Effect of High Reactivity Coke for Mixed Charge in Ore Layer on Reaction Behavior of Each Particle in Blast Furnace

Abstract

A low coke rate operation in blast furnace is desired to decrease the carbon input and mitigate global warming problem. However, low coke rate operation tends to cause the gas permeability to deteriorate. The mixing of small-size coke (nut coke) including high reactivity coke in ore layer is considered to be a promising way to improve permeability and increase reaction efficiency in a blast furnace. Although adding a nut coke mixing to an ore layer is predicted to be empirically effective in low coke rate operation, there is little actual data on microscopic phenomena of each particle in the packed bed. In the present study, an Euler-Lagrange approach was introduced to precisely understand the influence of the packed bed structure on the reaction behavior of each particle in the three-dimensional particle arrangement.It was observed that the heterogeneity on the reaction rate and temperature distribution was influenced by the particle arrangement. When high-reactivity coke was used at approximately 1 273 K, although CO gas fraction increased, the gaseous phase temperature decreased due to the active solution loss reaction rate of the nut coke in the mixed layer. As a result, the ore reduction rate decreased. The contribution of high-reactivity coke to the ore reduction rate depends on the particle arrangement through the heat transfer and reaction heat. Accordingly, in the case of the mixed charge of the high reactivity nut coke in the ore layer, the design of the packed bed structure is important.

Effect of Coke Particle Arrangement on Reduction and Gasification Reaction in Mixed Layer of Ore and Coke

“…As a further detailed simulation study, several numerical simulations on the effect of the particle arrangement of carbonaceous materials and ores on the reduction and gasification reactions in the ore layer have been conducted. 19,20) However, since these studies focused on the vertical arrangement of the particle layers in the packed bed, the effect of the individual particle arrangements on the reduction and gasification reactions and the close arrangement of the ore and carbonaceous material was not discussed.…”

Review on Modeling and Simulation of Blast Furnace

“…This new approach, although being, thus, far verified at much lower temperatures than those within a real BF, can in principle be applied to ore particles with the support of physical experiments, which eliminates the arbitrary treatment of ore softening and melting behaviors in the DEM modeling of BFs. Natsui et al modeled the flow, heat and mass transfer in a simplified cylindrical reactor by a 3D CFD‐DEM model and considered the iron ore reduction by CO. Later, this model was extended to include the reduction by H 2 . Peters and Hoffmann developed a 1D CFD‐DEM model to investigate iron ore reduction against the measurement.…”

Recent Progress on Advanced Blast Furnace Mathematical Models Based on Discrete Method

“…38) Figure 29 shows the calculation results when a mixed layer containing either high reactivity coke or conventional coke was arranged below or above an ore layer. Generally, the progress of ore reduction is delayed by the temperature decrease which occurs when using high reactivity coke.…”