Chemical-looping combustion: An emerging carbon-capture technology

Artikel i vetenskaplig tidskrift, 2016

Chemical-looping combustion (CLC) has been identified recently as a high-potential carbon-capture- and-storage technology. In chemical-looping combustion (CLC) , oxygen is transferred from an air reactor to a fuel reactor by means of a solid oxygen carrier The CLC process can be configured as two coupled fluidized-bed boilers, but packed-bed configurations, with the possibility of pressurizing, are also being considered. To transfer oxygen from the combustion air to the fuel, oxygen carriers are used. This avoids direct contact between air and fuel, and, after condensation of water, relatively pure CO2 is obtained in a separate exhaust stream from the fuel reactor. Thus, energy-consuming flue-gas separation is avoided. A critical aspect of CLC processes is oxygen-carrier performance, which has a strong effect on the economic viability of the technology. Parameters such as particle size, density, porosity, strength, attrition resistance, reactivity, and conversion efficiency, along with environmental aspects and cost, define the performance of the oxygen carrier. Besides the conversion efficiency, the mechanical (crushing) strength of the particles is extremely important because it determines the resistance to attrition and hence the operational-use hours (lifetime) of the particles e relationship between attrition resistance and the crushing strength is not straightforward, yet a crushing strength greater than 1 N is considered to be a good indication for acceptable attrition resistance.