A TLT Based Nanosecond Pulsed Plasma Source With A Repetitive Spark Gan And Its Water Treatment

Pulsed power technology is an important way to generate plasma as it can achieve greater power,higher energy efficiency and produce more active particles.To meet the needs of industrialization,pulsed plasma source is in the development of lower cost,smaller volume,higher repetition frequency,greater stability and longer lifetime,while switching technology is still a key factor that restricts it.Applying high-voltage pulsed power technology to water treatment can naturally incorporate a variety of advanced oxidation methods,making it a very promising new type of water treatment way.In this paper,a coaxial spark switch with three-electrodes double-gaps is designed,based on it,a set of TLT nanosecond pulsed plasma source is then constructed and its output characteristics are investigated as well.Applying TLT pulsed plasma source to water treatment,the effects of parameters of pulsed plasma source and reactor on the oxidation efficiency as well as energy utilization of methylene blue are studied,to be referred by the pulsed plasma water treatment technology and its industrialization amplification.Main content and conclusions are summarized as follow:a)A MW pulsed plasma source is developed,constructed with initial power,high-voltage unit,spark gap switch and load.The high-voltage unit consists of transformer,rectifier circuit and LCR trigger circuit.And the self-designed spark switch adopts a coaxial structure with three electrodes and two gaps,besides,it is integrated with a capacitor and the TLT input side to reduce the volume and stray inductance.The TLT pulsed power can achieve frequency of 500 pps,and when it is connected in series to the matching water resistor,it can realize double voltage output,and when the parallel output is used,it can realize double current output.The rise time and width of pulse is 12.5 ns and 27 ns respectively.Different output modes only affect the pulse amplitude and the basic characteristics are all the same.b)From the perspective of discharge waveform and energy efficiency,the effect of the input voltage on the line-plate water treatment reactor discharge is basically limited to the amplitude,but the increase of the input voltage will increase the discharge energy,and make the energy efficiency rise first and then decrease.c)The decolorization process of methylene blue is basically linear with energy consumption.Increasing the voltage and the frequency can both increase the input energy,making the oxidation efficiency of methylene blue along with the energy consumption rise.Under typical reaction conditions,moderate oxidation efficiency and low energy consumption can be obtained,about 0.91 Wh/mg.At the same SIE,raising the voltage can get higher oxidation efficiency than increasing the frequency.The rise of conductivity will cause energy consumption to drop first and then increase,at 50 μS/cm,the energy consumption reaches a minimum energy consumption of 0.83 Wh/mg.Besides,taking water circulation can increase oxidation efficiency and reduce energy consumption.d)The generation of hydrogen peroxide also has a linear relationship with the input energy.Under the typical electrical conditions,the water treatment device can receive the yield of hydrogen peroxide approximately at 3.2 g/kWh,which is a relatively high level in the plasma liquid system.The hydrogen peroxide yield can be improved by a higher voltage or frequency as energy increased.However,high conductivity will reduce hydrogen peroxide production,as ion deteriorates energy utilization,and may directly hinder the generation of hydrogen peroxide too.