Abstract
The combustion characteristics and kinetics of high- and low-reactivity metallurgical cokes in an air atmosphere were studied by thermogravimetric instrument. The Coats–Redfern, FWO, and Vyazovkin integral methods were used to analyze the kinetics of the cokes, and the kinetic parameters of high- and low-reactivity metallurgical cokes were compared. The results show that the heating rate affected the comprehensive combustion index and combustion reaction temperature range of the cokes. The ignition temperature, burnout temperature, combustion characteristics, and maximum weight-loss rate of low-reactivity coke (L-Coke) were better than high-reactivity coke (H-Coke). Low-reactivity coke had better thermal stability and combustion characteristics. At the same time, it was calculated via three kinetic analysis methods that the combustion activation energy gradually decreased with the progress of the reaction. The coke combustion activation energy calculated by the Coats–Redfern method was larger than the coke combustion activation energy calculated by the FWO and Vyazovkin methods, but the laws were consistent. The activation energy of L-Coke was about 4~8 kJ/mol more than that of H-Coke.
Highlights
The iron and steel industry is energy intensive and is the second largest user of energy in the world industrial sector
In order to reduce CO2 emissions from the ironmaking system, researchers have successively proposed a series of low-carbon ironmaking solutions based on hydrogen reduction, such as blast-furnace injection of hydrogen-bearing materials, coaldust fuel and natural gas, the “Ultra-Low CO2 Steelmaking” (ULCOS) emissions project, and “CO2 ultimate reduction in steel-making process by innovative technology for cool Earth 50” (COURSE 50) [4,5,6,7]
Vmax is an important parameter of the characteristics of the reaction coke, corresponding to the point where the reaction rate is the fastest in the weight-loss process, and the vmax is A at the lowest peak point of the derivative thermogravimetry (DTG) curve
Summary
The iron and steel industry is energy intensive and is the second largest user of energy in the world industrial sector. In the lower part of the blast furnace, after the iron ore is reduced and dripped, coke becomes the only lumpy material. It is affected by factors such as temperature, CO2, slag, molten iron, and gas flow, and needs to ensure its stability, support the upper charge of the blast furnace, ensure that the blast-furnace column does not collapse, and produce smoothly [11,12]. Qi et al studied the effect of the Stefan flow on coke dissolution with metallurgical cokes of low, medium, and high reactivity [15]. Note: ad—air dry basis; M—moisture; V—volatile matter; A—ash; FC—fixed carbon
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