Molecular Dynamics Simulation On The Decomposition Of Hydrate Under The Action Of Inhibitor

Natural gas hydrate is an emerging energy source that has attracted widespread attention both domestically and internationally.Its main distribution area is in permafrost regions such as the deep sea and land.After combustion,it only produces a small amount of carbon dioxide and water,which is far less harmful than coal,natural gas,and other resources.Moreover,due to its large reserves,it is widely recognized as a substitute resource for oil and other resources worldwide.However,its existence also has certain hazards.On the one hand,if temperature and pressure are not properly controlled during the extraction process of hydrates,it will cause harm to the environment,such as,it will exacerbate the greenhouse effect,cause seabed collapse,and cause changes in marine ecology.On the other hand,natural gas hydrates tend to cause pipeline blockage during gas transmission pipeline operation,so inhibiting the growth of natural gas hydrates has become a hot research topic.At present,there are mainly heating method,dehydration method,depressurization method,pigging method,and inhibitor injection method at home and abroad to inhibit or delay the formation of hydrates,with chemical inhibitor injection method being the most commonly used.In this paper,the molecular dynamics simulation of s I type methane hydrate under the action of inhibitors will be carried out through Materials Studio software.The thermodynamic inhibitors ethylene glycol（（CH₂OH）₂）,glycerol（C₃H₈O₃）and the kinetic inhibitor polyvinyl pyrimidine（PVP）will be selected.By analyzing the final conformation of the simulation system,the mean square displacement and the radial distribution function,discuss the effects of temperature,pressure,and inhibitor concentration on the rate of hydrate decomposition.The research results indicate that the hydrate can exist stably without adding any substance;after adding the inhibitor,it was found that the decomposition of hydrate can be accelerated by increasing the temperature and decreasing the pressure,and the decomposition of hydrate is best at 25MPa;in addition,when the concentrations of ethylene glycol,glycerol,and PVP are23.7%-30.4%,23.5%-38.7%,and 3.63%,respectively,the decomposition effect of hydrates is better.By comparing the decomposition of hydrates by two thermodynamic inhibitors,it was found that glycerol has a better effect than ethylene glycol.Finally,the synergistic effect of two inhibitors on hydrates was studied.The results showed that the hydrate can be decomposed better with the combination,and the concentration of the two inhibitors used is lower than that when they are used alone.The inhibiting mechanism of the inhibitor combination is the synergistic effect of the rate of hydrogen bond breaking within the hydrate by the thermodynamic inhibitor and the rate of hydrate growth inhibition by the kinetic inhibitor to offset the rate of hydrate growth,thus inhibiting hydrate growth.