A numerical study of coal gasification flame with one-dimensional turbulence model

摘要

In the near nozzle region in an entrained flow coal gasifier, strong interactions exist between coal gasification and turbulent fluctuations. These interactions have essential effects on coal gasification process and shall be considered. Based on proposed particle-eddy interaction model and spatially developing One Dimensional Turbulence (ODT) method, instantaneous coal gasification flames are simulated with a finer mesh resolution up to Kolmogorov scales. Characteristics of coal gasification flames are studied based on instantaneous realization and average results. It is observed that central fuel rich region is formed firstly due to rapid devolatilization process and slower particle dispersion rate in the near nozzle region. Then stronger heterogeneous coal char reactions occur at the edge of gasification flame. As the oxygen diffusion develops, the high temperature region merges at the center line in the developed region. Size-dependent coal gasification process and particle-eddy interactions are also studied in this paper. Concept of particle response time is shown in a straight way by comparing instantaneous scalars of coal particles and local gas phase.