This paper summarizes the development status of high-efficiency electric arc furnace smelting technology, green production technology and intelligent control technology at home and abroad, among which green and intelligent are the future development trends of electric arc furnace steelmaking technology.
Key words: electric arc furnace steelmaking; scrap steel preheating; high efficiency; green; intelligent
Electric arc furnace is a kind of equipment that uses the thermal effect of electric arc to convert electric energy into heat energy, and directly heats and melts metal through radiation and electric arc. Electric arc furnace steelmaking has many advantages in environmental protection, investment and efficiency. The proportion of electric furnace steel production in the total steel production in the world has increased from 7.3% in the early 1950s to 32%~35%. In 2018, the global average proportion of electric furnace steel was 28.8%, of which the United States accounted for 68%, the European Union accounted for 41.5%, and Japan accounted for 25%, while China was only about 11.6%, which was significantly lower than the average level. The lower proportion of electric furnace steel was caused by One of the important reasons for high energy consumption and heavy pollution in the steel industry. At present, more than 95% of the world’s electric furnace steel production is produced by electric arc furnaces. Short-process steelmaking with electric arc furnace steelmaking as the core has become one of the important processes of the entire steel production. “Focus on the development of short-process electric furnace steelmaking with scrap steel as raw material” is one of the major strategic decisions to realize the sustainable development of the iron and steel industry. Throughout the history of development, EAF steelmaking has developed a series of related technologies around the overall goal of “energy saving, consumption reduction, and productivity improvement”. In the 1960s and 1970s, the development of electric arc furnace steelmaking technology was dominated by the improvement of productivity, and ultra-high power electric arc furnaces and related technologies were developed; To shorten the smelting cycle, the waste heat utilization of waste gas has gradually been paid attention to, and a series of scrap steel preheating technologies have been developed, such as basket type, double furnace shell type, shaft furnace type and horizontal continuous feeding type. At the same time, the strengthening of environmental protection awareness and the rapid development of artificial intelligence technology have put forward new requirements for electric arc furnace steelmaking technology and pointed out a new development direction. Electric arc furnace steelmaking technology integrates various modern equipment and comprehensive technologies of supporting technologies. On the basis of efficient smelting, intelligence and greening are the future development directions of electric arc furnaces. This paper discusses the future development direction of EAF steelmaking technology by reviewing the development status of EAF steelmaking technology in recent years.
Efficient smelting technology of electric arc furnace
The high-efficiency production of electric arc furnaces has the characteristics of global coordination and continuous production. The goal of high efficiency in the electric arc furnace smelting process is to reduce the power-on time, shorten the smelting cycle, and minimize the power consumption of smelting; specific measures mainly include increasing power, increasing chemical energy input intensity, and reducing non-energized operation time.
Large-scale electric arc furnace capacity
Production practice has proved that in terms of technical and economic indicators (such as smelting electricity, electrode unit consumption and cost, etc.), the productivity and energy utilization rate of large-scale electric arc furnaces are higher than those of small and medium-sized electric arc furnaces. At present, the electric arc furnace is developing towards the direction of large-scale furnace capacity. The mainstream electric arc furnace capacity in industrially developed countries is 80-150 t, and has gradually increased to 150-200 t. For example, Italian company Danieli (DANIELI) has successfully manufactured the world’s largest DC electric arc furnace with a furnace capacity of 420 t, as shown in Figure 1, the design productivity of this electric arc furnace is 360 t/h, and it has the characteristics of high efficiency and low operating cost , can improve the production efficiency and steel quality of steel mills; it has been used in the production of low-carbon steel, ultra-low carbon steel and advanced deoxidized killed steel, with an annual output of 2.6 million tons.
Figure 1 420t DC electric arc furnace
According to the statistics of China’s Ministry of Industry and Information Technology and other relevant departments, the production capacity ratio of China’s electric arc furnaces by tonnage in 2015 is shown in Figure 2; domestic production capacity of large-capacity electric arc furnaces of 100 t and above accounted for 30.8% of the total production capacity of electric arc furnaces. The proportion is the highest; the production capacity of electric arc furnaces of 75 t and above accounts for 56.6% of the total production capacity of electric arc furnace steelmaking. In addition, there are still 21.9% of the backward production capacity below 60 tons, which shows that under the guidance of the policy of environmental protection, production restriction and elimination of backward production capacity, domestic steel mills still have a large room for improving the efficiency of electric arc furnaces through capacity replacement.
Figure 2 Proportion of EAF production capacity by tonnage in 2015
In 2018, the nominal volume of 70-120 t accounted for 80% of the new electric arc furnaces in China. China’s electric arc furnaces are developing rapidly towards equipment large-scale and modernization, but there is still a big gap between them and industrially developed countries.
Ultra-high power supply technology
According to the power supply power, electric arc furnace transformers can be divided into three categories: ordinary power (RP), high power (HP) and ultra-high power (UHP). From the 1960s to the present, the concept of ultra-high power electric arc furnace steelmaking has dominated the development of electric arc furnace steelmaking production technology for nearly 60 years, and its core idea is to maximize the capacity of the main transformer. High-power electric arc furnace transformers are the basis for meeting the high efficiency of electric arc furnace steelmaking and realizing ultra-high power supply. The main parameters and technical and economic indicators of the manufacturer to manufacture 100 t EAF transformers are shown in Table 1.
To achieve ultra-high power supply, a scientific and reasonable power supply system that coordinates power fluctuations and stabilizes arcs is particularly important. In order to optimize the power supply system at the Tamsa steel plant in Taina, Mexico, a model with the function of modifying and optimizing the power supply system of the electric arc furnace was developed and applied during 2016 and 2017. The model is based on energy balance (electrical/chemical energy), energization time, Automatically optimize the power supply curve according to the changing rules of parameters such as stability and radiation index. Tamsa Steel Plant used this model to redesign the power supply system. While keeping the energy consumption level basically unchanged, the production capacity of the electric arc furnace increased by 9.8%, and the productivity improvement effect was obvious. The main advantages of using ultra-high power power supply are: shortening the smelting time and improving production efficiency; improving electric heating efficiency and reducing power consumption; easy to match with the production rhythm of refining and continuous casting, so as to achieve high-efficiency and low-consumption production. After the ultra-high power transformation of the 70 t electric arc furnace, the productivity increased from 27 to 62 t/h, as shown in Table 2.
Melt pool stirring integration technology
The agitation intensity of the traditional electric arc furnace steelmaking molten pool is weak, and the material and energy transfer in the furnace is slow. The use of technologies such as ultra-high power power supply and high-intensity chemical energy input has not fundamentally solved the problems of insufficient stirring intensity of the molten pool and slow transfer of material energy. In order to speed up the smelting rhythm, compound blowing technologies such as enhanced oxygen supply and bottom blowing stirring, as well as electromagnetic stirring technology have been developed successively. The new generation of electric arc furnace molten pool stirring technology is a combination of enhanced oxygen supply, bottom blowing stirring and electromagnetic stirring, which can meet the technical requirements of electric arc furnace smelting under the condition of multiple furnace materials. Combined blowing technology for electric arc furnace steelmaking is becoming more and more mature, and has been widely applied in industry. For example, Xining Special Steel, Tianjin Steel Pipe, Xinyu Special Steel, Hengyang Steel Pipe and other enterprises in China have successfully applied the combined blowing technology for electric arc furnace steelmaking. The effect is good and the cost is effectively reduced. Table 3 shows the comparison of the industrial effects before and after the technological transformation of some electric arc furnaces in China.
Compared with the compound blowing technology, the electric arc furnace electromagnetic stirring technology has a narrower popularity, but its molten pool stirring effect is better, and the industrial application effect has a good response. Take the electromagnetic stirring equipment (ArcSave) developed by ABB as an example. The electromagnetic stirring technology effectively improves the material and energy transfer rate in the molten pool, which is more conducive to the melting of scrap steel, accelerates the uniform composition and temperature of molten steel, and improves the production capacity of the electric arc furnace. See Table 4 for the improvement effect of relevant indicators after the transformation of Steel Dynamics Inc (SDI) Roanode electric arc furnace ArcSave.
Hot charging hot metal technology
Due to the shortage of power resources and the shortage of high-quality steel scrap resources, in recent years, some electric arc furnace steelmaking plants have added a certain amount of molten iron in the steelmaking process, that is, the electric arc furnace steelmaking process of hot charging of molten iron, which effectively shortens the electric arc furnace smelting cycle At the same time, it helps enterprises flexibly respond to price fluctuations in the scrap steel market, which has certain economic benefits. Hot charging molten iron technology is widely used in electric arc furnace steelmaking process, such as China Zhongtian Iron and Steel Company and Tianjin Iron and Steel Company. Furnaces are specially designed and modified. The economic and technical indicators of the electric arc furnace after hot charging of molten iron in a domestic steel mill are shown in Table 5. Practice has shown that hot charging of molten iron in modern electric arc furnaces is very effective in shortening the smelting cycle and reducing power consumption.
In the long run, when the cost of steel scrap smelting is comparable to that of converter smelting or has a certain competitiveness, the production of ordinary carbon steel by EAF smelting does not need to increase the economic and technical indicators related to EAF by adding molten iron. It is still necessary to add molten iron to dilute harmful impurity elements in molten steel.
Green production technology of electric arc furnace
The green production of electric arc furnaces is mainly to reduce energy consumption, reduce pollutant emissions and improve resource recycling efficiency. In order to realize the green production of electric arc furnaces, key technologies such as waste heat recovery, coke replacement, dioxin prevention and scrap preheating-continuous feeding have been developed successively.
Waste heat recovery technology
During the smelting process of the electric arc furnace, a large amount of high-temperature dust-containing flue gas will be generated, and the heat taken away by it is about 11% of the total input energy of the electric arc furnace, up to 20%. It is of great significance and also has huge economic benefits. The iRecovery technology developed by Tenova converts the waste heat of high-temperature flue gas generated by the electric arc furnace into steam. The flow of the iRecoveryStage2 system is shown in Figure 3. The iRecovery technology is based on the tube-tube heat exchange structure and working principle similar to the traditional heat recovery system, using cooling water to recover heat energy from the electric arc furnace exhaust gas pipeline; the difference from the traditional heat recovery system is that the iRecovery technology uses high-pressure and high-temperature hot water (180~250 ℃) is used as a heat exchange medium to recover the heat of high-temperature dusty exhaust gas, thereby reducing the heat loss caused by evaporation and separation of exhaust gas.
In recent years, many electric arc furnaces around the world have adopted iRecovery waste heat recovery technology, such as South Korea’s Hyundai, China’s Tianjin Steel Pipe and other enterprises, and the industrial application of this technology has achieved good results. See Table 6 for the results of using waste heat recovery technology in electric arc furnaces of some typical enterprises.
Coke Substitution Technology
In the traditional electric arc furnace smelting process, in order to meet the requirements of molten pool heating, stirring and foaming slag submerged arc, carbon matching is required. In the green production of electric arc furnaces, the consumption of non-renewable fossil energy such as coke should be reduced as much as possible. One of the current ways to reduce coke consumption is to use alternative fuels, such as the use of “waste” produced in the daily life cycle, such as rubber tires and plastic products, such “waste” can not only be a good substitute for electric arc furnace steelmaking It can also avoid environmental protection problems caused by the accumulation of “waste”. Australia’s Onesteel Iron and Steel Company and the University of New South Wales (UNSW) have completed a series of electric arc furnace smelting in Sydney Steel Mill (SSM) and Laverton Steel Mill (LSM) steel plants, using rubber and plastic to partially replace coke as a foaming agent for foam slag. Steel Industry Tests. SSM and LSM steel mills use Polyethylene Injection Technology (PIT) to spray the mixture of rubber and coke into the electric arc furnace. The effect is better than that of coke slagging alone. At the same time, Onesteel Iron and Steel Co., Ltd. conducted an industrial test in LSM steel plant to make high molecular polymer and carbon powder into small pieces to replace coke. 1.2 min is shortened, and the effective power is increased by 0.4 MW. The electric arc furnace uses waste tires and waste plastics to make steel, which can effectively reduce coke consumption, improve the thermal efficiency and productivity of the electric arc furnace, and improve the recycling rate of resources at the same time, which has obvious economic and social benefits.
|Table 7 Benefits of using PIT technology in a typical electric arc furnace|
|Reduced power consumption/(kW h t-1)||2.8||2.4||5.1|
|Reduced toner consumption/(kg furnace-1)||12.0||16.2||12.0|
|Reduced oxygen consumption/(m³ t-1)||2.3||1.9||1.6|
|Reduced natural gas consumption/(m³ t⁻ 1)||1.9|
|Increase active power/MW||1.0||0.8||2.0|
|Total injection amount/(kg t⁻ 1)||5.2||9.8||12.0|
Dioxin prevention and control technology
Dioxin has a long physical, chemical, and biological degradation period, resulting in a very high content in water sediments and food chains; Dioxin enters the human body through the food chain, which will seriously damage the human body system, such as endocrine, immune, nervous system, etc., which are referred to as “toxin-transmitters”. Dioxins are extremely harmful to the environment and humans. The prevention and control of dioxin pollution has become one of the most important issues in the environmental protection of metallurgical industry. In the production process of the iron and steel industry, in addition to the sintering process, electric arc furnace steelmaking is the main source of dioxins. According to Mckay G’s research, the formation of dioxin requires two main conditions: one is that there must be organic matter in the combustion process; the other is that chlorine gas must participate in the combustion reaction. Regarding the formation mechanism of dioxins, Dickson LC, Gullett B K, Huang H, Hunisinger H, Takasuga T, etc. have done a series of studies, and reached a consensus on the formation conditions of dioxins. Since scrap steel usually contains chlorides and oily hydrocarbons, a certain amount of dioxin fumes will be produced during the electric arc furnace smelting process, which will cause environmental pollution problems. For the emission of dioxins in the electric arc furnace steelmaking process, the following main measures can be taken. (1) Scrap steel pretreatment: Sorting scrap steel to minimize the amount of scrap steel containing organic matter entering the furnace, while strictly controlling the total amount of chlorine sources entering the electric arc furnace; preheating treatment is not suitable for scrap steel containing organic matter. (2) Quenching treatment of primary flue gas: the temperature of the primary flue gas of the electric arc furnace must be controlled above 1000 °C. Minimize the residence time of flue gas in the dioxin formation temperature range, such as the rapid cooling of flue gas by evaporative cooling tower technology, which has a significant effect in preventing the formation of dioxins. (3) Apply inhibitors: spray alkaline substance powder (such as limestone or quicklime) into the flue at a temperature range of 600-800 ℃, which can reduce the source of available chlorine that causes dioxin formation; spray ammonia at 250-400 ℃ It can also inhibit the production of dioxins. The environmentally friendly ecological electric arc furnace ECOARCTM (Figure 4) developed in Japan has a relatively complete waste gas emission treatment system, which can effectively solve environmental pollution problems such as dioxin. The electric arc furnace body consists of a scrap steel melting chamber and a preheating shaft furnace directly connected to the melting chamber. The rear section is equipped with a thermal decomposition combustion chamber, a direct spray cooling chamber and a dust removal device. The thermal decomposition combustion chamber can completely decompose the organic waste gas including dioxin, and can meet the residence time of the flue gas in the high-temperature area; the spray cooling chamber can quickly cool down the high-temperature flue gas to prevent the secondary formation of dioxin. However, due to the large volume of the furnace body of the ECOARCTM electric arc furnace, the difficulty of separating the shaft and the difficulty of online replacement of refractory materials, it is difficult to maintain the equipment. Therefore, the development of high-efficiency, low-cost EAF dioxin control technology is still one of the current research hotspots.
Scrap steel preheating – continuous feeding technology
Modern electric arc furnace steelmaking mostly adopts scrap steel preheating-continuous feeding operation, using high-temperature flue gas to preheat scrap steel, which can effectively solve the problem of smoke and dust in the traditional electric arc furnace smelting process. In addition, the operation of large amount of reserved steel is adopted, the melting efficiency of scrap steel is high, and the smelting of flat molten pool is realized to the greatest extent, which meets the requirements of high efficiency, high productivity, low cost and low harmful gas emission of modern electric arc furnace steelmaking. In terms of electric arc furnace scrap preheating-continuous feeding, we have successively developed and applied basket-type scrap steel preheating electric arc furnaces, double-shell electric arc furnaces, vertical electric arc furnaces and Consteel electric arc furnaces. The basket-type scrap steel preheating electric arc furnace is gradually being replaced by the new electric arc furnace due to problems such as high power consumption, long smelting cycle and serious environmental pollution; the double-shell electric arc furnace is due to low preheating efficiency, large Consteel electric arc furnace has problems such as low scrap steel preheating temperature and dioxin emission not up to standard, but its production is in good condition and the power grid is impacted. Small size, reliable and controllable feeding, etc., are widely used at present; early shaft electric arc furnaces have problems such as low equipment reliability and large maintenance, and are gradually withdrawing from the market. At present, many metallurgical equipment manufacturing companies at home and abroad have developed a variety of new types of scrap steel preheating-continuous feeding electric arc furnaces based on the concepts of Consteel electric arc furnaces and vertical electric arc furnaces, such as the Danieli FASTARC 0 electric arc furnace developed based on the concept of horizontal continuous feeding; The SMS SHARC electric arc furnace, the Japanese ECOARCTM ecological electric arc furnace, and the Pratt Quantum electric arc furnace developed by the concept of advanced feeding; at the same time, the step-feed electric arc furnace is also derived, such as the CISDI-AutoARCTM green intelligent electric arc furnace of China Metallurgical Corporation, and Scrap steel preheating-continuous charging system independent of electric arc furnace, such as environmental pre-heating and continuous charging system EPC (Environmental Pre-heating and Continuous Charging System) jointly developed by KR Company and CVS Company. The Consteel electric arc furnace (Fig. 5) uses the high-temperature waste gas generated by smelting to continuously preheat the scrap steel in the feeding channel while feeding continuously. The preheating temperature of the scrap steel before entering the furnace is 200-400 ℃; Enter the preheat recovery system. Consteel electric arc furnace realizes continuous preheating, continuous feeding, continuous melting, and flat bath smelting of scrap steel, which improves productivity, improves environmental conditions inside and outside the workshop, and reduces power consumption and electrode consumption.
While the early vertical electric arc furnace was smelting, the steel scrap needed for the next furnace was added into the vertical shaft with the overhead basket, and the scrap steel was held by the finger bracket. The high-temperature exhaust gas directly contacted the scrap steel for preheating, and the scrap steel temperature was as high as 600~700 ℃. The SHARC electric arc furnace (Fig. 6) belongs to the improved shaft furnace type electric arc furnace. Its biggest feature is that there are two semicircular shafts on the electric arc furnace, which can keep the high-temperature exhaust gas in the shafts to carry out natural convection preheating on the scrap steel, and the molten pool is stable. The feeding method still adopts the overhead basket; the ECOARCTM ecological electric arc furnace (Fig. 4) uses the shaft furnace shaft to preheat scrap steel, which can realize continuous feeding of light and thin scrap steel. The preheating temperature exceeds 600 ℃, the molten pool is stable, and the productivity is high; Quantum The electric arc furnace (Fig. 7) belongs to the improved finger bracket shaft furnace type electric arc furnace. The scrap steel is added to the shaft in batches by lifting the tilting chute by the scrap hoist on the top of the furnace, and the shaft and the furnace cover are fixed to solve the problem of the original finger bracket. The disadvantage of many faults is to tilt the furnace body to achieve slag-free tapping.
Fig6.SHARC Electric arc furnace
Environmentally friendly charge preheating and continuous charging system EPC (environmental pre-heating and continuous charging system) is a shaft-type charge preheating device, and the matching electric arc furnace adopts a large steel retention operation process (more than 40% of the tapping amount) , so this type of electric arc furnace can run smoothly and continuously. Furnace material is continuously fed into the furnace through the side wall charging port, without opening the furnace cover, avoiding heat loss and flue gas emission. The EPC system can be moved to the vicinity of the upper furnace shell of the electric arc furnace, and it can be closely connected with the feeding port and the exhaust duct of the side wall of the electric arc furnace. Its specific process flow is shown in Figure 8.
See Table 8 for the comparison of technical indicators and scrap preheating effects of typical electric arc furnaces. By summarizing the high-efficiency preheating characteristics of electric arc furnaces, we can know the future development trend of scrap steel preheating technology: (1) The whole process of electric arc furnace smelting is sealed to avoid heat loss caused by opening the cover; although the preheating effect of horizontal feeding electric arc furnace needs to be further improved, but The feeding is controllable and reliable, and the equipment is stable; the scrap steel preheating efficiency of the vertical electric arc furnace is high. In recent years, most of the new electric arc furnaces have a vertical feeding structure; Improve the efficiency of scrap steel preheating, and then improve energy utilization and increase the production capacity of electric arc furnace; (3) The design concept of scrap steel preheating technology should meet the latest environmental protection standards, reduce energy consumption, and reduce greenhouse gas emissions; (4) New electric arc furnace steelmaking It is necessary to comprehensively consider the aspects of scrap steel preheating, continuous feeding, flat melting pool smelting, waste heat recovery, waste gas treatment, etc., to ensure efficient and green production of electric arc furnace steelmaking.
Intelligent control technology of electric arc furnace
In recent years, a series of intelligent monitoring technologies and control models have been applied in the electric arc furnace steelmaking process, such as intelligent batching, intelligent control of electrodes, intelligent sampling temperature measurement, intelligent monitoring and control of foam slag, online analysis of furnace gas, end point Composition forecasting, cost optimization of the smelting process, and overall intelligent control of the electric arc furnace steelmaking process, etc., the application of monitoring and control technology has greatly improved the intelligence level of the electric arc furnace steelmaking process.
Electrode intelligent adjustment control technology
Electrode adjustment control technology is one of the key technologies for realizing intelligent power supply of electric arc furnace, and its control effect directly affects important economic performance indicators such as electric energy consumption and smelting cycle of electric arc furnace. In recent years, there are mainly three kinds of mature intelligent electric arc furnace electrode adjustment control technologies in the world: IAFTM and SmartArcTM in the United States, and SimeltRNEC system in Germany. The technical comparison of the international typical EAF electrode adjustment control system is shown in Table 9.
At present, the SIMETAL electrode control system developed based on PLC and industrial computer hardware platform is the latest intelligent electrode control system for electric arc furnaces. Figure 9 shows the SIMETAL Simelt system. This control system can make dynamic responses according to actual process requirements and improve process efficiency. . On this basis, the research and development of the next-generation electrode control system mainly focuses on process parameters and algorithm adaptation, data recording, data evaluation and integrated process visualization, and high reliability.
Intelligent sampling and temperature measurement of electric arc furnace
The time consumed in the temperature measurement and sampling of molten steel during the electric arc furnace steelmaking process is one of the key links that restrict the electric energy consumption and production efficiency of the electric arc furnace. In view of the poor safety and high cost of traditional manual temperature measurement and sampling, a series of new technologies for automatic temperature measurement and sampling have been developed and promoted. At present, the more advanced temperature measurement methods are robot automatic temperature measurement and non-contact temperature measurement. The SIMETAL LiquiROB electric arc furnace robot (Fig. 10) launched by voestalpine can perform fully automatic temperature measurement and sampling operations, can automatically replace samplers and temperature measurement probes, and detect invalid temperature measurement probes. automatic control.
Fig10.SIMETAL LiquiROB Electric arc furnace robot
SIMETAL RCB Temp (Fig. 11) is a non-contact temperature measurement system developed by voestalpine. It relies on supersonic oxygen jet technology to preheat scrap steel during feeding to accelerate the melting speed of scrap steel. The jet injects oxygen and once the specified level of temperature uniformity is reached, the system switches to temperature mode where the temperature is analyzed at extremely short intervals.
Fig11.SIMETAL RCB Temp Non-contact temperature measurement
Intelligent monitoring and control of foam slag
The foam slag process of the electric arc furnace is mainly carried out by combining visual observation and manual carbon spraying operation. Semi-automatic systems based on current signals and harmonic content can only assist operators to a certain extent in the foaming slag process. Optimize the foam slag intelligent monitoring and control scheme to ensure that the arc and molten pool are completely and stably covered by the foam slag, which can not only save resources and reduce power consumption, but also help reduce production costs and heat loss. It is a fully automatic operation of the smelting process important aspects of. The Simelt SonArc FSM foam slag monitoring system (Figure 12) developed by Siemens ensures the fully automatic foam slag process, and the sound sensor lays the foundation for accurate monitoring and analysis of the foam slag height; Provides guidance to minimize consumption metrics.
The electric arc furnace door cleaning and foam slag control system PTI SwingDoorTM (Figure 13) developed by PTI Company of the United States can reduce the entry of outside air and improve the sealing of the steelmaking process; its integrated oxygen lance system replaces the furnace door cleaning manipulator or furnace door The oxygen lance automatically cleans the furnace door area. The system controls the slag flow by controlling the opening and closing of the furnace door, so as to control the existence time of the foamy slag in the furnace, thereby ensuring the thickness of the slag layer in the furnace during the smelting process, reducing energy consumption and improving the heat transfer efficiency of the arc.
Overall intelligent control of electric arc furnace steelmaking process
The intelligent control of electric arc furnace is not limited to the automation of a certain equipment, the intelligence of a certain link monitoring and control, but starts from the overall electric arc furnace steelmaking, the data collection and process mechanism of the whole smelting process from the initial batching to the final steel tapping Combined with process operation, data analysis, data decision-making, data evaluation and final process control are carried out to realize the overall optimization of the electric arc furnace steelmaking process and reduce human intervention, so as to achieve the overall intelligent control of the electric arc furnace steelmaking process. The Danieli Q-Melt automated arc furnace system (Fig. 14) integrates a process control monitor and manager that automatically recognizes deviations from the expected behavior of the electric arc furnace steelmaking process and allows it to automatically return to the scheduled melting process. This system mainly includes Q-REG Plus electrode dynamic adjustment control system, LINDARC exhaust gas analysis system and MELT-MODEL process control and optimization system. Among them, the MELT-MODEL process control and optimization system is the core of the Q-MELT system. It cooperates with the electrode adjustment system and the exhaust gas analysis system to dynamically adjust the electric arc furnace smelting process through chemical composition analysis or electrical characteristic curves, so that the smelting process is always optimal. state of the art.
The iEAF intelligent control system developed by Tenova (Fig. 15) relies on process information fed back by sensors (such as exhaust gas analysis, electrical harmonics, current and voltage) and controllable parameters (oxygen and fuel flow, oxygen injection, carbon powder injection, and electrode management) to have full control over the electric arc furnace. This system increases production efficiency, improves production management, saves energy and reduces consumption and reduces CO2 emissions by reducing smelting operation variables and enhancing the stability of electric arc furnace operation.
Conclusion and Outlook
Under the guidance of the idea of “energy saving, consumption reduction, and productivity improvement”, electric arc furnace steelmaking has developed many technologies for high-efficiency smelting, green production and intelligent control, and green and intelligent technologies will play an important role in the future development of electric arc furnace steelmaking. importance will become increasingly prominent. In the future, electric arc furnace steelmaking will further optimize the intelligent monitoring and control model and the overall intelligent control model of the electric arc furnace based on the whole process of batching, power supply, oxygen supply, auxiliary energy input, slag making, etc., and develop low energy consumption, less pollutant emissions and resources Recycling green production technology, perfecting the electric arc furnace steelmaking process integrating operation, process, quality, cost and environmental protection, and finally realizing the goal of green, intelligent, efficient and low-cost steelmaking by electric arc furnace, further promoting the transformation of the steel industry upgrade.