Abstract
Energy consumption is directly related to the energy supply and production costs of gas-based direct reduction ironmaking, which is an effective choice to reduce the energy consumption of iron making. In this paper, the minimum Gibbs free energy principle was used to calculate the equilibrium composition under the conditions of reduction gas consisting of hydrogen and carbon monoxide (hydrogen concentration of 0–100%, reduction gas amount of 0–6.0 mol, reduction temperature of 790–1100 °C, and 0.5 mol Fe2O3). According to the enthalpy change, a simplified energy consumption model of a gas-based direct reduction ironmaking process was established, and the energy consumption per mole of metallic iron produced was calculated in detail. The following conclusions were drawn: at the stage when the reduction reaction occurred, the utilization rate of hydrogen or carbon monoxide remained unchanged with the increase in the amount of reduction gas or the increase in the hydrogen concentration of initial gas. The direct energy consumption increased with the increase in the hydrogen concentration at 790–980 °C and the opposite was true at 980–1100 °C. At 790–980 °C, the total energy consumption per ton of iron was greater than 0 and increased with the increase in initial hydrogen concentration from 40% to 100%, and it was less than 0 and increased with the increase in initial hydrogen concentration from 0% to 30%. It was possible to achieve zero total energy consumption with a hydrogen concentration of 30% and a 973 °C reduction.
Highlights
The iron and steel industry were regarded as the largest energy consumption manufacturing sector [1]
The purpose of this paper is to investigate the possibility of minimum energy consumption for gas-based direct reduction iron
Different amounts of reduction gas and different reduction temperatures were set to investigate the effects on the reduction products, gas utilization, and energy consumption
Summary
The iron and steel industry were regarded as the largest energy consumption manufacturing sector [1]. The conventional coke-based blast furnace consumes a large amount of energy [2,3], such as coke, oxygen, pulverized coal, etc., so non-blast furnace technologies are expected to reduce energy consumption and carbon emission [4]. The consumption of natural resources for ironmaking continuously decreases, but still, there is a lot of potential for further savings [5]. The energy savings can be obtained by reducing energy consumption and improving energy recovery [6,7]. Any modification leading to improvement of energy utilization needs to be emphatic. Gas utilization rate is an important indicator reflecting the operating state and energy consumption of blast furnaces [8] and non-blast furnaces [9]
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