Oxy-Fuel combustion in an entrained flow reactor for regeneration of spent Calcium Looping sorbents

Abstract

Calcium Looping (CaL) is one of the most promising technologies for large-scale CO₂ capture of flue gases from power plants and industrial processes. A Ca-based sorbent, mostly CaO derived from limestone, is used to capture CO₂ in the first step, while being regenerated in the second step. The aim of this study was to investigate the regeneration step of a novel CaL concept, which uses Ca(OH)₂ as CO₂ capture sorbent for backup power plants (“BackCap” concept). The spent sorbent after CO₂ capture was calcined in an entrained flow reactor, using oxy-fuel conditions. In particular, the calcination degrees of the sorbent that were reached during a few seconds residence time in the reactor, were of main interest in this study. Therefore, experiments including parameter variations were carried out in a drop-tube and an entrained flow reactor to calcine the carbonated Ca(OH)₂ particles. Calcination degrees of almost 0.6 were reached within the test facility used, while calcining in short residence times (i.e. <5 s) under oxy-fuel conditions. The experimental results obtained were implemented into a calcination model, indicating that full calcination of particles under oxy-fuel conditions is possible within reasonable residence time (i.e. 10 s).