Geometrical parameter evaluation of a 0.5 MWth bench-scale oxy-combustion burner

Abstract

Carbon capture and storage (CCS) technologies are one of the most relevant energy pathways to mitigate medium-term climate change effects. They will contribute up to 20% of the total CO2 emission reduction by 2035. Oxy-combustion is considered a promising CCS technology applicable in fossil-fuel power plants. Much effort has been made to develop oxy-combustion at large scale. However, there are still fundamental issues and technological challenges that must be addressed before this technology can be considered for commercialization. Recent research on coal oxy-combustion experimental facilities indicates stabilization problems and ignition delays when combustion occurs in CO2-rich environments. Advanced burner designs are required to ensure technological and economic feasibility of the process. Computational Fluid-Dynamics tools were used to evaluate the behaviour of a 0.5MWth bench-scale oxy-burner. Key geometrical parameters were analysed, such as combustion chamber diameter, chamber length and angle of the quarl. Simulations showed that a length of 6m ensures complete coal combustion. The results indicated that the combustion chamber diameter and the quarl angle have an influence on coal ignition, stability, flame shape and CO concentration. Higher values of those parameters produced greater hot recycled flow, which means higher temperatures and greater flame stability. Coal ignition was also improved. A 1500-mm chamber diameter and a 50° quarl angle were selected as optimal values for both parameters. CFD modelling makes it possible to analyse the behaviour of different oxy-burner configurations and to optimize the combustion process under oxy-combustion conditions.