To explore the solutions of saving energy and cost of the rotary hearth furnace (RHF) direct reduction process, this paper constructed an energy consumption model, an economic evaluation model, and a carbon emission calculation model of the RHF direct reduction process. According to the actual production conditions of a steel plant, the influence of combustion air temperature and oxygen enrichment rate on the energy consumption, cost, and carbon emission of the RHF direct reduction process were studied. The calculation results show that for every 50 °C increase in the combustion air temperature, the process energy consumption, comprehensive cost, and carbon emission reduce by about 11 kgce, 42 CHY, and 44 kg, respectively. For every 2 pct increase in the oxygen enrichment rate of the combustion air, the corresponding values are about 10 kgce, 26 CHY, and 37 kg, respectively. In addition, the mathematical model established in this paper can be used to calculate the process energy consumption, cost, and carbon emissions under different raw material and fuel conditions, which is of great theoretical significance for the green and low-carbon transformation of the RHF direct reduction process.
{"title":"Research on Mathematical Model and Process Parameter Optimization of Rotary Hearth Furnace Process Toward Energy and Cost Saving","authors":"Yingpeng Dong, Yanbing Zong, Runsheng Xu, Yuancheng Huang, Jianliang Zhang, Rongrong Wang, Jinpeng Shi, Yongsheng Yang","doi":"10.1007/s11663-024-03190-3","DOIUrl":"https://doi.org/10.1007/s11663-024-03190-3","url":null,"abstract":"<p>To explore the solutions of saving energy and cost of the rotary hearth furnace (RHF) direct reduction process, this paper constructed an energy consumption model, an economic evaluation model, and a carbon emission calculation model of the RHF direct reduction process. According to the actual production conditions of a steel plant, the influence of combustion air temperature and oxygen enrichment rate on the energy consumption, cost, and carbon emission of the RHF direct reduction process were studied. The calculation results show that for every 50 °C increase in the combustion air temperature, the process energy consumption, comprehensive cost, and carbon emission reduce by about 11 kgce, 42 CHY, and 44 kg, respectively. For every 2 pct increase in the oxygen enrichment rate of the combustion air, the corresponding values are about 10 kgce, 26 CHY, and 37 kg, respectively. In addition, the mathematical model established in this paper can be used to calculate the process energy consumption, cost, and carbon emissions under different raw material and fuel conditions, which is of great theoretical significance for the green and low-carbon transformation of the RHF direct reduction process.</p>","PeriodicalId":18613,"journal":{"name":"Metallurgical and Materials Transactions B","volume":"111 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-24DOI: 10.1007/s11663-024-03213-z
Y. J. Hu, J. Y. Wang, W. Zhai, B. Wei
Two ultrasonic modes, i.e., continuous and pulsed ultrasounds, were introduced into the directional solidification process of Cu68.3Al27.6Ni4.1 alloy. A columnar-to-equiaxed structure transition occurred to primary β(Cu3Al) phase within continuous ultrasonic field, which was accompanied with a grain size reduction by 7.5 times. Under pulsed ultrasound, β phase maintained the fine columnar structures with a similar grain size. In the former case, numerous β phase nucleation sites formed ahead of solid/liquid (S/L) interface because of the large local undercoolings induced by transient cavitation. Meanwhile, intensive acoustic streaming suppressed the liquid temperature gradient from 120 to 85 K/cm, which interrupted the solute transportation along heat flow direction and resulted in equiaxed microstructures. Under the intermittent ultrasonic action in the latter case, fewer nucleation sites were generated near S/L interface but small columnar β grains were split from the original ones under stable cavitation. Since no steady convection was driven, the liquid temperature gradient of 110 K/cm remained almost constant, making those grains grow into refined columnar structures. Under the action of pulsed ultrasound, the yield strength was enhanced by a factor of 1.5 because of grain refinement strengthening, together with 94 pct shape recovery rate due to columnar grain structures.
{"title":"Ultrasounds Induced Microstructure Transition and Improved Mechanical Property of Directionally Solidified Ternary Cu–Al–Ni Alloy","authors":"Y. J. Hu, J. Y. Wang, W. Zhai, B. Wei","doi":"10.1007/s11663-024-03213-z","DOIUrl":"https://doi.org/10.1007/s11663-024-03213-z","url":null,"abstract":"<p>Two ultrasonic modes, <i>i.e.</i>, continuous and pulsed ultrasounds, were introduced into the directional solidification process of Cu<sub>68.3</sub>Al<sub>27.6</sub>Ni<sub>4.1</sub> alloy. A columnar-to-equiaxed structure transition occurred to primary <i>β</i>(Cu<sub>3</sub>Al) phase within continuous ultrasonic field, which was accompanied with a grain size reduction by 7.5 times. Under pulsed ultrasound, <i>β</i> phase maintained the fine columnar structures with a similar grain size. In the former case, numerous <i>β</i> phase nucleation sites formed ahead of solid/liquid (S/L) interface because of the large local undercoolings induced by transient cavitation. Meanwhile, intensive acoustic streaming suppressed the liquid temperature gradient from 120 to 85 K/cm, which interrupted the solute transportation along heat flow direction and resulted in equiaxed microstructures. Under the intermittent ultrasonic action in the latter case, fewer nucleation sites were generated near S/L interface but small columnar <i>β</i> grains were split from the original ones under stable cavitation. Since no steady convection was driven, the liquid temperature gradient of 110 K/cm remained almost constant, making those grains grow into refined columnar structures. Under the action of pulsed ultrasound, the yield strength was enhanced by a factor of 1.5 because of grain refinement strengthening, together with 94 pct shape recovery rate due to columnar grain structures.</p>","PeriodicalId":18613,"journal":{"name":"Metallurgical and Materials Transactions B","volume":"94 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1007/s11663-024-03209-9
Yoongu Kang, In-Ho Jung
In the present study, a well-known Iida’s equation for surface tension was modified to improve the predictivity of the surface tension of pure liquid metals. A semi-empirical equation for the surface tensions (({sigma }_{m})) of liquid metal at its melting temperature proposed by Iida et al. uses a generalized (alpha ) value of 0.51 to represent the ratio of the distance required to separate one atomic pair from its equilibrium distance. This study improved the predictability of the equation by refining the (alpha ) value using the equilibrium interatomic distance (({r}_{e})) and atomic radius (({r}_{a})). Assigning an accurate (alpha ) value for each element greatly improves the prediction accuracy of the surface tension for liquid metals. Furthermore, the critical temperature (({T}_{c})) was calculated based on the interatomic distance (({r}_{c})) at ({T}_{c}) and temperature coefficient of density ((d{rho }_{T})/(dT)) and used to predict the temperature dependence coefficient of surface tension ((d{sigma }_{T})/(dT)). As results, more accurate surface tensions of 42 liquid metals were predicted over the entire liquid state temperature.
{"title":"Model for Surface Tension of Pure Liquid Metals: Revisit to Iida’s Model","authors":"Yoongu Kang, In-Ho Jung","doi":"10.1007/s11663-024-03209-9","DOIUrl":"https://doi.org/10.1007/s11663-024-03209-9","url":null,"abstract":"<p>In the present study, a well-known Iida’s equation for surface tension was modified to improve the predictivity of the surface tension of pure liquid metals. A semi-empirical equation for the surface tensions (<span>({sigma }_{m})</span>) of liquid metal at its melting temperature proposed by Iida <i>et al.</i> uses a generalized <span>(alpha )</span> value of 0.51 to represent the ratio of the distance required to separate one atomic pair from its equilibrium distance. This study improved the predictability of the equation by refining the <span>(alpha )</span> value using the equilibrium interatomic distance (<span>({r}_{e})</span>) and atomic radius (<span>({r}_{a})</span>). Assigning an accurate <span>(alpha )</span> value for each element greatly improves the prediction accuracy of the surface tension for liquid metals. Furthermore, the critical temperature (<span>({T}_{c})</span>) was calculated based on the interatomic distance (<span>({r}_{c})</span>) at <span>({T}_{c})</span> and temperature coefficient of density (<span>(d{rho }_{T})</span>/<span>(dT)</span>) and used to predict the temperature dependence coefficient of surface tension (<span>(d{sigma }_{T})</span>/<span>(dT)</span>). As results, more accurate surface tensions of 42 liquid metals were predicted over the entire liquid state temperature.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>","PeriodicalId":18613,"journal":{"name":"Metallurgical and Materials Transactions B","volume":"67 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1007/s11663-024-03212-0
Indrani Mukherjee, Prosenjit Das
The present study speaks of development of a two-dimensional phase field (PF) model to simulate the cooling slope rheoprocessing of the novel Al-15Mg2Si-4.5Si composite, in view of process optimization and investigation of physics of microstructure formation. In case of cooling slope rheoprocessing, the composite melt starts losing its superheat once it impinges over the slope and transforms into semi-solid slurry during its length of travel over the slope. After experiencing shear flow over the slope, the melt fills an isothermal slurry holding furnace where it undergoes coarsening for a certain length of time. The present PF model simulates how heterogeneous nucleation of solid grains is supposed to happen within the melt, during cooling slope processing, adopting a seed undercooling-based nucleation model. Moreover, the PF model implements a grain coarsening model to simulate the isothermal globularization process of the evolving solid grains of primary Mg2Si and primary Al phases. The interfacial free energy of Al–melt interface is taken from literature, whereas a molecular dynamics (MD) model is employed to estimate the interfacial energy value of the Mg2Si–melt interface. The cooling rate values employed in the present PF model for different melt pouring temperatures are determined experimentally from initial trial experiments, whereas the validation experiments are performed to collect the slurry samples from chosen locations of the melt flow front over the slope and from isothermally kept slurry holding furnace. Micrographs obtained from the above samples confirm the accuracy of the developed 2D PF model to capture microstructural morphology of the composite slurry. Moreover, the model predictions of quantitative parameters such as grain diameter, shape factor/sphericity, and solid fraction are found to be close to the experimental measurements. For example, a representative simulated value of grain size and sphericity of primary Mg2Si grains, after 8 minutes of slurry holding, are as follows: 24.01 and 0.834 μm, whereas the corresponding experimental values are 29.0 and 0.885 μm, respectively.