Parametric evaluation of a particle dispersion submodel used in a two-dimensional, pulverized-coal combustion code

Abstract

Particle dispersion data collected with a laser-based diagnostic technique are used to evaluate the performance of a particle dispersion submodel incorporated in a two-dimensional, comprehensive, pulverized-coal combustion code. In this code, the gas-phase mechanics is formulated in an Eulerian framework, whereas the particle phase is based on a Lagrangian scheme. The turbulence is described by the two-equation, k-t model. The experimental data available include radial profiles of small (0.4-3.5 pm) and large (3.5-98 pm) particle velocities and size-resolved particle number density of pulverized-coal particles for both reacting and isothermal conditions at different axial stations in a laboratory-scale, axisymmetric, controlled-profile reactor. Various parameters were varied during the reacting cases: the secondary air flow rate, secondary swirl number, and the initial coal-size distribution. For the isothermal conditions, only the secondary air temperature is varied for both swirling and nonswirling cases. It is observed that a reduced swirl number of 0.8 instead of the experimental swirl number of 1.4 gave relatively better predictions for the gas-phase aerodynamics, particle number density, and particle trajectory calculations for all the swirling cases. Some limitations of the particle dispersion submodel as well as the experimental data are acknowledged.

Simulation of Particle Transport and Deposition in a Combustor

“…Sommerfeld and Qiu (1993) studied particle dispersion in a pipe expansion non-reacting swirling flow using numerical simulations and Phase-Doppler anemometry (PDA). Shirolkar and Queiroz (1993) developed a pulverized-coal combustion code to study particle dispersion in a axisymmetric reactor and compared their simulation results with the experimental data collected with a laser-based diagnostic technique. They used a k -E type turbulence model in their simulations and the effect of thermophoresis on particle movement was not considered.…”

“…The instantaneous fluctuation velocity field is generated by a Gaussian filtered white noise model. In this study, the combustor used in the experimental study of Eatough (1991) and Shirolkar and Queiroz (1993) is modeled. The simulated results for fluid axial, radial and tangential mean velocities are compared with the corresponding experimental data.…”

“…In this section, gas flow simulation results for a axisymmetric combustor, which is the same combustor used by Eatough (1991) and Shirolkar and Queiroz (1993), are described. The combustor inlet system consists of a primary airlfuel stream, surrounded by a secondary air stream to which varying degrees of swirl can be created by a moveable-block swirl generator.…”

Particulate behavior in a controlled-profile pulverized coal-fired reactor: A study of coupled turbulent particle dispersion and thermal radiation transport. Final technical progress report

“…The coal-type used in the experiments was the Utah Blind Canyon coal. The different coal properties required as input conditions for the simulations is also presented in Shirolkar and Queiroz (1993).…”