A Microscopic Numerical Simulation of Carbon Dissolution in Different Coke Shapes in the Dripping Zone of Blast Furnace

Abstract

The carbon dissolution of coke pieces in hot metal mainly influences the carbon content and carbon saturation temperature in the ironmaking process. The liquid metal and slag start to drop down in the dripping zone (DZ) which is located the lower part of blast furnaces. The dissolution of carbon in liquid metal and slag droplets passing the stagnant hot gas flow in the fixed coke bed of the dripping zone were observed by a multi-droplet model based on the Computational Fluid Dynamics (CFD) method. The uniform-coke pattern was set in the model following the preferred distribution of a one-layer packed bed from a water droplet experiment. The different coke shapes relating to the shape factor from 0.75-1.0 were observed in a 40mm-coke bed. For one-time drainage, the carbon dissolution slightly increased after flow in the coke bed zone and showed a high percentage on the coke surface. The concavity and convexity of coke pieces have more effect on the interaction between liquid and coke surface. Besides, the carbon dissolution can be investigated to approach the coke consumption in one coke channel and estimate the carbon content and carbon saturation temperature of liquid metal after draining.

Effect of pulverized coal residues on the blast furnace streaming conditions

“…Thus, the coal-air dispersion streams with a reduced gas velocity along the centre zone and the left side of the model, which explains the slightly lower pressure drops in the two zones (Figure 9). Similar results can also be observed by numerical simulations [3,16]. It can also be seen that with increasing injection rate, the pressure drop increases, which is related to the increasing amount of coal particles in the model (increase in the quantity of char holdups).…”

“…The multiphase flow behaviour, particularly the effect of injected coal powder in the dripping zone, was also studied using the CFD module of the COMSOL Multiphysics ® software [16]. It has been assumed that the properties of the coal power do not change during their flow to the dripping zone.…”

“…Figure 5 shows that the velocity of powder increases when its grain size is reduced. However, it does not change when the amount of coal powder (or its concentration in blast in vol.-%) is increased.

Figure 5. The average velocity of powder (m s –1 ) in the coke bed at different amounts and coal particle diameters ( t s : simulation time) [16].

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“…Figure5. The average velocity of powder (m s -1 ) in the coke bed at different amounts and coal particle diameters (t s : simulation time)[16].…”