Numerical Investigation Of Pulverized Coal And Reducing Gas Injection Into Blast Furnace Tuyere Under Oxygen Enriched

In recent years,global climate change.resource shortage and other problems have become increasingly prominent.Energy conservation and emission reduction have become a huge challenge facing the world.The iron and steel industry accounts for about 15%of industrial CO2 emissions and energy consumption.As an important unit of iron and steel production,the blast furnace cannot be replaced in the short term,and the CO2 emission of the blast furnace accounts for about 70%of the steel industry.Reducing the carbon input of the blast furnace is the core of CO2 emission reduction,which can be achieved through operations such as rich hydrogen and recycling top gas.In this article,the low carbon blast furnace ironmaking process is analyzed and constructed at the injection process level:Reveal the physicochemical characteristics and influence laws of the raceway.which provides basis for the regulation of the raceway;A variety of novel tuyere injection mechanism is designed to obtain the co injection flow combustion behavior of pulverized coal and reducing gas,which provides guidance for the tuyere injection test of blast furnace.Firstly,the zonal heat and mass balance model of the blast furnace is established,and the reasonable operation area of oxygen and hydrogen enrichment and the potential of carbon saving are obtained.The study shows that the oxygen enriched operation of the blast furnace can increase the theoretical combustion temperature of the tuyere,reduce the top gas temperature,and increase the productivity;Rich hydrogen at tuyere can greatly reduce the direct reduction degree of iron and carbon consumption;The oxygen rich and hydrogen rich process of blast furnace can effectively reduce carbon input,but the energy input and the calorific value of top gas increase;The coupling hydrogen enrichment of top gas recycling oxygen blast furnace can not only reduce the carbon input of blast furnace.but also reduce the energy input;Top gas recycling oxygen blast furnace coupled with hydrogen injection can reduce carbon by 23.2%and save energy by 9.1%.Then,based on Euler multiphase flow theory,a three-dimensional numerical model of gas-solid flow reaction in the lower part of the blast furnace was established.The evolution process,shape and size,gas-solid flow characteristics of the raceway were studied,and the influence of tuyere injection parameters on it was obtained,which provides a basis for the control of the raceway of the blast furnace.The results show that the particles in the raceway circulate rapidly counterclockwise,while the particles in the lower part move slowly counterclockwise;The chemical boundary of the raceway is larger than its physical boundary;At the same blast flow rate,oxygen enrichment can effectively promote the expansion of the raceway,and its size increases significantly;With the increase of tuyere velocity,the size of raceway increases greatly;The increase of the blowing angle of the tuyere reduces the kinetic energy of the gas on the axis of the tuyere,so the depth of the raceway is significantly reduced,while the height and width are slightly increased;Under the same gas flow rate and oxygen condition,carbon monoxide injection can promote the extension of the physical depth of the raceway,but it is not significant;hydrogen injection reduces the gas kinetic energy of the tuyere and the size of its raceway.In order to guide the blast furnace tuyere injection,a three-dimensional numerical model of gas powder flow combustion was established,and the flow combustion process of oxygen enriched pulverized coal and coalbed gas injection in 1580m3 blast furnace tuyere was investigated.The results show that the coal burnout decreases with the increase of coalbed methane injection;The combustion of methane consumes oxygen,inhibits the combustion of volatile matter of pulverized coal and the reaction between fixed carbon and oxygen,and finally reduces the reaction rate of fixed carbon,which reveals the competitive combustion process between coalbed methane and pulverized coal;With the increase of oxygen enrichment,the coal burnout increases,but not significantly;With the decrease of coal injection,the coal burnout increases;Under 25.8%oxygen blast condition,80Nm3/tHM of coalbed gas is injected,and when the coal injection ratio is reduced from 153.4Kg/tHM to 133.4Kg/tHM.the amount of unburned coal is equivalent to that under traditional conditions.For the 30%,40%and 50%oxygen blast blowing decarbonized gas process of 430m3 blast furnace,five types of injection mechanisms are designed,namely,Sleeve Type Lance-Traditional Tuyere,Single Lance-Through Tuyere,Single Lance-Semi Through Tuyere,Sleeve Type Lance-Through Tuyere and Sleeve Type Lance-Semi Through Tuyere.The flow and combustion characteristics of pulverized coal and reducing gas are simulated.The results show that the gas peak temperature in the raceway of injecting decarburized gas is higher than that of traditional blast furnace;The sleeve type gas/pulverized coal lance is not suitable for injecting a large amount of decarburized gas.The sleeve type oxygen coal lance can promote pulverized coal combustion to a certain extent by injecting oxygen,but with the increase of oxygen injection,its inhibition effect on pulverized coal temperature rise is greater than the benefits of combustion.The injection of the Through Tuyere gas transmission pipe shall ensure the full mixing and diffusion combustion of oxygen,pulverized coal and gas.which is conducive to the improvement of pulyerized coal burnout.For the top gas recycling oxygen blast furnace(430m3)injection process,the reaction of high temperature gas and oxygen gives off a lot of heat,which promotes the later temperature rise of pulverized coal and the reaction of fixing carbon,and the burning rate of pulverized coal is higher than that of traditional blast furnace.In the Sleeve Type Oxygen Coal Lance-Through Tuyere injection mechanism,the pulverized coal burnout at the exit of the raceway is 22.3%higher than that of the traditional blast furnace.The Single Lance-Through Tuyere injection mechanism is used to directly inject all oxygen into the raceway,which can avoid the local high temperature zone in the tuyere.The coal burnout is only 58.8%.6.8%higher than that of the traditional blast furnace working condition.Compared with the top gas circulating oxygen blast furnace,its tuyere coupled methane injection consumes oxygen and generates a lot of H2O,which is not conducive to the combustion reaction and heat release of fixed carbon and O2 in the pulverized coal,which ultimately leads to the reduction of pulverized coal burnout.