| Blast furnace coal injection is an important means for iron and steel enterprises to realize the sustainable development of reducing cost and increasing efficiency.It is used to replace coke as a part of heat source and reducing agent in the reduction reaction of blast furnace,and to relieve the pressure caused by coking.A series of physical and chemical properties of 2500m~3 pulverized coal used for blast furnace injection in a steel plant were studied in this paper.The results show that the volatile content of bituminous coal is higher than that of other two kinds of coal,and its hydrogen oxygen content is higher than that of other two kinds of coal.The sulfur content of bituminous coal and Xinjiang raw coal is the same,and the sulfur content of washed clean coal is the highest.The high and low calorific value of the three kinds of coal decreases in order of bituminous coal,washed clean coal and Xinjiang raw coal,the initial deformation temperature of bituminous coal is the lowest,and the initial deformation temperature of washed clean coal and Xinjiang raw coal is quite equal.The grindability index of three kinds of coal is reduced in turn,the grindability of clean coal,bituminous coal and Xinjiang raw coal is reduced,the char-slag characteristic index of three kinds of coal is the same,and the adhesion of combustion product is similar.Thermogravimetric and explosive experiments of mixed coal with different proportions showed that the explosive of mixed coal was enhanced with the increase of bituminous coal ratio.The flame length of mixed coal with washed clean coal was less than 100 mm,and the mixed coal of bituminous coal and Xinjiang raw coal was strong explosive,flame length was more than 350 mm,longer than that of corresponding bituminous coal.Using Factsage software to carry out the relevant calculation in the current state of blast furnace,the best clinker ratio is sinter:titanium ball:South African block ore:Pu ball:Australia ore use ratio of 68.5%:1.1%:14.1%:15%:1.3%,respectively.Under this condition,the slag viscosity and alkalinity are better,and the air permeability of the column is better,which is beneficial to the smooth running of blast furnace.Increasing the ratio of coal injection will lead to a certain deterioration of BF.It is necessary to improve the distribution of gas flow in combustion zone by adjusting the parameters of blast system.By using the fluent software,it is found that the change of blast temperature and oxygen-enriched rate has little effect on the change trend of gas composition in the gyro zone of tuyere,but the change of blast temperature and oxygen-enriched rate promote the combustion reaction of pulverized coal.To ensure certain blast humidity is an important means of regulating blast furnace under the condition of high air temperature and oxygen-enriched coal injection. |
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