• 한국대기환경학회지
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• 제28권4호
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• pp.446-453
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• 2012

Destruction and removal efficiency (DRE) of $SF_6$ was tested with varying degrees of ionization and initial concentrations of $SF_6$. The applied dose of ionization energy varied from 0 to 400 kGy. The initial concentration of $SF_6$ 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 $SF_6$ increased with an increasing amount of dose and current. Regardless of initial concentration of $SF_6$, 90% level of DRE was achieved by applying over 10 mA of electrical current.

• Bulletin of the Korean Chemical Society
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• 제28권8호
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• pp.1383-1388
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• 2007

Recently, the semiconductor and display industries have tried to reduce the emissions of perfluorocompounds (PFCs) from the globally environmental regulation. Total amount of PFC emission can be calculated from the flow rate and the partial pressures of PFCs. For the precise measurement of PFC emission amount, the mass flow controlled helium gas was continuously injected into the equipment of which scrubber efficiency is being measured. The partial pressures of PFCs and helium were accurately measured using a mass spectrometer in each sample extracted from inlet and outlet of the scrubber system. The flow rates are calculated from the partial pressures of helium and also, PFC destruction and removal efficiency (DRE) of the scrubber is calculated from the partial pressure of PFC and the flow rate. Under this method, the relative expanded uncertainties of the flow rate and the partial pressures of PFCs are ± 2% (k = 2) in case the concentrations of NF3 and SF6 are as low as 100 μmol/mol.

• 한국환경과학회지
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• 제21권9호
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• pp.1163-1169
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• 2012

Destruction and removal efficiency (DRE) of $SF_6$ was tested with low degrees of ionization. The applied dose of ionization energy varied from 63.70 to 212.34 kGy. The initial concentration and flow rate of $SF_6$ gas were 1,000 ppm and 50L/min, respectively. In order to increase the DRE, injection of conditioning agent ($H_2$) were conducted. The DRE of $SF_6$ increased about 2 times with injection of $H_2$ gas.

• 한국대기환경학회지
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• 제26권6호
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• pp.690-696
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• 2010

Abatement of perfluorocompounds (PFCs) used in semiconductor and display industries has received an attention due to the increasingly stricter regulation on their emission. In order to meet this circumstance, we have developed a radio frequency (RF) driven plasma reactor with multiple annular shaped electrodes, characterized by an easy installment between a processing chamber and a vacuum pump. Abatement experiment has been performed with respect to $CF_4$, a representative PFCs widely used in the plasma etching process, by varying the power, $CF_4$ and $O_2$ flow rates, $CF_4$ concentration, and pressure. The influence of these variables on the $CF_4$ abatement was analyzed and discussed in terms of the destruction & removal efficiency (DRE), measured with a Fourier transform infrared (FTIR) spectrometer. The results revealed that DRE was enhanced with the increase in the discharge power and pressure, but dropped with the $CF_4$ flow rate and concentration. The addition of small quantity of $O_2$ lead to the improvement of DRE, which, however, leveled off and then decreased with $O_2$ flow rate.

• 대한환경공학회지
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• 제34권6호
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• pp.391-396
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• 2012

전자빔을 이용하여 반도체 공정에서 배출되는 $NF_3$ 가스 분해 연구를 수행하였다. 본 연구에서 흡수선량은 0에서 400 kGy 범위였고, 전류강도는 0~20 mA범위였다. 또한, 처리 대상 가스의 농도 범위는 500~2,000 ppm이었다. 그리고 조사시간의 영향을 알기 위해서, 조사시간을 각각 5초, 10초, 15초, 20초 등으로 달리 하면서 실험을 수행하였다. 흡수선량 및 전류 강도가 증가할수록 가스의 분해효율은 증가하였다. 하지만 처리 대상가스의 농도가 증가할 때는 분해효율이 감소함을 알 수 있었다. 흡수선량이 약 400 kGy일 때 처리가스의 분해효율은 약 90% 정도를 나타내었다.

• Bulletin of the Korean Chemical Society
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• 제28권4호
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• pp.520-528
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• 2007

A practical and efficient disposal of PCBs (polychlorinated biphenyls) in waste transformer oil by a chemical dechlorination process has been reported. The transformer oil containing commercial PCB mixtures (Aroclor 1242, 1254 and 1260) was treated by the required amounts of PEG 600 (polyethylene glycol 600), potassium hydroxide (KOH) and aluminum (Al), along with different reaction temperatures and times. The reaction of PEG with PCBs under basic condition produces arylpolyglycols, the products of nucleophilic aromatic substitution. The relative efficiencies of PCB treatment process were assessed in terms of destruction and removal efficiency (DRE, %). Under the experimental conditions of PEG600/KOH/Al/100 oC/2hr, average DRE of PCBs was approximately 78%, showing completely removal of PCBs containing 7-9 chlorines on two rings of biphenyl which appear later than PCB no. 183 (2,2',3,4,4',5',6-heptaCB) in retention time of GC/ECD. However, when increasing the reaction temperature and time to 150 oC and 240 min, average DRE of PCBs including the most toxic PCBs (PCB no. 77, 105, 118, 123 and 169) in PCB family reached 99.99% or better, with the exception of PCB no. 5 and 8 (2,3-diCB and 2,4'-diCB). In studying the reaction of PEG with PCBs, it confirmed that the process led to less chlorinated PCBs through a stepwise process with the successive elimination of chlorines. The process also permits complete recovery of treated transformer oil through simple segregating procedures.

• 한국대기환경학회지
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• 제16권6호
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• pp.665-674
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• 2000

A major source of the hazardous waste generated is from chemical industries producing plastics, herbicides, pesticides and chlorinated solvents. All of these processes produce a class if hazardous waste termed the chlorinated hydrocarbons(CHCs), either directly or from undesirable side reactions. In this study, we investigated the destruction characteristics of hazardous waste through incineration. A nonequilibrium combustion model was used to describe the effect of the chemical kinetics due to the flame inhibition characteristics of $CCl_4$ which was used as the surrogate of hazardous waste. A parametric screening studies was made in a dump incinerator proposed in this study. The dump incinerator showed high $CCl_4$ DRE(Destruction and Removal Efficiency) as 5 nines. $CCl_4$/CH$_4$ ratio appeared to be most important in the destruction of $CCl_4$ through incineration.

• Bulletin of the Korean Chemical Society
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• 제23권6호
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• pp.817-824
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• 2002

Granular activated carbon(GAC) is highly effective in removing organic compounds which are resistant to biological disintegration in wastewater treatment. However, GAC has reached its full adsorptive capacity, GAC needs to be regenerated before it can be used for a further adsorption cycle. Countercurrent oxidative reaction (COR) technique has been developed and evaluated for the regeneration of spent GAC. Various parameters such as flame temperature, the loss of carbon, destruction and removal efficiency (DRE) of organic compounds, surface area, surface structure, adsorptive capacity, etc. were examined to determine the performance of COR. The results of these tests showed that adosorptive capacity of regenerated GAC was completely recovered, the loss of carbon was controllable, flame temperature was high enough to insure complete destruction and removal $(\geq99.9999%)$ of specific organics of interest, polychlorinated biphenyls (PCBs), that are thermally stable, and on formation of toxic byproducts such as polychlorinated dibenzo-p-dioxins (PCDDs) or polychlorinated dibenzofurans (PCDFs) were detected during the regeneration process. The COR technique is environmentally benign, easy to use and less copital intensive than other available regeneration technologies.

• 분석과학
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• 제19권6호
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• pp.535-543
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• 2006

현재 반도체 및 LCD(Liquid Crystal Display) 제조 공정에 널리 사용하는 $NF_3$는 국제적으로 대기중 배출량에 대한 규제를 실시 중인 온실가스 중의 하나다. 온실가스의 배출량 감축을 위하여 국내 대상 산업체들은 $NF_3$ 배출량의 감소에 지속적으로 노력을 해 오고 있다. 본 연구는 LCD를 제조하는 국내 3사에 설치된 $NF_3$ 처리용 전기가열방식 스크러버(scrubber)의 제거효율(DRE, Destruction and Removal Efficiency)과 process chamber에서의 $NF_3$ 사용 비율(use rate in process)을 측정하였다. 스크러버의 효율을 정확하게 측정하기 위하여, 비활성 기체인 He을 일정 유량으로 주입시켜주는 방법으로 시료를 채취하고, 정밀 가스질량분석기(Gas-MS)를 이용하여 시료 중 화학종들의 분압을 측정하였다. 세 회사에 설치되어 있는 스크러버의 효율을 측정한 결과, 2004년 이전에 설치한 스크러버의와 그 이후 개선한 스크러버의 DRE는 각각 52%와 95% 이상임을 확인하였다. 또한 Process chamber의 $NF_3$ 사용 효율은 1세대 및 2세대 공정라인에 설치한 RFSC(Radio Frequency Source Chamber)의 경우 75% 보다 낮지만, 3세대 이상 라인에 설치한 RPSC(Remote Plasma Source Chamber)의 경우는 95% 이상으로 측정이 되었다. 반도체 및 디스플레이 공정에 개선된 스크러버와 RPSC식 process chamber를 사용할 경우 $NF_3$ 배출량을 99.95% 이상 줄일 수 있을 것으로 예상된다. 따라서 $NF_3$에 대한 국내 3사의 온실가스 감축 목표가 성공적으로 이루어 질 것으로 예상된다.

• Nuclear Engineering and Technology
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• 제44권1호
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• pp.21-32
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• 2012

Fluorinated compounds mainly used in the semiconductor industry are potent greenhouse gases. Recently, thermal plasma gas scrubbers have been gradually replacing conventional burn-wet type gas scrubbers which are based on the combustion of fossil fuels because high conversion efficiency and control of byproduct generation are achievable in chemically reactive high temperature thermal plasma. Chemical equilibrium composition at high temperature and numerical analysis on a complex thermal flow in the thermal plasma decomposition system are used to predict the process of thermal decomposition of fluorinated gas. In order to increase economic feasibility of the thermal plasma decomposition process, increase of thermal efficiency of the plasma torch and enhancement of gas mixing between the thermal plasma jet and waste gas are discussed. In addition, noble thermal plasma systems to be applied in the thermal plasma gas treatment are introduced in the present paper.