A series of improvements in prolonging the AOD refractory lining life in Baosteel are introduced and analyzed in this paper,including modification of the AOD shell shape, adjustment of the top slag components and sele...A series of improvements in prolonging the AOD refractory lining life in Baosteel are introduced and analyzed in this paper,including modification of the AOD shell shape, adjustment of the top slag components and selection of the side-blowing tuyeres. Firstly,the layout of side-blow tuyeres was altered with the angle between each two tuyeres being 22.5° instead of the original 18° ,and the connection of the outside steel shell in the side-blow area was modified from the former platform shape with great stress concentration into a new smooth circle shape. Secondly,the slag components were changed from the former CaO-FeO-SiO： system to the CaO-MgO-SiO2 system. Besides, the basicity of the top slag was kept higher than 1.8 ,and the MgO content in the slag was kept within the range of 8% - 12%. Finally,tuyeres with an inner diameter 13% smaller than that of the original tuyeres were used. Based on these research and optimization work,the thermodynamics and kinetics in the AOD refining bath has been improved markedly, and the campaign of the AOD has been prolonged from 45 heats at the beginning of its start-up to the current 185 heats. Meanwhile,the yield of chromium alloy and the decarburization efficiency have also been improved.展开更多
To address the challenges posed by tunnel construction in the alpine region,silica fume mixed concrete is commonly used as a construction material.The correlation between silica fume content and the lining life requir...To address the challenges posed by tunnel construction in the alpine region,silica fume mixed concrete is commonly used as a construction material.The correlation between silica fume content and the lining life requires immediate investigation.In view of this phenomenon,the durability of unit lining concrete is predicted by analyzing three key indicators:carbonation depth,relative dynamic elastic modulus,and residual quality.This prediction is achieved by integrating the Entropy Weight Method,Grey theory life prediction model and BP artificial neural networks using data from tests and predictions of these indicators.Then,the Entropy Weight-Grey theory-BP Network Model is compared with other methods to analyze the predicted life.Finally,verify the sci-entificity of this model,and the optimum silica fume content of unit concrete lining is verified.The results showed,1)The addition of silica fume will accelerate the carbonization of unit concrete lining,and slow down the freeze-thaw cycle and sulfate erosion.2)The utilization of artificial neural networks is essential for enhancing the realism of the data,as it emphasizes the significance of silica fume content.3)Silica fume content of 10%results in the longest life and is the most suitable for lining construction.4)A comparison between single-factor and multi-factor predictions indicates that the multi-factor approach yields a longer maximum life.This improvement can be attributed to the inclusion of additional factors,such as freeze-thaw cycles and carbonation,which enhance the predicted life when employing these methods.In conclusion,the Entropy Weight-Grey Theory-BP Network life prediction Model is well-suited for tunnel lining in the alpine sulfate area of northwest China.展开更多
The most enduring clichéabout Shakespeare is that he is timeless and universal,although the first claim is unprovable and the second all too easily disproved.Nevertheless,the extraordinary global popularity and s...The most enduring clichéabout Shakespeare is that he is timeless and universal,although the first claim is unprovable and the second all too easily disproved.Nevertheless,the extraordinary global popularity and significance that he has attained is remarkable.So even if we can dismiss the implausible hyperbole of Shakespeare’s universality and timelessness,there still is something that demands explanation.Why do all those who do care about Shakespeare care(and there are,one must admit,a remarkable number of them)?What is it that they care about?展开更多
Based on theoretical analysis and experiment, when the difference between the ropes length is ensured, the radius difference between the rope grooves and the difference of the rope strain of a double rope friction hoi...Based on theoretical analysis and experiment, when the difference between the ropes length is ensured, the radius difference between the rope grooves and the difference of the rope strain of a double rope friction hoist will decrease with the increasing of hoisting times. Then the rope grooves cutting are not needed. If the connection form of the ropes or the structure of the frictional wheel of a four ropes friction hoist are changed into as a double ropes hoists, the hoist rope grooves will not need to be cut as well, and the working time will be saved and the service life of the rope lining will be lengthened also.展开更多
文摘A series of improvements in prolonging the AOD refractory lining life in Baosteel are introduced and analyzed in this paper,including modification of the AOD shell shape, adjustment of the top slag components and selection of the side-blowing tuyeres. Firstly,the layout of side-blow tuyeres was altered with the angle between each two tuyeres being 22.5° instead of the original 18° ,and the connection of the outside steel shell in the side-blow area was modified from the former platform shape with great stress concentration into a new smooth circle shape. Secondly,the slag components were changed from the former CaO-FeO-SiO： system to the CaO-MgO-SiO2 system. Besides, the basicity of the top slag was kept higher than 1.8 ,and the MgO content in the slag was kept within the range of 8% - 12%. Finally,tuyeres with an inner diameter 13% smaller than that of the original tuyeres were used. Based on these research and optimization work,the thermodynamics and kinetics in the AOD refining bath has been improved markedly, and the campaign of the AOD has been prolonged from 45 heats at the beginning of its start-up to the current 185 heats. Meanwhile,the yield of chromium alloy and the decarburization efficiency have also been improved.
基金funded by the Technology Funding Scheme of China Construction Second Engineering Bureau LTD(2020ZX150002)the National Natural Science Foundation Project of China(12262018).
文摘To address the challenges posed by tunnel construction in the alpine region,silica fume mixed concrete is commonly used as a construction material.The correlation between silica fume content and the lining life requires immediate investigation.In view of this phenomenon,the durability of unit lining concrete is predicted by analyzing three key indicators:carbonation depth,relative dynamic elastic modulus,and residual quality.This prediction is achieved by integrating the Entropy Weight Method,Grey theory life prediction model and BP artificial neural networks using data from tests and predictions of these indicators.Then,the Entropy Weight-Grey theory-BP Network Model is compared with other methods to analyze the predicted life.Finally,verify the sci-entificity of this model,and the optimum silica fume content of unit concrete lining is verified.The results showed,1)The addition of silica fume will accelerate the carbonization of unit concrete lining,and slow down the freeze-thaw cycle and sulfate erosion.2)The utilization of artificial neural networks is essential for enhancing the realism of the data,as it emphasizes the significance of silica fume content.3)Silica fume content of 10%results in the longest life and is the most suitable for lining construction.4)A comparison between single-factor and multi-factor predictions indicates that the multi-factor approach yields a longer maximum life.This improvement can be attributed to the inclusion of additional factors,such as freeze-thaw cycles and carbonation,which enhance the predicted life when employing these methods.In conclusion,the Entropy Weight-Grey Theory-BP Network life prediction Model is well-suited for tunnel lining in the alpine sulfate area of northwest China.
文摘The most enduring clichéabout Shakespeare is that he is timeless and universal,although the first claim is unprovable and the second all too easily disproved.Nevertheless,the extraordinary global popularity and significance that he has attained is remarkable.So even if we can dismiss the implausible hyperbole of Shakespeare’s universality and timelessness,there still is something that demands explanation.Why do all those who do care about Shakespeare care(and there are,one must admit,a remarkable number of them)?What is it that they care about?
文摘Based on theoretical analysis and experiment, when the difference between the ropes length is ensured, the radius difference between the rope grooves and the difference of the rope strain of a double rope friction hoist will decrease with the increasing of hoisting times. Then the rope grooves cutting are not needed. If the connection form of the ropes or the structure of the frictional wheel of a four ropes friction hoist are changed into as a double ropes hoists, the hoist rope grooves will not need to be cut as well, and the working time will be saved and the service life of the rope lining will be lengthened also.
