A multi-functional micro-arc plasma spraying system was developed according to aerodynamics and plasma spray theory. The soft switch IGBT （Insulated Gate Bipolar Transistor） invert technique, micro-computer control ...A multi-functional micro-arc plasma spraying system was developed according to aerodynamics and plasma spray theory. The soft switch IGBT （Insulated Gate Bipolar Transistor） invert technique, micro-computer control technique, convergent-divergent nozzle structure and axial powder feeding techniques have been adopted in the design of the micro-arc plasma spraying system. It is not only characterized by a small volume, a light weight, highly accurate control, high deposition efficiency and high reliability, but also has multi-functions in plasma spraying, welding and quenching. The experimental results showed that the system can produce a supersonic flame at a low power, spray Al2O3 particles at an average speed up to 430 m/s, and make nanostructured AT13 coatings with an average bonding strength of 42.7 MPa. Compared to conventional 9M plasma spraying with a higher power, the coatings with almost the same properties as those by conventional plasma spray can be deposited by multi-functional micro-arc plasma spraying with a lower power plasma arc due to an improved power supply design, spray gun structure and powder feeding method. Moreover, this system is suitable for working with thin parts and undertaking on site repairs, and as a result, the application of plasma spraying will be greatly extended.展开更多
NOx is generally composed of NO,NO2,N2O,N2O4,and N2O5,which may form photochemical smoke and may lead to acid rain,greenhouse effect and destruction of the ozone layer in the atmosphere.In this paper,a new pneumatic s...NOx is generally composed of NO,NO2,N2O,N2O4,and N2O5,which may form photochemical smoke and may lead to acid rain,greenhouse effect and destruction of the ozone layer in the atmosphere.In this paper,a new pneumatic spraying scrubber was developed for recovering NOx from metallurgical exhaust.In this device,NOx was converted into nitric acid,which was then recycled in the oxidization reactor.Compared with conventional pneumatic spraying scrubbers,the self-developed pneumatic spraying scrubber had significant advantages,such as the simple structure without liquid circulation pump,easy operation,energy conservation,and the high recovery rate.The influences of various parameters,such as the spray tube height,the spray nozzle diameter,the concentration and temperature of the absorbent,and the operating pressure,on the recovery of NOx were also investigated.The best NOx removal efficiency was 76.08%.When the spray tube height was 0.74 m,the nozzle diameter was 0.5 mm,the absorbent content was 5%at 30℃,and the operating pressure was 0.15-0.17 MPa.The invented pneumatic spraying scrubber successfully solves the problems of high-concentration NOx absorption and regeneration of nitric acid.In addition,the device can also absorb other harmful gases and provide a possible new treatment process for air pollution control.展开更多
文摘A multi-functional micro-arc plasma spraying system was developed according to aerodynamics and plasma spray theory. The soft switch IGBT （Insulated Gate Bipolar Transistor） invert technique, micro-computer control technique, convergent-divergent nozzle structure and axial powder feeding techniques have been adopted in the design of the micro-arc plasma spraying system. It is not only characterized by a small volume, a light weight, highly accurate control, high deposition efficiency and high reliability, but also has multi-functions in plasma spraying, welding and quenching. The experimental results showed that the system can produce a supersonic flame at a low power, spray Al2O3 particles at an average speed up to 430 m/s, and make nanostructured AT13 coatings with an average bonding strength of 42.7 MPa. Compared to conventional 9M plasma spraying with a higher power, the coatings with almost the same properties as those by conventional plasma spray can be deposited by multi-functional micro-arc plasma spraying with a lower power plasma arc due to an improved power supply design, spray gun structure and powder feeding method. Moreover, this system is suitable for working with thin parts and undertaking on site repairs, and as a result, the application of plasma spraying will be greatly extended.
基金National Natural Science Foundation of China(No.U1660107)
文摘NOx is generally composed of NO,NO2,N2O,N2O4,and N2O5,which may form photochemical smoke and may lead to acid rain,greenhouse effect and destruction of the ozone layer in the atmosphere.In this paper,a new pneumatic spraying scrubber was developed for recovering NOx from metallurgical exhaust.In this device,NOx was converted into nitric acid,which was then recycled in the oxidization reactor.Compared with conventional pneumatic spraying scrubbers,the self-developed pneumatic spraying scrubber had significant advantages,such as the simple structure without liquid circulation pump,easy operation,energy conservation,and the high recovery rate.The influences of various parameters,such as the spray tube height,the spray nozzle diameter,the concentration and temperature of the absorbent,and the operating pressure,on the recovery of NOx were also investigated.The best NOx removal efficiency was 76.08%.When the spray tube height was 0.74 m,the nozzle diameter was 0.5 mm,the absorbent content was 5%at 30℃,and the operating pressure was 0.15-0.17 MPa.The invented pneumatic spraying scrubber successfully solves the problems of high-concentration NOx absorption and regeneration of nitric acid.In addition,the device can also absorb other harmful gases and provide a possible new treatment process for air pollution control.
