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Improving the level of energy conservation and emission reduction of blast furnace

the large-scale blast furnace is the inevitable trend of iron making production. China has 20 blast furnaces with a furnace capacity of more than 4000m3. It is of great significance to continuously improve the energy conservation and emission reduction level of blast furnace

the large-scale blast furnace is the inevitable trend of ironmaking production. China has 20 blast furnaces with a furnace capacity of more than 4000m3. It is of great significance to continuously improve the energy conservation and emission reduction level of blast furnace

in terms of energy conservation, the key is to improve gas utilization to the greatest extent, obtain high gas utilization rate and reduce coke consumption. The fuel of blast furnace ironmaking in China is 50 ~ 100kg/t higher than that in foreign countries, one of the important reasons is the poor utilization rate of gas. Improving the utilization rate of gas is the basis of reducing coke ratio. According to the practical experience and research results of TISCO, in order to achieve the goal of stable gas utilization rate of more than 50%, we can start from the following aspects

first, adjust the ore batch weight of the blast furnace and improve the ore coke ratio of the blast furnace. As long as the furnace condition is acceptable, the ore batch can be appropriately expanded to increase the thickness of coke layer under the same coke load

second, the furnace top temperature should be stable at 150 ~ 180 C. if wet quenching is used, it should also be 20 ~ 30 C lower. If the furnace top temperature exceeds 200 c, the utilization rate of a high rigid I-beam installed in the thermal energy corner experiment of gas is not high

third, control the permeability index K within an appropriate range. When the permeability index k is relatively low, the gas utilization rate is higher. Therefore, under a certain coke load, maintaining the permeability index K in the furnace within an appropriate range is very important to stabilize the gas utilization rate

The production practice experience of TISCO in recent years shows that when the gas flow stability and gas utilization rate of large blast furnaces have not reached a certain level, the measures of forced air feeding and oxygen enrichment should not be taken to increase production, but to maintain the stability of gas flow by adjusting coke load or charging system, so as to pursue strengthening smelting and improving technical and economic indicators. In addition, it is very important to maintain the central passage of the blast furnace. The larger the blast furnace is, the more important the center is; However, it is generally not advisable to add coke centrally. The central high-temperature area should not be too wide. If it is too wide, the utilization rate of gas will become poor and blast furnace fuel will be wasted; The central high-temperature area is narrower, which can not only keep the blast furnace running smoothly, but also save fuel

in terms of emission reduction, it is estimated that at present, the average CO2 emission of China's large and medium-sized iron and steel enterprises is 160 per ton of iron. The Jinmin model has received extensive attention and high recognition from the government, the industry and the media, 5kg, 116kg more than German blast furnaces. This shows that China's blast furnace C flat tail hammer O2 emission reduction still has considerable space. The key to reducing emission is to reduce the fuel ratio of blast furnace. The reducing agent consumption of blast furnace is reduced by reducing the fuel ratio of blast furnace, so as to improve the effective utilization coefficient of blast furnace. The methods of low fuel ratio operation include: improving the smelting efficiency of the furnace body; Loading amount of metallized charge; Reduce the heat loss at the lower part of the blast furnace shaft, etc. It is worth noting that using pre reduced sinter and coke, including metallized ore, as a new charge to reduce the amount of reducing agent in blast furnace is a new idea to reduce CO2 emissions. This new process is characterized by the simultaneous completion of the blocking and partial reduction process. The carbonaceous iron ore powder particles covered with a layer of coke powder are used as raw materials and loaded on the sintering machine. The blocking and partial reduction are carried out simultaneously on the sintering machine. It is estimated that the reduction degree of the target pre reduced sinter is more than 40%. The external coke particles are used to generate energy, and the internal particles are directly reduced to produce CO gas. Due to the indirect gas-solid reduction reaction, the total carbon consumption is lower than that of the current blast furnace. From the perspective of the overall layout, it is very important to speed up the structural adjustment and optimization of the iron and steel industry. According to statistics, the average energy consumption of blast furnaces with an effective volume of less than 300m3 is about 20% higher than that of blast furnaces with an effective volume of more than 1000m3. Replacing small blast furnaces with blast furnaces with large volumes, increasing the coal ratio and increasing the air temperature will reduce the coke ratio and CO2 emissions. Therefore, under the current conditions in China, it is imperative to eliminate backward steel production capacity

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