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Study on the three-phase flow of the water transfer export elbow of natural gas hydrate

Chen Wei, Xu Hai-Liang, Wu Bo, Yang Fang-Qiong

Archives of Mining Sciences

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2022

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Vol. 67, no. 2

239--258

EN

The Euler multiphase flow and population equilibrium model were used to simulate the three-phase flow field in the bubble expansion stage of the outlet curved pipe section. The influence of the ratio of the bending diameter and the volume fraction of the gas phase on the pressure loss is revealed, and the safety range of the optimum bending diameter ratio and the volume fraction of the outlet gas phase is determined. The results show that the three-phase flow in the tube is more uniformly distributed in the vertical stage, and when the pipe is curved, the liquid-phase close to the pipe wall gathers along the pipe flank to the outside of the pipe, the solid phase is transferred along the pipe flank to the inside of the pipe, and the gas phase shrinks along the pipe flank to the inner centre. The maximum speed of each phase of the three-phase flow in the elbow is at the wall of the tube from 45° to 60° inside the elbow, and the distribution law along the axial direction of the pipe is about the same as the distribution law of volume fraction. The pressure loss of the elbow decreases with the increase of the bend diameter ratio, when the bend diameter ratio increases to 6, the pressure loss of the pipe decreases sharply, and the pressure loss decreases slowly with the increase of the bend diameter ratio. When the gas phase volume score in the elbow reaches 70%, there will be an obvious wall separation phenomenon, to keep the system in a stable working state and prevent blowout, the gas phase volume score should be controlled within 60%.

2

Main features of gas hydrates

Kutnyi B. A., Abdullah N. M.

Journal of New Technologies in Environmental Science

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2017

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Vol. 1, nr 4

165--170

EN

Natural gas hydrates are specific combinations of two very common substances: water and natural gas. If these substances come into contact at high pressure and low temperature, the solid mass is formed, similar to ice. Huge amounts of hydrate deposits are found in the seabed of the ocean floor and in the polar zones, where they are kept in the thermobaric conditions that permit formation of gas hydrates. Synonymous with the term "hydrate" are gas hydrates, methane hydrates, or clathrates (from the Greek "frame"). The basic structural element of hydrates is crystal lattice of water molecules, inside of which gas molecules are located. Hydrate structure is similar to the structure of ice, but differs from the latter by the fact that gas molecules are located inside the crystal cells rather than between them. Outside hydrates are looking like ice, although they can be seen not frequently. They do not behave like ice. If a match is brought to them, they flash. When conventional hydrocarbon reserves can not provide energy to the growing economy and population, then they will be substituted with the so-called unconventional hydrocarbon reserves in the form of gas hydrates.

3

Natural gas hydrate promotion capabilities of toluene sulfonic acid isomers

Jarrahian A., Heidaryan E.

Polish Journal of Chemical Technology

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2014

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Vol. 16, nr 1

97-102

EN

The purpose of this study was to investigate the natural gas hydrate promotion capabilities of the hydrotrope Toluene Sulfonic Acid (TSA) isomers as an additive. The capabilities of TSA isomers were measured with different concentrations. The optimum additive concentration for hydrate formation was determined for the given pressure, temperature, mixing condition, and cooling time. The natural gas hydrate promotability of para-TSA was found to be 20% and 35% more than meta-TSA and ortho-TSA respectively at the optimum concentration. Beyond the optimum TSA concentration, the hydrate formation declined as the ice formation reduced the overall gas-to-water volume ratio in the hydrates.