Design And Development Of A New Vertical Type Heat Accumulating Magnesium Reduction Furnace And Study On Key Problems

In recent years, the industry of magnesium production in our country has had a rapid development. All kinds of new processes and technology emerge in endlessly. However, the priority now is that manufacturing enterprise quantity is many but scale is very small and construction is blind. Some enterprises have problems of high energy consumption, severe pollution and poor technology management. Therefore, measures of modifying magnesium reduction system, reducing recovery time and increasing the reduction efficiency must be taken to achieve environmental effects of energy saving. It’s also the fundamental way to realize the sustainable development of magnesium industry.On the basis of the study of magnesium reduction principle, magnesium reduction furnace, which applied high temperature air combustion technology, is thermodynamically analyzed in this paper. Thermodynamic analysis includes flow field analysis and temperature field analysis. In this paper, a new vertical staggered type heat accumulating magnesium reduction furnace is designed to improve heat utilization efficiency of magnesium reduction furnace and reach the environmental effects of energy saving. Factors that affect thermal efficiency and heat conduction problem in reduction jar are analyzed and improvement program is proposed.Choosing turbulence model, the standard k-ε equation model and non-premixed combustion model, making use of Gambit and Fluent simulation software, the application of high temperature air combustion technology in the magnesium reduction furnace is studied. Under the condition of different air preheating temperature, air gas absolute speed and air gas relative speed, flow field distribution in reduction furnace is studied. By analyzing the distribution law of temperature in reduction jar varying with time, a new optimization method for heat conduction problem design is put forward. The air preheating temperature has a great deal to do with the influence of temperature field and velocity field in reduction furnace. With the air preheating temperature increasing, the uniformity of air and gas gets improved and the flame front area increases. The vortex exists in the reduction jar, cause a dilution effect on the fuel and air, which makes it possible for high temperature air combustion. Flue gas reflux deflects the flame to the wall and reduces the symmetry of flame in vertical direction. The absolute velocity of the air and gas has little influence on temperature field and velocity field in the furnace, while has an enormous effect on relative velocity. When jet velocity ratio increases, the mixture of air and gas bring forward, the furnace temperature distribution is more uniform and outer edge of flame tend to expand. If the air speed very low, air kinetic energy reduces and the flame length decreases. The pattern of heat exchange between furnace and reduction jar is mainly radiation heat transfer, while convection heat transfer as supplementary. When the external temperature reaches the process requirements, as heat exchange amount between furnace and reduction jar is small, heat-transfer coefficient, which is low, has become the main factor that influence the reduction efficiency. Adding a nonreducing high-temperature material, reduction time is shortened, reduction efficiency is improved. In another hand, temperature difference in reduction jar is little, the quality of reduction products is improved and the production is increased.After having studied the subject, optimum process parameters, the air preheating temperature is1000℃and air gas jet velocity ratio is1:2, are determined. The quality of raw material of a improved reduction jar decreased by1/16and the reduction time of a improved reduction jar is reduced by1/4. In general, the reduction time is reduced, the reduction efficiency is increased, the quality of reduction products is improved and the production is increased.