Analysis of the Wettability Effect on Slag Holdup in a Fixed Bed of Carbonaceous Particles Using CFD-DEM Simulations

Slag holdups in a fixed bed of carbonaceous particles were investigated using three-dimensional (3D) computational fluid dynamics (CFD) and discrete element method (DEM) simulations. In particular, the effect of improved wettability on the slag holdup, as a result of the formation of a SiC coating on the carbonaceous particle surface, was investigated. Wettability with four different contact angles (i.e., 10, 20, 60, and 118 deg) and coke particles with three various diameters (8 mm, 10 mm, and 12 mm) were considered. It was found out that the total slag holdup was increased with increasing contact angles. At each contact angle, the total holdup decreased with an increase in particle size. The static holdups of particles having contact angles of 60 and 180 deg could be sufficiently predicted using the empirical equation suggested by Jang et al. On the contrary, the static holdups of particles having contact angles of 10 and 20 deg could be sufficiently predicted with the empirical equation proposed by Kawabata et al. and Fukutake and Rajakumar or Chew et al., respectively. The dynamic holdup was in reasonable agreement with the empirical equation suggested by Otake and Okada.