Numerical Study on Dissociation of Gas Hydrate and Its Sensitivity to Physical Parameters     

白玉湖  李清平  喻西崇  冯国智 《中国海洋工程》2007,21(4):625-636

The natural gas hydrate resource is tremendous.How to utilize the gas from hydrates safely is researchers' concern.In this paper,a one-dimensional model is developed to simulate the hydrate dissociation by depressurization in hydrate-bearing porous medium.This model can be used to explain the effects of the flow of multiphase fluids,the endothermic process of hydrate dissociation,the variation of permeability,the convection and conduction on the hydrate dissociation.Numerical results show that the hydrate dissociation can be divided into three stages:a rapid dissociation stage mainly governed by hydrate dissociation kinetics after an initially slow dissociation stage governed mainly by flow,and finally a slow dissociation stage.Moreover,a numerical approach of sensitivity analysis of physical parameters is proposed,with which the quantitative effect of all the parameters on hydrate dissociation can be evaluated conveniently.  相似文献   

Submarine slope stability analysis during natural gas hydrate dissociation: Discussion     

Chaoqi Zhu  Yonggang Jia 《Marine Georesources & Geotechnology》2020,38(6):753-754

Abstract

Volume change during natural gas hydrate dissociation is important for calculation of excess pore pressure and corresponding submarine slope stability. A short discussion is presented here to the paper of Wang et al. including some notes about the standard condition and parameters used in their model. This discussion calls attention to the wrong use of standard temperature and pressure during calculation of volume change, excess pore pressure, and submarine slope stability.  相似文献   

甲烷水合物分解过程模拟实验研究   总被引：4，自引：2，他引：2  

陈强  业渝光  孟庆国  刘昌岭 《现代地质》2008,22(3):475-479

以甲烷为主要成分的天然气水合物被看作是一种新型的油气资源,研究水合物分解特征有助于水合物的开采利用。采用实验模拟的方法进行了甲烷水合物分解率研究,实验中采用了等容升温分解和不同粒径多孔介质体系常压分解等方法研究水合物的分解特征。从p=4.5MPa下进行的等容分解实验结果发现,当釜内温度为5.18~8℃时水合物快速分解并一直持续到13℃分解结束,且等容分解过程中反应釜内压力与釜内温度呈良好的函数对应关系。常压分解研究使用了5种不同粒径沉积物作为反应介质,在T=1℃的条件下进行水合物分解实验,结果发现粒径在0.063~0.35mm范围的沉积物对水合物的分解速率为1.11×10-5~2.41×10-5mol/s,但分解速率并没有随粒径大小发生有规律的变化。  相似文献   

Estimation of the dissociation energy of CO+ from spectroscopic data     

R. R. Reddy  R. Viswanath 《Journal of Astrophysics and Astronomy》1990,11(1):67-72

The potential energy curves for theX ² Σ⁺ andB ² Σ⁺ states of CO⁺ have been constructed by the Rydberg-Klein-Rees (RKR) method as modified by van der Sliceet al. The dissociation energy is estimated to be 7.70±0.19 eV by the method of curve fitting using the five parameter Hulburt-Hirschfelder’s function. The estimated value is in good agreement with the value (7.839 eV) given by Misraet al. Carefull observation of the results reveals that accurateD ₀ value for CO⁺ is 8.33 eV  相似文献   

碳酸钾焙烧分解富钾页岩的实验研究   总被引：4，自引：2，他引：4  

苗世顶  马鸿文郑骥 章西焕 《岩石矿物学杂志》2004,23(3):273-278

通过实验探讨了富钾页岩 碳酸钾体系热分解反应过程。以富钾页岩分解率为目标函数，正交实验表明：最佳焙烧温度为820-830℃，富钾页岩：碳酸钾(质量比)=1．00：1．51，最佳焙烧时间60min，生料粒度60～80目。并用热重／差热分析和X粉晶衍射进行分析，拟合热力学数据，初步分析了反应机理。  相似文献   

Influence of the olivine additive fineness on the oxidation of magnetite pellets     

S. P. E. Forsmo  A. Hgglund 《International Journal of Mineral Processing》2003,70(1-4):109-122

Olivine is used as an additive in Luossavaara–Kiirunavaara AB (LKAB) blast furnace pellets. The LKAB iron ore is magnetite which oxidizes to hematite during the sintering process. Olivine retards the oxidation of magnetite pellets if the threshold temperature of magnesioferrite formation is exceeded.In this study, we have developed a thermogravimetric measuring method to study the relationship between the olivine reactivity in green pellets and the olivine fineness. A less reactive olivine makes the pelletizing process more tolerant of excessively high temperatures in the green pellets during oxidation.The reactivity of olivine decreases when the amount of fine tail in olivine is decreased. The top size is limited by balling. Grinding tests in pilot scale show that if the olivine additive is ground in closed circuit with a ball mill keeping good control over the top size, the olivine fineness can be appreciably decreased without disturbing balling. The olivine reactivity can be decreased by 40% compared to the reference olivine in the production plant. Also, savings can be made on both the grinding energy and grinding media consumption. The results in both pilot scale and full production scale show that better oxidation in the grate due to a coarser olivine additive improves the low temperature reduction strength (LTD, ISO 13930) in pellets.The measuring method developed for the olivine reactivity enabled evaluation of different particle-sizing methods for olivine characterisation. The screening size fraction %−45 μm showed a good correlation to olivine reactivity in green pellets within a very large measuring range. The correlation of laser diffraction analysis to the olivine reactivity showed, however, that the laser diffraction measuring method is affected too much by variations in the large particles.  相似文献   

以芳香族重氮盐为电离试剂的常压热解化学电离质谱法的初步研究     

张燮罗明标  王志畅周瑜芬刘淑娟  李建强杨新磊 《华东地质学院学报》2005,28(4):370-376

首次提出采用苯胺、1-幕胺、H-酸重氮盐对甲苯、萘、蒽等稠环芳烃类化合物进行常压热解化学电离质谱研究，考察了热解温度、升温速率、重氮盐用量等对初级离子信号的影响。探讨了常压热解化学电离的一般机理，对所获得的稠环芳烃的自由基阳离子进行了二级质谱鉴定，可以通过二级质谱来对某些同分异构体进行鉴定。该方法对α-苯并蒽的检测限为10fg．可望在无须样品预处理的情况下对包括稠环芳烃和氨基酸在内的非极性和极性化合物进行质谱分析。  相似文献   

Comparison of binding abilities of fulvic and humic acids extracted from recent marine sediments with UO₂     

C. Munier-Lamy  Ph. Adrian  J. Berthelin  J. Rouiller 《Organic Geochemistry》1986,9(6)

Potentiometric titrations were used to measure conditional stability constants of UO₂²⁺-fulvic acid and UO₂²⁺-humic acid complexes. Both 2:1 and 1:1 COO^-:UO₂²⁺ binding were observed. With decreasing metal concentration (2.5·10⁻⁴-6.25·10⁻⁵ M) increasing amounts of UO₂²⁺ were in the form of 1:1 humate complexes and 2:1 fulvate complexes. Despite the high nitrogen content and the low acidic OH group content, the successive stability constant values were similar to those determined for divalent cations associated with fulvic and humic compounds isolated from soils. Stability constant values increase simultaneously with increasing ionization of the humic (or fulvic) acid polyelectrolytes and with decreasing metal concentration.  相似文献   

Vibrational Spectroscopic Analysis of Borates in Mother Liquid of Brine after Potassium Separated     

YU Xiaoping  GUO Yafei  WANG Qin  DENG Tianlong 《《地质学报》英文版》2014,88(Z1):391-392

正It is well known that boron exists as polyborate anions in aqueous solution.Boron atom can coordinates to three or four oxygen atoms and borate can exist as not only the monomer but also the polymer.The polymerization  相似文献   

三维实验模拟双水平井联合法开采天然气水合物     

冯景春  李小森  王屹  张郁  李刚  陈朝阳 《现代地质》2016,30(4):929-936

为研究联合法开采天然气水合物,在水合物三维实验开采模拟平台中利用双水平井进行降压联合注温水开采水合物实验,得到温度和压力分布、产气、产水、三相饱和度变化与开采方法的传热特性。整个开采过程可以分为自由气释放阶段、静置阶段、降压开采阶段和注热开采阶段。研究结果表明在自由气释放阶段和静置阶段有二次水合物生成。在注热阶段,水合物在降压和注热的协同作用下进行分解。反应釜中的水合物最终被完全分解,并且本研究的能效比高于前人利用垂直井进行降压联合热吞吐分解水合物的能效比,表明利用双水平井进行降压联合注温水是一种有效的分解水合物的方法。  相似文献