| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 101 === In this study, an apparatus which can be operated at high pressure and low temperature conditions was built and operated to measure the thermodynamic properties of liquid water-hydrate-vapor (Lw-H-V) three-phase dissociation temperatures and pressures for cabon dioxide hydrate in the presence of additives by employing the isochoric method, and the kinetic formation rate of carbon dioxide hydrates was measured by the method of pressurization in isochoric system.
In thermodynamic work, two cyclic ketons(Cyclopentanone and Cyclohexanone), three cyclic ethers (1,3,5-Trioxane, 2,5-Dihydrofuran and 1,3-Dioxolane) and 2-Methyl-2-Propanol were chosen as additives. The experimental results showed that the addition of Cyclopentanone, 1,3,5-Trioxane, 2,5-Dihydrofuran and 1,3-Dioxolane in carbon dioxide system had effective promotion effects on formation of carbon dioxide in comparison with pure water system at a given pressure, and they could broaden the hydrates stability region. Furthermore, the promotion effect could increase as the concentration of additives increased. With concentration of 15wt% Cyclopentanone, 1,3,5-Trioxane, 2,5-Dihydrofuran and 1,3-Dioxolane additives, the dissociation temperatures were increased about 6.9 K、6.4 K、8.1 K and 5.6 K respectively. In addition, the hydrate dissociation conditions for brine systems with 3.5 wt% NaCl were also measured in this study. The promotion effect for carbon dioxide hydrate formation in brine environments were also observed with cyclic ether additives. However, the promotion effects in the presence of cyclic ether additives in the salt system was less than those in the pure water system. On the other hand, the inhibition effects were observed when adding Cyclohexanone and 2-Methyl-2-Propanol in carbon dioxide system; the equilibrium conditions shifted to higher pressure and lower temperature in comparison with pure water system. The dissociation temperature for additions of Cyclohexanone and 2-Methyl-2-Propanol in carbon dioxide systems decreased respectively 0.5 K and 2.2 K at most at a given pressure in comparison with those in pure water system.
It seemed that 2-Methyl-2-Propanol could increase the quantity and the formation rate of carbon dioxide hydrates in thermodynamic results so 2-Methyl-2-Propanol was chosen as additive in kinetic experiments. The kinetic results proved 2-Methyl-2-Propanol could reduce the induction time of forming carbon dioxide hydrates in comparison with pure water system, and hydrate formation rate and amount of hydrate forming in 2-Methyl-2-Propanol system increased about twofold than pure water system. In conclusion, 2-Methyl-2-Propanol was effective kinetic promoter to form carbon dioxide hydrates in this work.
|
|---|
