Calcium Looping: Sorbent and Process Characterization in a 20 kW_th Dual Fluidized Bed

Abstract

This paper presents an experimental investigation at a 20 kW th calcium looping (CaL) facility with a twofold focus. The first objective is on assessing the multicyclic behavior of limestone under continuous dual fluidized bed (DFB) operation. Different carbonation conditions were employed to derive a mathematical expression that is valid to compare the results from DFB and thermogravimetric analysis (TGA) with adequate accuracy. A preliminary screening of three morphologically distinct limestones was conducted by TGA including exposure to SO 2 and H 2 O during carbonation. The second objective is to analyze the influence of multiple process variables (i.e., temperature, CO 2 loading, and H 2 O concentration) on the performance of the 20 kW th CaL facility's bubbling fluidized bed carbonator. Within the investigated range of operating conditions, the chosen carbonator design allowed for CO 2 capture efficiencies as high as 0.99 mol/mol, yielding an apparent carbonation rate (k S φ) of 0.09 s −1 . Paving the way to a more flexible usage of CaL systems, the proposed carbonator design could be integrated into the existing load-following power plants, in preference to a conventional circulating fluidized bed carbonator that is heavily penalized when forced to operate under low capacity factors.