| At present, problems of high energy consumption, high pollution, low grade and energy waste seriously have been existed in electric melting magnesium industry in China. Carrying out research on magnesium melting waste heat recovery technology is the urgent demand of energy saving and emission reduction in China. And it is also an inevitable choice of realizing green production and following a new path of industrialization with energy conservation and environmental protection.Melting magnesium after smelting contains a large amount of waste heat resources. However, Due to the large volume and the thick rubber, internal heat cannot be exported rapidly, bringing extremely difficulties to waste heat recovery. For the problem about waste heat recovery of magnesium melting, research team has been put forward solutions to waste heat recovery by using the fin to recycle hot air, water recovery system and tower which can preheat materials, but all above had not obvious effect. In order to overcome the disadvantages of low heat transfer, complex system and higher initial investment, based on analyzing and summarizing the existing technology about waste heat recovery of magnesium melt, this paper presents the integrated kiln about waste heat recovery of magnesium melting, and the study is carried out in following aspects:Firstly, based on the thermal test and practical production conditions, this paper designed the integrated kiln about waste heat recovery of magnesium melting, instructed the main technological process and gave design of structural parts. By using reciprocating grate transportation, this craft achieved heat exchange between magnesium melting and magnetite, and accomplished cooling process of magnesium melting and preheating process of magnetite simultaneously. Secondly, based on the idea of segments method, this paper analyzed heat transfer process in the kiln for waste heat recovery, established temperature calculation model of rubber on the surface of magnesium melting, grate, furnace wall, air and magnetite respectively. In order to establish foundation for solving the model with segment method, this paper analyzed for magnesium melting internal heat transfer process, convective heat transfer between air and furnace wall, convective heat transfer between magnesium melting and magnetite, and radiation heat transfer process as well.Thirdly, by using the main variable correction method to solve the model with segment method, temperature and heat flux distribution curve of magnesium melting surface, grate, air and magnetite were gotten. Associated with the finite difference method, temperature profile about fused magnesium lump in every section can be concluded, which will help optimize the thermal parameter analysis.Finally, this paper analyzed effects of different thermal parameters to the process of waste heat recovery, used orthogonal experiment to analyze different operating conditions comparatively, and got the best thermal parameters in the kiln about waste heat recovery: height of material layer is0.25m, wind speed is4m/s, and porosity is0.4. The efficiency of the whole heat recovery system is30.37%, meeting the technical design requirements. |
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