Liquid waste decomposition by long DC arc under atmospheric pressure

Li, Tianming; Watanabe, Takayuki; Ochi, Kaoru; Otsuki, Koji

doi:10.1016/j.cej.2013.07.003

Cited by 8 publications

(4 citation statements)

References 33 publications

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“…Besides this classical configuration, there are several other designs, addressing the need of specific optimization for specific applications, like for example discharges with multiple electrodes [3,4], a magnetically stabilized gliding arc (MGA) reactor [5], a reactor with vortex gas flow [6,7], etc. The GAD is very promising for various applications, such as CO 2 conversion [7,8], dry reforming of methane [9,10], N 2 fixation [11,12], surface treatment [13] and even waste treatment [14]. This type of discharge is attractive, because it allows the generation of relatively dense plasma in the order 10 20 -10 22 m -3 while sustaining a relatively low gas temperature below 2000-3000 K. Taking into account that the electron temperature in these discharges is in the order of 1-2 eV, it is clear that GADs produce thermally non-equilibrium plasmas, which are found to be preferable for various plasma assisted gas conversion processes [1].…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional modeling of energy transport in a gliding arc discharge in argon

Kolev

Bogaerts

2018

Plasma Sources Sci. Technol.

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In this work we study the energy transport in a gliding arc discharge with two diverging flat electrodes in argon gas at atmospheric pressure. The discharge is ignited at the shortest electrode gap and it is pushed downstream by a forced gas flow. The considered current values are relatively low and therefore a non-equilibrium plasma is produced. We consider two cases, i.e., with high and low discharge current-28 mA and 2.8 mA, and a constant gas flow of 10 L/min which has a significant turbulent component of the velocity. The study presents an analysis of the various energy transport mechanisms responsible for the redistribution of the Joule heating to the plasma species and the moving background gas. The objective of this work is to provide a general understanding of the role of the different energy transport mechanisms on the arc formation and sustainment, which can be used for the improvement of existing or new discharge designs. The work is based on a 3D numerical model, combining a fluid plasma model, the Shear Stress Transport Reynolds Averaged Navier-Stokes (SST RANS) turbulent gas flow model and a model for gas thermal balance. The obtained results show that at higher current, the discharge is constricted within a thin plasma column with several hundred of Kelvins above room temperature, while in the low current discharge, the combination of intense convective cooling and low Joule heating prevents discharge contraction and the plasma column evolves to a static non-moving diffusive plasma, continuously cooled by the flowing gas. As a result, the energy transport in the two cases is determined by different mechanisms. At higher current and constricted plasma column, the plasma column is cooled mainly by turbulent transport, while at low current and unconstricted plasma, the major cooling mechanism is energy transport due to non-turbulent gas convection. In general, the study also demonstrates the importance of turbulent energy transport in redistributing the Joule heating in the arc and its significant role for the arc cooling and the formation of the gas temperature profile. In general, the turbulent energy transport lowers the average gas temperature in the arc and thus it allows additional control of thermal non-equilibrium in the discharge.

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Section: Introductionmentioning

confidence: 99%

Three-dimensional modeling of energy transport in a gliding arc discharge in argon

Kolev

Bogaerts

2018

Plasma Sources Sci. Technol.

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“…Therefore, the residence time of the treated material is sufficiently long. Numerical (Choi et al, 2013) and experimental studies (Li et al, 2012) have been reported and feasibility of long DC arc process for organic waste decomposition was revealed (Li et al, 2013). Effect of external magnetic field on the arc fluctuation have also been clarified.…”

Section: Introductionmentioning

confidence: 98%

Effect of External Magnetic Field on Long DC Arc Characteristics with Rng-shaped Anode

et al. 2021

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Fluctuation phenomena of plasma jet flow in an innovative long DC arc system with a ring-shaped anode were successfully clarified by a high-speed camera visualization. The long DC arc with long electrode gap distance more than 350 mm has been applied to gas decomposition due to its advantages of long plasma length, resulting in long residence time of treated gas. However, large heat loss at a conventional hemispherical-shaped anode was a critical issue in the long DC arc system. Therefore, the ring-shaped anode was utilized to convert large energy loss at the anode into the plasma jet flow. High-speed camera observation revealed the effect of external magnetic field on the fluctuation phenomena. Plasma jet fluctuates with the frequency of several tens Hz when the magnetic field was applied. These understanding of arc and plasma jet fluctuation enables to improve the capability of long DC arc system.

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“…Many studies on applied techniques using these thermal plasmas have been addressed. Studies on nanoparticle synthesis (Shigeta and Murphy, 2011;Kodama et al, 2014), surface modification (Maruyama et al, 2016), and waste treatment (Heberlein and Murphy, 2008;Li et al, 2013) were reported.…”

Section: Introductionmentioning

confidence: 99%

Effects of working pressure on temperature characteristics in multiphase AC arc

Okuma

Imatsuji

Hashizume

et al. 2018

JFST

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Temperature characteristics of a multiphase AC arc in various working pressures were investigated by an innovative observation system consisting of a high-speed video camera and band-pass filters. Thermal plasmas have been widely applied to many industrial fields because of their unique advantages such as high temperature, high enthalpy, and rapid quenching capability. In particular, the multiphase AC arc is advantageous in terms of large plasma volume and high energy efficiency. Therefore, this heat source has been applied to innovative material processing such as in-flight glass melting, and functional nanoparticles fabrication. However, the temperature field and its fluctuation characteristics in the multiphase AC arc have not been understood because of the difficulties of temperature measurement due to their rapid fluctuation in millisecond timescale as well as the axisymmetric spatial characteristics. To understand and control the fluctuation phenomena is important to realize this method as industrial technology. Temperature measurement system using a high-speed camera was constructed to visualize the temperature fields of the multiphase AC arc. The fluctuations in the two-dimensional intensity distributions of particular line emissions from atomic argon were successfully observed. By analyzing these images using the Boltzmann plot method, the temperature distribution was estimated. The experimental results indicated that the arc temperature fluctuated in the range from 6,000 to 12,000 K. Higher temperature, smaller arc existence area, and decrease in the diameter of the arc were observed with an increase of working pressure. The arc temperature in the multiphase AC arc is sufficiently high to treat the refractory metals and ceramics powders at high processing rate.

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Liquid waste decomposition by long DC arc under atmospheric pressure

Cited by 8 publications

References 33 publications

Three-dimensional modeling of energy transport in a gliding arc discharge in argon

Three-dimensional modeling of energy transport in a gliding arc discharge in argon

Effect of External Magnetic Field on Long DC Arc Characteristics with Rng-shaped Anode

Effects of working pressure on temperature characteristics in multiphase AC arc

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