There is no shortcut for the hottest steel enterpr

2022-08-14
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There is no shortcut for steel enterprises to save energy and reduce emissions

Guide: in recent years, with China's rapid economic growth, resource and energy consumption constraints have become apparent, and the contradiction between energy supply and demand has become increasingly prominent. As a resource intensive industry with large consumption of energy, water and ore resources, the iron and steel industry has a particularly arduous task in pollution prevention and emission reduction, energy conservation and consumption reduction. From policy

in recent years, with the rapid growth of China's economy, resource and energy consumption constraints have become apparent, and the contradiction between energy supply and demand has become increasingly prominent. As a resource intensive industry with large consumption of energy, water and ore resources, the iron and steel industry has a particularly arduous task in pollution prevention and emission reduction, energy conservation and consumption reduction

at the policy level, the state has successively issued a number of relevant policies and measures to promote the process of energy conservation and emission reduction in the steel industry, and made a series of regulations on environmental protection, energy consumption, production scale and other aspects of steel enterprises. In August 2012, the 12th Five Year Plan for energy conservation and emission reduction issued by the State Council proposed that by the end of the 12th Five Year Plan, China's energy consumption per 10000 yuan GDP should be reduced by 16%, chemical oxygen demand (COD) and sulfur dioxide emissions should be reduced by 8% respectively, of which sulfur dioxide emissions from the steel industry should be reduced by 27%, and the total emissions of ammonia nitrogen and nitrogen oxides should be reduced by 10% respectively. Therefore, from the policy perspective, iron and steel enterprises are still facing great pressure on energy conservation and emission reduction

the author believes that during the "12th Five Year Plan" period, iron and steel enterprises should implement various tasks and indicators of energy conservation and emission reduction. On the one hand, they should start from the enterprise itself, follow the whole process control of source prevention, cleaner production and end treatment, and the principles of energy efficient utilization, resource recycling and waste recycling, systematically integrate and optimize existing technologies, and promote the application of advanced new energy conservation and emission reduction technologies. Specifically, we should focus on the implementation of the "three removal and three integration" technology, that is, the prevention and control technology of steel air pollution focusing on sintering flue gas desulfurization, the treatment and utilization technology of steel wastewater focusing on comprehensive wastewater desalination, and the disposal and utilization technology of steel solid waste focusing on the dezincification of iron containing dust and mud; The system integrates and optimizes the energy-saving and emission reduction technology of sintering production process, the dry purification of converter and blast furnace flue gas and the comprehensive utilization of waste heat and residual pressure, and the system integrates and optimizes the treatment and utilization of metallurgical slag and the waste heat utilization technology in the process, so as to finally realize the "three low and three high efficiency" of iron and steel production, namely, low consumption, low sulfur, low carbon, efficient conversion and utilization of energy, efficient disposal and harmlessness of pollution, and efficient utilization and resourcefulness of resources. On the other hand, promoting energy conservation and emission reduction also requires the corresponding policy support of the state

there are still "shortcomings" in the energy conservation and emission reduction work of steel enterprises.

from the energy conservation and emission reduction situation during the "Eleventh Five Year Plan" period, China's steel industry has achieved the sustainable development of green manufacturing in the steel industry by relying on the progress of key energy conservation and emission reduction technologies. Most iron and steel enterprises have popularized and applied the energy-saving and emission reduction measures of "three dry and three utilization" in key production fields, and achieved good results

taking the iron and steel enterprises in Hunan Province as an example, Valin Group adheres to the concept of promoting cleaner production and developing circular economy, comprehensively adopts and implements new energy-saving and emission reduction processes and technologies such as high-temperature and high-pressure dry quenching, sintering flue gas desulfurization, waste heat utilization, etc., greatly improves various environmental protection and energy consumption indicators, and significantly improves the environmental quality of the enterprise. Lengshuijiang iron and Steel Co., Ltd., a private iron and steel enterprise, has also significantly increased its attention to energy conservation and environmental protection in recent years, and its main energy consumption and pollutant emission indicators have been significantly improved

however, during the "Eleventh Five Year Plan" period, there are still some problems in the energy conservation and environmental protection work of Hunan Iron and steel industry, including that the sulfur dioxide emissions of individual iron and steel enterprises did not meet the requirements of Hunan provincial government control indicators; The comprehensive utilization potential of waste heat, residual pressure, residual gas and other secondary energy needs to be tapped; The water recycling utilization rate is about 95%, which has not yet met the requirements of national steel enterprises; The emission of smoke and dust in the waste gas is relatively large. There is no dust wetting system at the tail of the sintering machine and the whole grain. There is no dust containing waste gas collection system for the coal loading and coke discharging of the existing old coke oven. The dust removal facilities such as coke crushing and screening of iron making are not perfect, and the wet dust removal process is still in use; The backward and aging equipment is seriously polluted, which urgently needs to be eliminated and treated; Although single energy-saving and emission reduction technologies are widely used, they lack system integration optimization and overall planning

the above problems existing in the iron and steel industry in Hunan Province can also be seen as the epitome of the overall situation of energy conservation and environmental protection in China's iron and steel industry to a certain extent. How to improve this situation and further promote the implementation of energy conservation and emission reduction, the author believes that enterprises, countries and other aspects should work together

take measures to promote energy conservation and emission reduction in steel enterprises

according to the production characteristics of steel enterprises, the author suggests that the work of energy conservation and emission reduction in steel enterprises can be promoted from the following four aspects:

first, in the field of energy conservation, accelerate the promotion and application of new energy-saving technologies and strengthen the comprehensive utilization of secondary energy

strengthen the management and energy-saving transformation of power supply and electrical equipment, and promote the high-efficiency and energy-saving transformation of inefficient industrial furnaces and kilns. The power supply equipment of iron and steel enterprises includes lines, transformers, circuit breakers, etc., and the electrical equipment is mainly the motors of water pumps and fans. Enterprises can reduce the loss of power supply and electrical equipment by reasonably adjusting the layout of substations and capacitors, shortening low-voltage power supply lines, and regulating power factors; Improve the operation efficiency of fan and water pump by reasonably configuring the capacity of water pump and fan. For pumps and fans with large fluctuation of operating load and wide regulation range, frequency conversion regulation can be adopted; For pumps and fans that do not need continuous medium supply, they should stop running in time, or configure variable-frequency regulation to reduce the supply in time. These measures can achieve significant power saving effect. For the transformation of the lighting system in the factory, we can combine the implementation of the road map of phasing out incandescent lamps in China, increase the promotion and application of energy-saving lamps, and phase out inefficient lighting products such as incandescent lamps for general lighting in stages. At the same time, vigorously promote the energy-saving transformation of the old and inefficient boiler room system and the high-efficiency combustion technology transformation of the steel rolling heating furnace, and constantly improve the thermal efficiency and operation management level of industrial kilns. After these measures are in place, it is roughly estimated that the power consumption per ton of steel in Hunan Iron and steel enterprises alone can be reduced from the current 560 kwh to 520 kwh, with an annual power saving of about 800million kWh and an effect of more than 500million yuan

strengthen the comprehensive utilization of waste heat, residual pressure, residual gas and other secondary energy, and reduce the energy consumption level and energy cost of iron and steel enterprises. Steel enterprises should continue to promote the application of new energy-saving processes such as sintering waste heat power generation, blast furnace residual pressure power generation, direct molten iron into the furnace, hot charging and hot delivery of billets. Enterprises can track and pay attention to the development of energy-saving technologies such as waste heat of coke oven flue gas, waste heat of blast furnace water flushing, waste heat of steel-making flue gas and steel slag, and waste heat utilization of steel rolling heating furnace flue gas, and put forward transformation and use plans in combination with the actual situation of enterprises. Generally speaking, the power generation by coke dry quenching waste heat is estimated to be about 50 kwh/ton of iron according to the coke production of 350 kg/ton of iron; Sintering waste heat power generation is calculated by 1.5 times the ore iron ratio, which can achieve about 25 kwh of power generation per ton of iron; Waste heat from steelmaking can generate electricity of about 30 kwh per ton of iron; Steel rolling waste heat power generation can achieve about 10 kwh of power generation per ton of iron. If the proportion of self generated electricity of Hunan Iron and steel enterprises can be increased from the current 45% to 75%, it can add about 3billion kwh of self generated electricity every year, with an efficiency of more than 1.2 billion yuan

vigorously promote the application of mature technologies such as coking coal humidification (CMC) and blast furnace dehumidification. The pre iron process is the main component of the production cost of iron and steel complex, accounting for about 70% of the total cost. On the premise of constantly improving the level of internal management and production operation, we must accelerate the application of mature energy-saving and consumption reduction technologies such as coking coal humidification and blast furnace dehumidification. Taking the humidification of coking coal as an example, after adopting this technology, the coking heat consumption will be reduced by 62.0 MJ/T (equivalent to 2.12 kg standard coal) for every 1% reduction in the water content of coal. Due to the reduction of the moisture content of the charged coal, the bulk density of the charged coal is increased and the dry distillation time is shortened. Therefore, the production capacity of the coke oven can be increased by 7% to 11%, the thermal performance indicators such as the post reaction strength (CSR) of the coke can be increased by 1% to 3%, and the weak cohesive coal can be added by 8% to 10% (that is, it can increase the use ratio of relatively cheap 1/3 coking coal, gas coal and lean coal, reduce the ratio of high priced coking coal and fat coal), and optimize the coking coal blending structure. At the same time, it can reduce the amount of ammonia by 1/3 and reduce the production load of wastewater treatment device; It can reduce the greenhouse effect, and the average carbon dioxide emission per ton of coal can be reduced by about 35.8 kg. The stability of coal moisture can maintain the stability of coke oven operation, which is conducive to extending the service life of coke oven. If all existing coke ovens in Hunan Iron and steel enterprises adopt coal humidification technology and achieve the expected results, 10000 tons of standard coal can be saved in one year, the output can be increased by about 500000 tons, and about 500000 tons of weak cohesive coal with relatively low price can be used. The annual economic benefit can be more than 100million yuan, and 179000 tons of carbon dioxide emissions can be reduced

the energy-saving effect of blast furnace dehumidification is also obvious. According to rough statistics, the coke ratio can be reduced by 0.8 kg/T ~ 1 kg/T for every 1 g/standard cubic meter of humidity reduction, and the temperature of the combustion zone can be increased by 9 ℃, and the coal injection can be increased by 1.5 kg/T ~ 2 kg/T. Therefore, eliminating the influence of atmospheric humidity on furnace conditions can stabilize the operation of blast furnace and increase production by 3%~8%. At the same time, the dehumidifier has the function of secondary dust removal, which can protect the blower rotor and prolong the service life of the blast furnace blower. For blast furnace blowers with large air volume, the power can be saved by 5.4% - 10.2%. The saved power can offset the power consumed by the dehumidification device itself to achieve "negative energy dehumidification". If this technology can be applied to all blast furnaces in Hunan Iron and steel enterprises and achieve the expected results, 100000 tons of coke can be saved every year, about 800000 tons of pig iron can be increased, and more than 300million yuan of benefits can be achieved

second, in the field of environmental protection, we should promote cleaner production and strengthen the emission reduction of major pollutants

comprehensively promote sintering flue gas desulfurization, track and pay attention to the policy requirements and technical development of denitration, dioxin removal and other aspects, and carry out relevant work in advance. The sulfur dioxide emission of steel enterprises accounts for about 11% of the sulfur dioxide emission of national industrial enterprises, nitrogen oxide accounts for 7%, and dioxin accounts for 30%. Among them, sulfur dioxide, nitrogen oxide and dioxin in the sintering process account for 50% - 60% of the total emissions of iron and steel enterprises. Therefore, strengthening the emission control of sintering process is the main content of reducing harmful gas emission. On the one hand, for sintering machines that have not yet built desulfurization facilities, it is mandatory that iron and steel enterprises must be completed and put into operation within a limited time; On the other hand, for sintering production lines that have built desulfurization facilities, desulfurization efficiency must be further improved. At the same time, we should follow up and pay attention to the policy requirements and technological development of denitration and dioxin removal, increase financial support, and encourage steel enterprises to build such environmental protection facilities

increase the treatment of flue gas dust removal to meet the requirements of the national implementation of the treatment of fine particulate pollutants (PM2.5) in the atmosphere and the standard conditions of iron and steel enterprises. The dust emission of iron and steel enterprises accounts for about 15% of the dust emission of national industrial enterprises. Therefore, strengthening the prevention and control of smoke and dust pollution in iron and steel enterprises is an inevitable requirement to promote the treatment of fine particulate pollutants in the atmosphere to meet the standard. First, dust removal devices should be built as soon as possible in workplaces where smoke and dust emissions exceed the standard; Second, accelerate the elimination of backward process equipment and reduce smoke (powder) dust emissions; Third, use advanced and mature technology to transform and improve the dust removal facilities that have been built. Especially for the existing smelting equipment (blast furnace, rotary

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