Kinetic Study On The Formation Of Carbon Dioxide Hydrate In An Impinging Stream Reactor

In recent years,climate warming has become increasingly severe.Reducing the emission of greenhouse gases,particularly carbon dioxide,is the most serious environmental problem.The absorption of carbon dioxide by hydrate is a new separation technology,which has the advantages of high separation efficiency and simple process.However,there are still many problems from laboratory research to industrial application,such as slow hydrate formation,high energy consumption and large cost of gas compression.The formation of hydrates is a typical gas-liquid-solid multiphase reaction process,involving multiphase heat and mass transfer.Therefore,the enhancement of multiphase transport process could promote the formation of hydrates.From the traditional stirring,spraying,bubbling,to the recent continuous-jet,high gravity,and so on,the new hydrate reactors are also being developed.Impinging stream technology is a new development of the enhancement method in recent years.The interphase relative speed is extremely high,and which can effectively enhance the interphase transfer.It has been successfully applied to the chemical industry such as combustion,crystallization and mixing.In this work,it is the first time that impinging stream technology has applied in the field of hydrate formation.A new type of vertical irrotational liquid-continuous impinging streams hydration reactor was designed and manufactured.The research object was carbon dioxide hydrate,the kinetic characteristics of carbon dioxide hydrate formation in the impinging stream reactor were investigated.The pressure changes in the system during the process of hydrate formation under different conditions of temperature,pressure,and rotating speed?impinging strength?were investigated,and the kinetic parameters such as gas consumption,hydration rate constant,space velocity and activation energy were analyzed.The following results have been obtained through experimental research:?1?The kinetic characteristics of hydrate formation at different temperatures were investigated.The results showed that the effect of temperature on the pressure changes in the system during the hydration process was weak.?2?The kinetic characteristics of hydrate formation under different initial pressures were investigated.The results showed that with the increase of initial pressure,the pressure in the system decreased fast.The gas consumption and hydration rate constants had a linear relationship with the initial pressure.Increasing the initial pressure increased the fugacity of the initial state,which improved the fugacity difference between the initial state and the equilibrium state,thus increased the driving force of the hydration reaction,and accelerated the formation of hydrate.Therefore,increasing the initial pressure could effectively promote the formation of hydrates.?3?The kinetic characteristics of hydrate formation under different rotating speeds?impinging strength?were investigated.The results showed that with the increase of the rotational speed?impinging strength?,the pressure curve of the system became steeper and the pressure difference between the initial state and the final state was also increased.The gas consumption increased with the increase of rotating speed,and had a linear relationship.However,the hydration rate constant first increased and then decreased.The maximum value of the hydration rate constant was 7.05×10^-8 mol²/?s·J?,at this time the rotational speed was 600 r/min,and the impinging strength was 0.21,and the hydration reaction rate was the fastest.?4?The larger the initial pressure and the faster the speed,the space velocity of the hydration reactor increase with the linear relation.?5?Kinetic analysis of the formation process of carbon dioxide hydrate was carried out.The activation energy E_a of hydrate formation under this experimental condition was 24.74 kJ/mol.The kinetic characteristics of CO₂ hydrate formation in liquid-continuous impinging stream reactor were investigated,and the application fields of the impinging stream technology were extended,and new options for carbon dioxide capture were provided.