Key Takeaways & Executive Findings
- •• Reducing carrier gas injection rate from 4000 to 2000 m3/h increases tuyere temperature and CO/H2 mole fractions but decreases pulverized coal burnout. • Increasing carrier gas temperature by 20 K raises raceway temperature by 20.6 K, enhancing volatile release and combustion, yet only 1.16% burnout improvement from 373 to 393 K. • Optimal carrier gas temperature is around 373 K to balance coal transport and combustion performance. • Using air as carrier gas boosts pulverized coal burnout by 2.69% compared to N2, offering a practical strategy for efficiency improvement.
Abstract
The mixing injection of natural gas and pulverized coal into the blast furnaces shows a promising technological approach in the context of global carbon reduction initiatives. Carrier gas and coal pass through the air inlet of coal lance, and the characteristics of carrier gas affect the flow in the air inlet and the combustion efficiency of coal, so it is very important to study the change of carrier gas characteristics in the lower part of blast furnace. By means of numerical simulation, the influence of carrier gas characteristics (injection rate, composition, and temperature) on the mixed combustion of natural gas (NG) and pulverized coal in the tuyere raceway of Russian blast furnace was analyzed. When N2 is used as carrier gas, the injection rate of carrier gas is reduced from 4000 to 2000 m3/h, the average tuyere temperature is increased (1947.42 to 1963.30 K), the mole fractions of CO and H2 are increased, and the burnout rate of pulverized coal is decreased. Increasing the carrier gas temperature is helpful to improve the burnout of pulverized coal. For every 20 K increase of carrier gas temperature, the average temperature in the raceway increases by 20.6 K, which promotes the release and combustion of volatiles, but the increase of carrier gas temperature from 373 to 393 K only leads to 1.16% burnout change. Considering the transportation characteristics of pulverized coal, it is suggested that the carrier gas temperature should be kept at about 373 K to obtain the best performance. It is worth noting that when air is used as carrier gas, the burnout rate of pulverized coal is increased by 2.69% compared with N2.
1. Introduction
Carbon emissions have become the international focus under the topic of global warming and climate change. Notably, in 2022, the industrial sector accounts for approximately a quarter of the global energy system's CO2 emissions, with blast furnace ironmaking process accounts for about 70% of industrial energy consumption and carbon dioxide emissions [1–2]. In 2023, approximately 1.286 billion tons of pig iron were produced globally, with blast furnaces accounting for over 90% of this output. Renowned for its economy and high yield, blast furnace ironmaking remains the primary method in steel manufacturing [3–4]. This process is heavily reliant on carbon-rich fuels such as coke and pulverized coal, leading to significant energy consumption (21–23 GJ/t) and CO2 emissions in the range of 2.0–2.2 t/t [5], accounting for more than 70% of both energy usage and carbon dioxide emissions of steel plants [6]. However, traditional blast furnace operations have reached a near technological plateau after over two centuries of development, limiting the scope for substantial reductions in carbon fuel consumption and CO2 emissions through conventional optimization strategies like increased oxygen enrichment and blast temperature [7–8].
Presently, a primary method for mitigating CO2 emissions in blast furnace ironmaking involves the injection of hydrogen as a partial substitute for coke or coal powder, utilizing it as a reducing agent [9–11]. Natural gas has high hydrogen content and calorific value, making it beneficial for blast furnace smelting. This technology originated in the former Soviet Union and the United States, and experience from multiple countries has proven its efficiency. As a result, natural gas has emerged as the most promising candidate fuel for widespread adoption in the short to medium term [12].
The injection of natural gas into a blast furnace alters the thermodynamic state of the tuyere raceway, reducing thermal energy, and the mechanism behind this remains to be explored. Numerical simulation has become the primary research method due to the difficulties in experimental observation. Various studies have focused on the application of natural gas in blast furnaces under different operating parameters [13–16]. Wang et al. [17–18] proposed that increasing oxygen and reducing coal during mixed injection can improve burnout efficiency; Kawale et al. [19] found that placing the natural gas lance ahead of the coal lance can enhance coal b...
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Jianliang Zhang, Sijia Duan, Cuiliu Zhang, Runsheng Xu, Ternovykh Aleksei, Johannes Schenk, Yunjian Zhao (2025). Numerical analysis of carrier gas characteristic effects on flow dynamics and combustion efficiency in natural gas and pulverized coal injection. Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报). https://doi.org/10.1007/s12613-025-3124-8
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Frequently Asked Questions
What is the effect of reducing carrier gas injection rate on blast furnace performance?
Reducing the carrier gas injection rate from 4000 to 2000 m3/h increases the average tuyere temperature from 1947.42 K to 1963.30 K, increases the mole fractions of CO and H2, but decreases the burnout rate of pulverized coal.
How does carrier gas temperature affect pulverized coal combustion?
Increasing carrier gas temperature improves pulverized coal burnout. For every 20 K increase, the average raceway temperature rises by 20.6 K, promoting volatile release and combustion. However, increasing from 373 K to 393 K only yields a 1.16% burnout change, suggesting an optimal temperature around 373 K.
What is the impact of using air instead of nitrogen as carrier gas?
Using air as carrier gas increases the burnout rate of pulverized coal by 2.69% compared to nitrogen, indicating a potential efficiency improvement.
Why is numerical simulation used in this study?
Numerical simulation is used because experimental observation of the tuyere raceway in blast furnaces is difficult. It allows detailed analysis of flow dynamics and combustion efficiency under varying carrier gas characteristics.
What is the significance of this research for carbon reduction in steelmaking?
This research supports the optimization of natural gas and pulverized coal co-injection in blast furnaces, which is a promising approach to reduce carbon emissions in ironmaking, a major contributor to industrial CO2 emissions.
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