Abstract: With the development of society and the reduction of the earth's resources, various industries have put forward higher requirements than before, and also brought more challenges. However, for the blast furnace ironmaking industry, due to the gradual reduction of the earth's fossil fuels, the industry does not have sufficient resources, resulting in the slow development of the industry. Therefore, the blast furnace ironmaking industry urgently needs to optimize energy and resources. It is necessary to reduce fuel and power consumption, strengthen secondary energy recovery, and save energy and reduce emissions.
Keywords: blast furnace ironmaking energy energy saving and consumption reduction
I. Introduction
Since the reform and opening up, China's industry has developed rapidly. By 2017, China produced 73.2313 million tons of crude steel and 16.6784 million tons of pig iron, accounting for about 50% of the world's total steel production. The steel industry is also an industry with high energy consumption, and energy conservation and consumption reduction have become the top priority of the sustainable development of the steel industry.
The ironmaking system includes an ironmaking process, a sintering process, and a coking process. In iron and steel enterprises, the direct energy consumption of this system accounts for about 70% of the total energy consumption, and it is the key link of energy conservation in iron and steel enterprises. At the same time, because the system will also generate a large amount of secondary energy such as blast furnace gas and coke oven gas in the production process, the utilization effect of these secondary energy can not only affect the energy (power) medium balance of iron and steel enterprises, but also affect the protection of enterprises. The development of environmental work [1].
The energy consumption of the ironmaking process includes the power item, the fuel item, and the recovery item. Power items include electricity, industrial water, purified water, steam, blast, oxygen, nitrogen, compressed air, etc. The fuel item includes blast furnace gas, pulverized coal, coke oven gas, and coke, and the recovery item includes blast furnace gas recovery, hot blast furnace flue gas heat recovery, TRT power generation and blast furnace slag waste heat recovery. In the ironmaking system, after deducting the recycling item, the fuel consumption accounts for about 90%, and the power consumption only accounts for about 10% [2]. Therefore, the focus of reducing energy consumption in iron-making systems should be placed on reducing fuel consumption. In addition, energy recovery also has a great impact on reducing the energy consumption of the ironmaking process. Doing a good job in energy recovery is a very powerful measure to reduce the energy consumption of the ironmaking process.
2. Measures for energy saving and consumption reduction of iron-making system
1. Energy saving measures for sintering process
Taking WISCO as an example, WISCO carried out energy-saving renovation of its sintering workshop in 2001, and adopted a new process of "thick material layer - fuel addition - small ball sintering", and the thickness of the material layer was increased from 420mm to 600mm[3] , the particle size larger than 3mm in the mixture has been increased from 50% to 70%, and the additional ratio of pulverized coal has reached about 70%. kg/t.
2. Energy saving measures of coking process
Taking Wuhan Iron and Steel as an example, the coking company of Wuhan Iron and Steel Co., Ltd. actively carried out the technical transformation work centering on the enlargement of coke ovens. The transformed coke ovens have adopted a lot of energy-saving and environmental protection technologies, such as the use of the interlocking technology of the four major vehicles and the professional furnace structure; the computer has adopted PLC program-controlled furnace temperature control technology auxiliary equipment, and also adopts The instrument of the DCS system and the quenching system of the low-moisture coke quenching process of the United States Steel Association are professional technologies. At the same time, the environmental protection technology of coal charging and dust removal has been adopted to realize zero discharge of waste water, smoke and dust control and other pollution in the entire production system. It has many advantages such as reducing energy consumption, improving coke strength, and good environmental protection conditions. guarantee.
3 Energy saving measures of blast furnace process
3.1 Implementing the Refinement Policy
Take Shougang as an example. The material basis for the stable and smooth energy saving and consumption reduction of blast furnaces is finesse. In order to improve the quality of incoming raw fuels, in 2006, the iron smelting plant of Steel adopted a new model of supply chain management. The professionals who inspected the raw fuels and the supply companies went to the raw fuel manufacturers to inspect the quality of the raw fuels. "The tentacles reach the periphery", and comprehensively grasp the trend of the quantity and quality of the raw fuel entering the plant [4]. For the quality problems of the raw fuel, professional personnel respond to the blast furnace in time to minimize the impact of the quality fluctuation of the raw fuel on the blast furnace.
3.2 Oxygen-enriched blast
The functions of the rich blast are: (1) The oxygen-enriched blast can improve the strength of smelting and increase the output; (2) The nitrogen content after oxygen enrichment is reduced, which can relatively increase the CO concentration in the belly, which can affect the indirect reaction. (3) The oxygen-enriched blast can improve the combustion of the injected fuel; (4) the oxygen-enriched blast can also increase the calorific value of the gas at the top of the furnace, which is very beneficial to the increase of the air temperature [5].
3.3 Continuously improve the coal injection ratio
When pulverized coal is injected at the tuyere of the blast furnace, first, most of the coke in the blast furnace can be replaced by non-coking coal resources rich in resources, which can not only alleviate the current shortage of coking coal resources, but also appropriately reduce the amount of coke in the blast furnace. The pollution caused to the environment in the process of smelting; second, because the operation of high coal ratio is to replace part of the coke with coal, it can not only reduce the cost per ton of iron, but also enhance the market competitiveness of blast furnace ironmaking [6]. Of course, when increasing the coal ratio, we must pay attention to the amount of unburned powder. The amount of unburned powder is generally lower than about 15%-20% of the coal injection amount. The blast furnace has adverse effects. Figure 1 below shows the change trend of Shougang's coal injection ratio and fuel ratio from 2004 to 2008.
3.4 To maintain a reasonable distribution of gas
The core of blast furnace ironmaking is to distribute gas reasonably. Because the reasonable distribution of gas can make the furnace condition stable and smooth, it can also improve the utilization rate of gas and reduce the fuel ratio.
4 Increase the utilization of secondary energy
1) Increase the utilization of waste heat of hot blast stove waste gas: Because the temperature of hot blast stove flue gas of blast furnace is generally around 250-350OC, the flue gas volume is large and has a lot of waste heat. It is recycled to generate other energy so that the ironmaking process reduces energy consumption. Moreover, recovering the waste heat of the blast furnace flue gas is an effective measure to increase the air temperature and reduce the fuel ratio.
2) Utilize the pressure of the blast furnace top to increase the power generation of the pressure difference: the pressure energy and thermal energy of the blast furnace top gas make the gas work through the turbine expander, convert it into mechanical energy, and drive the generator.

Fig.1 Change trend of coal injection ratio and fuel ratio of Shougang from 2004 to 2008
3. Conclusion
With the development of society and economy, the energy consumption of the earth is increasing, and the energy reserves of the earth are getting less and less, which leads to the rise of the prices of various energy sources. As a giant energy-consuming industry, the iron and steel industry must save energy and reduce consumption in order to survive before new energy sources are developed, especially the energy saving and consumption reduction of iron-making systems, and the use of secondary energy and energy recycling must be strengthened. thereby reducing costs. In addition to the above technical energy saving and consumption reduction, steel companies must strengthen energy management to reduce unnecessary energy consumption to achieve the purpose of energy saving.