توضیحات
ABSTRACT
A thermodynamic model for predicting pressure – temperature phase diagrams of structure II and structure H clathrate hydrates of methane, carbon dioxide, or hydrogen sulfide in the presense of “water-insoluble” organic componds is presented. The model is based on equality of water fugacity in the aqueous and hydrate phases. The solid solution theory of van der Waals – Platteeuw (vdW-P) is used for calculating the fugacity of water in the hydrate phase. The PengRobinson (PR) equation of state (EoS) is employed to calculate the fugacity of the compounds in gas phase. It is assumed that the gas phase is water and promoter free and the organic compounds do not have considerable effects on water activity in liquid phase. The results of this model are finally compared to existing experimental data from the literature. Acceptable agreement is found between the model predictions and the investigated experimental data.
INTRODUCTION
Clathrate hydrates are inclusion compounds, which are composed of H2O and guest species . They are stabilized by the guest molecules enclathrated in the hydrogen-bonded water cages. At relatively high pressures and low temperatures, water molecules form various crystalline structures generally depending on the size and shape of the guest molecule(s) . Three common structures, structures I (sI), II (sII), and H (sH) are known to form, as a function of the size and shape of the guest molecules . sI and sII contain two types of cavities (small and large) while sH contains three types of cavities (small, medium, and large) . Recently, novel technologies utilizing gas hydrates have been proposed. These clathrate structures may be used as media for the storage and transportation of natural gas and even hydrogen . Therefore, various experimental and theoretical investigations have been done so far to determine the phase equilibria of corresponding systems and the capacity of gas storage in hydrate structures. Mooijer-van den Heuvel et al. studied the formation of sII gas hydrates of cyclic organic compounds like tetrahydropyran (THP) and cyclobutanone (CB).
Year: 2013
Publisher : 2nd National Iranian Conference on Gas Hydrate (NICGH)
By : Arash Kamran-Pirzaman , Amir H. Mohammadi , and Hassan Pahlavanzadeh
File Information: English Language/ 12 Page / size: 531 KB
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سال : 1392
ناشر : دومین کنفرانس ملی هیدرات گاز (NICGH)
کاری از : آرش کامران-پیرزمان، امیرحسین محمدی و حسن پهلوان زاده
اطلاعات فایل : زبان انگلیسی / 12 صفحه / حجم : KB 531
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