Experimental Study on Hydrate Formation with Synthesized CH₄/CO₂/N₂ Ternary Mixtures

Abstract

The variations in the equilibrium conditions of the hydrate phase between different gas components can be employed for gas separation. The use of hydrate-based gas separation technologies for CH4 recovery from biogas has gained prominence. In this study, the formation of a ternary mixture gas hydrate with CH4, CO2, and N2 was studied. The amount of gas consumed and the hydrate formation rate were calculated using pressure and temperature variations during the reaction. Gas composition changes, the CH4 recovery factor, and CO2 split ratio were the key parameters considered to evaluate the technical feasibility of HBGS. Results indicated that the formation of the mixture gas hydrate depends on the driving force between the hydrate equilibrium conditions and operating conditions. The process of hydrate formation can be divided into two stages: Most of the CO2 formed the hydrate in the first stage, and both CH4 and N2 may have entered the hydrate structure in the second stage. For a given gas, the CO2 separation and CH4 recovery could not be optimized for one specific P–T condition. The powder X-ray diffraction measurements indicated that the ternary mixture gas hydrate was an structure I. The experimental results herein can provide data and theoretical support for CH4 purification and CO2 separation from biogas.

Experimental Study on the Dissociation Equilibrium of (CH4 + CO2 + N2) Hydrates in the Mixed Sediments

“…Kvamme et al , explored the thermodynamic limitations of (CO 2 + CH 4 + N 2 )-mixed hydrates after flue gas swapping combining with the actual situation of the Ignik Sikumi field test . Zang et al , measured the hydrate equilibrium data of (CO 2 + CH 4 + N 2 ) in pure water systems. Their results revealed that the increased N 2 and CH 4 content in the gas phase can shift hydrate phase boundary to the inhibited region, and the equilibrium curves of (CO 2 + CH 4 + N 2 )-mixed hydrates were situated between that of pure CO 2 and CH 4 hydrates.…”

Insights into multistep depressurization of CH4/CO2 mixed hydrates in unconsolidated sediments

“…The reason for this was that unconsolidated sand can provide larger surface area between gas and water, causing more thermodynamically favorable CO 2 captured in hydrate [57]. Additionally, differences of RH(CH 4 /CO 2 ) between unconsolidated sand and bulk water were related to gas compositions [52] and P-T conditions [53] besides the factor of porous media. Nevertheless, lower RH(CH 4 /CO 2 ) in unconsolidated sediments implied that CO 2 was more preferably encaged in hydrate than CH 4 .…”

Separation of Xenon from Noble Gas Mixtures of Argon, Krypton, and Xenon Using Gas Hydrate Technology

“…These examples demonstrate the need to conduct further research on the application of gas hydrate technology for gas separation. Currently, a significant number of research articles focus on gas hydrate-based separation, such as methane recovery, methane storage, CO 2 capture , and storage, ,, water treatment and desalination, and separation processes including juice concentration in food technology among other areas of study. , To date, there is still a need to expand knowledge on the potential of gas hydrate technology in separating numerous other gas–gas mixtures, especially noble gas mixtures …”