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Investigation into Equivalency of Synthetic Test Circuit Used for Operational Tests of Thyristor Valves for UHVDC

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高压电器 2012年第9期48卷 1-6,15页

作者： ZHOU hui-gao YANG xiao-hui XU fan Xi'an High Voltage Apparatus Research Institute Co. Ltd. Xi'an 710077 China

With the growth of capacity of high voltage direct current(HVDC) transmission lines,the ratings of thyristor valves,which are one of the most critical equipments,are getting higher and *** of performance of thyristor valves particularly designed for HVDC project plays an important role in the handover of products between the manufacturer and the *** test facilities based on philosophy of direct test cannot meet the requirements for modern thyristor *** test facilities with high ratings are necessarily built based on philosophy of synthetic *** the conventional direct test circuit,the later is an economical and feasible solution with less financial investment and higher test ***,the equivalency between the synthetic test and the direct test should be analyzed technically in order to make sure that the condition of verification test in a synthetic test circuit should satisfy the actual operation condition of thyristor valves existing in a real HVDC project,just as in a direct test *** analysis is focused in this paper,covering the scope of thyristor valves' steady state,and transient *** the basis of the results achieved,a synthetic test circuit of 6 500 A/50 kV for operational tests of thyristor valves used for up to UHVDC project has newly been set up and already put into service in Xi'an High Voltage Apparatus Research Institute Co.,Ltd.(XIHARI),*** of the results have been adopted also by a new national standard of China.

关键词： equivalency operational test synthetic test circuit thyristor valve UHVDC

Intelligent Control of Grate-kiln-cooler Process of Iron Ore Pellets Using a Combination of Expert System Approach and Takagi-Sugeno Fuzzy Model

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Journal of Iron and Steel Research International 2016年第5期23卷 434-441页

作者： Gui-ming YANG xiao-hui fan Xu-ling CHEN xiao-xian HUANG Zong-ping LI School of Minerals Processing and Bioengineering Central South University

Grate-kiln-cooler has become a major process of producing iron ore pellets in China. Due to the diversity of the raw materials used and the multi-device multi-variable characteristics,this process still encounters with control problem. An attempt was proposed to deal with this issue. The three-device-integrated feature of the process was firstly analyzed to obtain control strategy,and then an intelligent control system using a combination of expert system approach and Takagi-Sugeno（ T-S） fuzzy model was developed. Expert system approach was used to diagnose and remedy the abnormal conditions,while T-S fuzzy model was used to stabilize the thermal state. In the construction of T-S fuzzy rules,antecedents were identified by fuzzy c-mean clustering algorithm incorporated with subtractive clustering algorithm,and consequent parameters were identified by recursive least square algorithm. The control system was applied in a Chinese pelletizing plant and the application results demonstrated its effectiveness of stabilizing the thermal states within three devices.

关键词： intelligent control grate-kiln-cooler expert system fuzzy model iron ore pellet

Effect of Biochar as Reductant on Magnetizing-roasting Behavior of Pyrite Cinder

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Journal of Iron and Steel Research International 2015年第5期22卷 371-376页

作者： xiao-hui fan Qiong DENG Min GAN Hai-bo WANG School of Minerals Processing and Bioengineering Central South University

The effect of biochar substituted for anthracite as reductant on magnetizing-roasting pyrite cinder was in- vestigated. The key of magnetizing-roasting is the gasification reaction between reductants and CO2. Since biochar could react with CO2 more rapidly at lower temperature, the reactivity of biochar is better than that of anthracite. The gasification of biochar could produce reducing condition of φco/（φco--φco2 ） about 10 %- 20 % between 700-- 800 ℃, which is in accord with the atmosphere and temperature of Fe2 O3 reduction. So it is beneficial to the reduc- tion of iron mineral of pyrite cinder. Compared with anthracite, bioehar could decrease the roasting temperature from 825 to 750 ℃ and roasting time from 20 to 15 min, which shows that a better effect of magnetization could be ob- tained in the condition of lower temperature and shorter time. Using biochar as reductant, iron concentrate extracted from pyrite cinder as about 64% iron grade could be produced, and the recovery is over 90% under the condition of above 90% grinding particle less than 0. 045 mm and magnetic intensity of 0. 124--0. 194 T.

关键词： pyrite cinders biochar magnetizing roasting conversion rate

Optimization of Cooling Process of Iron Ore Pellets Based on Mathematical Model and Data Mining

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Journal of Iron and Steel Research International 2015年第11期22卷 1002-1008页

作者： Gui-ming YANG xiao-hui fan Xu-ling CHEN xiao-xian HUANG Xi LI School of Minerals Processing and Bioengineering Central South University

Cooling process of iron ore pellets in a circular cooler has great impacts on the pellet quality and systematic energy exploitation. However, multi-variables and non-visualization of this gray system is unfavorable to efficient production. Thus, the cooling process of iron ore pellets was optimized using mathematical model and data mining techniques. A mathematical model was established and validated by steady-state production data, and the results show that the calculated values coincide very well with the measured values. Based on the proposed model, effects of important process parameters on gas-pellet temperature profiles within the circular cooler were analyzed to better understand the entire cooling process. Two data mining techniques—Association Rules Induction and Clustering were also applied on the steady-state production data to obtain expertise operating rules and optimized targets. Finally, an optimized control strategy for the circular cooler was proposed and an operation guidance system was developed. The system could realize the visualization of thermal process at steady state and provide operation guidance to optimize the circular cooler.

关键词： iron ore pellet circular cooler model data mining optimization

Prediction of suitable water content in granulation of sintering mixture based on Litster's model

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Journal of Iron and Steel Research International 2024年第3期31卷 552-560页

作者： fang-lei Dai xiao-hui fan xiao-xian Huang Xu-ling Chen Min Gan Zhi-yun Ji Zeng-qing Sun School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083HunanChina

Suitable water content plays a decisive role in the granulation of sintering ***,a method was proposed to predict the suitable water content for effective granulation on the basis of Litster's granulation *** granulation effectiveness of a sintering mixture was predicted by the model,with the allowance error of±10%.The effects of the water absorption properties,particle size composition and content of adhesive particles on the suitable water content were *** results showed that the allowable error of prediction was within±0.5%compared to the experimentally determined suitable water *** an increase in adhesive powder content of mixtures with higher water absorption,the suitable water content increased to achieve similar granulation ***,as the amount of concentrates increased,the suitable water content first increased and then remained *** influence of the water absorption characteristics of the adhesive particles on the suitable water content was less than that of their particle size composition in the mixture.

关键词： Adhesive particle Sintering mixture Granulation effectiveness Suitable water content

Thermodynamic analysis and reaction behaviors of alkali metal elements during iron ore sintering

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Journal of Iron and Steel Research International 2019年第6期26卷 558-566页

作者： xiao-hui fan Yan-nan Wang Min Gan Zhi-yun Ji Yang Zhou Xu-ling Chen School of Minerals Processing & Bioengineering Central South University Changsha 410083 Hunan China

Reaction thermodynamics and behaviors of alkali metal compounds were studied by FactSage7.1 and sinter pot trials. Main transformation behavior of alkali metal compounds was divided into three parts: part of alkali metal chloride was gasified and emitted into the flue gas, and most of alkali metal chloride turned into sulfate, which was remained in the finished sinter, through reacting with sulfur oxide;KAlSi3O8 and NaAlSi3O8 were transformed into KAlSi2O6, NaAlSi2O6 and alkali metal oxides by reacting with calcium oxide. Moreover, newly formed alkali metal oxides turned into sulfate and silicate, entering finished sinter finally. Only a small amount of KAlSi3O8 and NaAlSi3O8 were reduced into gaseous alkali metals in ambient strong reduction atmosphere and removed into the flue gas. 21.67% of potassium and 14.56% of sodiumentered flue gas. In finished sinter, alkali metal elements existed in the form of alkali metal sulfate, silicate and aluminosilicate. The influences on alkali metal elements distribution, basicity (mass ratio of CaO to SiO2 in sinter), sulfur content, chloride content and coal ratio of raw materials indicated that increasing basicity level, rising coal ratio and adding CaCl2 promoted the removal of alkali metal elements into the flue gas. However, with sulfur content increasing in raw materials, alkali metal elements distribution ratio in the finished sinter rose.

关键词： Ironoresintering Potassium Sodium Thermodynamics Distribution Alkali metal

Migration behavior of solid fuel particles during granulation process and its influence on combustion property

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Journal of Iron and Steel Research International 2023年第11期30卷 2153-2162页

作者： Zhi-yun Ji Yi-fan Wang xiao-hui fan Gai-ge Zhao Min Gan Le-yun Tang Yong Tu xiao-long Wang Hao-xiang Zheng Xu-ling Chen xiao-xian Huang Zeng-qing Sun School of Minerals Processing and Bioengineering Central South UniversityChangsha410083HunanChina Hunan Valin Xiangtan Iron and Steel Co. Ltd.Xiangtan411101HunanChina

Iron ore sintering process is the main CO_(2) emission source throughout the integrate steelworks,which primarily comes from the combustion of solid *** the combustion efficiency and reducing the solid fuel consumption are important ways to reduce the CO_(2) emission in the sintering *** the efficient combustion of fuel,the migration behavior and combustion characteristics of solid fuel in the granulation process were *** results indicated that during the granulation process,fuel particles with size less than 0.5 mm mainly migrated into the granules with grain size of 1-3,3-5 and 5-8 mm;fuel particles with size of 0.5^(-1)mm mainly migrated into granules of 1-3 mm;fuel particles with size of 1-3,3-5 and 5-8 mm mainly entered the granules with the same grain *** the increase in fuel particles grain size from-0.5 to+8 mm,the combustion efficiency exhibited a firstly-increasing and then decreasing tendency,while the NO_(x) exhibited a decreasing *** reason can be described that finer fuel particles(-1 mm)easily distributed in the outer layer of the granules,which combusted fiercely due to its larger specific surface area,leading to the development of incomplete combustion and the conversion of fuel nitrogen;the combustion efficiency of larger fuel particles was restricted by the inner diffusion of O_(2),which then contributed to the reduction of NO_(x) under the inadequate combustion atmosphere.

关键词： Iron ore sintering Granulation Solid fuel distribution Pollutant emission Combustion efficiency

Influence of oxygen-rich hot air composite gas medium on sintering performance and function mechanism

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Journal of Iron and Steel Research International 2024年第5期31卷 1071-1081页

作者： Min Gan Hao-xiang Zheng xiao-hui fan Zhi-yun Ji Qiang Li Ming Wu Yi-fan Wang xiao-long Wang Yu-feng Wu Xu-ling Chen Zeng-qing Sun xiao-xian Huang School of Minerals Processing and Bioengineering Central South UniversityChangsha410083HunanChina Shanxi Taigang Stainless Steel Co. Ltd.Taiyuan030003ShanxiChina

Hot air sintering technology is used to improve the quality and production efficiency of sintered ***,the current thick layer condition highlights the disadvantage of the low oxygen potential of the hot air sintering ***,it is considered to use oxygen enrichment sintering to improve the environment of hot air *** sintering,hot air sintering,and oxygen-rich hot air sintering were compared through sintering cup experiments,and the influence of hot air and oxygen-rich hot air on sintering indexes was *** air reduced the vertical sintering velocity,while improved the yield and tumbler ***-rich hot air sintering contributed to improving the vertical sintering velocity while ensuring the quality of sintered ore,thus comprehensively improving production *** the action of hot air,the highest temperature of the sintering layer increased and the high-temperature holding time was *** oxygen enrichment,the combustion efficiency of fuels in the upper layer of materials was promoted,which optimized heat distribution in the middle and lower layers of materials and increased the content of calcium ferrite in the sintered ore,thus strengthening the sintering process.

关键词： Iron ore sintering Hot air sintering Oxygen enrichment Function mechanism

Structure Model of Granules for Sintering Mixtures

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Journal of Iron and Steel Research International 2014年第10期21卷 905-909页

作者： Li-shun YUAN xiao-hui fan Min GAN Gui-ming YANG Yi WANG School of Minerals Processing and Bioengineering Central South University

Structure model of granules, boundary value of nucleus and powder, and the relationship between granula- tion efficiency and boundary value were investigated. Granules of sintering mixtures are composed of adhesive powder and nucleus. In the mixtures, particles larger than 1.00 mm act as nucleus and particles smaller than 0.25 mm act as adhesive powder. Particles with size between 0.25--1.00 mm can be adhesive powder as well as nucleus depending on the granulation conditions. When the boundary value is close to 0.25 mm, the granulation efficiency is lower than 50%. When the boundary value is close to 1.00 mm, the granulation efficiency is above 90%. The boundary value is influenced by the iron ore type, granulation moisture, fineness of raw materials and burnt-lime activity. Good adhe- sive capability, suitable moisture content, appropriate particle size distribution and high burnt-lime activity make the boundary value move towards 1.00 mm and improve the granulation efficiency.

关键词： iron ore sintering structure model granulation