• 한국안전학회지
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• 제27권5호
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• pp.77-87
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• 2012

Compared to a batch reactor, where all reactants are initially charged to the reactor, the semi-batch reactor presents serious advantages. The feed of at least one of the reactants provides an additional way of controlling the reaction course, which represents a safety factor and increases the constancy of the product quality. The aim of this study was to investigate the characteristics of thermal hazard such as a feed time, catalysis concentration and solvent concentration in methylthioisocyanate(MTI) synthesis reaction process. The experiments were carried out by the Multimax reactor system and Accelerating rate calorimeter(ARC). The MTI synthesis reaction process has many reaction factors and complicated reaction mechanism of multiphase reaction. Through this study, we can use as a tool for assessment of thermal hazard of other reaction processes by applying experiment method provided.

• Journal of Microbiology and Biotechnology
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• 제13권3호
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• pp.378-384
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• 2003

Mesophilically-grown granular sludge seeded in thermophilic UASB reactor was monitored to better understand the start-up process of the reactor. The reactor was fed with a synthetic wastewater containing glucose. As COD loading rate increased stepwise, methane production rate increased. Maximum values of COD removal efficiency (95%) and methane production rate (5.3 l/day) were achieved by approximately day-80 and remained constant afterward. However, physicochemical and microbial properties of granules kept changing even after day-80. Specific methanogenic activity (SMA) was initially negligible, and increased continuously until day-153 and remained constant afterward, showing the maximum value of $1.51{\pm}0.13\;g\;CH_4-COD/g$ VSS/day. Deteriorated settling ability of granules recovered the initial value by day-98 and was maintained afterward, as determined by sludge volume index. Initially reduced granule size increased until day-126, reaching a plateau of 1.1 mm. Combined use of fluorescence in situ hybridization and confocal laser scanning microscopy (CLSM) allowed to localize families of Methanosaetaceae and Merhanosarcinaceae in granules with time Quantitative analyses of CLSM images of granule sections showed abundance patterns of the methanogens and numerical dominance of Methanosaeta spp. throughout the start-up period. The trend of SMA agreed well with abundance patterns of the methanogens.

• Journal of Biosystems Engineering
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• 제43권1호
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• pp.14-20
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• 2018

Purpose: The purpose of this study was to investigate the performance of a vacuum pyrolysis system, to analyze bio-oil characteristics, and to examine the applicability for farm-scale capacity. Methods: The biomass was pyrolyzed at 450, 480, and $490^{\circ}C$ on an electric heat plate in a vacuum reactor. The waste heat from the heat exchanger of the reactor was recycled to evaporate water from the bio-oil. The chemical composition of the bio-oil was analyzed by gas chromatography-mass spectrometry (GC-MS). Results: According to the analysis, the moisture content (MC) in the bio-oil was approximately 9%, the high heating value (HHV) was approximately 26 MJ/kg, and 29 compounds were identified. These 29 compounds consisted of six series of carbohydrates, 17 series of lignins, and six series of resins. Conclusions: Owing to low water content and the oxygen content, the HHV of the bio-oil produced from the vacuum reactor was higher by about 6 MJ/kg than that of the bio-oil produced from a fluidized bed reactor.

• 상하수도학회지
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• 제30권6호
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• pp.745-753
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• 2016

The objective of this study was to investigate design factors of the electrolysis reactor through the CFD(computational fluid dynamics) simulation technique. Analyses of velocity vector, streamline, chloride ion concentration distribution showed differences in flow characteristics between the plate type electrode and the porous plate type electrode. In case of the porous plate type electrode, chlorine gas bubbles generated from the anode made upward density flow with relatively constant velocity vectors. Electrolysis effect was more expected with the porous plate type electrode from the distribution of chloride ion concentration. The upper part of the electrolysis reactor with the porous plate type electrode had comparatively low chloride concentration because chloride was converted to the chlorine gas formation. Decreasing the size and increasing total area of rectifying holes in the upper part of cathodes, and widening the area of the rectifying holes in the lower part of cathodes could improve the circulation flow and the efficiency of electrolysis reactor.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.546-555
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• 2019

Since the first nuclear reactor first critical, nuclear systems has gone through four generations of history, and the fourth generation nuclear system will be truly realized in the near future. The notions of SVBR and lead-bismuth eutectic alloy coolant put forward by Russia were well received by the international nuclear science community. Lead-bismuth eutectic alloy with the ability of the better neutron economy, the low melting point, the high boiling point, the chemical inertness to water and air and other features, which was considered the most promising coolant for the 4th generation nuclear reactors. This study mainly focuses on the structural design optimization of the 4th-generation reactor coolant pump, including analysis of external characteristics, inner flow, and transient characteristic. It was found that: the reactor coolant pump with a central symmetrical dual-outlet volute structure has better radial-direction balance, the pump without guide vane has better hydraulic performance, and the pump with guide vanes has worse torsional vibration and pressure pulsation. This study serves as experience accumulation and technical support for the development of the 4th generation nuclear energy system.

• 대한기계학회논문집 C: 기술과 교육
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• 제3권4호
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• pp.299-305
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• 2015

미래에너지의 해법으로 원자력에너지를 이용한 물분해 수소생산시스템의 핵심기술을 개발하였다. 안전성을 보장할 수 있는 제4세대 원자로인 초고온가스로의 고열을 이용하여 황요오드 열화학적인 방법으로 물을 분해하여 수소를 생산하는 기술이다. 원자력수소생산 핵심기술은 초고온에서의 열을 공급하는 것을 모사하는 초고온 실험기술, 초고온가스로의 안전성을 모사하는 연구, 초고온가스로의 노심과 안전성을 해석할 수 있는 도구의 개발, 초고온가스로에 사용하는 연료제조기술, 물을 분해하여 열화학적인 방법으로 수소를 생산하는 기술로 구성된다. 원자력수소생산에 필요한 핵심기술을 개발하고 실험실 규모로 입증하였으며, 대규모 실용화를 위해서 선결되어할 미완성 기술을 제시하였다. 본 기술은 제4세대 원자로개발 국제공동연구로 수행한 기술로서 향후 미래의 원자로 기술이다.

• 한국물환경학회지
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• 제20권4호
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• pp.339-345
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• 2004

The characteristics of $H_2$ production from livestock wastewater were investigated through an anaerobic acid forming process using Clostridium beijerinckii and the photosynthetic process using Rhodobacter sphaeroides. The submerged separation membrane was installed in the acid forming reactor, The photosynthetic process is composed of two reactors(photosynthetic reactor 1 and photosynthetic reactor 2) which is connected continually. The removal rate of COD and the production of volatile fatty acid(VFA) in the acid forming process were approximately 50% and 1000mg/L, respectively. The 70% of COD in the effluent of acid forming process was removed through the photosynthetic process. The production of $H_2$ in the photosynthetic reactor 1 and 2 was 50 and $25mLH_2/gVFA_{COD}$, respectively. The values of Y in acid forming reactor, photosynthetic reactor 1 and 2 was 0.2263, 0.0601 and 0.0393, respectively. The acetic acid and butyric acid produced in acid forming process were converted to $H_2$ by photosynthetic bacteria.

• 상하수도학회지
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• 제27권1호
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• pp.21-29
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• 2013

Present study was conducted to evaluate the performance of Anaerobic Hybrid Reactor (AHR) combined with two types of anaerobic attached growth reactors at mesophilic temperature ($37^{\circ}C$). The reactor was operated at the influent substrate condition of 19,400 mg/L soluble chemical oxygen demand (sCOD). The organic loading rate (OLR) and flow rate were varied in the range of $9.5{\sim}22.5kg/m^3$. day and 10.6 ~ 26.0 L/day respectively since start-up was done. The COD removal efficiency of 93 % was measured at the OLR of $14kg/m^3$. day in AHR. However a reduction in removal efficiency to as low as 85 % could have been related to a combined effect of high concentration suspended solids (SS) concentration over 3,800 mg/L. On the other hand the total COD removal efficiencies were measured to be 96.3 % and 96.2 % for AHR+APF and AHR+ADF respectively. The pH of the POME was adjusted to neutral range by using sodium bicarbonate at the initial stages of the reactor feed, later stages pH adjustment was not required as the pH was maintained in the desired neutral range due to self-buffering capacity of the reactor. The reactor proved to be economically acceptable and operationally stable. The biogas was measured to have $CH_4$ and $CO_2$ with a ratio of 35:65, and methane gas production rate was estimated to be $0.17{\sim}10.269L\;CH_4/g\;COD_{removed}$.

• 대한화학회지
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• 제50권1호
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• pp.14-22
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• 2006

방전을 이용한 화학반응기의 기본 모델은 관통형 속 빈 음극 방전셀을 응용하였다. 최근 글로우 방전은 원자분광학에 있어서 방출원으로서의 역할과 더불어 원자화 장치로서 점차적으로 그 연구의 범위를 넓혀가고 있으며, 미량분석, 철강분석, 표면 분석 등에 널리 사용되고 있으며 타 분석 기기와의 접목 등을 통하여 상당한 기술적 성과가 이루어지고 있다.1 또한 본 연구 이전에 기초적인 글로우방전의 성질과 방출 특성에 대해서도 여러 차례 재검토된 바 있어 본 실험에 활용할 수 있었다.2-3 지난 1993년에는 저온의 플라즈마를 이용하여 대기중의 유독가스의 처리에 대한 연구가 발표되었으며, 이 논문에 의하면 연속적인 공기의 흐름 하에서 직류 글로우 방전을 이용하면 유해성 가스인 SO2와 NO의 제거가 가능하다고 보고되었다.4 이를 바탕으로 본 연구에서는 안정적인 공기 플라즈마의 형성과 관통형 양, 음극관 안으로 모든 흐름공기가 음 글로우(Negative glow)영역을 통과하도록 고효율 반응기를 설계하였다. 현재 본 연구에서 디자인한 속 빈 음극관 형 글로우 방전은 경제성이 우수하며 사용하기 쉽다는 것 외에도 방출원 으로서의 장점도 제공함을 관찰하였다.

• Korean Chemical Engineering Research
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• 제51권2호
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• pp.272-278
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• 2013

퇴비공장 또는 공공시설에서 발생되는 악취폐가스의 대표적인 제거대상 오염원인 암모니아를 포함한 악취폐가스를 처리하기 위하여 여러 운전 조건 하에서의 광촉매반응기와 바이오필터로 구성된 하이브리드시스템을 운전하였다. 암모니아 총 제거효율은 하이브리드시스템의 운전부하가 운전 단계별로 커졌음에도 불구하고 약 80%로 유지되었다. 광촉매반응기에서의 암모니아 제거효율은 광촉매반응기로의 암모니아 유입부하량이 증가함에 따라서 광촉매반응기의 암모니아 제거효율은 65%에서 약 22%로 감소하였다. 같은 암모니아 유입부하량일지라도 암모니아농도가 클 때보다 적은 경우에 광촉매반응기의 암모니아 제거효율이 상대적으로 높았다. 반면에 바이오필터의 경우는 운전 전반부에는 암모니아 처리효율이 현저하게 억제되었으나 광촉매반응기의 경우와 반대로 시간이 경과하면서 암모니아 유입부하량이 증가함에도 불구하고 바이오필터의 암모니아 제거효율은 지속적으로 약 78%까지 증가하여서 Lee 등의 연구결과에서의 암모니아 제거효율과 비슷하게 도달하였다. 광촉매반응기에 의한 최대 암모니아 제거용량($EC_{PR}$)은 약 16 g-N/$m^3$/h 이었고, 바이오필터에 의한 암모니아 제거용량($EC_{BF}$)은 운전 초기에 암모니아 총 부하가 작은 경우에는 암모니아 총 부하증가에 따른 $EC_{BF}$의 증가추세가 미약하였으나 운전 후반부에 암모니아 총 부하가 큰 경우에는 암모니아 총 부하증가에 따른 $EC_{BF}$의 증가추세가 급격하게 커졌다. 하이브리드시스템 운전 6단계에서 암모니아 총 부하가 약 80 g-N/$m^3$/h일 때에 광촉매반응기에서의 $EC_{PR}$은 약 16 g-N/$m^3$/h이었고, 2차 공정이고 주공정인 바이오필터에 걸리는 암모니아 부하는 나머지인 약 64 g-N/$m^3$/h이고 주공정인 바이오필터의 $EC_{BF}$은 약 48 g-N/$m^3$/h로 산출되었다. 이러한 바이오필터의 암모니아 제거용량은 Kim 등의 연구결과로서 최대 암모니아 제거용량인 1,200 g-N/$m^3$/day와 거의 비슷하였다.