Effect Of Ultrasound On The Formation Process Of CO₂ Hydrate

Hydrate technology can be applied to the fields of replacement of natural gas,gas separation,desalinated seawater,gas storage and transportation,and the hydrate technology is simple to operate and has no pollution to the environment,which has attracted the attention of many researchers.The growth conditions of gas hydrates are harsh,the induction period is long,the formation rate is low,and the conversion rate is low.In order to enable the rapid formation of hydrates,the researchers found that the ultrasonic waves can significantly increase the rate of hydrate formation.Therefore,the effect of ultrasound on the formation process of CO2 hydrate is studied under the self-designed test bench.Under the different experimental temperatures,the effects of different subcooling on the formation of CO2 hydrate were studied when ultrasonic waves with the same parameters were input.Under the condition of pressure of 2 MPa and temperature of 276 K,the influence of ultrasound with different parameters on the formation of CO2 hydrate was studied.The parameters were ultrasonic power ratio,total ultrasonic action time,ultrasonic input time and ultrasonic gap time.Through experimental research,it is found that:(1)the input of ultrasonic waves can rapidly produce CO2 hydrate under conditions of less subcooling.The greater the degree of subcooling,the more the amount of CO2 hydrate formed,the faster the reaction rate,the more the formation of CO2 hydrate can be promoted;(2)With the increase of ultrasonic power ratio and the increase of total ultrasonic action time,the gas consumption showed a trend of decreasing first and then increasing.When the power ratio was 70%and the total action time was 8 min,the formation rate of CO2 hydrate was the largest.With the increase of each ultrasonic action time,the gas consumption increases,and the CO2 hydrate formation reaches the maximum when the action time is 8 s.With the increase of the gap time,the gas consumption shows a trend of increasing and then decreasing.The gap time of 5 s is the best condition to promote the formation of CO2 hydrate.(3)The effect of ultrasonic on the formation of CO2 hydrate can be obtained by orthogonal test.The most important factor is the time of each ultrasound,then the total action time>gap time>ultrasound power ratio.The optimal combination is that the ultrasonic power ratio is 70%,the total action time is 1Omin,the ultrasonic time is 3 s,and the gap time is 5 s.