapid formation of gas hydrates is critical to use this novel technology. This work evaluated the natural gas hydrate formation process, which was compared from six parameters, including conversion of water to hydrate, storage capacity, the rate of hydrate formation, space velocity (SV) of hydrate reaction, energy consumption and hydrate removal. The literature was selected by analyzing and comparing these six parameters mentioned above, meanwhile placing emphasis on the three parameters of storage capacity, the rate of hydrate formation and space velocity of hydrate reaction. Through analysis and comparison, four conclusions could be obtained as follows. Firstly, the overall performance of the stirring process and the spraying process were better than other processes after analyzing the six parameters. Secondly, the additive types, the reactor structure and the reactor size had influence on the natural gas hydrate formation process. Thirdly, the energy consumption via reciprocating impact in the hydrate formation process was higher than that via stirring, spraying and static higee. Finally, it was one key for hydrate removal to realize the hydrate industrial production.     

螺旋内槽管内天然气-水-表面活性剂体系的水合物生成动力学计算

针对多组分气体（天然气）-水-表面活性剂体系在螺旋内槽管内的水合物生成过程,首先采用CFD方法结合群体平衡模型（PBM）,基于溶质渗透模型和Kolmogorov各向同性湍流理论对螺旋内槽管内气液传质系数进行了模拟;其次基于Kashchiev和Firoozabadi的经典水合物成核和生长理论,将其体系从单组分-水系统扩展到多组分气体（天然气-水-十二烷基硫酸钠）系统,同时结合经典结晶理论利用传质系数对水合物生长模型进行了修正,建立了适用于螺旋内槽管流动体系内天然气水合物生成动力学模型。通过模拟计算,获得不同水合物生产条件下天然气在水中的平均传质系数;进而利用Microsoft Visual C++编程计算得到不同条件下水合物生成动力学数据,在考察范围内,天然气水合物的成核速率随着反应体系有效表面能的增大而锐减,而水合物生成驱动力和生长速率未受影响,同时水合物生长速率随着流速和反应压力的增大及温度的降低而增大,成核速率随着压力的增大和温度的降低而增大。     

Hydrate formation from liquid CO2 in a glass beads bed

CO₂ sequestration in marine sediments as solid hydrates is a potential way to capture and store anthropogenic CO₂. In this study, hydrate formation from liquid CO₂ in marine sediments was simulated in a glass beads bed, and the factors affecting the kinetics of hydrate formation were investigated. The results indicated that the rapid initial hydrate formation with a high driving force always increases the mass transfer resistance, which slows down hydrate growth. The final ratio of water conversion is higher under conditions of low temperature and higher pressure. A smaller particle size is conductive to initial CO₂ hydrate growth, but the water conversion ratio in a bed with larger particles is slightly higher. Compared with other factors, the change in water saturation has an obvious effect on the final water conversion. To inhibit the initial hydrate formation during the injection process, in this paper, a kinetic inhibitor is proposed for pre-injection into marine sediments. This work shows that at a low pressure, a low-concentration inhibitor has an obvious inhibition effect on hydrate growth. However, at a high pressure, it is necessary to increase the concentration of inhibitor to produce an obvious inhibition effect.     

水合物法快速脱除天然气中二氧化碳

水合物法脱除天然气中CO2是一种新的天然气脱碳分离技术,可用于初步大量脱除高含CO2天然气和沼气中的CO2.为天然气脱碳提供一种工艺简单、流程快和环保的方法.笔者用CO2(摩尔分数为33.00％)/CH4混合气模拟高含CO2的天然气,在1L的反应釜内,研究混合气水合过程随压力和气水体积比的变化,分析水合过程的温度、压力...     

三维中试装置内水合物降压分解动力学规律

利用196L三维装置研究了含下伏气层水合物藏的降压分解规律。对比研究了单竖直井实验和竖直井-水平井双井开采的实验,实验结果表明,过大的降压幅度可能会导致开采井被雾沫夹带的水堵塞,对于含下伏气层的水合物藏,反应釜底部和近井区域由于局部气流速度过快导致更严重的温降。建立了经典格式的分解动力学模型,结果表明,对于三维装置,单独利用推动力和分解速率并不能准确反映水合物实际分解状况。利用水合物剩余分解比例校正后,推动力和分解速率呈线性关系,单井实验所拟合参数k=0.284mol/(min·MPa)与双井降压实验 k=0.279mol/(min·MPa)可以互相验证。     

甲烷-四氢呋喃-水体系水合物生成动力学的实验和模型化研究

研究了透明鼓泡塔中含促进剂四氢呋喃（THF）体系中甲烷水合物的生成动力学.分别考察了进气速率、温度、压力、水合物体积分数对甲烷消耗速率的影响.根据Chen-Guo水合物生成机理,采用基础水合物生成反应的量纲1 Gibbs自由焓变-ΔG/RT作为反应的推动力,建立了水合物生成动力学模型,模型中考虑了体系温度、压力和气液接触比表面积的影响.把模型应用于甲烷气体消耗速率的计算,其模型预算结果与实验数据吻合良好,实验结果和反应动力学模型将有助于工业水合反应器的设计和操作条件的设定.     

CH4、CO2及CH4+C2H6+C3H8在纯水、SDS水溶液和含石英砂体系中水合物相平衡条件的测定

Phase equilibrium conditions of gas hydrate in several systems were measured by the step-heating method using the cylindrical transparent sapphire cell device. The experimental data for pure CH4 or CO2 + deionized water systems showed good agreement with those in the literatures. This kind of method was then applied to CH4/CO2 + sodium dodecyl sulfate (SDS) aqueous solution, CH4/CO2 + SDS aqueous solution + silica sand, and (CH4 + C2H6 + C3H8) gas mixture + SDS aqueous solution systems, where SDS was added to increase the hydrate formation rate without evident influence on the equilibrium conditions. The feasibility and reliability of the step-heating method, especially for porous media systems and gas mixtures systems were determined. The experimental data for CO2 + silica sand data shows that the equilibrium pressure will change significantly when the particle size of silica sand is less than 96 μm. The formation equilibrium pressure was also measured by the reformation of hydrate.     

Experimental determination of methane hydrate dissociation curve up to 55 MPa by using a small amount of surfactant as hydrate promoter

Methane hydrate equilibrium has been studied upon continuous heating of the water-hydrate-gas system within the temperature range of 275-300 K. This temperature range corresponds to equilibrium pressures of 3.15-55 MPa. The hydrate formation/dissociation experiments were carried out in a high-pressure reactor under isochoric conditions and with no agitation. A small amount of surfactant (0.02 wt% sodium dodecyl sulfate, SDS) was added to water to promote hydrate formation. It was demonstrated that SDS did not have any influence on the gas hydrate equilibrium, but increased drastically both the hydrate formation rate and the amount of water converted into hydrate, when compared with the experiments without surfactant. To understand and clarify the influence of SDS on hydrate formation, macroscopic observations of hydrate growth were carried out using gas propane as hydrate former in a fully transparent reactor. We observed that 10^-3 wt% SDS (230 times less than the Critical Micellar Concentration of SDS) were sufficient to prevent hydrate particles from agglomerating and forming a rigid hydrate film at the liquid-gas interface. In the presence of SDS, hydrates grew mainly on the reactor walls as a porous structure, which sucked the solution due to capillary forces. Hydrates grew with a high rate until about 97 wt% of the water present in the reactor was transformed into hydrate.Our data on methane hydrate equilibrium both confirm already published literature data and complement them within the pressure range of 20-55 MPa.