Mathematical Simulation on Solid Flow in COREX Melter Gasifier Using Discrete Element Method

Abstract

Based on the principle of discrete element method (DEM), a 2D slot model of COREX melter gasifier has been established to analyze the solid flow pattern, velocity field and porosity distribution at a microscopic level. The results show that the solid flow pattern changes from linear mode to curving down on the both sides by means of joining tracer particles, which states that the descending velocity near the furnace wall is higher than the velocity near the furnace center. The results also confirm that the solid flow can be divided into several different flow zones including dead zone where the velocity of particle is low or motionless, the plug flow zone where the velocity distribution is uniform, and the channel flow zone which is located between the dead zone and the plug flow zone. The velocity distribution is asymmetric showing that there exits segregation phenomenon in the furnace, and the porosity distribution also clarifies this phenomenon. The influence of raceway in the vertical direction is limited to the region of 0.18 m from the hearth bottom level. The decrease of raceway size causes that the active region with higher velocity becomes shrink and the height of dead zone increases remarkable. The porosity is 0.37 in the dead zone, while in the raceway the porosity is 0.65, the porosity in the plug flow zone is between 0.37 and 0.65, and the porosity of upper free space is about 1.