Study On The Influence Of Single Coal Characteristics On The Combustion Behavior Of Blended Coal

At present,blast furnace injection coal mixing technology is widely applied in industry.On the one hand,it can promote the rational application of resources,alleviate the supply and demand of metallurgical coke,on the other hand,it can reduce the coke ratio,adjust the condition of the blast furnace,reduce pollution and improve the environment.Blending coal is a method to improve coal ratio by blending coal on the premise of considering the substitution rate of coal coke.But the process of pulverized coal mixed combustion is very complicated and there are still many uncertain factors.In this paper,three kinds of anthracite and six kinds of bituminous coal are used as experimental raw materials to explore the influence of single coal characteristics on the combustion process of mixed coal,which provides a theoretical basis for the optimization of mixed coal injection ratio in blast furnace.In this paper,Fourier infrared spectrometer and thermogravimetric analyzer were used to analyze the functional group structure and combustion performance of 9 kinds of pulverized coal samples.It was found that the structure of organic functional groups had a great influence on the combustion performance of pulverized coal.The atomic distribution of aliphatic hydrocarbon and aromatic hydrocarbon of anthracite containing more hydrogen atoms in the main chain and branch side chain of aliphatic hydrocarbon was similar to that of bituminous coal.The volatile substance is more active in low temperature area than ordinary anthracite.In addition,pulverized coal with higher content of oxygen-containing functional groups and lower degree of condensation of aromatic compounds has better combustion performance at low temperature because of its higher volatile activity.Based on the detection of single coal characteristics,two kinds of coal,three kinds of coal and four kinds of coal are mixed respectively,and the interaction between various coal samples in the process of mixed combustion is explored.Through the comparison of theoretical combustion curve and experimental combustion curve,it is found that when the mixed coal is mixed with bituminous coal with higher volatile content,the experimental combustion curve peaks in the low temperature region are more obvious than the theoretical combustion curve.However,the combustion of volatile matter and fixed carbon in mixed coal is relatively independent due to the fast volatilization decomposition speed.The curve of experimental combustion rate shows an obvious inflection point,and the reaction shows a bimodal parabolic trend.The combustion time of mixed coal is longer than that of single coal.When anthracite with aliphatic hydrocarbon and aromatic hydrocarbon carbon atom distribution similar to bituminous coal is mixed into the coal,the heat released by the pyrolysis of volatile matter drives the combustion of fixed carbon.The combustion of mixed coal has obvious promotion effect and the combustion curve is smooth and stable single-peak parabola.In order to further explore the influence of single coal characteristics on blended coal,CPD model was used to predict the product yield under the conditions of rapid pyrolysis of mixed coal.The structural characteristics of functional groups affected the components and yields of blended coal pyrolysis products,and the yield of each component of light gas further affected the ignition characteristics and combustion effect of coal.Among them,the higher the content of aliphatic hydrocarbon and the longer the length of aliphatic hydrocarbon carbon chain,the higher the yield of coal tar,CO and CO2 yield increased with the increase of the content of carboxyl,carbonyl and other active groups in the oxygen-containing functional group,and the CH4 yield was proportional to the content of methyl group.