Phase equilibrium and dynamic behavior of methane hydrates decomposition via depressurization in the presence of a promoter tert‑butanol

Abstract The vapor–liquid equilibrium (VLE) or vapor–liquid–liquid (VLLE) phase boundaries and the liquid–vapor–hydrate three-phase coexistence pressures are measured at temperatures from 276 K to 285 K for the mixtures of water + methane +9 mass% or 20 mass% of tert ‑butanol, a methane hydrate promoter. The Peng–Robinson equation of state is utilized to correlate the VLE data and then to estimate the methane solubility in the liquid phase before and after methane hydrate decomposition. In the presence of tert ‑butanol, the dynamic behavior of methane hydrate decomposition is also investigated at temperatures from 276 K to 285 K through a depressurization process. During the course of hydrate dissociation, data acquisition system collects the dynamic data, including temperature profile, pressure, and total volume of released methane. A first-order kinetic model represents satisfactorily the hydrate dissociation behavior. It is found that the rate constant of methane-hydrate dissociation significantly increases by using the promoter, tert ‑butanol.