(6b) CO2 Capture with Modified Lime-Based Pellet Sorbents

Authors: 
Manovic, V. - Presenter, CanmetENERGY
He, I. - Presenter, CanmetENERGY
Wu, Y. - Presenter, CanmetENERGY

CO2 capture with modified lime-based pellet sorbents

Yinghai Wu, Vasilije Manovic, Ian He and Edward J. Anthony

CanmetENERGY, Natural Resources Canada

1 Haanel Dr. Ottawa, ON K1A1M1

Abstract

Calcium looping technology is being developed as a promising method for capturing CO2 from both flue and fuel gases, which typically contain relatively low concentration CO2 of <14%.   Calcium looping utilizes the reversible carbonation and calcination reactions of CaO (CaO + CO2  CaCO3) to produce a highly concentrated CO2 stream (>90%) suitable for sequestration. Here, modified lime-based pellets were studied as potential regenerable high-temperature CO2 sorbents using calcium aluminate cement binders to enhance pellet strength. A mechanical pelletizer was used for granulation of the powdered materials, specifically quick lime and hydrated lime, produced from Graymont limestone with the addition of spray water. The CO2 carrying capacity of both the pellet sorbents and the parent limestone was tested in a thermogravimetric analyzer (TGA) over repeated calcination/carbonation cycles. In addition, the attrition resistance of these pellets was examined using a bubbling fluidized bed (50 mm ID). The particle size distribution (PSD) of both the calcined pellets was determined before and after alternating calcination/carbonation cycles. It was found that the CO2 carrying capacity of pelletized sorbent was more stable over multiple cycles. Moreover, the results of attrition tests showed that high-temperature fluidization did not result in significantly pronounced attrition for the pellet sorbents.