Research On Partitioned Exciting Non-Equilibrium Plasma Reactor Array At Atmospheric Pressure

The ballast water discharge is increasing rapidly with the development economy and international trade of China. The alien species carried by ballast water seriously harmed marine environment. It is a safe and effective method of ballast water treatment which using advanced oxidation technology based on atmospheric electric field discharge. The core of this method is development of continuous, large-scale and efficient active oxygen particles generating device. Due to the geometric scale amplification effect, traditional large-scale active oxygen particles generating device is difficult to operate at more than thousands of hertz frequency. If the operating frequency is too low, active oxygen particles generating device have the problem of large volume, inefficient and difficult to improve the yield of active oxygen particles. Based on the requirement of advanced oxidation treatment of ballast water, and the technical route of high concentration active oxygen particles produced on a large scale by atmospheric pressure strong electric discharge, the partitioned exciting non-equilibrium plasma reactor array has been researched. The following original conclusions are drawn:(1) The discharge mode of atmospheric pressure dielectric barrier discharge with asymmetric electrode structure has been investigated. The alternate discharge mode of micro streamer and micro like glow discharge is generated in high applied voltage. In this discharge mode, the micro streamer is generated in positive half cycle of discharge, and the micro like glow discharge is generated in negative half cycle of discharge. The synergism of dynamic strong electric field in the head of micro streamer and local strong electric field in the micro like glow discharge cathode fall region could enhance the local electric field in discharge gap.(2) The optimization approach of atmospheric pressure non-equilibrium plasma reactor is proposed. The asymmetric electrode structure and high applied voltage make the reactor to work at the alternate discharge mode of micro streamer and micro like glow discharge. The local electric field in the discharge gap was enhanced. Pre-oxidation treatment method is used to prevent the electrode surface from oxidating by oxygen plasma in the strong electric field. That increase the service life and discharge stability of the reactor. The highest active oxygen particles concentration produced by reactor is 165 g/m3, and the highest yield is 41.9 g/h, the yield per unit area is 1130 g/m2·h.(3) Partitioned exciting method is established to solve the geometrical scale amplification effect. The resonance parameters of discharge system is dispersed to partitioned exciting unit consisted of miniaturing high-frequency high-voltage transformer and atmospheric pressure non-equilibrium plasma reactor. The main advantage of the proposed method is to ensure the resonance frequency of discharge syetem constant when the scale of reactor array is increasing. The discharge system can work at the original high frequency.(4) The partitioned exciting power supply consisted of high power inverter and miniaturing high-frequency high-voltage transformer is designed and manufactured. The full-bridge inverter circuit consisted of four IGBT switching is employed for the main circuit. Output power and frequency are regulated by PWM control strategy. The range of output frequency of high power inverter is 5-11 kHz. The highest output power of high power inverter is 20 kW, which can drive 40 reactors at the same time. The miniaturing high-frequency high-voltage transformer is designed to fully consider the characteristics of high frequency high voltage output. The highest output voltage is 10 kV, the range of frequency of transformer is 5-11 kHz.(5) Partitioned exciting non-equilibrium plasma reactor array included 24 partitioned exciting units has been developed. In the case of practical application, the reactor array can produce the active oxygen particles at scale, which operate frequency is 8 kHz. The active oxygen particles concentration is 110.9 g/m3, the yield is 443.6 g/h. Comparing the conventional device, the volume is reduced, the operate frequency is significantly increased (lower than 1 kHz up to 8 kHz), the exciting voltage is reduced (higher than 10 kV drop to 2-4 kV). Partitioned exciting non-equilibrium plasma reactor array is the core technology device for advanced oxidation ballast water treatment.