염분 변화에 따른 가스 하이드레이트의 상평형 변화에 관한 연구

Abstract

The main methods of seawater desalination is either the evaporation using large amounts of fossil fuel or reverse osmosis (RO). For both of them, high energy consumption is inevitable. Therefore, a desalination process without the use of the above methods has been proposed using gas hydrate formation. Gas hydrates are inclusion compounds where small object gas molecules are encaged by hydrogen-bonded host water frameworks. Object gases are methane, ethane, propane, and SF6, R-134a, and so forth. They are classified as three different types, having two cubic structures (CS-I and CS-II) and one hexagonal structure (H). For example, the structure CS-I is composed of two polyhedral cavities, 512 (12 pentagonal faces) and 51262 (12 pentagonal and 2 hexagonal faces). In this work, three-phase (liquid phase – hydrate – gas phase) equilibria of CO2 and R-134a (1,1,1,2-tetrafluoroethane, HFC-134a) gas hydrates in artificial seawater are measured and how the three-phase equilibria are affected by the seawater concentration is discussed Using artificial sea salt, seawater samples of different concentrations were prepared. The reactor filled with 50 mL of artificial seawater reaches a steady state with CO2, stirred enough to be melted. At the steady state, temperature falling is observed at regular intervals and the changes in temperature and pressure of the reaction are recorded in real time on the computer. The same procedure was repeated at each seawater concentration.