Determination of Structure and Formation Conditions of Gas Hydrate by Using TPD Method and Flash Calculations

توضیحات

Abstract
In this work, satbility calculations and determination of gas hydrate structure in equilibrium conditions by using minimization of TPD function for  ethane-water system (SI), propane-water system (SII) and methane-methyl cyclo pentane-water system (SH) were performed. Based on results, at 274 K and 275 K temperatures, the liquid phase of methane-water system at 27 bar and 30 bar pressures, propane-water system at  .7 bar and 2.5 bar pressures and methane-methyl cyclo pentane-water system at 9.6 bar and 10.1 bar pressures was decomposed. As a result  of decomposition of liquid phase for these systems, two new phases, a new liquid phase and hydrate phase were formed. Subsequently,  multiphase flash calculations in order to determine the amount and composition of stable phases in equilibrium state were performed. For minimization of TPD function, Algorithm Genetic was used. The results Show good accuracy with data of Heriot Watt university hydrate model   (HWHYD).

Introduction

Gas hydrates are ice-like crystalline structures that forms in the presence of light gases such as methane and ethane or non-hydrocarbons gases  such as nitrogen and carbon dioxide with water. These gases are trapped in several different cages that forms different crystalline  structures like sI, sII or sH. Stability of gas hydrate crystalline is the result of hydrogen bonds between water molecules and van der waals forces  between water and gas molecules in structure lattice of hydrate. After designing the first gas transfer pipeline, blockage of pipelines with gas  hydrate by Hammerschmidt  in United State was introduced. Subsequent to this phenomenon, methods of prevention of gas hydrate  formation  n pipelines were studied. For the first time, thermodynamic principles of gas hydrate by Van der waals and Platteeuw  were studied.  Because of the problems that were the result of gas hydrate formation, many studies about prediction of gas hydrate formation conditions and  stability of gas hydrate were performed. Michelsen proposed a method for stability analysis calculations at certain temperature and pressure. This  ethod is based on minimization of tangent plane distance from Gibbs energy surface (TPD method).

Year: 2013

Publisher :  2nd National Iranian Conference on Gas Hydrate (NICGH)

By : H. Behjati Rad, F. Varaminian

File Information: English Language/ 15 Page / size: 559 KB

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سال : 1392

ناشر : دومین کنفرانس ملی هیدرات گاز (NICGH)

کاری از : بهجتی راد، فرامرزی ورامینین

اطلاعات فایل : زبان انگلیسی / 15 صفحه / حجم : KB 559

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