The Designs And Studies Of Front Preheating System Of Hot-blast Stove In Benxi Iron And Steel

Hot-blast stove is one of the important equipments in iron production process of the blast furnace due to its function of providing high-temperature air stably and constantly. The theories and practices show that the high-temperature air is the direct method to increase the utilization coefficient, reduce the coke ratio and increase the coal injection. With the process of iron-production technology, the studies of the factors, which can improve the air temperature and the thermal efficiency of the hot-blast stove and the application methods, are important due to the situation of insufficient blast-furnace gas, low calorific value and insufficient fuel of high calorific value such as coke oven gas and so on.The standard of air temperature in domestic iron and steel enterprises is studied. Furthermore, the illumination and the comparision of the common techonology for improving the air temperature at home and abroad are made. Consider the low air temperature on the6th hot-blast stove in Benxi iron and steel, the reworked program of front double preheating system for air and coalgas is proposed by the analysis of data and theoreticalbasis. At the same time, the design calculations of the program and the selection of the major equipments are made. In order to provide the theoretical basis for improving the air temperture and the thermal efficiency of the hot-blast stove, the software FLUENT is used to simulate the thermal process of the hot-blast stove.The main contents in this work are as follow:(1) Consider the long-term low air temperature on the6th hot-blast stove in Benxi iron and steel, the thermal equilibrium and the thermal efficiency are calculated by the analysis of design parameters of the equipments and operation status. Furthermore, the thermal status and the existing problems of this hot-blast stove are diagnosed. A brief reworked program is proposed on the basis of the diagnostic results and the final front preheating program in this work is determined by comparision.(2) The design of various process parameters and the selection of the major equipments are made by combining the actual data in Benxi iron and steel. The parameters, including the combustion temperature of the hot-blast stove, the combustion-supporting air volume and the coalgas volume of the hot-blast stove, the chamber temperature of the combustion furnace, the needed air volume and the coalgas volume of the combustion furnace, the air volume and the coalgas volume at inlet and outlet of the heat exchanger and the flue gas flow and so on, are calculated. The parameters, which include the combustion-supporting air pipeline and coalgas pipeline of the combustion furnace, the pipeline for preheating system and the pipeline for mixing air, are determined. The design and the selection of the combustor for combustion furnace, the combustion furnace, the turbolator heat exchanger for preheating the air and the coalgas and the heat exchange of heat pipe for preheating the air and the coalgas and so on are made.(3) The FLUENT is used to simulate and analyze the temperature fields, which are the one before the use of the front preheating system and the one after the use of the front preheating system, respectively, of the combustor and the regenerator for the6th hot-blast stove in Benxi iron and steel. The combustor model of the hot-blast stove and the single-hole pipeline of the regenerator are made according to the characristics and the assumption during the combustion and the transmission of air in the combustor and the regenerator. In addition, the temperature distributions and variations of the combustor and the regenerator are analyzed. The analyzed temperature in regenerator include the ones of the flue gas, the air and the grid bricks.