Rapid and continuous generation of methane hydrates under low pressure promotes the efficient capture of associated petroleum gas (APG)

Hydrates provide a new solution for the capture of associated petroleum gas, but poor generation efficiency of CH4 hydrates under low pressure impedes their application. In order to achieve hydrate rapid and continuous generation under low pressure, a new hydrate generation process was presented. The thermodynamic promoters of tetrahydrofuran (THF) and 1,3-dioxolane (DIOX) were used to reduce hydrate generation pressure, while hydrate generation kinetics were enhanced by a nano promoter (-SO3-@PSNS), and a spiral-agitated reaction equipment was applied to achieve the integration of hydrate generation, separation and storage. Hydrate structures were evaluated by Raman spectra, and THF or DIOX hydrates were found to form first within the initial 2–5 min before CH4 molecules enter hydrate cages. Exceptional hydration efficiencies were obtained at 1.5 MPa, and the t90 for mixed CH4/THF and CH4/DIOX hydrates are only 29.3 min and 51.6 min, respectively. Hydrate conversion ratios in the storage tank are separately 56.9 % and 52.3 % for mixed CH4/THF and CH4/DIOX hydrates, and CH4 storage densities increase by 185 % and 182 % compared with compressed CH4. Ultimately, the proposed process makes hydrate rapid and continuous generation under low pressure to be possible, it would accelerate the application of hydrates in APG capture.