Abstract
This paper addresses the modeling of the iron ore direct reduction process, a process likely to reduce CO2 emissions from the steel industry. The shaft furnace is divided into three sections (reduction, transition, and cooling), and the model is two-dimensional (cylindrical geometry for the upper sections and conical geometry for the lower one), to correctly describe the lateral gas feed and cooling gas outlet. This model relies on a detailed description of the main physical–chemical and thermal phenomena, using a multi-scale approach. The moving bed is assumed to be comprised of pellets of grains and crystallites. We also take into account eight heterogeneous and two homogeneous chemical reactions. The local mass, energy, and momentum balances are numerically solved, using the finite volume method. This model was successfully validated by simulating the shaft furnaces of two direct reduction plants of different capacities. The calculated results reveal the detailed interior behavior of the shaft furnace operation. Eight different zones can be distinguished, according to their predominant thermal and reaction characteristics. An important finding is the presence of a central zone of lesser temperature and conversion.
Highlights
The direct reduction (DR) of iron ore, usually followed by electric arc steelmaking, is an alternative route to the standard, blast furnace, basic oxygen route for making steel
In a DR shaft furnace, a charge of pelletized or lump iron ore is loaded into the top of the furnace and is allowed to descend, by gravity, through a reducing gas
We developed further the model of Ranzani Da Costa andWagner, Wagner,built builttotosimulate simulate the reduction section of shafts, operated with pure hydrogen
Summary
The direct reduction (DR) of iron ore, usually followed by electric arc steelmaking, is an alternative route to the standard, blast furnace, basic oxygen route for making steel. Subsequent studies developed models simulated reduction zone shaftfurnace furnacein. Subsequent studies developed models that that simulated the the reduction zone of of thethe shaft in one dimension [10,11]. We developed further the model of Ranzani Da Costa andWagner, Wagner,built builttotosimulate simulate the reduction section of DR shafts, operated with pure hydrogen [13,14,19]. REDUCTOR is a computational fluid dynamics (CFD)-type, two-dimensional model, model,describes which describes shaft alone. The shaft furnace description included in the plantin model, plant model, though based on similar equations, was intentionally made simpler and faster to run, though based on similar equations, was intentionally made simpler and faster to run, on process on process simulation software.
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