Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.

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The thermodynamic stabilities of semiclathrate hydrates were investigated in the tetra-n-butyl ammonium chloride (TBAC) aqueous solution (mole fraction of TBAC is 0.0323) + H2, + N2, + CH4, + CO2, and + C2H6 systems. The dissociation temperature of each semiclathrate hydrate is higher than that of the simple TBAC semiclathrate hydrate (hydration number is 30) except for the C2H6-containing system in the whole pressure region under the present experimental conditions. Isobaric dissociation temperatures of the TBAC + H2, + N2, + CH4, and + CO2 hydrates increase in this order. The temperature−pressure projection indicated that the hydrate structural transition occurs around 3 MPa in the TBAC + CH4 semiclathrate hydrate system, while the three-phase equilibrium curves of the other TBAC hydrate systems do not show any discontinuity in gradient under the present conditions.

The authors reviewed the correlations of power consumption in unbaffled and baffled agitated vessels with several kinds of impellers, which were developed in a wide range of Reynolds numbers from laminar to turbulent flow regions. The power correlations were based on Kamei and Hiraoka's expressions for paddle and pitched paddle impellers. The calculated correlation values agreed well with experimental ones, and the correlations will be developed the other types of impellers.