Flow Characterization in Particle‐Loaden Coal Burner Systems

Abstract

AbstractIn pulverized coal combustion, one of the most important parameters for pollutant formation in the near‐burner zone is the flow and mixing process of fuel and oxygen. To study the near‐field aerodynamics of pulverized coal burners, non‐intrusive optical measurements with Laser Doppler Velocimetry (LDV) were performed. In order to provide a better understanding of the mixing process of the small coal particles with the surrounding combustion air, the unavoidable formation of ropes and the dispersion of the particles was first investigated in an idealized two‐phase flow with glass beads under isothermal conditions.Furthermore, non‐intrusive measurements of velocity and turbulence intensities in the complex flow situation of radiating pulverized coal flames have been performed using a two component LDV system with a 15 W Argon‐ion laser, operating in backscatter mode. It has been used for flow characterization in a semi‐industrial pulverized coal combustion facility with a maximal thermal load of 500 kW. LDV is an indispensable research instrument to study the interdependencies between fluid flow, combustion reactions and pollutant formation processes in reactive flows. Additionally, results of numerical simulation obtained with a pulverized coal combustion code are validated with the LDV measurements and the experimentally observed phenomena are further explained. The influence of the flow pattern in the near‐burner region on pollutant emission will be discussed.