Analysis by multiphase multicomponent model of iron ore sintering based on alternative steelworks gaseous fuels

Abstract

This paper presents the numerical simulation of the technology of gaseous fuel utilisation for iron ore sintering. The proposed methodology is to partially replace the solid fuel by steelworks gases. A multiphase mathematical model based on transport equations of momentum, energy and chemical species coupled with chemical reaction and phase transformations was proposed to analyse temperature distributions of the process. A base case of actual industrial operation of a large sintering machine was monitored with thermocouples inserted into the sinter bed to validate the model. The model was used to predict four cases of fuel gas utilisation: feeding from N01 to N15 wind boxes with blast furnace gas (BFG); natural gas (NG); coke oven gas (COG); and a 50-50 mixture of BFG and COG. The model predictions indicated that for all cases the sintering zone is enlarged and the solid fuel consumption could be decreased. List of symbolsA surface area, m 2 m 23 C p heat capacity, J kg 21 K 21 d final solid agglomerated, m d initial initial micropellets charged, m d m solid component diameter, m d s solid phase mean diameter, m F s g interaction force on solid phase due to gas phase, N m 23 s 21 H enthalpy of the phase, kJ kg 21 P phase pressure, Pa Pr g~C p,g m g k g Prandtl number r m rates of chemical or phase transformations, kmol m 23 s R gas constant, J mol 21 K 21 Re g{s~r gŨ U g {Ũ U s m g d s particle Reynolds number S w source or sink terms for the w variables, (various) t time, s T temperature, KŨ U i phase velocity vector (i is the gas and solid), m s 21 x i spatial coordinates, m e i volume fractions, m 3 m 23 m phase effective viscosity, Pa s r i phase density (i is gas and solid), kg m 23 Q n mass fraction in equation (4) (calculated by the model), kg kg 21 w m solid diameter shape factor (m is the sinter feed, sinter return, limestone, fines, coke, mushy and bonding)

Characteristics of combustion zone and evolution of mineral phases along bed height in ore sintering

“…Combining Parker and Hottel's equation and the coke combustion rate equation for a quasi-particle, some scholars developed numerical simulation models of the temperature distribution in a sintering layer [14][15][16]. The quantitative parameters of bed combustion, including the flame front speed, duration time in CZ, and the maximum temperature, were simulated through numerical modeling [17][18][19]. Scholars also used the discrete element method to construct a comprehensive numerical simulation model to describe the structural changes in an iron ore sintering bed [20][21].…”

Three Dimensional Mathematical Model of the Iron Ore Sintering Proces

“…In the present model it is assumed that the liquid phase formed will move together with the remaining solid phase due to the viscosity and considering that the liquid are formed attached on the surface of the unmelted particles, thus, equations for momentum transfer and enthalpy of the solids will account for this mixture of viscous liquid and solid materials. In the present model, the temperaturecomposition dependent thermophysical properties are assumed to obeys the mixture rule to take into account the individual phase properties pondered by their phase volume fractions [5][6][7][8][9][10][11][12]. The equations for momentum, energy and chemical species are convective-diffusive type equations with source and sink accounting for the external or interphase interactions phenomena, taking into account the transient, convective, conductive and source terms [6][7][8][9][10][11][12].…”

“…The raw materials used in the iron ore sintering process are furnished by several sources, from iron ore(mining sinter feed) to dust recycling within the steelworks and addition of slag agents for blast furnace and selected materials to enhance the sinter product quality, namely reactivity and mechanical strength, which plays important role on the blast furnace performance. In the sintering machine operation, the combustion of the solid fuels(coke breeze or anthracite) begins at the top of the layers, and as it moves, a relative narrow band of ignition zone moves downward through the bed, that can be strongly affected by the quality of the raw materials [6][7][8][9][10][11][12]. Several chemical reactions and phase transformations are affected, not only due to the heat front changes, but also due to modifications of local gas composition and initial melting temperatures of the mixture of raw materials.…”

“…The focus of this paper is the sinter strand where most of the phenomena which determines the final properties of the sinter product is developed. Previous models addressed the sintering phenomena [1,5,[8][9][10][11][12]. At the present days, the reduction of CO2 emissions has become an urgent issue in the steel industry as countermeasure for greenhouse emissions.…”

Model-Based Optimization of Industrial Gas-Solid Reactors

“…Computational fluid dynamics (CFD) models are applied quite commonly now for simulation of fluid flow, especially because of the availability user-friendly simulation software such as Fluent TM , CFX TM , and COMSOL TM . CFD models have been applied, for instance, for the simulation of fluid flow as well as heat transfer in lime kilns, cement kilns (Mastorakos et al, 1999), for incineration of hazardous waste in a rotary kiln (Yang et al, 2003), for sintering of iron ores (de Castro et al, 2012), for gas flow in induration of iron ore pellets on a moving packed bed reactor (Cross et al, 1990); and for the production of polyethylene in a fluidized bed reactor (Kiashemshaki et al, 2006). Recently, coworkers (2013, 2014) developed a two-fluid continuum model based on kinetic theory of granular flow to investigate bubble formation in a gas-solid fluidized bed and validated the model with experimental data obtained using ultrafast electron beam X-ray tomography.…”