Study On Nitrogen Membrane Separation System For Mg Alloy Gas Protection

As the lightest commercialized metallic structural material at present,magnesium alloys have many advantages, such as, low density, high specific strength, high specific rigidity, good damping, good electromagnetic shielding and outstanding casting capability. They are finding more and more applications in automobile, motorbike, communication, aviation and electric tooling industries.Magnesium is prompt to ignition during its melting and casting processes. N2 mixed with SF6 is the most commonly used shielding gas capable of provide effective protection acknowledged at home and abroad. However, SF6 must be diluted in a carrying gas, such as CO2, N2 or dry air, to a certain level before use. Among the carrying gases used, N2 is most commonly used and inexpensive. The traditional shielding gas technique uses bottled N2 gas purchased outside, facing problems such as transportation, storage, management and cost. In order to eliminate the problems, use of N2 on-line nitrogen production equipment is imperative. However, the deep cold and PSA nitrogen online production system are expensive to buy and use, the nitrogen membrane separation technique is not suitable to use due to the lack of consideration of the needs Mg die-casting practice. Therefore, the development of a modified nitrogen membrane separation technique to meet the need of Mg casting production is of engineering importance.As part of R&D project named"magnesium shielding gas online generating devices"funded by Chongqing SinoST Co. Ltd, the present study is focused on the development of a central control unit for a N2 membrane separation device. Using an Industrial Computer as main control unit and man-machine interface, Configuration Software as software development platform, this study is devoted to the development of integrated control system for"nitrogen membrane separation system for Mg shielding gas protection". With the abundant monitoring menu, the control parameters and working process visualized, the control unit developed greatly reduces the malfunction of equipment and control operation, ensures the efficiency of nitrogen production while provides the flexibility and the versatility of system.At the same time of completing the system hardware collocation, software design and man-machine interface design, the effects of temperature, flow, pressure and other parameters on nitrogen purity have been studied. After a great deal of experiments, the optimal parameters were identified.