Investigation On Carbon Dioxide Capture Using Non-aqueous Amine Absorbent And Phase-change Absorbent In Rotating Packed Bed

In recent years,the greenhouse effect has become more serious with the large amount of CO2 emissions,which has a severe impact on the ecological environment.Currently,chemical absorption is the most widely researched CO2 capture technology in industry,especially for aqueous alcoholamine solutions.However,the volatility of aqueous alcoholamine solutions,the corrosion of equipment and the high regeneration energy consumption have limited their industrial application.The use of non-aqueous solvents or phase-change absorbents for CO2 capture has been found to have the potential to reduce the volatility and corrosiveness of solvents and decrease regeneration energy consumption,which can be used to compensate for the shortcomings of aqueous alcoholamine solutions.In this work,2-amino-2-methyl-1-propanol(AMP)-2-((2-aminoethyl)amino)ethanol(AEEA)-N-methyl pyrrolidone(NMP)non-aqueous absorbent and monoethanolamine(MEA)-1-butyl-3-methylimidazolium tetrafluoroborate([Bmim][BF4])-water(H2O)phase-change absorbent were used for CO2 absorption and desorption experiments in a rotating packed bed(RPB).The effects of different operating conditions on the absorption and desorption performance of the absorbents were investigated and a preliminary evaluation of their regeneration energy consumption was carried out.The main findings of the experiment were as follows.1.In absorption experiments with AMP-AEEA-NMP non-aqueous absorbent,the CO2 capture efficiency and KGa decreased with the increase of gas-liquid ratio and lean CO2 loading;the CO2 capture efficiency and KGa increased with growing rotation speed;the CO2 capture efficiency increased and KGa decreased with the increase of gas residence time;the CO2 capture efficiency and KGa first increased and then decreased with increasing absorbent temperature.When the lean CO2 loading was 0.035 mol CO2/mol amine,the CO2 capture efficiency were around 90%for the diffierent inlet CO2 concentrations of 5%,14%and 20%.It shows that the absorbent has good absorption performance.2.In desorption experiments with AMP-AEEA-NMP non-aqueous absorbeent,the increase in rich solvent flow rate,rotation speed,stripping steam flow rate,steam superheat temperature and rich solvent loading all had a positive effect on the CO2 regeneration process,but with growing values of the operating conditions,each factor will have no significant promotion effect on CO2 regeneration process,or even a negative effect,increasing the regeneration energy.In this experiment,the regeneration energy of this absorbent can be reduced to 2.46 GJ/ton CO2,which is 36.6%lower than that of 30%MEA in conventional packed tower process.3.The concentration of MEA was fixed at 30 wt%.The composition of the phase change absorbent was optimised by investigating the CO2 loading when liquid-liquid partitioning occurred and the absorption performance in RPB with different[Bmim][BF4]mass fractions of the absorbent.And the 30wt%MEA-30wt%[Bmim][BF4]-40wt%H2O absorbent system was selected for further investigated in absorption-desorption experiments under different operating conditions.4.The absorption experimental results showed that the CO2 capture efficiency and KGa decreased as the gas-liquid ratio increased;the CO2 capture efficiency and KGa increased as the rotation speed and absorbent temperature raised,and the CO2 capture efficiency rose and KGa reduced as the gas residence time increased.5.It is assumed that completely material transfer of MEA,the carbamate and[Bmim][BF4]is achieved during the liquid-liquid partitioning process.The desorption experiments were investigated by bubbling the rich solution of 42wt%MEA.In desorption experiments,the increase in rich solvent flow rate,rotation speed,stripping steam flow rate and steam superheat temperature all had a positive effect on the CO2 regeneration process,but the regeneration efficiency gradually decreased as the rich solvent flow rate increased.In this experiment,the regeneration energy of this absorbent can be reduced to 2.62 GJ/ton CO2,which is 32.5%lower than that of 30%MEA in conventional packed tower process.