Research On The Model Of Gas-Solid Reaction Of Hydrate Formation From Ice Powders

Due to the formation of gas hydrate from ices can be well controlled and is easier to obtain interfacial area and other parameters in experiments, while a large number of microscopic observation techniques can be used to characterize the properties of the details of this process, hence, the gas hydrate formatting from ices has been focused on. In the relational research on models, the main research direction is a description of the gas hydrate formation under the gas-solid reaction condition and building model based on the shrinking core model. The existing model can be divided into three categories, including models emphasized on that the hydrate formation is controlled by reaction process control, models which focus on gas diffusion process, and models considering both reaction process and diffusion process.This paper was carried out by the following theoretical research:Based on the diffusion theory, a gas-solid reaction model for gas hydrate formation from monosize ice powders was constructed and an effective diffusion coefficient through the gas hydrate shell was obtained by solving the diffusion equation. The model was not only applicable to a gas-solid reaction process with constant temperature and pressure, but also to one with a pressure drop due to gas consumption during hydrate formation, which breaks through the limitations of existing models for constant pressure requirements. In this study, two cases termed as M1 and M2 were discussed and compared with each other. In the M1 case, the spherical particle geometry was assumed to be squeezed by adjacent particles. In the M2 case, the effect of adjacent particles on the object particle geometry was neglected. The calculated results for these two cases were shown to be a little different. The gas effective diffusion coefficient was a critical parameter for accurately simulating the reaction process. It was found to vary during hydrate formation. In this model, the time-dependent gas effective diffusion coefficient was calculated by means of the measured gas pressure during hydrate formation. By solving the model, the degrees of hydrate formation were obtained, and the results corresponded with those gained from experimental data. In addition, the geometrical changes of the hydrate shell and ice powders were obtained during hydrate formation.In addition, this paper also discusses the models of gas hydrate formation from ices built in the cases of adapting to secondary pressurized, secondary heating, and adding surfactant to...