Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cok...Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cokes and their reactivity towards solution loss(SL),especially under hydrogen-enriched atmospheres.Six cokes were characterized,and their SL behaviors were examined under varying atmospheres to elucidate the effects of hydrogen enrichment.The results indicate that an increase in fixed carbon content leads to a decrease in the coke reactivity index(CRI)and an increase in coke strength after reaction(CSR),in the CO_(2) atmosphere,the CSR of coke increases from 35.76%−62.83%,while in the 90CO_(2)/10H_(2) atmosphere,the CSR of coke increases from 65.67%−84.09%.There is a good linear relationship between CRI and microcrystalline structure parameters of coke.Cokes with larger crystalline size,lower amorphous content,and smaller optical texture index(OTI)values show enhanced resistance to degradation and maintain structural integrity in BF.Kinetic analysis performed with the shifted-modified-random pore model(S-MRPM)reveals that alterations in pore structure and intrinsic mineral composition significantly influence the reaction rate.The introduction of a small amount of water vapor raises SL rates,whereas a minor addition of hydrogen(<10%)decelerates SL due to its incomplete conversion to water vapor and the reduced partial pressure of the gasifying agent.Thermodynamic calculations also indicate that the introduced hydrogen does not convert into the same fraction of water vapor.The shift from chemical reaction control to gas diffusion control as the rate-determining step with rising temperatures during SL process was confirmed,and the introduction of hydrogen does not notably alter SL behavior.This result demonstrated that introducing a small amount of hydrogen(<10%)can mitigate SL rates,thereby enhancing coke strength and reducing coke consumption and carbon emissions.展开更多
The existence of soil macropores is a common phenomenon.Due to the existence of soil macropores,the amount of solute loss carried by water is deeply modified,which affects watershed hydrologic response.In this study,a...The existence of soil macropores is a common phenomenon.Due to the existence of soil macropores,the amount of solute loss carried by water is deeply modified,which affects watershed hydrologic response.In this study,a new improved BP(Back Propagation)neural network method,using Levenberg–Marquand training algorithm,was used to analyze the solute loss on slopes taking into account the soil macropores.The rainfall intensity,duration,the slope,the characteristic scale of macropores and the adsorption coefficient of ions,are used as the variables of network input layer.The network middle layer is used as hidden layer,the number of hidden nodes is five,and a tangent transfer function is used as its neurons transfer function.The cumulative solute loss on the slope is used as the variable of network output layer.A linear transfer function is used as its neurons transfer function.Artificial rainfall simulation experiments are conducted in indoor experimental tanks in order to verify this model.The error analysis and the performance comparison between the proposed method and traditional gradient descent method are done.The results show that the convergence rate and the prediction accuracy of the proposed method are obviously higher than that of traditional gradient descent method.In addition,using the experimental data,the influence of soil macropores on slope solute loss has been further confirmed before the simulation.展开更多
In regards to soil macropores,the solute loss carried by overland flow is a very complex process.In this study,a fuzzy neural network(FNN)model was used to analyze the solute loss on slopes,taking into account the soi...In regards to soil macropores,the solute loss carried by overland flow is a very complex process.In this study,a fuzzy neural network(FNN)model was used to analyze the solute loss on slopes,taking into account the soil macropores.An artificial rainfall simulation experiment was conducted in indoor experimental tanks,and the verification of the model was based on the results.The characteristic scale of the macropores,the rainfall intensity and duration,the slope and the adsorption coefficient of ions,were chosen as the input variables to the Sugeno FNN model.The cumulative solute loss quantity on the slope was adopted as the output variable of the Sugeno FNN model.There were three membership functions,and the type of membership function was gbellmf(generalized bell membership function).The hybrid learning algorithm,which combines the back propagation algorithm with a least square method,was applied to train and optimize the network parameters,and the optimal network parameters were determined.The simulation results showed that the simulated values were consistent with the measured values.展开更多
The microstructure of coke has an important influence on its thermal properties.The solution loss reactions of coke in CO2 and H2O atmospheres were investigated by in situ observation.The results showed that the isotr...The microstructure of coke has an important influence on its thermal properties.The solution loss reactions of coke in CO2 and H2O atmospheres were investigated by in situ observation.The results showed that the isotropic components had a more vigorous reaction than the anisotropic components,and the solution loss reaction of the fine-grained mosaic structure was faster than that of the coarse-grained mosaic structure under the CO2 and H2O atmospheres.The coarse-grained mosaic structure and the flowing structure had a relatively higher anti-erosion ability in the CO2 atmosphere than in the H2O atmosphere,and there was no distinct difference in the solution loss of the isotropic structure under the CO2 and H2O atmospheres.The electron probe microanalysis showed that the Al-Si-Fe compounds in the carbon matrix had positive influence on the solution loss reaction of the anisotropic structure.The iron compounds were able to destroy the pore walls of coke and accelerate the solution loss rate of coke.展开更多
The Chinese standard method of GB/T 4000e2017 was unable to accurately measure the coke thermal properties in the large blast furnace.Therefore,the coke compressive strength(CCS)test at a high temperature was designed...The Chinese standard method of GB/T 4000e2017 was unable to accurately measure the coke thermal properties in the large blast furnace.Therefore,the coke compressive strength(CCS)test at a high temperature was designed to examine the coke thermal properties.Then,the large-scale coke model(sp^(2)C_(17421)sp^(3)C_(6579))was established.After,the ReaxFF molecular dynamics simulations were implemented to mimic the coke solution loss(CSL)and the CCS at the high temperature.It was found that the adsorption energy and the diffusion energy of micropores were greater than those of mesopores and macropores,indicating that the CSL reaction mainly happened in the coke micropore.It was discovered that the CSL reaction mechanism was the sp^(3)C oxidization mechanism with the transient state of ketene structure.And,it was detected that the CCS process was divided into the plastic deformation,the instantaneous fracture and the elastic deformation and yield,which was caused by the local reconstruction,the overall folding and the center stretching of carbon layer,respectively.By comparing simulated results with experiments,it was proved that obtained mechanisms were valid.The proposed experimental and simulated methods provided a novel method to measure and understand the coke thermal properties.展开更多
基金supported by National Natural Science Foundation of China(22178002,22178001)Natural Science Foundation of Anhui Province(2308085Y19)Excellent Youth Research Project of Anhui Provincial Department of Education(2022AH030045).
文摘Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cokes and their reactivity towards solution loss(SL),especially under hydrogen-enriched atmospheres.Six cokes were characterized,and their SL behaviors were examined under varying atmospheres to elucidate the effects of hydrogen enrichment.The results indicate that an increase in fixed carbon content leads to a decrease in the coke reactivity index(CRI)and an increase in coke strength after reaction(CSR),in the CO_(2) atmosphere,the CSR of coke increases from 35.76%−62.83%,while in the 90CO_(2)/10H_(2) atmosphere,the CSR of coke increases from 65.67%−84.09%.There is a good linear relationship between CRI and microcrystalline structure parameters of coke.Cokes with larger crystalline size,lower amorphous content,and smaller optical texture index(OTI)values show enhanced resistance to degradation and maintain structural integrity in BF.Kinetic analysis performed with the shifted-modified-random pore model(S-MRPM)reveals that alterations in pore structure and intrinsic mineral composition significantly influence the reaction rate.The introduction of a small amount of water vapor raises SL rates,whereas a minor addition of hydrogen(<10%)decelerates SL due to its incomplete conversion to water vapor and the reduced partial pressure of the gasifying agent.Thermodynamic calculations also indicate that the introduced hydrogen does not convert into the same fraction of water vapor.The shift from chemical reaction control to gas diffusion control as the rate-determining step with rising temperatures during SL process was confirmed,and the introduction of hydrogen does not notably alter SL behavior.This result demonstrated that introducing a small amount of hydrogen(<10%)can mitigate SL rates,thereby enhancing coke strength and reducing coke consumption and carbon emissions.
基金This research was financially supported by the National Natural Science Foundation of China(No.41301037)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.11KJB170008)Innovation and Entrepreneurship Training Program for College Students in Jiangsu Province(No.201910300106Y).For the help in carrying out the experiments,I wish to thank for Professor Rui Xiaofang,Hohai University,China.
文摘The existence of soil macropores is a common phenomenon.Due to the existence of soil macropores,the amount of solute loss carried by water is deeply modified,which affects watershed hydrologic response.In this study,a new improved BP(Back Propagation)neural network method,using Levenberg–Marquand training algorithm,was used to analyze the solute loss on slopes taking into account the soil macropores.The rainfall intensity,duration,the slope,the characteristic scale of macropores and the adsorption coefficient of ions,are used as the variables of network input layer.The network middle layer is used as hidden layer,the number of hidden nodes is five,and a tangent transfer function is used as its neurons transfer function.The cumulative solute loss on the slope is used as the variable of network output layer.A linear transfer function is used as its neurons transfer function.Artificial rainfall simulation experiments are conducted in indoor experimental tanks in order to verify this model.The error analysis and the performance comparison between the proposed method and traditional gradient descent method are done.The results show that the convergence rate and the prediction accuracy of the proposed method are obviously higher than that of traditional gradient descent method.In addition,using the experimental data,the influence of soil macropores on slope solute loss has been further confirmed before the simulation.
基金supported by the National Natural Science Foundation of China(No.41301037)the Natural Science Foundation of Jiangsu Province(BK20201136,BK20191401)+1 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.11KJB170008)Innovation and Entrepreneurship Training Program for College Students in Jiangsu Province(No.201910300106Y).
文摘In regards to soil macropores,the solute loss carried by overland flow is a very complex process.In this study,a fuzzy neural network(FNN)model was used to analyze the solute loss on slopes,taking into account the soil macropores.An artificial rainfall simulation experiment was conducted in indoor experimental tanks,and the verification of the model was based on the results.The characteristic scale of the macropores,the rainfall intensity and duration,the slope and the adsorption coefficient of ions,were chosen as the input variables to the Sugeno FNN model.The cumulative solute loss quantity on the slope was adopted as the output variable of the Sugeno FNN model.There were three membership functions,and the type of membership function was gbellmf(generalized bell membership function).The hybrid learning algorithm,which combines the back propagation algorithm with a least square method,was applied to train and optimize the network parameters,and the optimal network parameters were determined.The simulation results showed that the simulated values were consistent with the measured values.
基金This study was conducted with financial support from the National Natural Science Foundation of China(No.51574023).
文摘The microstructure of coke has an important influence on its thermal properties.The solution loss reactions of coke in CO2 and H2O atmospheres were investigated by in situ observation.The results showed that the isotropic components had a more vigorous reaction than the anisotropic components,and the solution loss reaction of the fine-grained mosaic structure was faster than that of the coarse-grained mosaic structure under the CO2 and H2O atmospheres.The coarse-grained mosaic structure and the flowing structure had a relatively higher anti-erosion ability in the CO2 atmosphere than in the H2O atmosphere,and there was no distinct difference in the solution loss of the isotropic structure under the CO2 and H2O atmospheres.The electron probe microanalysis showed that the Al-Si-Fe compounds in the carbon matrix had positive influence on the solution loss reaction of the anisotropic structure.The iron compounds were able to destroy the pore walls of coke and accelerate the solution loss rate of coke.
基金supported by National Natural Science Foundation of China(22478004,22078002 and 21878001)Joint Fund of the Yulin University and the Dalian National Laboratory for Clean Energy(YLU-DNL Fund 2022002)Major Project of Philosophy and Social Science Research in Anhui Universities Supported by Department of Education Anhui Province(2023AH040333).
文摘The Chinese standard method of GB/T 4000e2017 was unable to accurately measure the coke thermal properties in the large blast furnace.Therefore,the coke compressive strength(CCS)test at a high temperature was designed to examine the coke thermal properties.Then,the large-scale coke model(sp^(2)C_(17421)sp^(3)C_(6579))was established.After,the ReaxFF molecular dynamics simulations were implemented to mimic the coke solution loss(CSL)and the CCS at the high temperature.It was found that the adsorption energy and the diffusion energy of micropores were greater than those of mesopores and macropores,indicating that the CSL reaction mainly happened in the coke micropore.It was discovered that the CSL reaction mechanism was the sp^(3)C oxidization mechanism with the transient state of ketene structure.And,it was detected that the CCS process was divided into the plastic deformation,the instantaneous fracture and the elastic deformation and yield,which was caused by the local reconstruction,the overall folding and the center stretching of carbon layer,respectively.By comparing simulated results with experiments,it was proved that obtained mechanisms were valid.The proposed experimental and simulated methods provided a novel method to measure and understand the coke thermal properties.
