Keywords
absorption
regeneration
ammonium solution
calcium hydroxide
How to Cite
Abstract
The tests of this study were conducted by the semi-continuous flow experiments to absorb the carbon dioxide (CO2) gas in a bench-scale spraying column reactor. The absorption capacity and the regeneration efficiency of the absorbed ammonia (NH3) solution were determined. In this study, the maximum regeneration efficiency is 68.4% as the concentration of NH3 solution is 1% and the ratio of calcium hydroxide (Ca(OH)2) and CO2 is 1 as well. Furthermore, the absorption capacity of the NH3 solution decreases from 1.67 to 0.27 kg-CO2/kg-NH3 after regenerating four times due to the 30-38% loss each time. Regarding the regeneration kinetics between absorbed products and Ca(OH)2, the comparative degree of covered Ca(OH)2 during the reaction was recognized after fitting by a surface coverage model. Finally, the ammonium bicarbonate (NH4HCO3) reduced by Ca(OH)2 to calcium carbonate (CaCO3) solid and NH3 solution in the regeneration reactions was observed by scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS) pictures and X-Ray Diffraction (XRD) analyses. Although the NH3 solution can be regenerated by Ca(OH)2 effectively in this study, the overall benefit of this process should be estimated further in the energy aspect.
References
Bai H and Yeh AC. Removal of CO2 Greenhouse Gas by Ammonia Scrubbing. Ind Eng Chem Res 1997; 11: 2490-2493. http://dx.doi.org/10.1021/ie960748j
Yeh AC and Bai H. Comparison of Ammonia and Monoethanolamine Solvents to Reduce CO2 Greenhouse Gas Emissions. Sci Total Environ 1999; 228: 121-133. http://dx.doi.org/10.1016/S0048-9697(99)00025-X
Wang S, Liu F, Chen CH and Xu XC. Life cycle emissions of greenhouse gas for ammonia scrubbing technology. Korean J Chem Eng 2007; 24: 495-498. http://dx.doi.org/10.1007/s11814-007-0086-7
Hsu CH, Chu H and Cho CM. Absorption and Reaction Kinetics of Amines and Ammonia Solutions with Carbon Dioxide in Flue Gas. J Air & Waste Manage Assoc 2003; 53: 246-252. http://dx.doi.org/10.1080/10473289.2003.10466139
Bandyopadhyay A. Amine versus ammonia absorption of CO2 as a measure of reducing GHG emission: a critical analysis. Clean Technol Envir 2011; 13: 269-294. http://dx.doi.org/10.1007/s10098-010-0299-z
McLeod A, Jefferson B and McAdam EJ. Biogas upgrading by chemical absorption using ammonia rich absorbents derived from wastewater. Water Res 2014; 67: 175-186. http://dx.doi.org/10.1016/j.watres.2014.09.010
Shih SM, Ho CS, Song YS and Lin JP. Kinetics of the Reaction of Ca(OH)2 with CO2 at Low Temperature. Ind Eng Chem Res 1999; 38: 1316-1322. http://dx.doi.org/10.1021/ie980508z
Li ZD. Kinetics of the reaction of Ca(OH)2 with CO2. Master Dissertation, Department of Chemical Engineering, National Taiwan University 1996.
Song K, Jang YN, Kim W, Lee MG, Shin D, Bang JH, Jeon CW and Chae SC. Factors affecting the precipitation of pure calcium carbonate during the direct aqueous carbonation of flue gas desulfurization gypsum. Energy 2014; 65: 527-532. http://dx.doi.org/10.1016/j.energy.2013.11.008
United States Environmental Protection Agency. Inert Reassessment-Ammonium Carbamate. 2006. http://www.epa.gov/opprd001/inerts/carbamate.pdf
Hasib-ur-Rahman M and Larachi F. CO2 Capture in Alkanolamine-RTIL Blends via Carbamate Crystallization: Route to Efficient. Environ Sci Technol 2014; 46: 11443-11450. http://dx.doi.org/10.1021/es302513j
Chen HS, Dou BL, Song YC, Xu YJ, Wang XJ, Zhang Y, Du X, Wang C, Zhang XH and Tan CQ. Studies on absorption and regeneration for CO2 capture by aqueous ammonia. Int J Greenh Gas Con 2012; 6: 171-178. http://dx.doi.org/10.1016/j.ijggc.2011.11.017
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