High Efficiency Carbon Capture Solvent and Process for Low Pressure Flue Gas

The Challenge

Carbon Dioxide (CO2) is recognized as a major global warming contributor. Carbon capture and sequestration is part of the solution to reduce emission of CO2 to atmosphere. For high partial pressure of CO2, technologies are already very matured and it is a common practice for engineers to use MDEA and Piperazine to scrub CO2 from high pressure acid gas. However, for low pressure flue gas, such as gas turbine exhaust, we yet have not found a satisfying solution. A traditional approach is to use MEA as the solvent to absorb CO2 in the contactor, and strip off CO2 in the regenerator by heating. The heating duty of MEA solvent is about 4 GJ/tonne CO2. Do we have a better solution to reduce the heat load requirement to capture CO2?

The Solution

Engineers and scientists have been working on two different paths to answer the challenge. One path is to find the solvent that can absorb CO2 strongly and yet strip of CO2 easily with little amount of heat. The other path is to improve plant process design that integrates heat and power efficiently. This paper merges the two paths into one to deliver a complete engineering solution to capture CO2 from low pressure flue gas. The end result is much lower heating duty required to capture carbon dioxide, comparing to MEA.