Re-Engineering the alkanolamine absorption process to economize carbon capture
Hirasaki, George J.
Doctor of Philosophy
Climate change caused by carbon dioxide (CO2) released from the combustion of fossil fuels threatens to have a devastating impact on human life. Power plants that burn coal and natural gas to produce electricity generate more than half of global CO2 emissions. Separating the CO2 emitted at these large sources of emission, followed by long term storage has been proposed as short to medium term solution to mitigate climate change. Implementation of this strategy called 'Carbon Capture and Storage' would allow the continued use of fossil fuels while simultaneously reduce our CO2 emissions. Technologies such as the alkanolamine absorption process, used to separate CO2 from gas mixtures already exist. However, it is presently infeasible to use them for Carbon Capture and Storage due to their relatively large energy consumption. It is estimated that even with the use of state-of-the-art technology, the cost of electricity will increase by around 90%. The research presented in this dissertation is focused on developing novel strategies to limit the increase in the cost of electricity due to implementation of Carbon Capture and Storage. In order to achieve this objective, a process simulation software; ProMax® has been used to optimize the alkanolamine absorption process to suit Carbon Capture application. A wide range of process operating conditions has been analyzed for their effects on energy consumption. Included in this study are process conditions under which waste heat can be utilized for providing energy instead. Based on this analysis, some of the most energy efficient process configurations have been identified for an economic evaluation of their capital costs. This research has also led to the invention of novel absorbent blends which involve the replacement of water used in CO2 absorbents with alcohols. It has been shown that the use of these absorbents can significantly reduce energy consumption and thereby limit the increase in cost of electricity.