Optimization and Modeling of Helium Recovery from Natural Gas Through Hydrate-Based Gas Separation

Area of Science:

• Chemical Engineering
• Materials Science
• Energy Resources

Background:

• Helium is a finite strategic resource extracted from natural gas (NG), but its low concentration in NG poses separation challenges.
• Traditional separation methods are inefficient for low-helium NG, necessitating advanced techniques.

Purpose of the Study:

• To investigate the feasibility and optimize hydrate-based gas separation (HBGS) for efficient helium extraction from simulated NG.
• To analyze the thermodynamic and experimental performance of HBGS with tetrahydrofuran (THF) as a thermodynamic promoter.

Main Methods:

• Thermodynamic analysis of hydrate equilibrium pressure with varying THF concentrations.
• Single-stage and three-stage HBGS experiments using simulated NG with low helium content.
• Development and validation of a mathematical model to predict HBGS performance.

Main Results:

• Tetrahydrofuran (THF) significantly reduced hydrate equilibrium pressure by 92.11%.
• High THF concentration, low temperature, and high pressure enhanced gas processing capacity and helium purification but reduced recovery.
• The "hydrate shell effect" limited HBGS performance; optimizing the gas-liquid ratio improved helium concentration without sacrificing capacity but decreased recovery.
• Three-stage HBGS optimization resulted in a 25.07-fold helium enrichment (0.54 mol% to 13.54 mol%) and 87.34% recovery.
• The developed mathematical model predicted HBGS performance with a 2.09% average relative error.

Conclusions:

• HBGS is a promising technology for separating helium from low-concentration NG.
• Optimizing process parameters like THF concentration, temperature, pressure, and gas-liquid ratio is crucial for balancing helium enrichment and recovery.
• The developed mathematical model provides accurate predictions for HBGS performance, aiding in process design and scale-up.