Assessment of the different parameters affecting the CO 2 purity from coal fired oxyfuel process

Abstract

The oxyfuel process is one of the most promising options to capture CO 2 from coal fired power plants. The combustion takes place in an atmosphere of almost pure oxygen, delivered from an air separation unit (ASU), and recirculated flue gas. This provides a flue gas containing 80–90 vol% CO 2 on a dry basis. Impurities are caused by the purity of the oxygen from the ASU, the combustion process and air ingress. Via liquefaction a CO 2 stream with purity in the range from 85 to 99.5 vol% can be separated and stored geologically. Impurities like O 2, NO X, SO X, and CO may negatively influence the transport infrastructure or the geological storage site by causing geochemical reactions. Therefore the maximum acceptable concentrations of the impurities in the separated CO 2 stream must be defined regarding the requirements from transportation and storage. The main objective of the research project COORAL therefore is to define the required CO 2 purity for capture and storage.