Development of a Continuous Calcium Looping Process for CO2 Capture

• Main Author: Symonds, Robert
• Other Authors: Macchi, Arturo
• Language: en
• Published: Université d'Ottawa / University of Ottawa 2017
• Subjects: Calcium looping; CO2 capture
• Online Access: http://hdl.handle.net/10393/36454; http://dx.doi.org/10.20381/ruor-20734

Carbon capture and storage technologies are required in order to reduce greenhouse gas emissions, while continuing to utilize existing fossil-fueled power generation stations. Of the many developing post-combustion CO2 capture technologies, calcium looping appears promising due to its high thermal efficiency, technical feasibility at commercial-scale, and low sorbent cost. Calcium looping has now been performed at the larger-scale, but there is still a significant quantity of information about sorbent performance, the fate of trace pollutant emissions (specifically SO2 and HCl), dual fluidized bed operating configurations, and impact of realistic operating conditions that still needs to be determined. Based on an economic analysis of the process, three key parameters serve to have the largest potential economic impact: (1) the sorbent deactivation rate, (2) the Ca/C molar ratio, and (3) the rate of sorbent attrition. Therefore, a series of bench-scale, pilot-scale, and continuous pilot-scale testing were conducted to not only explore these parameters from an improvement standpoint, but accurately determine them under conditions expected at the commercial-scale. The presence of HCl did not have a significant impact on sorbent performance provided that steam is present during calcination, although issues with downstream corrosion could be a factor. High CO2 partial pressures during calcination, coupled with high temperatures and the presence of SO2, resulted in dramatically lower cyclic carbonation conversions and a reduced high CO2 capture efficiency regime. Continuous pilot-scale testing generated realistic, and more detrimental, values for sorbent carrying capacity, Ca/C molar ratio, sorbent make-up rates, and rate of sorbent elutriation, that can now be utilized for techno-economic evaluations and scale-up of the technology.