TRAJECTORIES OF BURNING COAL PARTICLES IN HIGHLY SWIRLING REACTIVE FLOWS

Finite-element computations and measurements of a strongly swirling fl ow with pulverized coal combustion are presented. The turbulent flow e xpands into a low confined combustion chamber which represents the geo metry of typical industrial furnaces. Detailed in-flame measurements o f velocity, temperature, and gas concentrations were made by suction p robes at several cross sections. These data are used for the detailed evaluation of higher-order turbulence models in connection with coal c ombustion. In modeling the particle-gas flow, the momentum equations a re solved by considering the particle phase as a continuum and neglect ing the mean slip velocities between the two phases. Trajectories of t he individual particles treated as inert matter are subsequently compu ted employing a Lagrangian method after a convergent flow field soluti on is obtained. The external forces which influence the particles' mot ion are considered and compared. Additionally, in a more realistic app roach, the mass loss of the coal particles due to devolatilization and char-burnout is taken into account. The influence of the gas-phase tu rbulence modeling on the particle motion is also investigated.