Recent publications demonstrated that human emissions of greenhouse gases (GHG) are very likely warming our planet and therefore actions to mitigate such emissions are needed. Carbon dioxide (CO2) is the main GHG produced by the combustion of fossil fuels in power and energy production facilities. It is anticipated that until 2030, fossil fuels will be the dominant source of energy, and that's why it is becoming crucial to develop technologies that reduce CO2 emissions [1,2]. CO2 can be potentially captured and then sequestered from fuel or flue gas streams using solid-based or solvent-based processes. The solvent-based processes include (1) chemical solvents; (2) physical solvents; and (3) mixed chemical/physical solvents.
The focus of this study is on physical solvents for CO2 capture from fuel gas streams. Ionic liquids are our physical solvent of choice because they have: (1) low vapor pressure to prevent solvent loss; (2) high selectivity for CO2 when compared with those of CH4, H2 and CO in the fuel gas stream; (3) low viscosity at the system temperature to minimize solvent pumping cost; (4) thermal and chemical stability to prevent degradation; (5) environmentally benign effects, and (6) non-corrosive behavior.
After obtaining the solubility and mass transfer parameters for the selected ionic liquid TEGO IL K5 experimentally, the data were used to simulate a large scale process, a so call “conceptual” process. This task was completed using an ASPEN simulator. First using an absorber (model as a packed bed) followed by a few regeneration units, in which pressure swing or temperature swing are used to regenerate the ionic liquid solvent. The simulation of the absorption process will help assess the performance of the TEGO IL K5 as a physical solvent for CO2 capture.
The technical effort was performed in support of ongoing Carbon Dioxide research at the National Energy Technology Laboratory of the U.S. Department of Energy under RDS contract DE-AC26-04NT41817.
1. Holt, N. A. H.; Owens, W.; Buchanan, T.; DeLallo, M.; Schoff, R.; White, J.; Wolk, R. "Evaluation of Innovative Fossil Fuel Power Plants with CO2 Removal," EPRI, Palo Alto, CA, U.S. Department of Energy - Office of Fossil Energy, Germantown, MD and U.S. Department of Energy/NETL, Pittsburgh, PA, Report No. 1000316, December 2000, 2000. 2. Gale, J.; Bachu, S.; Bolland, O.; Xue, Z., "To Store or not to Store?," International Journal of Greenhouse Gas Control, 2007, Vol. 1(1), p. 1.