Analysis of decomposition characteristics of CO₂ hydrate slurry under ultrasonic action

Objective Given the challenge of meeting commercial standards for hydrate extraction due to low efficiency, ultrasonic waves can be employed to catalyze hydrate decomposition through various effects generated during their propagation in the medium. Exploring the characteristics of hydrate decomposition under multiple influencing factors with various interactive relationships, such as ultrasonic power ratios, action durations, and intervals, is of great significance to promoting the application of ultrasonic waves in the hydrate mining process.

Methods Single-factor experiments were conducted to investigate the effects of ultrasonic power ratios, total action durations, single action durations, and intervals on the decomposition characteristics of hydrate slurry. Building on this, the optimal combinations of ultrasonic parameters for promoting the decomposition of CO₂ hydrate slurry were determined through orthogonal experiments and experiments based on the response surface methodology.

Results Gas production from the decomposition of CO₂ hydrate slurry increased with higher power ratios, longer total action durations, longer single action durations, and shorter intervals. The effects of these factors on gas production were identified in descending order as follows: total action durations, single action durations, intervals, and ultrasonic power ratios. The interactive relationships among the factors were found to have influence on the selection of ultrasonic parameters for optimal combinations. Specifically, the optimal combination identified from orthogonal experiments consisted of a power ratio of 70.0％, total action duration of 8.0 min, single action duration of 8.0 s, and an interval of 2.0 s, resulting in a maximum gas production rate of 0.07 mol. In contrast, the optimal combination determined through response surface methodology included a power ratio of 67.7％, total action duration of 7.5 min, single action duration of 7.2 s, and an interval of 5.0 s, yielding a maximum predicted gas production rate of 0.065 mol.

Conclusion The research results provide additional insights to supplement existing studies on the influence of ultrasonic parameters on the decomposition characteristics of hydrate slurry, establishing a crucial theoretical foundation for ultrasonic-assisted hydrate mining.