MODELING OF FERRITE GRAIN GROWTH OF LOW CARBON STEELS DURING HOT ROLLING

For most commercial steels the prediction of the final properties depends on accurately calculating the room temperature ferrite grain size. A grain growth model is proposed for low carbon steels Q235B during hot rolling. By using this model, the initial ferrite grain size after continuous cooling and ferrite grain growing in coiling procedure can be predicted. In-plant trials were performed in the hot strip mill of Ansteel. The calculated final ferrite grain sizes are in good agreement with the experimental ones. It is helpful both for simulation of microstructure evolution and prediction of mechanical properties.

Optimal dynamic dispatch of surplus gas among buffer boilers in steel plant

As valuable energy in iron-and steel-making process,by-product gas is widely used in heating and technical processes in steel plant.After being used according to the technical requirements,the surplus by-product gas is usually used for buffer boilers to produce steam.With the rapid development of energy conservation technology and energy consumption level,surplus gas in steel plant continues to get larger.Therefore,it is significant to organize surplus gas among buffer boilers.A dynamic programming model of that issue was established in this work,considering the ramp rate constraint of boilers and the influences of setting gasholders.Then a case study was done.It is shown that dynamic programming dispatch gets more steam generation and less specific gas consumption compared with current proportionate dispatch depending on nominal capacities of boilers.The ignored boiler ramp rate constraint was considered and its contribution to the result validity was pointed out.Finally,the significance of setting gasholders was studied.

A process-level hierarchical structural decomposition analysis (SDA) of energy consumption in an integrated steel plant

A hierarchical structural decomposition analysis(SDA) model has been developed based on process-level input-output(I-O) tables to analyze the drivers of energy consumption changes in an integrated steel plant during 2011-2013. By combining the principle of hierarchical decomposition into D&L method, a hierarchical decomposition model for multilevel SDA is obtained. The developed hierarchical IO-SDA model would provide consistent results and need less computation effort compared with the traditional SDA model. The decomposition results of the steel plant suggest that the technology improvement and reduced steel final demand are two major reasons for declined total energy consumption. The technical improvements of blast furnaces, basic oxygen furnaces, the power plant and the by-products utilization level have contributed mostly in reducing energy consumption. A major retrofit of ancillary process units and solving fuel substitution problem in the sinter plant and blast furnace are important for further energy saving. Besides the empirical results, this work also discussed that why and how hierarchical SDA can be applied in a process-level decomposition analysis of aggregated indicators.

Fushun Steel Plant

Fushun Steel Plant is situated at thewestern part of Fushun city, Liaoning Pro-vince, 45 km from Shenyang. It is one ofthe major special steel plants in China.Established in 1937, Fushun Steel Planthas had a history of more than half century.Before 1948 it was a small-scale plant.From 1937 to 1948 the total steel productionwas only 58000 t. After foundation of PRCthere have been two stages of reconstruction;after the 1st stage (1958 to 1962) the plantbecame the first production base of su-peralloy and stainless steel in China: from1978 to 1983 (second stage) five sets oflarge advanced melting and hot workingequipment and ten sets of measurement

Effect of sinter layer porosity distribution on flow and temperature fields in a sinter cooler

When sinters are filled into the sinter cooler from the sintering machine, it is commonly seen that, due to segregation effects, sinters of larger size usually accumulate closer to the inner wall of the sinter cooler, whereas those of smaller size are to the outer wall. This nonuniform distribution of sinters has led to uneven cooling effect throughout the cooler. This causes the sinters leaving the cooler at a large temperature difference. This undesired temperature difference leads to the deformation and even the destruction of the conveyors. The computational fluid dynamics （CFD） technique was used in the present work to investigate the heat and fluid flow phenomena within the sinter cooler corresponding to the different distribution of sinter layer porosity, which was highly dependent on the arrangement and orientation of sinters within the sinter cooler. It is confirmed that a high mass flow rate within the sinter layer causes a low temperature region and vice versa. The flow fields for vertically reducing porosity distribution and random distribution are almost identical indicating the relative insignificance of convective heat transfer mechanism.

Affecting Factors and Improving Measures for Converter Gas Recovery

To change the undesirable present situation of recovering and using converter gas in steel plants in China, the basic approaches to improving the converter gas recovery rate were analyzed theoretically along with the change curves of the converter gas component content, based on the converter gas recovery system of Baosteel No. 2 steel- making plant. The effects of converter device, raw material, air imbibed quantity, recovery restricted condition, and intensity of oxygen blowing on the converter gas recovery rate were studied. Among these, the effects of the air im bibed quantity, recovery restricted condition, and intensity of oxygen blowing are remarkable. Comprehensive measures were put forward for improving the converter gas recovery from the point of devices, etc. , and good results were achieved.

Status of exhaust pollutantion reduction in sinter process

The mainly origin of the sulphur oxide,nitrogen oxide and dioxin(POPs) is sinter process.It is very difficult to separate the pollutantion for the large quantity of exhaust,the fluctuant range of flux and low density of pollutant.The desulfurization is just started in our country and the technique hasn't passed with efficient,steady and economical operation.As the environmental protection standard is more and more strict in our country,nitrogen oxide and dioxin will be controlld,too.Sintering gas desulfurization is emphasized in iron and steel industry.SO_2 emission reduction is serious.The sulphure flow is analyzed in this study.The process principles,advantage and disadvantage of some typical sintering gas desulphurization technologies,such as limestone/lime-plaster,ammonia-ammonium sulphate,seawater,magnesia,CFB,dense flow absorber,MEROS, NID,active carbon and so on,is described.The sinter process desulphurization technologies of steel plant both in China and abroad are listed.The development trend of sintering gas desulphurization is put forward that the technique of separate the sulphur oxide,nitrogen oxide and dioxin would be researched and the by-product efficiently used would be encouraged at the same time.

Output Model of Steel Plant

Based on the requirement of compactivity, continuity, and high efficiency, and taking full advantage of cushion capability of flexible parts such as external refining in new generation steel plant, an output model of steel plant was established in terms of matching between BOF and caster. Using this model, the BOF nominal capacity is selected, the caster output and equipment amount are computed, and then the steel plant output is computed.

Human-cyber-physical system for production and operation decision optimization in smart steel plants

Based on the core developmental demands of smart steel manufacturing plants, this review analyzes the essential characteristics of the steel manufacturing process and its implications for production and operation decision optimization(PODO). A discussion on the potential application of technologies, including the Industrial Internet, big data, cloud computing, and 5 G, in the PODO of smart steel plants based on the Industry 4.0 intelligent manufacturing and human-cyber-physical system(HCPS) is also presented. An adaptive update conception for a new dual-level cyber system(for management control and unit operation) of a flatstructured HCPS for steel plants is proposed to eliminate issues such as the hierarchical structure of the cyber system, the occurrence of data islands, and weak intelligence in PODO ability. Additionally, the review provided an in-depth analysis of the closed-loop decision logic of a dual-level HCPS. The critical technologies required for developing the HCPS model include data platforms and their associated application technologies, intelligent modeling, human-machine collaboration, and platform-based integration. Finally, suggestions are proposed to develop smart steel plants, including concept renewal, technological integration,and talent training.

Mercury mass flow in iron and steel production process and its implications for mercury emission control

The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%–49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%–36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven,sintering machine and blast furnace were 0.039–0.047 g Hg/ton steel, and for the electric furnace it was 0.021 g Hg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%–73% of total mercury emissions to air.

Production Planning System for the Whole Steelmaking Process of Panzhihua Iron and Steel Corporation

A production planning system is designed for the whole steelmaking process, which includes desulfurization, vanadium extraction, steelmaking and continuous casting processes of Panzhihua Iron and Steel Corporation. The system is composed of modeling module, data interface module, data analysis module, static planning module, re-planning module, plan evaluation module, plan simulation module and human-computer interaction module. The system is connected with the L3 system of steel plant by using the data interface module, which can receive the real time scheduling information to make the static plan and re-plan under production disturbances. The simulation and plan evaluation function of the system can assist decision-maker to check and modify the production plan. The simulation experiments with real process data show that the system can make a feasible, executable, and effective production plan, and deal with primary random disturbances during production process timely.

Causations of failure in megaprojects:A case study of the Ajaokuta Steel Plant project

This paper uses project organizational theories to draw lessons from a historic megaproject, the Ajaokuta Steel Plant （ASP）. Archival reports on the ASP were explored to identify the unique attributes of the project; the political wrangling that underplayed its evolution, its economic significance and organizational impacts. Findings suggest the goals of the ASP project were, and still are, unambiguous. Failure occurred as soeio-political forces aggravated the project＇s complex milestones. Stakeholders were impatient with pre-project investigations. During planning, owners ignored opinions that were contrary to their expectations. While delays lingered, pressures from the global economy weakened the project＇s motivation to succeed. These combined to turn the project＇s outcomes into a chaotic situation that triggered dire implications. Despite about 1400% overrun in cost, the success achieved on the plant was 28% at commission- ing. Contractors remained on site until eight years after commissioning. Six key elements of the 482 items in the ASP project contract were not delivered nearly 40 years on. A simplistic look at these suggests poor planning is the main problem. However, planning issues is not entirely strange in greenfield projects. The paper draws strength from project organization theories to explain what was poor about the planning. Socrates＇ generic management theory was used to explain the role of leadership in the failure of the ASP project. McGregor＇s Theory X and Theory Y explain the significance of stakeholders＇ integration in megaprojects. Systems and chaos theories were used to explain the sensitivity of the ASP project to uncertainties. Narratives on these combine well to inspire stakeholders of megaprojects on where and how to seek courage in making effective plans that can help achieve success in complex projects. While normative literature only recognizes project success in a definitive perspective, this study provides insights from failure as an instrument to trigger sublime reflections.

Pretreatment of metallurgical sewage via vacuum distillation driven by low-temperature exhausted gas from steel plants

The metallurgical sewage has very complex component and a significant environmental perniciousness and needs high treatment costs. In addition, too much low-temperature waste heat is emitted owing to the lack of suitable users. Considering these concerns, a low-temperature-driven pretreatment method via vacuum distillation was proposed to treat the sewage from the metallurgical production. It uses the sensible heat carried by low-temperature exhausted gases to drive the distillation of sewage. The distilled water can be reused into the process as new water supply, while the enriched wastewater is discharged into the sewage treatment center for subsequent treatment. Converter dust removal sewage was chosen to perform an experimental observation. The variations of chemical oxygen demand, ammonia nitrogen, suspended solids, electrical conductivity, and pH of the condensate under different vacuum degrees and evaporation rates were mainly investigated. It can be found that the quality of the condensate gets better under certain conditions, which validates the feasibility of the proposed approach. Furthermore, by comprehensively analyzing the water quality indices and their influencing factors, the optimal vacuum degree was suggested to be controlled between 0.07 and 0.09 MPa, and the best evaporation rate was between 40 and 60%.

AN IMPROVED LP MODEL FOR ENERGY OPTIMIZATION OF THE INTEGRATED IRON AND STEEL PLANT WITH A COGENERATION SYSTEM IN CHINA

In an integrated iron and steel plant with a cogeneration system, recycled energy is continuously transported into the cogeneration system and the electricity is continuously generated, and both of them could not be stored for a long time. Moreover, thegeneration and consumption of electricity is irregular, which may bring about more unexpected imbalances. Therefore, it is a crucial issue to schedule the entire energy system by optimizing the operation of energy utilization, which includes the raw energy in the production system, the generation electricity in the cogeneration system and the recycled energy in these two systems. In this paper, an improved Linear Programming model for energy optimization in the integrated iron and steel plant with a cogeneration system is established. The improved model focuses on controlling the whole energy flow and scheduling the whole energy consumption in the entire energy system between the production system and cogeneration system through optimizing all kinds of energy distribution and utilization in an integrated iron and steel plant with a cogeneration system. Case study shows that the improved model offers the optimal operation conditions at the higher energy utilization, lower energy cost and lower pollution emissions.