Abstract
Abstract CO2 injection into blast furnace tuyeres is a new technology to utilize CO2, aiming at expanding the way of CO2 self-absorption in the metallurgical industry. The decisive factor of whether CO2 can be mixed into a blast-furnace hot blast and the proper mixing ratio is the effect of CO2 injection on pulverized coal burnout. To investigate the effect of CO2 injection into tuyeres on pulverized coal burnout, a three-dimensional mathematical model of pulverized coal flow and combustion in the lower part of the pulverized coal injection lance-blowpipe-tuyere-raceway was established, and the effect of CO2 injection into tuyeres on pulverized coal combustion rate and outlet temperature is analyzed. The numerical simulation results show that the delay of pulverized coal combustion in the early stage is caused by the endothermic effect of the reaction of CO2 with carbon, and the burnout of pulverized coal is increased in the later stage due to the oxidation of CO2.
Highlights
In response to environmental changes caused by CO2 emissions, metallurgical workers have been committed to study how to use CO2 as a resource in the iron and steel industries
The temperature of the carrier gas (N2) of pulverized coal is fixed at 45°C, the pulverized coal and carrier gas enter from the left side entrance of the pulverized coal injection lance and the entrance is set as mass flow entrance; the hot blast uses oxygen-enriched air, which contains CO2 and water vapor, and its temperature is fixed at 1,200°C, the hot blast enters from the blowpipe and is set as mass flow entrance; the raceway of the blast outlet is in a highpressure state, the outlet is set as the pressure outlet and the pressure is set as 350 kPa; and the wall surface of the pulverized coal injection lance, blowpipe, and tuyere is set as the adiabatic wall surface
The delay of pulverized coal combustion is caused by the endothermic reaction of CO2 with carbon, and the delay is more obvious with the increase of fCO2
Summary
In response to environmental changes caused by CO2 emissions, metallurgical workers have been committed to study how to use CO2 as a resource in the iron and steel industries. After pulverized coal is injected into the tuyere of a blast furnace, some of them have to be gasified and burned instead of coke as a heating agent. It is very important to study the effect of CO2 injection on pulverized coal burnout. Due to the high temperature and bad environment of the blast furnace, the results of experiments on the effect of CO2 injection on pulverized coal burnout are not reliable [19]. The numerical simulation method can be used to understand the specific combustion characteristics of pulverized coal. It is an important tool for studying pulverized coal combustion at home and abroad [20,21]. The lower part of the pulverized coal injection lance-blowpipe-tuyere-raceway is established by using the numerical simulation method of the computational fluid dynamics. [16,17]; the RKE is used to simulate the combustion of pulverized coal
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