| Ironmaking is one of the most important operation in steel industry and provides the moderate materials for steel-making. In 21st century, the development of iron and steel industry is restricted with the challenge of environmental protection. It is a requirement for steel enterprises to research not only new control technology of all kinds of emissions and new manage technology of harmful waste on the basis of available process,but also innovating process of iron and steel production. Compared with the blast furnace, in smelting reduction non-coking coal and fine iron ore can be directly used, but the emission rate of carbon dioxide and unit energy consumption are still high in this technology which purely relied on coal. Based on achievement of Shanghai Enhanced Laboratory of Modern Metallurgy & Materials Processing, one research direction focused on reduction of metal oxides with H2-C mixture in a smelt bath has been carrying on. The basic idea of H2-C mixture reduction reflexes using hydrogen as main reductant and carbon as main heat generator in iron bath smelt reduction reactors on purpose to cut down total energy consumption and CO2 emission protect the environment.Aimed at independently innovated reduction technology of metal oxides with H2-C mixture, this thesis put forward firstly the thought to develop a balance model based on mass and heat balancing. This model can be used for balance calculation with input of composition parameters such as raw material, hot metal and coal, as well as operation parameters such as ratios of ore to slag,enrichment of oxygen and post combustion. Not only the accordance for process optimization, but also a foundation for kinetic model of metal oxides reduction in an iron bath reactor with H2-C mixture can be provided from the model.According to the kinetic characteristics, a thought of modeling method with multiple regions and fluxes was originally proposed. The reactor was separated into five regions and two fluxes, which are regions of post combustion, emulsification, side-blowing combustion, hydrogen bottom-blowing, smelt metal pool, fluxes of top ore and carbon side-blowing. Then part-models in different regions were built from theories for solid-liquid, solid-gas and gas-liquid reactions combining theories of shrinking core, combustion and deoxidization etc, and changes of temperature and concentration were coupled with chemical reaction which took place in solid, liquid and mixed gas phases. Then complex integration was adopted to reveal the kinetics behavior of this new metallurgical reactor. Boundary and initial conditions of all regions reflexes the compatibility of substance and energy aviations between different regions. After discretization treatment with Control-Volume-Method, the model was programmed for numerical simulation. Furthermore, a scaled-up laboratory experiment with capacity of 800kg was applied for the purpose of verifying the model reliability. The results showed that calculated contents and temperatures at given points were basically similar to the experimental values. The fluctuant range of the values around the calculation curve was small enough to testify the reliability of the kinetic model. These results laid a theoretical foundation for further industrial experiments.The applied target of theoretical modeling and numerical simulation was analysis and prediction for an enlarged experiment. The author used the balance model and kinetic model separately to simulate the million tons grade production in imagining. The balance model provided elementary coefficients for the kinetic model used to calculate the transient production, temperature distribution, unit energy consumption etc. The kinetic model was also used to estimate the important coefficients such as ratios of post combustion and carbon to hydrogen etc, providing in the future theoretical guidance and data support for industrial tests with a scale of million tons. |
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