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14 pages, 4781 KiB

Open AccessArticle

Optimization Study of Annular Wear-Resistant Layer Structure for Blast Furnace Tuyere

by Wentao Zhu, Jianliang Zhang, Yanbing Zong, Lei Zhang, Yanxiang Liu, Lifeng Yan and Kexin Jiao

Metals 2023, 13(6), 1109; https://doi.org/10.3390/met13061109 - 13 Jun 2023

Cited by 2 | Viewed by 1131

Abstract

A new tuyere small sleeve coating structure that balances the high thermal conductivity of the copper substrate with the high wear resistance of the protective layer was developed in this paper. This structure can achieve a low-carbon blast furnace by reducing the heat [...] Read more.

A new tuyere small sleeve coating structure that balances the high thermal conductivity of the copper substrate with the high wear resistance of the protective layer was developed in this paper. This structure can achieve a low-carbon blast furnace by reducing the heat loss from the tuyere. The 3D model was established via Solidworks for modeling and Ansys for numerical simulation, the temperature field of the annular wear-resistant layer structure tuyere small sleeve with different widths of the wear-resistant layer was analyzed and compared with the temperature and stress field of traditional tuyere small sleeve. The results show that the design of the annular wear-resistant layer structure of the tuyere small sleeve is more effective. The new annular wear-resistant layer structure for the tuyere small sleeve results in a decrease of 24 K in the average temperature of the wear-resistant coating. The comparison of this structure with tuyere sleeves without wear-resistant coatings shows a 16.7% reduction in heat loss, improves the wear resistance of the tuyere, providing new technological ideas for low-carbon blast furnace production. Compared with the tuyere sleeve completely covered with a wear-resistant coating, the maximum thermal stress of this structure decreased from 624.98 Mpa to 427.99 Mpa, resulting in a reduction of 31.5%, which is beneficial for the service life of the tuyere sleeve. The copper surface temperature of the new tuyere small sleeve is in a safe range when the temperature is below 2273 K. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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14 pages, 7786 KiB

Open AccessArticle

Numerical Analysis of Factors Affecting the Burden Surface and Porosity Distribution in the Upper Part of the Blast Furnace

by Han Wei, Henrik Saxén and Yaowei Yu

Metals 2023, 13(2), 292; https://doi.org/10.3390/met13020292 - 31 Jan 2023

Cited by 1 | Viewed by 1274

Abstract

A proper burden and porosity distribution of the bed in the upper shaft are important prerequisites for realizing a stable and efficient operation of the ironmaking blast furnace. The discrete element method was used to investigate the effects of the static friction coefficient [...] Read more.

A proper burden and porosity distribution of the bed in the upper shaft are important prerequisites for realizing a stable and efficient operation of the ironmaking blast furnace. The discrete element method was used to investigate the effects of the static friction coefficient between burden particles and shaft angle on the burden profile and porosity distribution in the bed formed by charging the burden with a bell-less charging equipment. The results indicate that a large static friction coefficient makes the particles stay closer to the impact point (i.e., where they fall) from the rotating chute. A large mixed region of the burden bed decreases the gas permeability, and an increase in the burden particle roughness will worsen this problem. The burden surface shape becomes flatter with an increase in the shaft angle. These findings explain the effect of particle properties and wall geometry on the inner structure of the burden bed. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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16 pages, 4079 KiB

Open AccessArticle

Numerical Analysis of Natural Gas Injection in Shougang Jingtang Blast Furnace

by Kai Wang, Heng Zhou, Yunpeng Si, Shuo Li, Pengfei Ji, Jianlong Wu, Jianliang Zhang, Shengli Wu and Mingyin Kou

Metals 2022, 12(12), 2107; https://doi.org/10.3390/met12122107 - 8 Dec 2022

Cited by 2 | Viewed by 1226

Abstract

A static model of blast furnace operation of natural gas (NG) injection was developed. The effect of NG injection on the raceway adiabatic flame temperature, the amount and composition of bosh gas, the direct reduction degree and fuel ratio were studied. The results [...] Read more.

A static model of blast furnace operation of natural gas (NG) injection was developed. The effect of NG injection on the raceway adiabatic flame temperature, the amount and composition of bosh gas, the direct reduction degree and fuel ratio were studied. The results showed that under no thermal compensation, the heat loss of the whole blast furnace increases, which means the heat surplus of the whole furnace is sufficient. However, the heat in the high-temperature zone of the blast furnace is insufficient, showing the characteristics of “cold at bottom and hot at the top”. Based on the comparison of heat loss in the high-temperature zone after NG injection with the reference condition, if the heat loss is consistent with the reference case, the suitable NG injection volumes are 17.3, 34.6, 52 and 69.3 m³/t when the coal ratio is reduced by 20, 40, 60 and 80 kg/t, respectively. With the increase of the suitable NG injection volumes, the adiabatic flame temperature gradually decreases, the amount of bosh gas slightly increases, and the overall fuel ratio reduces gradually. The effect of other thermal compensation operations, such as increasing blast temperature and addition of oxygen on the NG injection, were also investigated. The findings of this work can be used as a theoretical basis to guide plant operations for NG injection in blast furnaces. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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14 pages, 4282 KiB

Open AccessArticle

Automatic Control of Hot Metal Temperature

by Yoshinari Hashimoto, Ryosuke Masuda, Max Mulder and Marinus M. (René) van Paassen

Metals 2022, 12(10), 1624; https://doi.org/10.3390/met12101624 - 28 Sep 2022

Cited by 3 | Viewed by 1685

Abstract

To achieve the automation of blast furnace operation, an automatic control system for hot metal temperature (HMT) was developed. Nonlinear model predictive control (NMPC) which predicts up to ten-hour-ahead HMT and calculates appropriate control actions of pulverized coal rate (PCR) was constructed. Simulation [...] Read more.

To achieve the automation of blast furnace operation, an automatic control system for hot metal temperature (HMT) was developed. Nonlinear model predictive control (NMPC) which predicts up to ten-hour-ahead HMT and calculates appropriate control actions of pulverized coal rate (PCR) was constructed. Simulation validation showed that the NMPC algorithm generates control actions similar to those by the operators and that HMT can be maintained within ±10 °C of the set point. The automatic control system using NMPC was then implemented in an actual plant. As a result, the developed control system suppressed the effects of disturbances, such as the changes in the coke ratio and blast volume, and successfully reduced the average control error of HMT by 4.6 °C compared to the conventional manual operation. The developed control system has contributed to the reduction of reducing agent rate (RAR) and CO₂ emissions. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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8 pages, 1921 KiB

Open AccessArticle

Study on Precipitation and Dissolution Mechanisms of Graphite in Hot Metal of Blast Furnace

by Meng Xie, Hongtao Wang, Mingrong Huang, Ping Wang, Yang Song and Zhanxia Di

Metals 2022, 12(10), 1608; https://doi.org/10.3390/met12101608 - 26 Sep 2022

Viewed by 1103

Abstract

Graphite precipitation in the hot metal of a blast furnace (BF) has a significant effect on the low permeability zone of the deadman. In this work, the precipitation mechanisms of graphite in the hot metal of BF were investigated and discussed. Furthermore, the [...] Read more.

Graphite precipitation in the hot metal of a blast furnace (BF) has a significant effect on the low permeability zone of the deadman. In this work, the precipitation mechanisms of graphite in the hot metal of BF were investigated and discussed. Furthermore, the theoretical flame temperature of tuyere raceway, the center temperature of the deadman, and the critical temperature of graphite precipitated from the hot metal, were calculated and the graphitic carbon cycle and graphite enrichment mechanisms in the void of the deadman were analyzed. The results showed that the theoretical flame temperatures of the two BFs used in this study varied from 2100

^{\circ}

C to 2200

^{\circ}

C and the average center temperatures of the deadman in 4350 m³ and 1280 m³ BFs were 1329.08

^{\circ}

C and 1386.74, respectively. Moreover, graphite can precipitate from the hot metal and be enriched in the void of the deadman under certain conditions. It was assumed in this work that graphite is precipitated in the form of a 2 mm sphere and the precipitation rate of graphite in hot metal is approximately 1.01 × 10⁻⁸ kg/s. With variation in BF conditions, the precipitation–enrichment–dissolution process of graphite occurs continuously in the deadman of the BF. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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13 pages, 4521 KiB

Open AccessArticle

Estimation of the Blast Furnace Hearth State Using an Inverse-Problem-Based Wear Model

by Chengbo Zhang, Binbin Hou, Lei Shao, Zongshu Zou and Henrik Saxén

Metals 2022, 12(8), 1302; https://doi.org/10.3390/met12081302 - 3 Aug 2022

Cited by 1 | Viewed by 2052

Abstract

An undisturbed and well-controlled hearth state is an essential prerequisite for achieving a long campaign life and low production costs in an ironmaking blast furnace, because hearth wear and hot metal and slag drainage are crucial factors in its operation. With the objective [...] Read more.

An undisturbed and well-controlled hearth state is an essential prerequisite for achieving a long campaign life and low production costs in an ironmaking blast furnace, because hearth wear and hot metal and slag drainage are crucial factors in its operation. With the objective to estimate the hearth state of the refractory of a three-taphole blast furnace, a wear model of the hearth erosion and skull formation was developed. The model is based on thermocouple readings in the hearth lining and solves an inverse heat conduction problem for a series of co-axial vertical slices, where the erosion and skull lines are optimized simultaneously. The model is optimized for fast computation by adopting a novel procedure featuring fixed mesh during the looping calculation. The results revealed that the hearth refractory showed an elephant-foot-shaped profile with excessive erosion in the hearth periphery, indicating that liquid flows are suppressed in the hearth bottom and that the permeability of the core of the deadman is low. These findings were further elaborated and confirmed by a comparison between the estimated hearth state and other key operation variables, including the coke rate, blast kinetic energy, and residual carbon appetite of the hot metal. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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15 pages, 3589 KiB

Open AccessArticle

Numerical Study on Combustion Behavior of Semi-Coke in Blast Furnace Blowpipe-Tuyere-Combustion Zone

by Yang You, Zhuang Zheng, Rui Wang, Qingqing Hu, Yanhui Li and Zhixiong You

Metals 2022, 12(8), 1272; https://doi.org/10.3390/met12081272 - 28 Jul 2022

Cited by 7 | Viewed by 1485

Abstract

Injecting low-cost semi-coke is critical to reducing blast furnace production costs. The combustion behavior of the co-injection of semi-coke and undersized coke powder is still rarely studied. In this work, a three-dimensional CFD mathematical model was established to simulate the gas velocity, temperature, [...] Read more.

Injecting low-cost semi-coke is critical to reducing blast furnace production costs. The combustion behavior of the co-injection of semi-coke and undersized coke powder is still rarely studied. In this work, a three-dimensional CFD mathematical model was established to simulate the gas velocity, temperature, composition distribution and burnout of semi-coke during the combustion of pulverized semi-coke. The influence of mass fraction of semi-coke on the composition and burnout in the combustion zone of blast furnace was also studied. The results show that the maximum concentrations of CO and H₂ in the combustion zone are 36% and 8%, respectively. With the decrease of the semi-coke ratio in the blended coal, the fixed carbon content and the calorific value of the blended coal increase, but the burnout of the blended coal reduces. When bituminous coal is single injected, the burnout reaches 70%, which is higher than that of semi-coke. In actual production, for the semi-coke and coke powder injecting into the blast furnace, a proportion of bituminous coal can be appropriately added to improve the burnout rate of the coal blends and increase the H₂ content in reducing gas. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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13 pages, 3325 KiB

Open AccessArticle

Influence of Variable-Diameter Structure on Gas–Solid Heat Transfer in Vertical Shaft Cooler

by Tengfei Qi, Haifeng Li, Yongjie Zhang and Lei Shao

Metals 2022, 12(7), 1187; https://doi.org/10.3390/met12071187 - 12 Jul 2022

Cited by 2 | Viewed by 1183

Abstract

In order to improve the heat transfer between high-temperature sinter and cooling gas in a vertical shaft cooler, a new furnace type with variable-diameter structure was proposed, and the influence of variable-diameter structure on gas–solid heat transfer in vertical-shaft cooler was studied by [...] Read more.

In order to improve the heat transfer between high-temperature sinter and cooling gas in a vertical shaft cooler, a new furnace type with variable-diameter structure was proposed, and the influence of variable-diameter structure on gas–solid heat transfer in vertical-shaft cooler was studied by CFD-DEM coupling method in the current work. The results show that variable-diameter structure can increase the quantity of low-temperature sinter as well as the outlet cooling gas temperature, and can improve the uniformity of sinter and cooling gas temperature along the width, at the cost of significantly increasing the cooling gas pressure. By changing the parameters of the variable-diameter structure, it was found that a smaller width of the vertical section or a larger angle of the contraction section led to a better sinter–gas heat transfer. The influence of vertical section width on cooling gas pressure was more obvious. It is suggested that when designing and using the vertical shaft cooler with variable-diameter structure, consideration should be given to the effect of sinter–gas heat exchange and the pressure of cooling gas. Furthermore, the occurrence of material blockage and excessive equipment height should be avoided. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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13 pages, 4190 KiB

Open AccessArticle

Development and Implementation of Decision Support Systems for Blast Smelting Control in the Conditions of PrJSC “Kamet-Steel”

by Yurii S. Semenov, Yevhen I. Shumelchyk, Viktor V. Horupakha, Igor Y. Semion, Sergii V. Vashchenko, Oleksandr Y. Khudyakov, Igor V. Chychov, Iryna H. Hulina and Rostyslav H. Zakharov

Metals 2022, 12(6), 985; https://doi.org/10.3390/met12060985 - 8 Jun 2022

Cited by 3 | Viewed by 1535

Abstract

This article presents a description of three decision support systems (DSS) in the mode of an adviser to the technological personnel of blast furnaces (BF), which were implemented by the Iron and Steel Institute of Z.I. Nekrasov (Dnipro, Ukraine) or underwent pilot testing [...] Read more.

This article presents a description of three decision support systems (DSS) in the mode of an adviser to the technological personnel of blast furnaces (BF), which were implemented by the Iron and Steel Institute of Z.I. Nekrasov (Dnipro, Ukraine) or underwent pilot testing as part of the automated control system of the BF shop of PrJSC “Kamet-steel” (Kamianske, Ukraine). The first DSS for managing the thermal state was implemented in 2021; it includes the entire list of information necessary for personnel in a convenient and compact form, generates recommendations in case of technology deviations, and, in the case of incorrect actions by the personnel, signals the need for correct actions. The main recommendations from the DSS are to correct the raceway adiabatic flame temperature, coke consumption when its characteristics are specified in (indicators of strength and abrasion, fractional composition, humidity, ash and sulfur), and ore load change. Using the system allows both reducing the specific coke consumption and preventing unplanned downtime. The second DSS for controlling the distribution of fuel additives over air tuyeres is based on information on thermal loads determined on water-cooled elements of tuyere tools. The main recommendations from the DSS are to adjust the amount of injected pulverized coal fuel on individual tuyeres in order to ensure a uniform distribution of the raceway adiabatic flame temperature around the circumference of the BF and, as a result, the energy efficiency of BF smelting. The third DSS for adjusting the parameters of the charging mode is based on information from the means of controlling the temperatures of the gas flow above the surface of the charge in the BF. The functioning of this DSS is based on determining the reference curves for the distribution of the gas flow along the BF radii, corresponding to the minimum consumption of coke and maximum productivity, and on the search for solutions by direct and iterative optimization methods, which allow one, by adjusting the charging parameters, to ensure a rational distribution of charge materials and gas flow in the BF. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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20 pages, 9927 KiB

Open AccessArticle

Investigation of the Hearth Erosion of WISCO No. 1 Blast Furnace Based on the Numerical Analysis of Iron Flow and Heat Transfer in the Hearth

by Ao Ni, Chengzhi Li, Wei Zhang, Zhixin Xiao, Dongliang Liu and Zhengliang Xue

Metals 2022, 12(5), 843; https://doi.org/10.3390/met12050843 - 15 May 2022

Cited by 4 | Viewed by 1590

Abstract

The campaign life of a blast furnace is largely limited by the erosion state of its hearth section. Therefore, the study of hearth erosion is important for blast furnace ironmaking. In this study, the hearth erosion of the WISCO No. 1 blast furnace [...] Read more.

The campaign life of a blast furnace is largely limited by the erosion state of its hearth section. Therefore, the study of hearth erosion is important for blast furnace ironmaking. In this study, the hearth erosion of the WISCO No. 1 blast furnace was investigated in combination with the numerical analysis of the iron flow and heat transfer in the hearth. The distributions of the wall shear stress and the temperature in the hearth were simulated and the hearth sections with high erosion risk were discussed. The hearth lining with higher shear stress is generally located near the taphole region and the 1423 K isotherm is totally located inside the hearth lining structure, with a deeper position in the central part of the hearth bottom. Based on the measurement data from the hearth damage investigation, the erosion state of the hearth bottom and the lower part of the hearth sidewall is more serious. The erosion line at the hearth bottom showed a typical “pot-bottom” shaped contour and for the hearth corner section, the average erosion depth was about 1/3 of the total wall thickness. The empirical expressions between the hearth erosion depth and the wall shear stress and the temperature were established. Moreover, the effects of key iron tapping factors on the wall shear stress and the effect of the hearth’s refractory structure on the heat transfer in the hearth are respectively discussed, aiming to provide more suggestions for hearth protection. Full article

(This article belongs to the Special Issue Mathematical Modelling of the Ironmaking Blast Furnace)

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