Study On Mixed Absorption Solutions And Technologies For CO₂ Absorption

Carbon dioxide is considered as the major grennhouse gas (GHG) for its massive emission, which causes global warming. Therefore, how to lower CO2 emission to curb global warming, has been the major challenge facing China and the rest countries in the world, and has become immediate areas of reasch focus of researchers in the various fields.In recent years, four amines, involving piperazine (PZ), 1-(2-Aminoethyl) piperazine (AEPZ), diethylenetriamine (DETA) and triethylenetetramine (TETA), have attracted growing interests of researchers because of their high reaction rate with CO2. There are some reported studies indicate these four amines have an excellent performance in CO2 absorption.In this work, firstly, four aqueous amine blends solutions, involving DETA+PZ, DETA+AEPZ, TETA+PZ and TETA+AEPZ solution with a total concentration of 30 wt%, were used for CO2 absorption in packed column. The effect of activator concentration, liquid flow rate, gas flow rate, inlet CO2 concentration and temperature on CO2 capture efficiency were investigated. The results indicate that adding some amount PZ or AEPZ can enhance CO2 capture efficiency compared to individual DETA or TETA solution. However, adding an excess of AEPZ is not favorable to CO2 absorption. From the experimental results, DETA+PZ shows the best performance in CO2 absorption and TETA+AEPZ exhibits the worst.On the basis of experiment results of packed column, we used 25% DETA+5% PZ solution for CO2 absorption in rotating packed bed. The effect of rotation speed of rotor, PZ concentration, liquid flow rate, gas flow rate, retention time of gas, inlet CO2 concentration and temperature on CO2 capture efficiency and KGa were systematically investigated. The experimental results indicate rotation speed, liquid flow rate, temperature, gas flow rate and retention time of gas have a significant effect on CO2 capture efficiency and KGa, and PZ concentration and inlet CO2 concentration and have a non-remarkable impact on these relatively. The appropriate operation conditions are rotation speed of 1000-1200 rpm, liquid flow rate of 11 L·h-1, PZ concentration of 5% and temperature of 40-50 ℃. When gas flow rate increases is 2.0 m3·h-1,CO2 capture efficiency can obtain above 90%. According to experimental results, the experimental correlation of KGa for CO2 absorption in RPB with DETA+PZ was developed, with deviations within 20% compared to experimental results.In addition, comparison of performance in CO2 absorption between RPB and packed column shows RPB have a large advantage in CO2 absorption under the similar operation conditions.