X射线粉晶衍射-拉曼光谱法研究含甲烷双组分水合物结构及谱学特征

天然气水合物的晶体结构主要取决于客体分子种类与组成,目前单组分水合物的结构和谱学特征较为明确,但多组分水合物相关研究较少。为解决多组分水合物的结构识别问题,探讨其谱学特征,本文实验合成了甲烷-丙烷(CH_(4)-C_(3)H_(8))和甲烷-四氢呋喃(CH_(4)-THF)两种含CH_(4)双组分水合物以及CH_(4)、C_(3)H_(8)和THF等三种单组分水合物,并采用低温X射线粉晶衍射(PXRD)和显微激光拉曼光谱进行了表征。结果表明:CH_(4)-C_(3)H_(8)和CH_(4)-THF双组分水合物的晶格常数a分别为17.2312×10^(-10) m和17.2241×10^(-10) m,为典型的Ⅱ型结构水合物,与相应C_(3)H_(8)和THF单组分水合物结构相同。在CH_(4)-C_(3)H_(8)水合物中,CH_(4)在大、小笼中均有分布,呈现两个特征拉曼峰(2900cm^(-1)和2911cm^(-1));C_(3)H_(8)仅分布在大笼,与单组分水合物相比,其C—H伸缩振动峰峰位几无变化,而C—C伸缩振动峰(873cm^(-1))向低频迁移约3cm^(-1)。在CH_(4)-THF水合物中,大笼被THF占据,CH_(4)仅填充在小笼中(2910cm^(-1));双组分水合物中,THF分子C—C和C—H伸缩振动峰峰位均与单组分水合物基本一致。分析认为,含CH_(4)双组分水合物的结构类型与其相应的大分子水合物一致,大分子对双组分水合物的晶体结构特征具有决定作用。同时,大分子影响了CH_(4)分子在笼型结构中的分布,致使双组分水合物的拉曼光谱特征存在显著差异。研究结论对基于谱学特征识别多组分水合物微观结构具有重要的指导意义。

浅谈组分大于全烃的现象的研究和探讨

气测录井过程中出现烃组分分析的甲烷含量大于全烃含量的现象,导致甲方管理人员的质疑和困惑,本文通过实验证实,录井过程中出现甲烷含量高于全烃含量的现象对于全烃和烃组分资料均无任何影响。

豫西煤层瓦斯解吸特征与时间关系的研究

为了进一步了解煤层瓦斯解吸过程,更好地掌握瓦斯解吸特征,利用现场不同的取样方法,并在不同的暴露时间情况下,对豫西煤层残余瓦斯含量和甲烷组分变化进行了系统研究。研究结果表明,煤层残余瓦斯含量在煤样罐密封效果好的情况下,煤样测试结果与暴露时间无直接关系;煤样罐插上穿刺针头导通大气的情况下,煤样分别存留1,2,3,4,5 d,瓦斯含量遗失分别为15.13%、30.73%、68.17%、73.63%、76.29%,甲烷组分遗失分别为33.23%、59.71%、86.19%、90.98%、93.09%;煤样在完全暴露2 h和4 h的情况下,瓦斯含量遗失分别为24.80%、68.33%,甲烷含量遗失分别为54.53%、83.12%,甲烷遗失速度较快。

Caking property and active components of coal based on group component separation

The content and the caking index of the heavy,the dense medium and the loose medium components of coal,obtained by extraction and stripping with CS_2/N-methyl-2-pyrrolidinone mixed solvent(1:1 by volume),were studied and correlated with the caking property of raw coals.Images of the three group components after heat treatment were analyzed.The results show that both caking index(G) and maximum thickness of plastic layer(Y) of coals have a good linear relationship with the content of the medium component;the dense medium and the loose medium components are the two key factors to determine the caking property of raw coals-they are the source materials of fluidity and swelling of coal,respectively;the heavy component without the swelling and fluidity was cohered by the other components;two new indexes,which can extend current understanding of the caking properties,were introduced.

Influence of microwave treatment under a hydrogen or methane atmosphere on the flotability of the macerals in Shenfu coals

The modification of Shenfu coals by a microwave treatment carried out under a hydrogen or a methane atmosphere, and the subsequent maceral separation by flotation, are described in this paper. The surface contact angle and the Zeta potential of the coal macerals were measured both with and without the treat- ment. The results show that the surface wettability of SFF (Shenfu Fusain) and SFV (Shenfu Vitrain) can be changed by the microwave treatment. An increase in the difference in surface wettability of SFF and SFV causes in a subsequent increase in the enrichment of inertinite and vitrinite. The results of the Zeta potential measurements show that the surface potentials of SFF and SFV are also changed by the treatment.

Calculation of Gas-Liquid Critical Curves for Binary Systems Containing Methane

The critical curves for binary systems of methane combined with nitrogen, carbon monoxide, carbon dioxide, ethane, propane, butane and water at temperatures from 125 K to 650 K and pressures from 3.5 MPa to 250 MPa were calculated by using Heilig-Franck equation of state. This equation of state contains a repulsion term and an attraction term for intermolecular interaction. With pairwise combination rules for these potentials, three adjustable parameters are needed. The results showed that the critical curves of the former six binary systems belonged to type I, and CH4＋H2O system belonged to type III. The calculated data were compared with the experimental data,which yielded good results for the pressure-temperature, pressure-composition and temperature-composition behaviors of the seven systems. Moreover, the values of the adjustable parameters were obtained from the calculation of the critical curves. They can also be used for other relevant calculation.

Explosive limits of mixed gases containing CH_4,CO and C_2H_4 in the goaf area

The explosive gases CO and C2H4, released mainly flammable gases during the process of coal self-ignition, are of the most important ingredients of the multi-component gases in goal areas, along with CH4. We have determined some of the parame- ters of explosive properties of the one-component gases CH4, CO and C2H4 using an explosive trial device of polybasic explosive gas mixtures and emphasized particularly the effect on the limits of explosive concentration of the binary explosive mixed gases CH4＋CO, CH4＋C2H4, as a function of the amount of CO, C2H4 and inert flame resisting gases （N2, CO2）. The experimental results show that the effect of inert gases on the explosive limits of mixed gases, given the property of explosive gas, is obvious： the inert gases （N2, CO2） possess some inhibitory effects on the explosion of the multi-component explosive gas mixtures. The results will provide some experimental support to suppress the occurrence of the gas explosions in goaf areas and provide some directions for designing explosion-proof electric equipment and fire arresters.

甲烷-乙烷超声速流动液化过程的数值模拟

为了推广超声速旋流分离技术在天然气液化领域的应用,对甲烷-乙烷双组分在Laval喷管中超声速流动液化过程进行了理论研究与数值模拟。运用流体力学计算软件Fluent,结合流动控制方程,分析了入口温度、入口压力、背压及组分对双组分液化过程的影响。研究结果表明:适当降低入口温度或提高入口压力,将使甲烷-乙烷双组分临界液化温度和压力降低,且停留在气液两相区和液相区的范围增大,促进双组分的液化;当温度升高至330 K时,双组分处于液化的临界状态;背压升高至20%将会导致喷管内产生激波,激波的出现使得喷管内的温度、压力突变,破坏了稳定的液化环境,不利于液化过程的顺利进行;甲烷含量越高,发生液化时所需温度和压力越低,液化区域范围越小,越难发生液化。