| The high-voltage pulsed liquid-phase discharge is an interdisciplinary technology integrating subjects of pulsed power technology, plasma-environmental science and plasma physics. Strong oxidizing free radicals in plasma are generated during discharge process, which can oxidize the organics in solution efficiently and non-selectively, and thus the technology has been widely applied for organic solution treatment. Study on electrical characteristics of high voltage pulsed liquid-phase discharge in organic solutions is expected to provide new research idea of optimizing the liquid-phase discharge condition as well as improving the organic solution treatment efficiency. In this paper, the needle-plate liquid discharge reactor was used to occur liquid discharge, taking the high voltage pulsed liquid-phase discharge in organic solutions as the research goals, and effects of electrical parameters on the discharge characteristics were explored. The main research contents and conclusions are as follows:(1) The modeling analysis of pulse discharge system was carried out. The over-damped non-volatile state was observed as the best state of pulse-forming capacitor charging circuit and the interleaving transformation of resistivity and capacitance of reactor led to the formation of complex waveform of pulsed discharge. The numerical value of electrostatic field for needle-plate liquid-phase discharge reactor was investigated using the finite element simulation software, Ansoft-Maxwell. It was found that the electric field intensity had linear relationship with the excitation voltage, reducing the exposed length of needle tip into solution favored the discharge occurrence, and optimizing the electrode gap and curvature radius of needle tips could achieve stable discharge.(2) The electrical characteristic of high-voltage pulse discharge in high viscosity and high conductivity chitosan solution was studied. It was found that the high-voltage pulse discharge plasma could effectively reduce the viscosity of chitosan solution. After60min treatment, the viscosity of chitosan solution with initial concentration of20g/L decreased by75%. Discharge intensity was enhanced by increasing the pulse peak voltage and pulse-forming capacitor. With the increase of the electrode gap, the pulse width became wider, but the slope of Ⅰ-Ⅴ curve didn’t increase linearly with the decrease of electrode gap. When raising the air amount injecting into the reactor, the equivalent resistance between electrodes increased, leading to the decrease of the oscillation of pulse waveform, which benefited to discharge process.(3) The electrical characteristic of high-voltage pulse discharge in methylene blue dye solution was investigated. The maximum injecting energy efficiency of pulse power occurred at the pulse frequency60Hz and input power voltage50V. Increasing the solution conductivity could improve energy efficiency. Voltage waveform pulse width decreased with increasing the number of streamer discharge channels, but the current pulse width was basically unchanged, and also affected little on the single pulse injection energy. The discharge energy could be used efficiently when the pulse-forming capacitance was optimized between3to5nF. The discharge modes could change from pulsed corona discharge to spark discharge when increasing the air quantity or magnifying the pulse-forming capacitance. It was also found that increasing pulse forming capacitor as well as pulse frequency could significantly accelerate the decolorizing rate of methylene blue in solution. The solution conductivity increased gradually with the treatment time and the solution temperature was raised causing by the liquid discharge heat.(4) A comparative research on electrical characteristics of high-voltage discharge in methylene blue solution and chitosan solution indicated that the discharge current in chitosan solution was higher than that in the methylene blue solution under to experimental conditions of the same initial conductivity and the same pulse peak voltage. |
PDF Full Text Request