A covering liquid method to intensify self-preservation effect for safety of methane hydrate storage and transportation

摘要

In this work,experiments and comprehensive insights into the proposed covering liquid method to intensify self-preservation effect for methane(CH_(4))storage are presented.The CH_(4)hydrate decomposition percentage was 17.6%with the pressure of 0.61 MPa after 12 h at 266.0 K without a covering liquid,which can be reduced to 12.4%,13.8%,13.0%,and 8.3%with the pressure of 0.26 MPa,0.33 MPa,0.51 MPa,and 0.37 MPa by covering with tetrahydrofuran(THF),cyclopentane(CP),cyclohexane,and n-tetradecane,respectively.When the temperature for CH_(4)hydrate decompositionwas 274.2 K,covering with THF,CP,cyclohexane,and n-tetradecane failed to inhibit CH_(4)hydrate decomposition.The results suggested that the covering liquid may form a new solid layer(a hydrate layer or other solidified layer)around the CH_(4)hydrate,which inhibit CH_(4)transfer below the freezing point of water.However,the new solid layer cannot resist the fast transfer of CH_(4)from decomposed CH_(4)hydrate above the freezing point of water.The same phenomenon was also observed in a sodium dodecyl sulfonate(SDS)-dry solution CH_(4)hydrate formation system.Therefore,the covering method can only intensify the self-preservation effect below the freezing point of water,but cannot generate a self-preservation effect.