Investigation of flame characteristics using various design parameters in a pulverized coal burner for oxy‐fuel retrofitting

摘要

Summary In oxy‐coal combustion for carbon capture and storage, oxygen and recirculated CO 2 are used as oxidizers instead of air to produce CO 2 ‐rich flue gas. Owing to differences between the physical and chemical properties of CO 2 and N 2 , the development of a burner and boiler system based on fundamental understanding of the flame type, heat transfer, and NOx emission is required. In this study, computational fluid dynamic analysis incorporating comprehensive coal conversion models was performed to investigate the combustion characteristics of a 30 MWth tangential vane swirl pulverized coal burner. Various burner design parameters were evaluated, including the influence of the burner geometry on the swirl strength, direct O 2 injection, and O 2 concentrations in the primary and secondary oxidizers. The flame characteristics were sensitive to the oxygen concentration in the primary oxidizer. The performance of direct O 2 injection around the primary oxidizer with low O 2 concentration was dependent on the mixing of the fuel and oxidizer. The predictions showed that swirl number adjustment and careful direct oxygen injection design are essential for retrofitting air‐firing pulverized coal burners as oxy‐firing burners.