Numerical Study On Heat Transfer And Fluid Flow In Top-Combustion Regenerative Hot Blast Stove

Hot blast stove is an important part of blast furnace iron-making production. The major function of the hot blast stove is providing high temperature and continuous hot air for the blast furnace, and the high blast temperature is one of the effective measures to improve the yield and quality of cast iron in the blast furnace iron-making and reduce the production and energy consumption. So the temperature and the duration of the hot air is the evaluation criteria for the hot blast stove performance. Therefore, it is essential to master the law of flow and heat transfer in the hot blast stove, especially the process of the flue gas heating the regenerator and the process of the regenerator heating the air decides the air temperature and duration.In order to master the law of flow and heat transfer in hot blast stove, this paper establishes three-dimensional flow and heat transfer model of combustion period and blowing period. And this paper uses the porous model as the regenerator to simulate the whole hot blast stove. While establishing the experimental model based on similar principles to 1:12 to test the accuracy of the mathematical model. According to the results of numerical simulation to analysis the factor which constraints hot blast stove efficiency and propose improved methods. And compare the situations of the flow and heat transfer between the traditional model and the modified model by using the same mathematical model, and research the performances advantages and disadvantages of the traditional model and the modified model.The working process of hot blast stove is divided two periods:combustion period and blowing period. In the combustion period, blast furnace gas and combustion-supporting air mix and get into the combustion chamber with vortex state to complete the combustion process. Then enter the regenerator, exchange the heat and finally flow out of the stove. The simulation results show that the highest temperature of the whole hot blast stove is 1650K, and the average temperature of the furnace chamber is 1500K; in the blowing period, the cold air exchange the heat with the hot regenerator, and the time of outlet air temperature in more than 1000℃ is 9550s. While this paper finds the vortex center in the combustion chamber significantly deviate from the geometric center. The reason is the nozzle of uneven distribution of flow velocity and the import and export pressure difference when blast furnace gas and combustion-supporting air get into the combustion burner. The experiment of the traditional model shows the same law:the airflow inside the furnace is downward rotation motion, and top-down intensity gradually weakened. But in the different flow conditions, the ribbon in the center is swinging shows that the vortex center slightly deviation.Against the situation of the uneven distribution of velocity and pressure of each nozzles, this paper puts forward some modified models:three to the inlet type, rotary to the inlet type and three to the rotating inlet type. After simulating these modified models, this paper finds that the vortex center of three to the inlet type is the center of the geometry, and the heating situation of the regenerator is better. The highest temperature can reach 1690K, and the average temperature of the furnace combustion chamber is 1550K. The time of outlet air temperature in more than 1000℃ is 10450s. The velocity inside the combustion burner of rotary to the inlet type has increased, but the vortex center deviates from the geometric center. The time of outlet air temperature in more than 1000℃ is 9700s. Three to the rotating inlet type has the same situation with rotary to the inlet type. The time of outlet air temperature in more than 100CTC is 9050s. Above all, the effect of three to the inlet type is better.While this paper also put forward two kinds of different nozzle angle models. Compare two kinds of different nozzle angle models to the traditional model, the different nozzle angle models have no big difference in the working process of the hot blast stove. Although these models have different high temperature distribution, they have the similar internal vortex and the similar time of the outlet air temperature in more than 1000℃.Thus it is desirable by using the FLUENT software to simulate top-combustion regenerative hot blast stove to master the law of flow and heat transfer in the furnace. And the result is reliable basis for the design of hot blast stove by using porous model for regenerator to simulate the whole stove.