Experiments and simulations for continuous recovery of methane from coal seam gas (CSG) utilizing hydrate formation

A systematical investigation of a continuous hydrate separation method for recovering methane from Coal seam gas (CSG) is presented. The CSG gas was continuously separated into two gas flows: dissociated gas flow (high CH4 content) and residual gas flow (low CH4 content). The effects of temperature and the concentration of tetra butyl ammonium bromide (TBAB) on the hydrate forming pressure of CSG were investigated. Then the time evolution of the gas compositions and the gas flow rates during long-term operation of the hydrate-based separation was investigated. After that, the effects of different operating conditions (temperature, pressure, the concentration of the TBAB in the solution, the CSG flow rate and the TBAB solution flow rate) on the separation were investigated. The multistage separation process was simulated based on the single stage separation experimental results. The concentration of the CH4 was enhanced from 34.62% to 79.86% in the high CH4 content gas and was reduced from 34.62% to 8.74% in the low CH4 content gas. The recovery rate of the CH4 was 83.94%.