Jae-Yong Ryu

Chlorination of dibenzofuran and dibenzo-p-dioxin vapor by copper (II) chloride.

Dibenzofuran (DF) is formed from phenol and benzene in combustion gas exhaust streams prior to particle collection equipment. Subsequent chlorination at lower temperatures on particle surfaces is a potential source of chlorinated dibenzofuran (CDF). Gas streams containing 8% O(2) and approximately 0.1% DF vapor were passed through particle beds containing copper (II) chloride (0.5% Cu, mass) at temperatures ranging from 200 to 400 degrees C to investigate the potential for CDF formation during particle collection. Experiment duration was sufficient to provide an excess amount of DF (DF/Cu=3). The efficiency of DF chlorination by CuCl(2) and the distribution of CDF products were measured, with effects of temperature, gas velocity, and experiment duration assessed. Results of a more limited investigation of dibenzo-p-dioxin (DD) chlorination by CuCl(2) to form chlorinated DD (CDD) products are also presented. The efficiency of DF/DD chlorination by CuCl(2) was high, both in terms of CuCl(2) utilization and DF/DD conversion. Total yields of Cl on CDF/CDD products of up to 0.5 mole Cl per mole CuCl(2) were observed between 200 and 300 degrees C; this suggests that nearly 100% CuCl(2) was utilized, assuming a conversion of two moles of CuCl(2) to CuCl per mole Cl added to DD/DF. In a short duration experiment (DF/Cu=0.3), nearly 100% DF adsorption and conversion to CDF was achieved. The degree of CDF chlorination was strongly dependent on gas velocity. At high gas velocity, corresponding to a gas-particle contact time of 0.3 s, mono-CDF (MCDF) yield was largest, with yields decreasing with increasing CDF chlorination. At low gas velocity, corresponding to a gas-particle contact time of 5 s, octa-CDF yield was largest. DF/DD chlorination was strongly favored at lateral sites, with the predominant CDF/CDD isomers within each homologue group those containing Cl substituents at only the 2,3,7,8 positions. At the higher temperatures and lower gas velocities studied, however, broader isomer distributions, particularly of the less CDD/CDF products, were observed, likely due to preferential destruction of the 2,3,7,8 congeners.

Is chlorination one of the major pathways in the formation of polychlorinated naphthalenes (PCNs) in municipal solid waste combustion

The chlorination patterns of unsubstituted naphthalene were studied using a laminar flow reactor with a 1 cm particle bed of 0.5% (mass) copper(II) chloride (CuCl2) mixed with silicon dioxide (SiO2), operated over a temperature range of 100 to 400 °C and at gas velocities of 2.7 and 0.32 cm/s. The polychlorinated naphthalene (PCN) yield increased until a temperature reached at 250 °C, where a peak yield of 3.07% (percent of naphthalene input, carbon basis) was observed. All PCN homologue groups, mono- through octa-chlorinated naphthalenes, were observed. To test the hypothesis that PCNs in combustion processes are formed via chlorination pathways, the PCN homologue and isomer patterns from the experiments were compared with those observed in municipal solid waste combustion (MSW) incinerators. PCN congeners with 1,4-substituents dominated formation in the naphthalene chlorination experiments, whereas 2,3-substituents were major congeners in both MSW combustion flue gas and fly ash samples. These results suggest that contrary to the hypothesis, chlorination is not a primary PCN formation route in either the flue gas or fly ash from MSW combustion. Even so, naphthalene chlorination pathways presented in this paper provide an improved means for evaluating PCN formation mechanisms in combustion processes.

Dioxin and furan formation on CuCl2 from chlorinated phenols with one Ortho chlorine

The formation of chlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs) on CuCl2 particlesfrom four phenols with one ortho chlorine was studied in a flow reactor over the temperature range 300 to 450°C and contrasted with gas-phase results between 500 and 700°C. Heated nitrogen gas streams containing 7/8% oxygen, 1.7% benzene vapor, and equal amounts of 2-chlorophenol 2,3-dichlorophenol, 2,3,5-trichlorophenol, and 2,3,4,5-tetrachlorophenol vapor (450 ppmv, each) were passed through a particle bed containing 0.5% (mass) CuCl2: the nominal gas particle contact time was 0.3 s. CDD/F product yields of greater than 1% phenol conversion were observed between 350 and 425°C. Unlike gas-phase CDD/F formation, formation on CuCl2 favored CDDs over CDFs, and CDDs were formed predominantly with loss of one chlorine atom. While total CDD/F yields varied significantly with temperature, CDD/F isomer distributions did not. Thus, isomer patterns may provide a fingerprint for CDD/F formation from phenol precursors. Based on results of experiments with single phenol precursors, phenol precursors were assigned to all CDD/F products 2,3,4-Trichlorophenol was found to have the greatest propensity to form CDDs, whereas 2,3-dichlorophenol and 2,3,4,5-tetrachlorophenol were found to have the greatest propensity to form CDFs. Similar to gas-phase CDD/F formation, these results on CuCl2 suggest that chlorine substitution at phenol meta sites favors CDF formation, whereas chlorine substitution at ortho and para sites favors CDD formation.

Destruction of

The destruction study of gas emitted from the semiconductor industry is performed with electron-beam technology. Absorbed dose (kGy) and current ranged from 0 (0) to 400 kGy (20 mA). The concentration of gas ranged from 500 to 2,000 ppm. In order to assess the effect of a residence time on DRE (Destruction and Removal Efficiency, %), experiments also conducted at different irridiation times of 5 sec, 10 sec, 15 sec and 20 sec respectively. As absorbed dose and current increased, DRE of was also increased. However, DRE (%) of decreased with increasing the concentration of gas. The DRE of was about 90% at an absorbed dose of 400 kGy.

NF_3

Destruction and removal efficiency (DRE) of was tested with varying degrees of ionization and initial concentrations of . The applied dose of ionization energy varied from 0 to 400 kGy. The initial concentration of gas also varied from 1,000 ppm to 2,500 ppm. In order to assess the effect of a residence time on DRE (Destruction and Removal Efficiency, %), experiments were also conducted at different irradiation times of 3, 5, 10, 15, and 20 sec, respectively. The DRE of increased with an increasing amount of dose and current. Regardless of initial concentration of , 90% level of DRE was achieved by applying over 10 mA of electrical current.

Emitted from Semiconductor Process by Electron Beam Technology

The pressure drop through pulse air jet-type bag filter is one of the most important factors on the operating cost of bagfilter houses. In this study, the pilot-scale pulse air jet-type bag filter with about 6 m2 filtration area was designed and tested for investigating the effects of the four operating conditions on the total pressure drop, using the coke dust collected from a steel mill factory. When the face velocity is higher than 2 m/min, it is not applicable to on-spot due to the increase of power expenses resulting from a high-pressure drop, and thus, 1.5 m/min is considered to be reasonable. The regression analysis results show that the degree of effects of independent parameters is a order of face velocity > concentration > time > pressure. The results of SPSS answer tree analysis also reveal that the operation time affects the pressure drop greatly in case of 1 m/min of face velocity, while the inlet concentration affects the pressure drop in case of face velocity more than 1.5 m/min.

A Study on Destruction Potential of Sulfur Hexafluoride (SF 6 ) Using High Ionization Energy

This study summarizes the relations among concentration, water-soluble ions concentration, metallic element Components characteristics and SPSS in negative ion and metallic element of particle in Miryang.(By the urban area, the industrial complex area and the suburban area according to the season) concentration of total 72 samples collected from 3 sites turned out to range from 3.47 to 34.7 , and the average concentration was the suburban area-the kin nup(16.00 ) > the urban area-the roof of the old Miryang university(10.32 ) > the industrial complex-Sapo industrial complex(10.29 ). In particular, the suburban area had concentration 1.5 times those of urban area, industrial complex. It was thought although the site was suburban and farm-side without pollutants around, it had a higher concentration value influenced by external factors including the brickyard, small-scale incinerator, driving range construction, construction on the Daegu-Busan express and the widening of the four-lane road between Miryang-Anyang nearby. As for water-soluble ions among particle collected in Miryang area, accounted for 60% and , was 30% in spring and summer. And accounted for 50% and was 35% in fall and winter. The AI value of metallic Components among particle collected in Miryang area had a high value influenced by the apartment complex construction and the extension work of road. The industrial complex area had Zn concentration 3 times, and Fe concentration 2 times those of urban area and suburb area. When it comes to the relation with metallic elements in urban area, the highest coefficient of correlation was between Cr-Fe with 0.85, and Pb-Cd turned out in the reverse correlation. Among metallic elements, the coefficients of correlation between Zn and Cr, Mn, Fe, NI were high in industrial complex area. The highest coefficient of correlation was between Mn-Zn with 0.88, meanwhile Ni and Cu, Cd turned out in the reverse correlation in the suburb area. These coefficients of correlation are attributed to the difference in pollutant sources, rather than difference in pollutant and non-pollutant.

Prediction of the Efficiency of Factors Affecting Pressure Drop in a Pulse Air Jet-type Bag Filter

The chlorination pattern of naphthalene vapor when passed through a 1 cm particle bed of 0.5% (mass) copper (II) chloride (CuCl2) mixed with silicon dioxide (SiO2) was studied. Gas streams consisting of 92% (molar) N2, 8% O2 and 0.1% naphthalene vapor were introduced to an isothermal flow reactor containing the CuCl2/SiO2 particle bed. Chlorination of naphthalene was studied from 100 to 400 o C at a gas velocity of 2.7 cm/s. Mono through hexachlorinated naphthalene congeners were observed at 250 o

The PM 2.5 Concentration and Components Characteristics in Miryang

Research results for the pressure drop variance depending on operation conditions such as change of inlet concentration, pulse interval, and face velocity, etc., in a pulse air jet-type bag filter show that while at whose pulse pressure is low, it is good to make an pulse interval longer in order to form the first layer, it may not be applicable to industry because of a rapid increase in pressure. In addition, the change of inlet concentration contributes more to the increase of pressure drop than the pulse interval does. In order to reduce operation costs by minimizing filter drag of a filter bag at pulse pressure , the dust concentration should be minimized, and when the inlet dust loading is a lower concentration, the pulse interval in the operation should be less than 70 sec, but when inlet dust loading is a higher concentration, the pulse interval should be below 30 sec. In particular, in the case that inlet dust loading is a higher concentration, a high-pressure distribution is observed regardless of pulse pressure. This is because dust is accumulated continuously in the filter bag and makes it thicker as filtration time increases, and thus the pulse interval should be set to below 30 sec. If the equipment is operated at 1m/min of face velocity, while pressure drop is low, the bag filter becomes larger and thus, its economics are very low due to a large initial investment. Therefore, a face velocity of around 1.5 m/min is considered to be the optimal operation condition. At 1.5 m/min considered to be the most economical face velocity, if the pulse interval increases, since the amount of variation in filter drag is large, depending on the amount of inlet dust loading, the operation may be possible at a lower concentration when the pulse interval is 70 sec. However, for a higher concentration, either face velocity or pulse interval should be reduced.