Objective The gas flow during the exploitation of sour gas fields often contains sour components such as carbon dioxide(CO2)and hydrogen sulfide(H2S),which are easy to form natural gas hydrates(hydrate for short)and cause pipeline blockages.The aim is to solve the problem of unclear mechanisms of sour component absorbers on hydrates,which could provide a theoretical for removing sour gas components and preventing hydrate formation.Methods In this paper,the isothermal and isochoric methods investigated the effects of the mass fraction,stirring state,and initial pressure of N-methyldiethanolamine(MDEA)solution on the absorption law of CO2.The effects of MDEA solution on the growth rate and macroscopic morphology of CO2 hydrate were also studied and compared to the conventional thermodynamic inhibitor ethylene glycol(EG).Results The study indicated that the absorption rate of CO2 showed a trend of increasing and then decreasing with the increase of the mass fraction of the MDEA solution.The stirring state and lower initial pressure could accelerate the absorption rate of CO2 and increase the amount of gas absorption.At the gas-liquid interface,hydrate crystals grew in a two-dimensional mode,and MDEA could change the macroscopic morphology of CO2 hydrates.Increasing the mass fraction of MDEA solution could significantly increase the time for CO2 hydrates to cover the surface of the solution and reduce the growth rate of CO2 hydrates.In contrast to the EG,the kinetic inhibition of MDEA hydrates was poorer,but the cover time of the hydrates film was longer,and the growth rate was slower.Conclusions It is analyzed that MDEA could form hydrogen bonds with water molecules in the solution and compete with hydrates for water molecules,reducing water activity.It could also combine with CO2,and compete with hydrates,significantly decreasing the growth rate of hydrate.The research results have theoretical significance for the guidance of the separation and capture of sour gases and natural gas transportation.
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