Absorption Performance For CO₂ Capture Process Using Aqueous Solutions Of Novel Amine Blends

In recent years,climate change and environmental problems caused by the massive emissions of carbon dioxide(CO2)have attracted increasing attention worldwide and the reduction of CO2 has become a global issue.The emission reduction of the large amount of CO2 from fossil-fired power plants is an important way to mitigate the climate change,and has become an important part of implementing the sustainable development strategy in China.The amine-based chemical absorption technologies are considered to be the most robust and promising methods for post-combustion CO2 capture due to their advantages of simple process,technological maturity and large absorption capacity.However,no significant achievement was found in the field of CO2 capture from fossil-fired power plants since the demonstration project in Huaneng Beijing power plant in 2007,due to the high energy cost and high corrosivity in regeneration process.Therefore,interest increased rapidly in development of novel effective absorbents with the advantages of high absorption capacity,low water content and low operation cost.In this thesis,new absorbents were proposed by blending 2-diethylaminoethanol(DEAE)/1-dimethylamino-2-propanol(DMA2P)with monoethanolamine(MEA)/piperazine(PZ).The absorption capacity is a key factor in evaluation of application potential of absorbents.Therefore,time dependence of CO2 absorption amount in DEAE-MEA,DEAE-PZ,DMA2P-MEA and DMA2P-PZ aqueous solutions were measured under different operating conditions in a self-designed reactor.The equilibrium absorption capacity and CO2 loading were determined.The solution concentration and temperature dependences of absorption capacity were demonstrated.The simulated flue gas with different CO2 partial pressures was used.The CO2 absorption performance in DEAE-MEA,DEAE-PZ,DMA2P-MEA and DMA2P-PZ aqueous solutions was measured,and the effects of CO2 partial pressure and trace SO2 on the absorption performance were analyzed.The viscosity and surface tension have significant influence on the design and simulation of tray column.Therefore,the viscosities and surface tensions of DEAE-MEA,DEAE-PZ,DMA2P-MEA and DMA2P-PZ aqueous solutions were measured under different operating conditions,and then correlated by using thermodynamic models.The effect of operating condition on viscosities and surface tensions was demonstrated.Absorption rate is an important parameter to evaluate the performance of absorbent.The apparent absorption rates of CO2 in DEAE-MEA,DEAE-PZ,DMA2P-MEA and DMA2P-PZ aqueous solution were determined based on the time dependence of CO2 absorption amount under series of temperatures,CO2 partial pressure and solution concentrations.The effects of operating condition on apparent absorption rate were demonstrated.The competition mechanism among solution concentration,viscosity and CO2 partial pressure on apparent absorption rate was demonstrated.Verification of CO2 removal efficiency in absorption column is one of the effective methods to evaluate the application potential of absorbents.The CO2 removal efficiency and total volumetric mass transfer coefficient were determined by using a self-designed tray column.The effects of solution concentration,inlet gas flow rate,inlet fluid flow rate and plate number on the removal efficiency and total volumetric mass transfer coefficients were illustrated.Comparison of the absorption performance of CO2 in DEAE-MEA,DEAE-PZ,DMA2P-MEA and DMA2P-PZ aqeuous solutions with that in MEA,MDEA-MEA,MDEA-[N1111][Gly]and DEAE-[N1111][Gly]aqeuous solutions was presented in this thesis.The results showed that those four new absorbents exhibit high CO2 absorption capacity and high apparent absorption rate.Meanwhile,the CO2 removal efficiency in tray column is satisfactory.The new absorbents are promising to improve the CO2 removal efficiency and lower the energy cost,thus have good application potential in CO2 capture process.