| 1. |
- Chai, Yifan, et al.
(author)
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Study on strength and reduction characteristics of iron ore powder-green carbon composite briquettes
- 2024
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In: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 377
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Journal article (peer-reviewed)abstract
- The metallurgical industry is a key sector for carbon emissions, and in recent years, there has been widespread attention on the use of biomass resources as a green, renewable, and carbon–neutral energy source material for low carbon ironmaking processes. The waste wood after hydrothermal-pyrolysis carbonization has the characteristics of low content of harmful elements and high content of fixed carbon. In this study, the waste wood after hydrothermal-pyrolysis two-step carbonization treatment was used as a reducing agent for the reduction of iron ore to prepare iron ore powder- green carbon composite briquettes (ICCB) with two carbon–oxygen ratios. The study investigated the effects of reduction behavior and reaction temperature on the reduction performance of the ICCB. The results indicate that with the increase in reaction temperature, the volume of the ICCB gradually contracts, leading to a reduction in mass. The shrinkage rate of the ICCB during self-reduction at 1200℃ is significantly higher than during co-reduction, and the shrinkage effect of the C/O 0.5 ICCB is more pronounced than that of the C/O 0.8 ICCB. Due to the excessive carbon content in the C/O 0.8 ICCB, the carbon cannot be fully consumed during the reaction process, resulting in consistently low compressive strength of the ICCB, with a compressive strength of 12 N after reduction at 1200℃. In contrast, the iron phase in the C/O 0.5 ICCB gradually recrystallizes during the reduction process, ultimately yielding plastic iron briquettes with compressive strengths exceeding 3000 N after different reaction behaviors at 1200℃. In summary, reducing the carbon-to-oxygen ratio and increasing the reaction temperature contribute to the volume contraction and enhanced compressive strength of the ICCB during the reduction process.
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| 2. |
- Kristan, Matej, et al.
(author)
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The first visual object tracking segmentation VOTS2023 challenge results
- 2023
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In: 2023 IEEE/CVF International conference on computer vision workshops (ICCVW). - : Institute of Electrical and Electronics Engineers Inc.. - 9798350307443 - 9798350307450 ; , s. 1788-1810
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Conference paper (peer-reviewed)abstract
- The Visual Object Tracking Segmentation VOTS2023 challenge is the eleventh annual tracker benchmarking activity of the VOT initiative. This challenge is the first to merge short-term and long-term as well as single-target and multiple-target tracking with segmentation masks as the only target location specification. A new dataset was created; the ground truth has been withheld to prevent overfitting. New performance measures and evaluation protocols have been created along with a new toolkit and an evaluation server. Results of the presented 47 trackers indicate that modern tracking frameworks are well-suited to deal with convergence of short-term and long-term tracking and that multiple and single target tracking can be considered a single problem. A leaderboard, with participating trackers details, the source code, the datasets, and the evaluation kit are publicly available at the challenge website1
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| 3. |
- Liang, Wang, et al.
(author)
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Life cycle assessment of blast furnace ironmaking processes : A comparison of fossil fuels and biomass hydrochar applications
- 2023
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In: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 345
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Journal article (peer-reviewed)abstract
- The impact of the iron and steel production process on the ecological environment cannot be ignored. This study aims to assess the impact of life cycle assessment on the traditional fossil fuel blast furnace ironmaking process and the biomass hydrochar blast furnace ironmaking process. The Simapro v9.0 software is used to comprehensively evaluate the life cycle impacts of biomass hydrochar in the blast furnace ironmaking process. The results show that the life cycle impact categories of the blast furnace ironmaking process mainly include global warming, non-renewable energy and respiratory inorganics. The global warming impact of the ironmaking process using hydrochar is 2054.00 kg CO2 eq, which is 420.61 kg CO2 eq less than that of traditional blast furnace ironmaking process. The global warming impact is mainly reflected in the emission of CO2 gas, and the main source is the generation of blast furnace gas and the use of sinter. The respiratory inorganics impact is mainly manifested in the emission of nitrogen oxides, sulfur oxides and particulates, which mainly comes from the mining of iron ore and the production of sinter. The non-renewable energy impact mainly comes from the coal resources, and the use of other renewable energy such as biomass energy is an important way to reduce the impact. Therefore, biomass hydrochar used in the metallurgical process is more suitable for sustainable devel-opment of the ecological environment.
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| 4. |
- Wang, Guangwei, et al.
(author)
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Application of catalysts in biomass hydrothermal carbonization for the preparation of high-quality blast furnace injection fuel
- 2023
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In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 283
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Journal article (peer-reviewed)abstract
- The low energy density of biomass is a crucial limitation for their application in the steel industry. This study used catalyst-catalysed hydrothermal carbonization (HTC) to prepare higher-quality hydrochar from biomass. The effects of acid-base homogeneous catalysts (Fe(NO3)3·9H2O and CaO), liquid phase product (circulating water) and carbonization temperatures on the physicochemical properties and microscopic morphology of hydrochars were investigated. The results showed that higher carbonization temperature, circulating water and Fe(NO3)3·9H2O all raised the higher heating value (HHV) of hydrochar. When 4% of Fe(NO3)3·9H2O was added, the HHV of hydrochar reached 30.05 MJ/kg, which was 1.15 times higher than without catalysts. The above three conditions can also make the ordering degree in the carbonaceous structure lower ordered and enhance the reaction performance of the hydrochar. Meanwhile, the addition of Fe(NO3)3·9H2O at 240 °C can reduce the hydrochar ignition and burnout temperatures and enhance the combustion performance. Moreover, it was demonstrated that circulating water promoted the HTC more than deionized water. In conclusion, adding Fe(NO3)3·9H2O or circulating water to the HTC process can produce higher-quality hydrochar.
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| 5. |
- Wang, Guangwei, et al.
(author)
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Co-hydrothermal carbonization of polyvinyl chloride and pyrolysis carbon black for the preparation of clean solid fuels
- 2024
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In: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 361
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Journal article (peer-reviewed)abstract
- Large quantities of polyvinyl chloride (PVC) and waste tires generated daily have the disadvantage of high content of harmful elements. They cannot be directly applied to blast furnace ironmaking. In this study, Cl in PVC and Zn in pyrolysis products of waste tires (pyrolysis carbon black, CB) were effectively removed by co-hydrothermal carbonization (co-HTC). The results indicated the dechlorination and dezincification efficiencies of co-HTC were improved by 2.78 % and 64.69 %, respectively, compared to HTC. Compositional analysis shows that the ash content of co-HTC is reduced by at least 7.67 % compared to conventional HTC. The hydrochar produced by co-HTC has an higher heating value (HHV) ranging from 30.67 to 34.13 MJ/kg. Results of physical and chemical characteristics analysis showed increasing the proportion of CB can reduce the C–H and -CHCl- functional groups and improve the carbon orderliness of the hydrochar. Combustion characteristics and kinetic analyses show that the combustibility of hydrochar increases with an increase in the proportion of PVC added to the co-HTC. The thermal stability and activation energy of the hydrochar increase with the addition of CB. Overall, this study has removed major harmful elements from PVC and CB through co-HTC, converting both into high-quality solid fuels that can be utilised in blast furnace ironmaking.
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| 6. |
- Wang, Guangwei, et al.
(author)
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Hydrothermal carbonization mechanism of agricultural waste under different conditions : An experimental and ReaxFF molecular dynamics study
- 2023
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In: Journal of the Energy Institute. - : Elsevier BV. - 1743-9671 .- 1746-0220. ; 110
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Journal article (peer-reviewed)abstract
- Different hydrothermal carbonization (HTC) conditions will affect the yield, physicochemical properties and application of agricultural waste hydrochar. The hydrochar prepared under different HTC conditions was systematically studied through various experimental methods, and the experimental results were further verified and explained by ReaxFF molecular dynamics method. The results show that the higher HTC temperature, higher liquid-solid ratio and longer reaction time can reduce the yield of solid product. The volatile content of rice straw (RS) hydrochar decreased with the progresses of HTC, but the fixed carbon content increased. The HTC process is accompanied by the breakage of C-H bonds, C-O bonds, C-C bonds and O-H bonds, with C-O bond breaks comprising the most. The HTC process is also accompanied by the C-C bonds regeneration, indicating that decomposition and polymerization reactions coexist in the HTC process. At higher HTC temperature and longer reaction time, RS hydrochar showed lower specific surface area and porosity. The effect of the HTC temperature is the largest, while the effect of holding time is the smallest. Therefore, to expand the potential use of RS hydrochar, it is important to thoroughly investigate the influence of HTC conditions on the physicochemical properties of RS.
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| 7. |
- Wang, Guangwei, et al.
(author)
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Preparation of Biomass Hydrochar and Application Analysis of Blast Furnace Injection
- 2023
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In: Energies. - : MDPI AG. - 1996-1073. ; 16:3
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Journal article (peer-reviewed)abstract
- Hydrothermal carbonization (HTC) technology was used to carbonize and improve biomass raw material to obtain hydrochar. The effects of HTC temperature and holding time on the yield, composition, structure, combustion behavior, and safety of hydrochar were studied systematically. In addition, the results show that with the increase in HTC temperature and the prolongation of holding time, the yield of hydrochar gradually reduces, the fixed carbon content of hydrochar increases, the volatile content decreases, and a large number of ash and alkali metals enter the liquid phase and are removed. Further, the analysis of the combustion properties and the structure of hydrochar can be observed in that, as the HTC process promotes the occurrence of polymerization reactions, the specific surface area gradually reduces, the degree of carbon ordering increases, and the combustion curve moves toward the high-temperature zone and gradually approaches bituminous coal. Since biomass hydrochar has the characteristic of being carbon neutral, blast furnace injection hydrochar can reduce CO2 emissions, and every 1 kg/tHM of biomass hydrochar can reduce CO2 emissions by 1.95 kg/tHM.
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| 8. |
- Wu, Jianlong, et al.
(author)
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Study on Direct Reduction in Carbon-Bearing Pellets Using Biochar
- 2023
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In: Sustainability. - : MDPI AG. - 2071-1050. ; 15:24
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Journal article (peer-reviewed)abstract
- As a renewable, carbon-neutral raw material, the application of biomass in steel production is conducive to reducing greenhouse gas emissions and achieving green and sustainable development in the steel industry. The heating and reduction process of a rotary hearth furnace was simulated under laboratory conditions to roast and reduce biochar carbon-bearing pellets with coke powder and anthracite carbon-bearing pellets as a comparison. This was conducted to investigate the impact of biochar as a reducing agent on the direct reduction in carbon-bearing pellets. Under various reduction temperatures, carbon/oxygen ratios, and reduction times, tests were conducted on the compressive strength and metallization rate of carbon-bearing pellets made using typical binder bentonite. Results show that with the increase in reduction temperature, the metallization rate of pellets increases, while the compressive strength initially decreases and then increases, reaching the lowest point at 900 degrees C and 1000 degrees C. When the ratio of carbon to oxygen is between 0.7 and 0.9 and the reduction time is between 15 and 25 min, carbon-bearing pellets meet the requirements of both the metallization rate and the strength, with the metallization rate above 80%. However, severe volume swelling and low strength were observed in biochar carbon-bearing pellets at 900 degrees C and 1000 degrees C, which negatively impacted multi-layered charging and heat transfer efficiency in the blast furnace. Therefore, a novel laboratory-prepared binder was introduced in the preparation process of biochar carbon-bearing pellets at an appropriate addition ratio of 5-8%. Without producing any swelling concerns, the inclusion of this binder considerably improved the compression strength and metallization rate of the pellets, enabling them to fulfill the standards for raw materials in the blast furnace.
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| 9. |
- Ye, Lian, et al.
(author)
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Feasibility analysis of plastic and biomass hydrochar for blast furnace injection
- 2023
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In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 263
-
Journal article (peer-reviewed)abstract
- Hydrothermal carbonization (HTC) technology upgrades combustible waste (CW) to high-quality fuel known as hydrochar. However, there is a research gap regarding the application limit of hydrochar instead of fossil fuels in blast furnaces. In this study, the physical, chemical, and metallurgical properties of hydrochar were thoroughly analyzed. The results showed that gross calorific value, grindability, ignition temperature, explosivity, combustion and gasification all improved by HTC process compared with the waste feedstocks. Moreover, the HTC process can effectively remove harmful elements (K, Na, Cl, and S) from feedstocks into liquid and gas phase without adding other reagents, reducing harmful effects in the blast furnace. Removal rates by HTC were >80% for alkali metals and >73.9% for Cl (reaching 98.18% for polyvinyl chloride hydrochar). The environmental benefit calculation shows that the CO2 emission reduction of replacing bituminous coal with 40% HTC-treated maize straw can reach 94.7 kg/tHM. The annual CO2 reduction can reach 1.7 x 107 kg and the annual coal reduction is 1.5 x 107 kg of a blast furnace. The results showed that hydrochar is a clean energy source compared with fossil fuel alternatives and meets the blast furnace injection requirements.
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| 10. |
- Zhang, Nan, et al.
(author)
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Physicochemical characteristics of three-phase products of low-rank coal by hydrothermal carbonization : experimental research and quantum chemical calculation
- 2022
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In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 261
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Journal article (peer-reviewed)abstract
- In this paper, the distribution characteristics of gas, liquid, and solid products of low-rank coal by hydrothermal carbonization (HTC) at different temperatures are studied. Advanced testing methods are used to explore changing rules of physicochemical characteristics. Reaction properties of different regions are explained based on the mechanism of quantum chemistry. Experimental results showed that as the temperature increases, the volatile content decreases, the fixed carbon content increases, and impurities are removed in the form of gas or ions. The coal aliphatic properties are reduced, whereas the aromatization degree is significantly enhanced. Meanwhile, the specific surface area after upgrading is reduced, but the average pore diameter is increased, and the pore structure density is enhanced. The content of carbon-containing groups increases but that of carbon-oxygen groups decreases, which corresponds to the O/C ratio. Theoretical calculation results demonstrate that the more negative and positive areas of the surface electrostatic potential (ESP), the smaller distribution proportion. The ESP value in the vicinity of oxygen-containing group is relatively negative, indicating that it is more reactive, which is a good proof of the experiment's conclusions. In summary, low-rank coal obtained after HTC meets the blast furnace injection requirements and can be used for injection.
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| 11. |
- Zhang, Nan, et al.
(author)
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Study of the comprehensive properties of low-rank coal using quantum chemical methods
- 2024
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In: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 375
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Journal article (peer-reviewed)abstract
- In this study, we performed a comprehensive analysis of the molecular structural characteristics of low-rank coal and predicted its chemical properties. Using quantum chemistry and wave function analysis, we extensively discussed electrostatic potential surfaces, spectral characteristics, electronic structure, and orbital composition of coal. Our findings reveal that regions exhibiting negative electrostatic potential display increased reactivity during reactions. Oxygen-containing groups in coal molecules exhibit strong hydrophilicity upon interaction with water, primarily through medium-strength and weak hydrogen bonds. Hydrophobic sites are predominantly located near the aliphatic side chains and aromatic core groups of the coal molecules. Additionally, oxygen and carbon atom orbitals dominate regions of lower energy density, correlating with volatile substances that undergo initial decomposition during coal heating. These results provide fundamental insights into the physical and chemical properties of low-rank coal from a molecular perspective.
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