In this work, a novel gas phase silent-packed bed hybrid discharge plasma reactor has been proposed, and its ability to control a simulative gas stream containing 240 ppm benzene is experimentally investigated. In order to optimize the geometry of the reactor, the benzene conversion rate and energy yield （EY） were compared for various inner electrode diameters and quartz tube shapes and sizes. In addition, benzene removal efficiency in different discharge regions was qualitatively analyzed and the gas parameter （space velocity） was systematically studied. It has been found that silent-packed bed hybrid discharge plasma reactor can effectively decompose benzene. Benzene removal proved to achieve an optimum value of 60% with a characteristic energy density of 255 J/L in this paper with a 6 mm bolt high-voltage electrode and a 13 mm quartz tube. The optimal space velocity was 188.1 h^-1, which resulted in moderate energy yield and removal efficiency. Reaction by-products such as hydroquinone, heptanoic acid, 4-nitrocatechol, phenol and 4-phenoxy-phenol were identified by mean of GC-MS. In addition, based on these organic by-products, a benzene destruction pathway was proposed.
为了考察等离子体活化空气产生臭氧对脱硫浆液中亚硫酸钙的氧化作用,采用沿面放电等离子体发生装置,探究了放电电压、曝气量、曝气气体温度以及亚硫酸钙浆液的浓度和温度等参数对亚硫酸钙氧化率的影响。结果表明,在室温条件下,当亚硫酸钙浓度为0.01 mol/L时,放电电压取15 k V、曝气量取1.0 m3/h时具有较好的放电氧化效果;较低的曝气气体温度和亚硫酸钙浓度、以及较高的浆液温度有利于亚硫酸钙的放电氧化。当放电电压为14 k V、亚硫酸钙浆液初始浓度0.01 mol/L时,放电氧化仅采用0.7 m3/h曝气量就可使其氧化率达到空气自氧化采用1.4 m3/h曝气量时的氧化率的1.49~1.59倍。当放电氧化的浆液浓度为空气自氧化的2倍时,其氧化率为空气自氧化的1.2~1.5倍,在降低工艺投资和运营成本方面具有明显优势。
An atmospheric-pressure argon plasma jet with screw ring-ring electrodes in surface dielectric barrier discharge is generated by a sinusoidal excitation voltage at 8 kHz. The discharge characteristics, such as rotational and vibrational temperature of nitrogen, electronic excitation temperature, oxygen atomic density, nitrogen molecular density, and average electron density, are estimated. It is found that the rotational temperature of nitrogen is in the range of 352 ～ 392 K by comparing the simulated spectrum with the measured spectrum at the C3Πu → B3Πg （△ν = 2） band transition, the electronic excitation temperature is found to be in the range of 3127 ～ 3230 K by using the Boltzmann plot method, the oxygen atomic and nitrogen molecular density are of the order of magnitude of 1016 cm-3 by the actinometry method, and the average electron density is of the order of magnitude of 1012 cm-3 by the energy balance equation. Besides, the effective power, conduction, and displacement current are measured during the discharge.
The oxidation of elemental mercury （Hg~） by dielectric barrier discharge reactors was studied at room temperature, where concentric cylinder discharge reactor （CCDR） and surface discharge plasma reactor （SDPR） were employed. The parameters （e.g. Hg^0 oxidation efficiency, energy constant, energy yield, energy consumption, and O3 concentration） were discussed. From comparison of the two reactors, higher Hg^0 oxidation efficiency and energy constant in the SDPR system were obtained by using lower specific energy density. At the same applied voltage, energy yield in the SDPR system was larger than that in the CCDR system, and energy consumption in the SDPR system was much less. Additionally, more 03 was generated in the SDPR system. The experimental results showed that 98% of Hg^0 oxidation efficiency, 0.6 J·L^-1 of energy constant, 13.7 μg·J^-1 of energy yield, 15.1 eV·molecule^-1 of energy consumption, and 12.7 μg·J^-1 of O3 concentration were achieved in the SDPR system. The study reveals an alternative and economical technology for Hg^0 oxidation in the coal-fired flue gas.
