N₂O Reduction and NOx Adsorption in Carbonator of Calcium Looping CO₂ Capture Process

Abstract

A dual-fluidized bed solid circulating system that comprised a bubbling bed carbonator and a fast fluidized bed regenerator was operated under a condition of Calcium Looping (CaL) CO₂ capture process. Calcined limestone (CaO) was employed as bed material. Gas mixture simulating flue gas from air-blown combustor consisted of CO₂, N₂O, NO, O₂, and N₂ was fed to the carbonator. Most part of the fed CO₂ was captured by the calcined limestone particles, then the partially carbonated particles were transported to the regenerator, in which thermal decomposition of CaCO₃ was carried out in air stream. The carbonator of CaL process was found to be effective for N₂O reduction when the sorbent particles had activity to capture CO₂. A part of NO in the feed gas was also adsorbed by CaO particles, then the adsorbed NO was transported to the regenerator, and released to the gas phase there, though the net decomposition of NOx was not observed. CaL process was revealed to be a multifunctional process of CO₂ capture, N₂O decomposition, and removal of a part of NO in the flue gas fed to the carbonator.