Flame pattern analysis for 60kWth flames under conventional air-fired and oxy-fuel conditions for two different types of coal

摘要

The present work is dedicated to the experimental investigation of the influence of fuel-type and oxidizer composition upon flame structure and behaviour of swirl-stabilized pulverized coal flames. Detailed flame measurements are conducted by employing a combination of flame-intrusive and non-intrusive measurement techniques which can provide complementary data about flow fields, major product species and radiative heat transfer from the flames. Four flames with constant thermal output (60kW(th)) and stoichiometry are employed. While previous studies of the same configuration were limited to one fuel (Rhenish lignite), the influence of fuel type is investigated here by additionally measuring the same set of parameter for Prosper Haniel bituminous coal. Two reactive atmospheres (conventional air and oxy-fuel with an O-2/CO2 ratio of 25/75 vol%) are employed to investigate the impact of changes in oxidizer. The combined analysis of measurement results show that flame length is predominantly controlled by the effective swirl intensity when the flame ignites and stabilizes in the vicinity of the burner. Further on, measurements from narrow-band flame imaging and heat flux measurements show that the location of peak combustion intensity is determined by the flow inlet conditions (at the burner). This being key parameters, that could be employed to match heat transfer profiles when transitioning from conventional air firing to oxy-fuel in existing power plants.