CO2 Capture Using PZ/DETA Mixture from Flue Gas of Natural Gas Power Plants in a Rotating Packed Bed

• Main Authors: Wu, Tsai-Wei, 吳采薇
• Other Authors: 談駿嵩
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/08918926879009853814

碩士 === 國立清華大學 === 化學工程學系 === 102 === Capture of CO2 from natural power plants flue gas by mixed aqueous alkanolamine in a rotating packed bed (RPB) in place of conventional packed bed (PB) absorber was studied. Piperazine (PZ) and Diethylenetriamine (DETA) with fast reaction rate and high CO2 capacity were mixed as CO2 absorbent, and the concentration of alkanolamine was raised in experiments to study the effects of concentration on CO2 capture and absorbent regeneration. In order to figure out the feasibility of RPB in substitution for PB, Aspen Plus simulation of CO2 capture in packed bed using MEA as absorbent was carried out, and the results were compared with RPB experiments results at the same operating conditions. Concentration of PZ/DETA mixed absorbents was raised from 2.5 m/2.07 m to 4 m/8 m, and the results showed that the absorbent with the best capture efficiency is PZ/DETA (4 m/6 m) when lean loading is 0, whereas when lean loading is about 0.5, the best CO2 capture absorbent is PZ/DETA (4 m/4 m). Although raising the concentration of absorbents may increase CO2 solubility and driving force for CO2 absorption, the viscosity also increases when raising up the concentration and lean loading of absorbents, leading to the increment of CO2 diffusive resistance and the advantages of raising the concentration was overwhelmed. Results from Aspen Plus simulation showed that at the same operating conditions, PB requires bigger volume than RPB to achieve same capture efficiency, and it’s more significant when lean loading is high, with PB volume reaching 4.6 times of RPB volume. Moreover, capture efficiency is better in RPB than in PB when the two reactors’ volumes are the same. Similarly, the difference of capture efficiency in two reactors is more significant when lean loading is high, reaching 63%. Effect of increasing gas flow rate on CO2 capture amount was also studied. If there is no limit to CO2 capture efficiency in CO2 absorption process, increasing gas flow rate can make CO2 capture amount upgraded to more than two times. And for RPB and PB with same volume, operating at high gas flow rate, the increased level of CO2 capture amount is more significant along with the increment of lean loading, reaching 4.6 times at most. The results above showed that the feasibility of RPB in place of PB is high. Comparison of absorption effects and regeneration energy of every absorbent showed that PZ/DETA (4 m/4 m) can be regenerated with 54.8% lower energy than conventional absorbent 30 wt% MEA. With its high CO2 capture efficiency and CO2 capacity, PZ/DETA (4 m/4 m) is an absorbent with potential.