Characterization Of Gas-Liquid Phase Gliding Arc Discharge

The characteristics of atmospheric gas-liquid phase gliding arc discharge used in the treatment of high level organic wastewater, have been systematically studied. This work will help us to further understand the interaction mechanisms in the gas-liquid phase gliding arc degradation process of the wastewater, and is significant to the reactor optimization and system integration.The discharge shape of atmospheric gas-liquid phase gliding arc has been investigated by the high-speed photography. There has been many factors analysised, such as carrier gas flow rate, droplet characteristics and arc voltage and current characteristics. The results show that: (l)the luminous intensities of the discharge area along the electrodes axis are obviously different, and the length of the discharge area with large carrier gas flow is shorter than small.(2) When the carrier gas flow rate is smaller, the arc roots on the electrode surface move slower and the arc breakdown time becomes longer due to the impediment of liquid droplets. In addition, the flame envelope of arc in gas-liquid phase is more obvious than the gas phase.(3)The arc fluctuation of the gas-liquid phase discharge can be characterized by restrike mode.(4)When the gas flow rate is less than 10L/min, the major charged droplet is the electric field charged.The characteristics of major reactive species (OH and NO) in the gas-liquid gliding arc at atmospheric pressure have been studied by means of optical emission spectroscopy (OES). The results show that: (l)When the working gas is air, oxygen, nitrogen or argon, the major radical is always OH radical which plays the significant role in the wastewater treatment; (2)The axial evolution of the relative emission intensity of OH and NO radicals exhibits the similar tendency, which is that first increasing and then decreasing; (3)The intensity of OH radical increases with the water feed rate, while the opposition phenomena, are observed for NO radical; (4)With the increase of gas flow rate, the axial distribution of OH radical changes obviously. The total intensity of OH radical is almost unchanged, while that of NO radical increases obviously; (5) In non-thermodynamic equilibrium region of the arc discharge, the intensities of both radicals increase with the input voltage; (6)There is an optimization of the input voltage and the electrodes gap. At the input voltage of 220V, the electrode gap is 3mm, the total intensity of OH radical increases greatest.Moreover, the axial distribution of electron density was determined from the Stark broadening of the Al atomic line (396.1nm).The electron density of gliding arc reaches its maximum of 10²³m^-3 in the arc creation zone, while this value is decreased by one order of magnitude at 7cm downstream of the electrode gap.