| Energy and environment problems interwoven together, which constitute the complex background of China’s economic and social development in the new period. China is the largest energy consumer, and it is also the biggest carbon dioxide producer in the world, which face to the environmental problems of "high carbon" and "high pollutant emissions". As a typical of high energy consumption and high emission industry, non-ferrous metals industry has been drawn attention. The "12th five-year plan" proposed the targets for saving energy and reducing pollutant emissions explicitly, and reducing the use of outdated capacity. Therefore, self-innovating technology of energy-conserving in smelting industry with technical renovations and elimination of eliminated lag process and equipment became the key technology of energy saving and emission reduction of nonferrous metallurgy industry.Oxygen enriched bath smelting technology realizes the rapid process of heat and mass transfer processes among three phase rapidly by injecting gas into the molten bath directly. The technology key is promoting the slagging and desulfation reaction faster and more thorough. In order to maintain the stability and efficiency of melting process, it is necessary to understand the rules of controlling fluid motion and change. To achieve the research purpose, this paper studies the fluid mixing and reaction process in double side blown bath smelting of Vanyukov furnace. By using numerical simulation, theoretical modeling and experimental measurement method, the fluid motion process were quantified and analyzed. The influence of operating parameters on flow process in molten bath were obtained. The main contents were researched in this paper:(1) The penetration behavior of side blown gas jet in the liquid was studied by experiment and theory. The basic characteristics of the jet stream were obtained through the experiments. The shapes of jet stream were classified, and then giving the division interval of modified Froude number and velocity. The flow field of gas jet can be divided into three main regions by structure partition of gas jet: forming region, bulk region and surface region, and each region of the flow fields has its own characteristics. The movement of bubble in the melt was studied on the basis of the force analysis of a single bubble. The theoretical model of the jet trajectory was improved based on the experimental results, which can provide a better description of the morphological structure of side blown gas jet in the liquid.(2)Three dimensional mathematical model coupling of multi-phase (gas phase slag phase and matte phase), multi-field (concentration field, velocity field and temperature field) has been established, and the numerical simulation on fluid flow, heat transfer and mass transfer in the molten bath under bubble flow regime and jet flow regime was conducted. The results showed that jet flow regime can provide a better reaction dynamic conditions for the smelting process. On the basis of this study, the effects of different conditions on the mixing performance under jet flow regime were further researched. According to the simulation results, the best technical parameters for Vanyukov furnace was shown as:furnace width with 2.5m, height of molten bath with 2m, nozzle angle with 25° and injection velocity with 250m/s. It increased 25% for the smelting capacity and simultaneously increased 24.7% and 21.1% for the containing gas rate and turbulent kinetic energy of slag layer respectively compared with the reference condition.(3)The movement processes of gas jet were researched by image processing technique. The calculation method of area index M was proposed, and the movement process of gas jet was quantified by the area index time series. The stirring processes were compared and analyzed. The results showed that the area index and the stability of gas jet increased with modified Froude number increasing. The injection depth also performed great effect on the area index, but not much on the stability of gas jet, meanwhile less for other factors. The stabilization time was obtained by 3 Sigma method and calculated the specific power. The performance of the stirring processes were evaluated based on two indexes of specific power and area index. The L2 showed the best whole performance during the stirring processes of several groups.(4)The Betti number was used to describe the liquid phase manifold of mixing process based on the flow visualization technique. The 0 dimensional Betti number reflected the mixing performance, and the 1 dimensional Betti number reflected the uneven degree of mixing. The mixing performances under different conditions were studied, and the results showed that the 0 dimensional Betti number increased with modified Froude number and injection depth increasing. The flow fields and chaotic characteristics of the mixing process were analyzed, and the results showed that the main flow was enhanced to promoting macromixing process individually though modified Froude number and blowing depth. The improving mixing performance will be achieved by frequency conversion method in stirring process which could destroy the original flow pattern and then make it chaotization to promote micromixing process. |
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