添加 2,5-二氫呋喃、3,4-二氫-2H-吡喃與異丙胺對於甲烷水合物分解狀態之實驗量測

Abstract

This study demonstrated the equilibrium conditions for the formation of methane hydrates in the presence of cyclic ethers and alkyl amine, i.e. 2,5-dihydrofuran, 3,4-dihydro-2H-pyran and isopropylamine. The three-phase (H-Lw-V) and the four-phase (H-Lw-La-V) equilibrium data in methane + water + additives systems were measured by using isochoric method in the range of pressures from 6 to 12 MPa and temperature up to 301 K. When 2,5-dihydrofuran, 3,4-dihydro-2H-pyran and isopropylamine were added into methane hydrates systems respectively, the hydrate equilibrium temperatures showed a large increase approximately 13 K for 2,5-dihydrofuran, or 3,4-dihydro-2H-pyran and 5 K for isopropylamine at a specific pressure. The experimental results presented that 2,5-dihydrofuran, 3,4-dihydro-2H-pyran and isopropylamine had great promotion effects on the formation of methane hydrates.Moreover, in order to stimulate the sea-water environment, the methane + 3.5 wt% NaCl+ additive systems, for example, 2,5-dihydrofuran or 3,4-dihydro-2H-pyran, were measured to acquire the equilibrium data of methane hydrate dissociation. With the existence of 3.5 wt% NaCl, the equilibrium temperature of the brine system reduced 1 to 2 K compared to the original system.On the other hand, we also showed the phase equilibrium data of the methane +water+ 2,5-dimethoxytetrahydrofuran system and the methane +water+ N,N-diethylhydroxylamine. At a given pressure, the equilibrium temperature of two ternary systems both shifted the H-Lw-V phase boundary to the lower temperature region than the methane +water binary system. The measured pressure range is 8 to 14 MPa. Finally, the experimental results revealed that 2,5-dimethoxytetrahydrofuran and N,N-diethylhydroxylamine are both inhibitors for methane hydrates. The greatest reduction of the equilibrium temperature when 20 wt% N,N-diethylhydroxylamine was added into methane hydrates is approximately 5 K at a specific pressure.