Simulation and Experimental Study of Methane-Propane Hydrate Dissociation by High Pressure Differential Scanning Calorimetry

Abstract

Binary and ternary systems composed of methane-water and methane-propane-water, respectively, were studied using high pressure differential scanning calorimetry. The methodology was validated by comparing results for the binary system to experimental data obtained in the literature. The hydrate dissociation temperatures for the ternary system (methane-propane-water) at 21 MPa were experimentally determined for different compositions of the gas mixture and mole fractions of propane higher than 0.1 in the ternary system. Our results are in good agreement with the values predicted by applying the Cubic Plus Association (CPA) equation of state coupled with van der Waals-Platteeuw model for the hydrate phase. Although experimental results are considered satisfactory for both binary and ternary systems, higher deviations between our values and the simulated ones for the ternary system, considering peak temperature instead of the extrapolated onset as the hydrate dissociation temperature, are believed to be a consequence of dynamic effects that promote the formation of a heterogeneous hydrate and are negligible for the binary system.

Minireview on the Thermodynamic and Kinetic Modeling of Ionic Liquid Promoted Inhibition of Gas Hydrate Formation

“…Menezes et al explored the high pressure dissociation of methane and propane hydrate by the CPA EoS. The hydrate phase is modeled by the vdW-P model.…”

“…The hydrate phase is modeled by the vdW-P model. Due to the bigger molecular size, propane fits into larger cavities of gas hydrate (5 12 6 4 ), and methane occupies the smaller cavities (5 12 ) . Hence thermodynamic stable configurations are formed when methane occupies small cavities and propane occupies large cavities.…”

“…X i A represents the fraction of sites A on molecule i which do not form bonds with other active sites, and the expression is similar to that used in SAFT-based models. 4 Menezes et al 48 explored the high pressure dissociation of methane and propane hydrate by the CPA EoS. The hydrate phase is modeled by the vdW-P model.…”

“…Due to the bigger molecular size, propane fits into larger cavities of gas hydrate (5 12 6 4 ), and methane occupies the smaller cavities (5 12 ). 48 Hence thermodynamic stable configurations are formed when methane occupies small cavities and propane occupies large cavities. However, the occupancy of large and small cavities is also dependent on the molar ratio of methane and propane.…”

Effect of Cyclopentane Hydrates on the Stability of Dodac and Aot Structures

“…So, the systems formed are emulsions, with the structure similar to the one shown schematically in Figure 7. Menezes et al (2018) has verified that the formation of methane hydrate by crystallization is limited by the interface area between the water and the gas. This interfacial area may change according to the size and disposition of the water droplets.…”