Packed Bed Non-thermal Plasma Reactor Research Articles

Evaluation of Toluene Decomposition and Byproducts by a Wet-type Packed-bed Nonthermal Plasma Reactor

Evaluation of Toluene Decomposition and Byproducts by a Wet-type Packed-bed Nonthermal Plasma Reactor

Evaluation of a Catalyst Packed-bed Nonthermal Plasma Reactor for VOC and PM Removal

Volatile organic compounds (VOCs) and particulate matter (PM) emitted from factories in the painting and printing industries, and various exhaust gas regulations have been implemented. VOCs are the cause of photochemical oxidants and suspended PM such as PM2.5, which has become a global environmental problem. As one of the solution technologies, catalysis nonthermal plasma (NTP) techniques have been studied as VOCs control methods. In this study, in order to extend the application to the treatment of water-soluble VOCs, a wet-type catalysis plasma reactor is proposed. As an initial step to evaluate proposed technique, the simultaneous removal of nanoparticles and toluene or typical VOCs, are performed at relatively high gas flow rates of 10 L/min. As catalyst pellets, α-alumina spheres are filled in the NTP reactor, and a MnO2 catalytic reactor is installed after the plasma reactor for ozone removal. Simultaneous removal of toluene and nanoparticles using dry and wet-type catalytic NTP reactors showed that the results used the wet-type reactor were superior in particle collection efficiency of 99%. As for the toluene removal efficiency, the dry-type was 91% and the wet-type was 73%, with the dry-type showing better results. However, the proposed wet-type catalysis NTP reactor could efficiently treat water-soluble VOCs, such as acetaldehyde and acetic acid.

Inactivation of airborne viruses using a packed bed non-thermal plasma reactor

Outbreaks of airborne infectious diseases such as measles or severe acute respiratory syndrome can cause significant public alarm. Where ventilation systems facilitate disease transmission to humans or animals, there exists a need for control measures that provide effective protection while imposing minimal pressure differential. In the present study, viral aerosols in an airstream were subjected to non-thermal plasma (NTP) exposure within a packed-bed dielectric barrier discharge reactor. Comparisons of plaque assays before and after NTP treatment found exponentially increasing inactivation of aerosolized MS2 phage with increasing applied voltage. At 30 kV and an air flow rate of 170 standard liters per minute, a greater than 2.3 log reduction of infective virus was achieved across the reactor. This reduction represented ~2 log of the MS2 inactivated and ~0.35 log physically removed in the packed bed. Increasing the air flow rate from 170 to 330 liters per minute did not significantly impact virus inactivation effectiveness. Activated carbon-based ozone filters greatly reduced residual ozone, in some cases down to background levels, while adding less than 20 Pa pressure differential to the 45 Pa differential pressure across the packed bed at the flow rate of 170 standard liters per minute.

Isopropanol removal using MnXOY packed bed non-thermal plasma reactor: Comparison between continuous treatment and sequential sorption/regeneration

MnXOY coated glass beads packed bed non-thermal plasma (NTP) reactor has been designed and operated for isopropanol (IPA) removal close to indoor air conditions. The IPA removal efficiency of continuous NTP treatment is compared with the sequential approach, i.e. adsorption of IPA on MnXOY and subsequent regeneration of the saturated MnXOY surface by non-thermal plasma. The comparison between both approaches has been achieved with the same packed bed reactor and model VOC under equivalent indoor air conditions. Firstly, based on carbon mass balance calculations, the continuous treatment has shown better performances from an IPA abatement point of view, as well as from a mineralization point of view. However, the characterization of ppb level side-products evidenced that the continuous treatment leads to a more significant release of organic side products which may impact indoor air quality. Secondly, both processes have been compared in terms of energetic costs regarding (i) IPA removal, and (ii) CO2 formation. Interestingly, it is evidenced that, to treat the same amount of IPA, the sequential approach requires 14.5 times less energy than the continuous NTP treatment process. Similarly, to produce the same amount of CO2, the sequential approach consumes 10 times less energy. This comparison evidences the interest of adsorption combined with subsequent non-thermal plasma regeneration for indoor air effluent treatment.

Development of Fiber Bragg Grating (FBG) as Temperature Sensor Inside Packed-bed Non-thermal Plasma Reactor

This paper presents early work on Fiber Bragg grating (FBG) as temperature sensor to monitor temperature variation inside a packed-bed non-thermal plasma reactor. FBG made from germania-doped fiber with center Bragg wavelength of 1552.5 nm was embedded inside non-thermal plasma reactor with sphere shape dielectric bead (barium titanate) and used to probe the temperature variation inside the reactor. The experimental works have proven that FBG is a suitable sensor to monitor temperature variation inside of reactor via LabVIEW program. Besides that, Optical Spectrum Analyzer (OSA) recorded Bragg wavelength shift as voltage of power supply increases, which indicate the non-uniform temperature variation occurring inside the reactor. However, it does not affect the chemical reaction inside the reactor because the temperature condition is in steady state.

Catalytic packed bed non-thermal plasma reactor for the extraction of hydrogen from hydrogen sulfide

The decomposition of hydrogen sulfide (H2S) to hydrogen and sulfur with Al2O3, MoOx/Al2O3, CoOx/Al2O3 and NiO/Al2O3 packed non-thermal plasma dielectric barrier discharge reactor was studied. The reaction was carried out with 5-mm discharge gap during the decomposition of 5 vol.% H2S at 150ml/min (STP) flow rate. Typical results indicated the conversion of ~50% at a specific input energy of ~0.92kJ/l H2S and 10% (in length) packed reactor showed the best conversion. Among the catalysts studied, MoOx and CoOx supported on Al2O3 showed high performance, which may be caused by synergy between plasma excitation of the carrier gas molecules and catalytic behaviour of MoOx and CoOx

Decomposition of dichloromethane and in situ alkali absorption of resulting halogenated products by a packed-bed non-thermal plasma reactor

For an effective decomposition and removal of organic halogenated compounds, a packed-bed non-thermal plasma reactor with in situ absorption of the resulting halogenated products by alkaline sorbent incorporated was proposed. In the plasma reactor, α-Al2O3 particles of 1 and 3 mm (mean particle diameter) were packed as solid dielectric medium to enhance the plasma power density in the reactor. Further, alkaline sorbent of Ca(OH)2 was doped onto the surface of α-Al2O3 particles, in order to remove halogenated products by in situ absorption with Ca(OH)2. A high-voltage and high-frequency pulsed power of −15 to 15 kV and 1 kHz was applied to the wire electrode of the plasma reactor by means of a DC power source. In the present study, as the sample of an organic halogenated compound that is most popularly used, we selected dichloromethane (CH2Cl2), and 500 ppm of the initial concentration of CH2Cl2 was fed into the reactor accompanied by air at a fixed flow rate of 500 × 10−6 m3 min−1 at room temperature. As a result, it was recognized that the amount of CH2Cl2 decomposed by non-thermal plasma in an α-Al2O3 particle bed increased with an increase in plasma input power. The ratio of decomposition of CH2Cl2 was almost 100% at 13 kV of electric power and 1 kHz frequency, and CO2, CH3Cl, COCl2, HCl, and Cl2 were observed as the major reaction products. On the other hand, when CH2Cl2 was introduced into the plasma reactor where α-Al2O3 particles doped with Ca(OH)2 were packed, the ratio of decomposition of CH2Cl2 became higher, compared to the case that α-Al2O3 particles were not doped with Ca(OH)2. Moreover, there were no halogenated by-product gases detected in the outlet gas from the reactor. As the solid reaction products, CaClOH and Ca(ClO)2·4H2O were detected on Ca(OH)2 by X-ray diffraction. From these findings, it was recognized that CH2Cl2 was decomposed more effectively without producing unwanted harmful halogenated by-products in the proposed non-thermal plasma reactor where α-Al2O3 particles doped with Ca(OH)2 sorbent were packed.

Odor Removal Characteristics of a Laminated Film-Electrode Packed-Bed Nonthermal Plasma Reactor

Odor control has gained importance for ensuring a comfortable living environment. In this paper, the authors report the experimental results of a study on the detailed characteristics of a laminated film-electrode and a laminated film-electrode packed-bed nonthermal plasma reactor, which are types of dielectric barrier discharge (DBD) reactor used for odor control. These plasma reactors can be potentially used for the decomposition of volatile organic compounds (VOCs) and reduction of NOx. The reactor is driven by a low-cost 60-Hz neon transformer. Removal efficiencies under various experimental conditions are studied. The complete decomposition of the main odor component, namely, NH3, is achieved in a dry environment. The retention times are investigated for the complete removal of NH3 in the case of the film-electrode plasma reactor and the film-electrode packed-bed plasma reactor. The removal efficiency of the former reactor is lower than that of the latter reactor. Mixing another odor component such as CH3CHO in the gas stream has no significant effect on NH3 removal efficiency.

대기압플라즈마 및 오존 분해촉매를 이용한 트리클로로에틸렌의 분해효율 증진 연구

본 논문은 비열평형 플라즈마와 촉매를 이용하여 트리클로로에틸렌의 효과적인 분해방법을 재안하였다. 이를 위하여 이산화망간과 알루미나 펠렛을 플라즈마 리액터 내부에 충진한 리액터를 설계하였다. 이산화망간 충진 리액터를 이용할 경우에는 산소를 포함한 가스중의 방전에 의해 발생된 오존이 촉매 표면애서 분해되는 동안에 발생된 산소원자 라디칼에 의하여 TCE의 분해율이 향상됨을 알 수 있었다. 그리고 알루미나를 충진한 경우에는 TCE는 DCAC로 산화되었으며, COx 및 Cl₂와 같은 저분자상으로 많이 분해되지 않았다. 그러나 알루미나 충진 리액터에 의한 플라즈마 처리된 가스를 리액터 후단에 설치한 이산화밍간 촉매를 통과시킴에 의하여 분해율이 매우 향상됨을 알 수 있었다. 따라서, 플라즈마 프로세스에 이산화망간을 응용함에 의하여 오존 분해에 따른 촉매 표면의 산소 원자 라디칼에 의하여 TCE 및 분해 생성불(DCAC)를 효율적으로 분해하는 것이 가능하다.

Odor Removal Characteristics of Barrier-Type Packed-Bed Nonthermal Plasma Reactor

Odor control has gained importance for ensuring a comfortable living environment. In this paper, the authors report the experimental results of a study of the detailed characteristics of a barrier-type packed-bed nonthermal plasma reactor used for odor control. This plasma reactor has been widely used for volatile organic compound (VOC) decomposition and NOx reduction. The reactor is energized by a low-cost 60 Hz AC power supply. Removal efficiency and the concentrations of byproducts are studied under various experimental conditions. The complete decomposition of the main odor component, namely, NH3, is obtained with minimal reaction byproduct formation (maximum N2O concentration, 10 ppm) in a dry environment. The decomposition is deteriorated by the addition of moisture. The minimum residence time is determined for the complete removal of NH3 in the case of the packed-bed plasma reactor. The pellet diameter has little effect on the removal tendency, and the reactor performed better than a silent corona. Mixing another odor component such as CH3CHO into the gas stream has little effect on the NH3 removal efficiency.

Atmospheric pressure of nitrogen plasmas in a ferro-electric packed bed barrier discharge reactor part I: modeling

Numerical modelling of ferroelectric packed bed nonthermal plasma reactor has been conducted to predict plasma parameters in a pure nitrogen environment. Simplified time averaged one-dimensional physical model based on Poisson's equation for electric field and transport equation for electrons was developed. The mean electron energy was obtained by a swarm relationship from calculated electric field profiles and plasma neutral conditions. For chemical model, N/sup +/, N/sub 2//sup +/, N/sub 3//sup +/, N/sub 4//sup +/, N/sup */, N/sub 2//sup */ and electron were considered where N/sup */ and N/sub 2//sup */ are the total excited atoms and molecules, respectively. The results show that all the plasma parameters increase with increasing applied AC voltage and pellet dielectric constant. The numerical results also show that the dominant ion is N/sub 4//sup +/ and the metastable molecule density is much higher than radical and the electron densities at atmospheric gas pressure.

NO/sub x/ concentration using adsorption and nonthermal plasma desorption

The gas flow rates for hazardous air pollutant emissions are generally large and their concentrations are low (in parts per million levels). When we try to directly treat the large flow rate and low concentration exhaust gas, the size of the equipment becomes large, resulting in high operating cost. The objective of this study is to convert the exhaust gas with large flow rate and low concentration into the one with small flowrate and high concentration by desorbing the absorbed gas from the absorbent pellets packed inside a barrier-type packed-bed nonthermal plasma reactor. In this paper, we especially focus on the difficulties of treating NO/sub x/. The absorbent pellets were molecular sieve spheres (MS-13X) made of zeolite with 1-nm pore diameter. The plasma desorption was carried out by applying the high voltage to the plasma reactor using any one of AC 60-Hz, AC 20-kHz, or pulse 210-Hz power supplies. We found out that NO/sub x/ could be desorbed effectively in the repeated adsorption and desorption process. Since the surface temperature increased rapidly, the desorption with AC 20 kHz took place not only by the electron impacts but also by the heat addition. In the desorption using the pulse power supply, the concentration rapidly increased and became maximum in a relatively short time. It was effective to close the reactor in the desorption process. It was successful to achieve a nonthermal plasma concentrating desorption of NO/sub x/ as the adsorption/desorption was repeated after more than 12 times.

By-Products NOx Control and Performance Improvement of a Packed-Bed Nonthermal Plasma Reactor

NOx are main toxic by-products in the effluent gas whendecomposing volatile organic compounds in air by a packed-bed plasmareactor. Several types of materials such as 13X zeolite, BaTiO3and Pd/Pt catalysts have been selected to be packed in the reactor, andmethane decomposition and NOx by-products in discharged gases areinvestigated at different range of reaction temperature and dischargeenergy density at atmospheric pressure. The ratios of methane decompositionpercentage/NOx concentration are used to assess these packed bedmaterials and reaction conditions. The results show that usingPd/γ-Al2O3 with lower percentage Pd as packedbed, and discharging with lower discharge density at higher reactiontemperature can reduce NOx output effectively and greatly improveperformance of the reactor.