| The fuel structure of the blast furnace includes lump coke,coke and injection fuel,and the injection fuel is mainly pulverized coal.In recent years,most of the blast furnaces at home and abroad have achieved a reduction in blast furnace fuel cost by increasing the amount of fuel injected and reducing coke consumption.However,as the blast furnace capacity is gradually expanded and the injection ratio is continuously increased,coke is particularly prominent as a column skeleton The world's high-quality coking coal resources and fat coal resources are increasingly tight,coke quality is declining,and the grade of furnace iron ore is generally low,these raw fuel conditions limit the increase in coal injection ratio of large blast furnaces.In this context,optimizing the ratio of block coke,nut coke and pulverized coal(fuel structure)used in blast furnaces is an effective way to reduce fuel consumption.Since 2014,the fuel structure of Guofeng blast furnace has been continuously optimized,gradually forming the basic mode of 1780 m3 blast furnace with 85 percent first-class coke and 15 percent tertiary coke,and 450 m3 blast furnace with 100 percent tertiary coke.Coal injection is made of bituminous coal,anthracite and,the upgraded coal,mixed and sprayed.Due to the decline of the quality of raw fuel in recent years,the blast furnace smelting has been greatly affected.The fuel ratio of Guofeng blast furnaces has increased and the coal ratio has also decreased.The coke particle size decreases,and the screening nut coke exceeds the original demand.This paper studies the performance of existing fuels,optimizes the proportion of coke and coal powder,and increases the proportion of coke/coal mixture blending furnace,which provides a basis for optimizing fuel structure,improving the blowing level and mixing the nut coke.The main findings are as follows:There are 11 kinds of coke used by Guofeng,and its production organization is more complicated.In this study,the coke test was firstly carried out to optimize the types of coke in the furnace,and the coke variety and matching scheme suitable for the production demand of Guofeng were determined,which improved the stability of coke quality.According to the above methods,the new varieties of coke have been tested for cost-effectiveness,and the on-site testing of blast furnace has little effect on the furnace conditions,which broadens the coke market and is conducive to cost reduction and efficiency increase.According to market fluctuations,timely adjust the fuel structure of Guofeng blast furnace and the scheme of injection and coal blending,make full use of the cost-effective advantages of different coal types,and improve the calorific value of mixed coal.By optimizing the injection from the practical perspective,conditions have been created for high-level coal injection.Practice has proved that Guofeng's current optimum coal injection ratio under raw fuel conditions should not exceed 170 kg/tHM,and the coke ratio remains at 350 kg/tHM.In the end,the suitable proportion of nut coke with ore was studied through a single furnace test.The ratio of nut coke is increased from zero to 56 kg/tHM,and fuel consumption is decreased.The test shows that when all tamped coke smelting is used,the coke ratio(including nut coke)is 370 kg/tHM,and the coal injection ratio is 170 kg/tHM,the coke ratio is 48-50 kg/tHM,and the blast furnace condition is stable and works well,with good air permeability and the lowest fuel ratio.Therefore,the coke rate in the furnace should not exceed 50 kg/tHM.When the coke quality decreases,the coke ratio can be appropriately increased to ensure the stablility of the blast furnace so as to reduce the fuel consumption. |
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