Новые методы получения газогидратов

Abstract

Investigations of hydrate formation and dissolution processes behind the shock wave of moderate amplitude in the water with bubbles of hydrate-forming gas under different initial static pressures and temperatures were made both experimentally and theoretically. A model of the process is presented. The numerical solution of the problem for the environment with bubbles of Freon-12, a mixture of carbon dioxide and carbon dioxide with nitrogen for various initial conditions and operational parameters of the process were obtained. The calculated results are in good agreement with the experimental data. The generalization of the experimental data on the gas content of the profiles behind the shock wave, the time of dissolution and hydrate forming were made based on the calculations of the proposed model. It is shown that the intensification of the process of hydrate formation is due to the fragmentation of the gas bubbles in the wave front, leading to a sharp increase in the interface area, as well as the appearance of movement relative to the liquid bubbles shattering. Hydrate formation is due to the sorption growth of hydrate film on the surface of the formed gas inclusions, the speed of the process is determined by the kinetic parameters, and heat and mass transfer at the interface is very important. The characteristic time of a hydrate formation behind the shock wave is several orders of magnitude shorter than the hydrate formation time in the known methods of obtaining hydrates and it is few milliseconds. It is shown that with increase in amplitude of the shock wave, and also with a decrease in temperature of the medium the dissolution rate of hydrate formation increases. Fraction of the gas passing into the hydrate state is the greater the greater the initial static pressure in the medium and amplitude of the shock wave. In the experimental research on the production of various types of gas hydrates using the method of explosive boiling ozone friendly refrigerant R134a hydrate, gas hydrate of carbon dioxide and propane gas hydrate were obtained. Additional research on the dynamics of degassing of samples at their expansion confirmed presence of significant gas hydrate content in the solid phase. The data obtained can be used for modeling of shock-wave processes in two-phase media for the formation of gas hydrates and the establishment of facilities for their production.