Analysis of Gas Source for the Replacement of CH4 with CO2 in Gas Hydrate Production from the Perspective of Dissociation Enthalpy

The dissociation enthalpies of CH4 hydrate, CO2 hydrate, and CO2–N2 mixture gas hydrate in the simulated submarine environment were calculated using their phase equilibrium data and the Clausius–Clapeyron equation. The results show that the dissociation enthalpy is related to the hydrate stability; that is, the ions in salt solution or seawater can reduce the dissociation enthalpy, while the effect of sediments on the dissociation enthalpy depends on the particle size in that the dissociation enthalpy is lower in sediments with smaller particle size. From the perspective of dissociation enthalpy, flue gas from a power plant can be directly used as the CO2 gas source for the replacement of methane in natural gas hydrate production, with the addition of a trace of tetrabutyl ammonium bromide (TBAB) additive without the use of pure CO2, so as to meet the required heat of CH4 hydrate exploitation and save energy for separating CO2 in flue gas.