Development of 3D transient wall filming mechanism during combustion by coupling Eulerian-Lagrangian approach and particle-wall interaction model

Abstract

In the present study, the developments of 3D wall filming mechanism for coal combustion in a small scale furnace under air and oxy-fuel combustion conditions are presented. The principle objective of this study is to develop the film flow behavior and particle deposition characteristics on the furnace refractory wall using a commercial CFD code coupled with some user-defined sub-routines. Eulerian-Lagrangian approach of the gas-particle flow is coupled with the particle-wall interaction mechanisms including particle capturing, entrainment and wall burning sub-models. A case study has been presented to validate the model in a small scale furnace by comparing the available temperature, species data for coal-water slurry combustion and reasonable agreement has been observed. Visualization of the transient film formation and flow characteristics under air and oxy-firing cases are presented. The film thickness deposited on the refractory wall was found to be reasonably in good range with the available data. The deposited film thicknesses for both the conditions are found in the range of 0–1.0mm. The average molten film velocity was 0.0001m/s due to higher viscosity and greater surface tension properties. Slightly higher amount of films are formed in oxy-firing condition due to slower char oxidation rate.