Unsteady Analyses of the Top Gas Recycling Oxygen Blast Furnace

Zhang, Wei; Zhang, Juhua; Xue, Zhengliang; Zong-shu, Zou; Qi, Yuan-hong

doi:10.2355/isijinternational.isijint-2016-090

Cited by 30 publications

(15 citation statements)

References 11 publications

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“…After the three types of coke samples employed were analyzed by XRD, their diffraction angles were acquired, and the graphitization degrees were calculated by Equations (13) and (14). Figure 11 reveals the correlation between the dissolution rate coefficient and the r 0 values of these three types of cokes.…”

Section: Effect Of Graphitization Degree On the Dissolution Ratementioning

confidence: 99%

“…After a large number of in-depth studies, with direct reduction [6][7][8][9] and smelting reduction [10][11][12][13][14][15][16][17][18][19] as its core, modern non-blast furnace ironmaking processes have been set up, and the flash ironmaking process [20][21][22][23] has stood out as one of them in recent years. In this process, a pile of coke bed is designed in the melting zone.…”

Section: Introductionmentioning

confidence: 99%

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Isothermal Kinetic Mechanism of Coke Dissolving in Hot Metal

Zhang

Hua

Dai

et al. 2019

Metals

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The carburization of molten iron is close to saturation in the blast furnace process, while that in the flash ironmaking process is uncertain because there is no pressure from solid charge and no carburization reactions occurring between the deadman and hot metal. Some experiments were conducted to reveal the kinetic mechanism of coke dissolving in carbon-iron melts. Reduced iron powder, electrolytic iron as well as chemical pure graphite were used as experiment materials. With high-purity argon injected as the protective gas, the specimens were heated up to 1873 K in a tubular resistance furnace to study the isothermal mechanism. The results show that the composition of the ferrous sample affects the dissolution rate. When the FeO content of the iron-bearing material rises from 0% to 4.76%, the apparent dissolution rate constant, kt, falls from 7.98 × 10−6 m/s to 5.48 × 10−6 m/s. There are some differences amongst the dissolution rate coefficients of different cokes despite interacting with similar carbon-iron melts, with coke 1 of 7.98 × 10−6 m/s, coke 2 of 5.17 × 10−6 m/s, and coke 3 of 3.77 × 10−6 m/s. Besides, this index decreases with the increase of the dissolution time and solely depends on the procedure of the mass transfer. A negative correlation is demonstrated between kt and the sulfur content in the iron bath as well. The content of silicon dioxide in the coke has a significant influence on kt. Additionally, the dissolution rate coefficient increases with the increase of the graphitization degree of coke.

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Section: Effect Of Graphitization Degree On the Dissolution Ratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Isothermal Kinetic Mechanism of Coke Dissolving in Hot Metal

Zhang

Hua

Dai

et al. 2019

Metals

Self Cite

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“…The mathematical analysis of solid flow in the BF or COREX is divided into three categories, namely, the continuous model [23], the discrete model [24][25][26] and the discrete−continuous model [27]. Furthermore, Zhang et al [28] used the unsteady model to demonstrate the typical unsteady analyses of the TGR-OBF processes. They found that under the default condition, it takes about six times for the main gas elements travelling from the tuyere zone to the furnace top, until the unsteady process becomes stable.…”

Section: Introductionmentioning

confidence: 99%

A downscaling cold model for solid flow behaviour in a top gas recycling-oxygen blast furnace

Wang²,

Liu³

et al. 2020

High Temperature Materials and Processes

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The top gas recycling-oxygen blast furnace (TGR-OBF) is a reasonable method used to reduce both coke rate and energy consumption in the steel industry. An important feature of this process is shaft gas injection. This article presents an experimental study on the gas–solid flow characteristics in a TGR-OBF using a two-dimensional cold model. The experimental conditions and parameters were determined using a series of similarity criteria. The results showed that the whole flow area in the TGR-OBF can be divided into four distinct flow zones, namely, the stagnant zone, the plug flow zone in the upper part of the shaft, the converging flow zone and the quasi-stagnant flow zone, which is similar to that in a traditional blast furnace. Then the effects of batch weight and the ratio (X) of the shaft injected gas flow rate to the total gas flow rate on solid flow behaviour were investigated in detail. With the increase in batch weight, the shape of the stagnant zone tends to be shorter and thicker. Furthermore, with the increase in X value from 0 to 1, the stagnant zone gradually becomes thinner and higher. The results obtained from the experiments provide fundamental data and a validation for the discrete element method–computational fluid dynamics-coupled mathematical model for TGR-OBFs for future studies.

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“…The reduction in CO2 emissions was estimated to be in the range of 10-25% [22] ( Figure 6). However, the TGR-OBF-CCS technology is relatively complicated, electricity consumption increases, and less electric power can be generated [27,[36][37][38]. An industrial TGR-OBF installation was put into operation in Anshan, China, in 2012 [39].…”

mentioning

confidence: 99%

“…Acronyms are explained in the text. Outlined based on literature data[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40].…”

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confidence: 99%

A General Vision for Reduction of Energy Consumption and CO2 Emissions from the Steel Industry

Holappa

2020

Metals

165

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The 2018 IPCC (The Intergovernmental Panel on Climate Change’s) report defined the goal to limit global warming to 1.5 °C by 2050. This will require “rapid and far-reaching transitions in land, energy, industry, buildings, transport, and cities”. The challenge falls on all sectors, especially energy production and industry. In this regard, the recent progress and future challenges of greenhouse gas emissions and energy supply are first briefly introduced. Then, the current situation of the steel industry is presented. Steel production is predicted to grow by 25–30% by 2050. The dominant iron-making route, blast furnace (BF), especially, is an energy-intensive process based on fossil fuel consumption; the steel sector is thus responsible for about 7% of all anthropogenic CO2 emissions. In order to take up the 2050 challenge, emissions should see significant cuts. Correspondingly, specific emissions (t CO2/t steel) should be radically decreased. Several large research programs in big steelmaking countries and the EU have been carried out over the last 10–15 years or are ongoing. All plausible measures to decrease CO2 emissions were explored here based on the published literature. The essential results are discussed and concluded. The specific emissions of “world steel” are currently at 1.8 t CO2/t steel. Improved energy efficiency by modernizing plants and adopting best available technologies in all process stages could decrease the emissions by 15–20%. Further reductions towards 1.0 t CO2/t steel level are achievable via novel technologies like top gas recycling in BF, oxygen BF, and maximal replacement of coke by biomass. These processes are, however, waiting for substantive industrialization. Generally, substituting hydrogen for carbon in reductants and fuels like natural gas and coke gas can decrease CO2 emissions remarkably. The same holds for direct reduction processes (DR), which have spread recently, exceeding 100 Mt annual capacity. More radical cut is possible via CO2 capture and storage (CCS). The technology is well-known in the oil industry; and potential applications in other sectors, including the steel industry, are being explored. While this might be a real solution in propitious circumstances, it is hardly universally applicable in the long run. More auspicious is the concept that aims at utilizing captured carbon in the production of chemicals, food, or fuels e.g., methanol (CCU, CCUS). The basic idea is smart, but in the early phase of its application, the high energy-consumption and costs are disincentives. The potential of hydrogen as a fuel and reductant is well-known, but it has a supporting role in iron metallurgy. In the current fight against climate warming, H2 has come into the “limelight” as a reductant, fuel, and energy storage. The hydrogen economy concept contains both production, storage, distribution, and uses. In ironmaking, several research programs have been launched for hydrogen production and reduction of iron oxides. Another global trend is the transfer from fossil fuel to electricity. “Green” electricity generation and hydrogen will be firmly linked together. The electrification of steel production is emphasized upon in this paper as the recycled scrap is estimated to grow from the 30% level to 50% by 2050. Finally, in this review, all means to reduce specific CO2 emissions have been summarized. By thorough modernization of production facilities and energy systems and by adopting new pioneering methods, “world steel” could reach the level of 0.4–0.5 t CO2/t steel and thus reduce two-thirds of current annual emissions.

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Unsteady Analyses of the Top Gas Recycling Oxygen Blast Furnace

Cited by 30 publications

References 11 publications

Isothermal Kinetic Mechanism of Coke Dissolving in Hot Metal

Isothermal Kinetic Mechanism of Coke Dissolving in Hot Metal

A downscaling cold model for solid flow behaviour in a top gas recycling-oxygen blast furnace

A General Vision for Reduction of Energy Consumption and CO2 Emissions from the Steel Industry

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