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김대기 ( Daegi Kim ),정철진 ( Cheol-jin Jeong ),김도용 ( Do-yong Kim ),김은주 ( Eun-ju Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2018 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2018 No.-
최근 연안 해역에서의 대규모 어업활동과 산업화로 인하여 해상 부유 폐기물 및 해저면의 침적 폐기물, 패각류, 퇴적 오염물 등 해양 폐기물 발생량의 증가로 인하여 해양 오염은 날로 심각한 상태에 이르고 있다. 해양폐기물은 해안으로 밀려오는 해안폐기물, 해수면에 떠다니는 부유폐기물, 바닥에 침적된 침적폐기물, 이렇게 세종류로 분류할 수 있으며, 이들 해양폐기물은 약 60% 이상은 육상 등 해변에서 발생되어지는 해안폐기물이며 그물류를 포함한 플라스틱이 대부분을 차지하며, 기후 및 지역의 특성에 따라 생활폐기물과 하수, 산업 및 연안의 영향을 받아서 발생하는 폐기물의 특성이 크게 변화한다. 본 연구에서는 해양폐기물을 재생에너지 (SRF) 자원으로의 활용을 위한 물리화학적 분석을 실시하였고, 연료로써 활용하기 위하여 해안폐기물의 염분의 함량 분석 및 제거 특성에 대해서 연구를 실시하였다. 해수 염분에 의한 해안폐기물의 염분 및 염소의 특성을 분석하였으며, 이에 따른 상관관계를 분석하였다. 물리적 제거특성을 통한 2차오염원을 최소로 하는 물리적 염분 제거 특성에 대한 연구를 실시하였다.
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승용디젤 엔진의 SCR(Selective Catalytic Reduction) 시스템에 있어서 질소산화물 배출 저감 인자 연구
김종학 ( Jong-Hag Kim ),김충곤 ( Choong-Gon Kim ),김대기 ( Daegi Kim ),유경선 ( Gyeong-Seon Yoo ),김임순 ( Im-Soon Kim ) 한국환경기술학회 2017 한국환경기술학회지 Vol.18 No.5
본 연구는 점차 강화되는 승용 디젤 차량에서 배출되는 NO<sub>x</sub> 규제(Euro-6)에 대응하기 위한 Urea-SCR 후처리 시스템의 NO<sub>x</sub> 저감 성능에 영향을 미치는 주요 인자에 대하여 연구를 수행하였다. 본 연구 결과 승용 디젤 차량에서 SCR 시스템의 NO<sub>x</sub> 저감 성능을 최적화하기 위해서는 Urea를 분사하는 분사 인젝터의 특성에 맞는 배기계 설치 최적화 설계와 NH<sub>3</sub> 유동 및 배압 확보에 적합한 혼합기(Mixer)의 선택이 필수적이며, 시스템 레이아웃 측면에서 Urea 분해 특성이 좋고 안정적인 시스템인 DOC+DPF+SCR 적용이 바람직하다. 또한 SCR 촉매 성능측면에서 700℃에서 25hr 열화 전후 활성이 변화가 거의 없어 모든 온도 영역에서 우수한 NO<sub>x</sub> 활성을 보이고 NH<sub>3</sub> 흡착량 변화가 적어 고온 내구성이 우수한 Cu-zeolite SCR 적용이 필요하다. This study attempts to clarify important factors affecting the NO<sub>x</sub> reduction performance of the urea-SCR after-treatment system in response to increasing regulations on NO<sub>x</sub> emissions from diesel passenger vehicles (Euro-6). The results and findings of the study indicate that the performance optimization of the SCR system in terms of NO<sub>x</sub> reduction in diesel passenger vehicles requires the optimized design and installation of the exhaust system fitting with the nature of its urea injector and the proper selection of its mixer allowing the formation of NH<sub>3</sub> flow and back pressure. When viewed from the system layout, it’s preferable to employ the DOC+DPF+SCR layout, which is characterized by good urea decomposition and high reliability. To put it in terms of the performance of SCR catalysts, it’s recommended to use Cu-zeolite SCR that exhibits excellent NO<sub>x</sub> activity in all ranges of temperature by displaying almost no activity change before and after 25 hours of deterioration at 700℃, and excellent durability against high temperature by showing little change in NH<sub>3</sub> adsorption under the same condition.
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Daegi Kim,Daeun Bae,Kwanyong Lee,Ki Young Park 한국폐기물자원순환학회 2015 한국폐기물자원순환학회 학술대회 Vol.2015 No.05
The hydrothermal carbonization is one of attractive thermo-chemical method to upgrade biomass to produce biochar with benefit method from the use of no chemical catalytic. Hydrothermal carbonization improved that the upgrading and dewatering algal biomass, microalga as Chlorella vulgaris, which is conducted at temperatures ranging from 180 to 350℃ with a reaction time of 30 min. These characteristic changes in algal biomass were similar to those of coalification reactions due to dehydration and decarboxylation with increase of hydrothermal reaction temperature. The biochar became a solid fuel substance, the characteristics of which corresponded with fuel between lignite and sub-bituminous coal. The results of this study indicate that hydrothermal treatment can be used as an effective means to generate highly energy-efficient renewable fuel resources using algal biomass.
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Kim, Daegi,Park, Seyong,Park, Ki Young Elsevier 2017 ENERGY Vol.141 No.-
<P><B>Abstract</B></P> <P>Hydrothermal carbonization is an attractive thermochemical method for upgrading organic waste and biomass. Hydrothermal carbonization's improvement of the upgrading and dewatering of fuel mixed with sewage sludge and low rank coal as peat was evaluated at temperatures ranging from 200 to 350 °C and at 60 min reaction time. The moisture content of mixed fuel (50:50 wt %) of sludge: peat was approximately 80.7%. Hydrothermal carbonization can improve sludge with a high moisture content as well as the mixed fuels increasing the latter's calorific value by reducing the hydrogen and oxygen contents of the solid products. Therefore, after the hydrothermal carbonization, the aromatic H/C and O/C ratios decreased due to of the chemical conversion. These results show that the hydrothermal carbonization process can be advantageous for improving the properties of mixed fuel to reusing and upgrading sludge and low rank coal. Upgraded fuel mixed with sewage sludge and peat is characteristically resistant to change in the carbon-functional groups, and their properties as determined via Fourier transform infrared (FTIR) spectroscopy, are discussed herein.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrothermal carbonization improved the characteristics of sludge and low rank coal as peat. </LI> <LI> The Hydrothermal carbonization enhanced also dewatering performance to reduce water content. </LI> <LI> The mixed fuel as sludge and peat improved the fuel properties to become coal-like fuel substances. </LI> <LI> The properties of peat can cover the properties of sludge to use renewable energy source. </LI> </UL> </P>
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Characteristics and Application of Hydrochar from Food Waste by Hydrothermal Carbonization
( Daegi Kim ),( Seong-kuk Han ),( Seyong Park ),( Eun-suk Jang ),( Ho Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2018 한국폐기물자원순환학회 심포지움 Vol.2018 No.1
The food waste as organic biomass has a low calorific value, high moisture, and high H/C and O/C atomic ratio which con not be suitable to use solid fuel. Hydrothemal carbonization is a promising technique to upgrade food waste closed to coal like fuel properties as increase of the calorific value. The hydrothermal carbonization is an advantage technology for food waste as wet basis biomass to biochar production. Besides, this research aims to provide a comprehensive overview for fuel property of hydrochar by hydrothermal carbonization. Different hydrothermal carbonization temperature lead to various solid yield, energy yield, and energy density of hydrochar are comprehensively discussed. In addition, the used of hydrochar from food waste to use bio-adsorbent to remove pollutants in wastewater are included. As conclusion, this is a comprehensive summary of recent hydrothermal carbonization for hydrochar as fuel and any application.
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( Daegi Kim ),( Daeun Bae ),( Kwanyong Lee ),( Ki Young Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2015 No.-
The hydrothermal carbonization is one of attractive thermo-chemical method to upgrade biomass to produce biochar with benefit method from the use of no chemical catalytic. Hydrothermal carbonization improved that the upgrading and dewatering algal biomass, microalga as Chlorella vulgaris, which is conducted at temperatures ranging from 180 to 350℃ with a reaction time of 30 min. These characteristic changes in algal biomass were similar to those of coalification reactions due to dehydration and decarboxylation with increase of hydrothermal reaction temperature. The biochar became a solid fuel substance, the characteristics of which corresponded with fuel between lignite and sub-bituminous coal. The results of this study indicate that hydrothermal treatment can be used as an effective means to generate highly energy-efficient renewable fuel resources using algal biomass.
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Daegi Kim,Kyung Jin Min,Kwanyong Lee,Min Sung Yu,Ki Young Park 대한환경공학회 2017 Environmental Engineering Research Vol.22 No.1
Struvite precipitation has been proven to be an effective method in removing and recovering ammonia nitrogen (N) and phosphate phosphorus (P) from wastewater. In this study, effects of pH, molar ratios and pre-treatment of effluent of anaerobically digested swine wastewater were investigated to improve struvite crystallization. The magnesium : ammonium : phosphate ratio of 1.2 : 1.0 : 1.0 was found to be optimal, yet the molar ratio in the wastewater was 1 : 74.9 : 1.8. From the analysis, the optimum pH was between 8.0 and 9.0 for maximal phosphate P release and from 8.0 to 10.0 for maximal ammonia N and phosphate P removal from real wastewater. Analysis from Visual MINTEQ predicted the pH range of 7-11 for ammonia N and phosphate P removal and recovery as struvite. For pre-treatment, microwave pre-treatment was ineffective for phosphate P release but ultrasound pre-treatment showed up to 77.4% phosphate P release at 1,000 kJ/L of energy dose. Precipitates analysis showed that phosphorus and magnesium in the collected precipitate had almost same values as theoretical values, but the ammonia content was less than the theoretical value.
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김대기 ( Daegi Kim ),정철진 ( Cheol-jin Jeong ),장은석 ( Eun-suk Jang ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 한국폐기물자원순환학회 추계학술발표논문집 Vol.2019 No.-
대규모 어업 활동과 경제개발로 인한 산업현장의 확대, 생활 수준의 향상에 따른 여가활동의 증가로 해상에 버려진 해양폐기물은 심각한 오염원으로 작용하고 있으며, 이러한 해양폐기물은 해양동물의 생태 및 해양 지역의 경제활동과 같은 해양 환경에 심각한 문제를 일으키고 있다. 해양폐기물은 해변에 방치된 해안폐기물, 떠다니는 부유성 폐기물, 침적된 침적성 폐기물로 분리할 수 있다. 해안폐기물의 특성은 밧줄류, 폐그물, 플라스틱병 등의 플라스틱류, 목재류, 섬유/고무류, 불연성(금속 및 유리 등), 스티로폼, 기타류로 분류하며, 플라스틱류가 높은 비율을 차지하고 있어, 높은 발열량의 특성을 갖는다. 높은 발열량의 특성을 갖지만, 해수 염분 등에 의한 피해 우려에 따라 적용은 미비한 상태이다. 본 연구에서는 해안폐기물의 성상별 염분의 농도를 파악하고, 고형연료(SRF)로 활용 가능성을 평가하였다. 해안폐기물의 성상에 따른 염소(Cl-)의 농도는 0.23-2.49%의 범위를 나타냈으며, 특히 목재의 경우가 가장 높은 2.49%를 나타냈다. 해안폐기물 구성비에 따른 고형연료를 제작하여 발열량을 측정한 결과 플라스틱류가 높은 함량을 나타내고 있어 5,500kcal/kg 이상의 발열량을 나타낸다. 우려했던 고형연료 염소의 기준 농도(0.5%) 이하로 나타났다.
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