• 한국가스학회지
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• 제18권4호
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• pp.63-67
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• 2014

Fischer-Tropsch 합성은 주로 긴 carbon 사슬을 가지고 있는 높은 점도의 왁스를 product로 생산한다. 촉매 고정층 반응기를 이용하여 Fischer-Tropsch 합성을 수행할 경우, 왁스는 촉매입자의 표면에서 생산되어 촉매입자 표면에 흡착되어 있다. 이런 왁스의 hold-up 현상이 반응기 전체의 압력강하는 증가시키고 내부 흐름을 막는 문제를 일으킨다. 따라서 반응기 내부에 왁스가 hold-up되는 현상에 대한 모델링을 통해 왁스 hold-up 현상을 최소화 할 수 있는 반응기 및 촉매 입자의 크기를 결정하는 설계 과정이 필요하다. 본 연구에서는 왁스가 hold-up된 촉매 입자와 기체 흐름 사이의 대류 물질 전달 실험 모델을 이용하여 반응기 구조 및 운전 조건을 고려할 수 있는 반응기 내부 왁스 hold-up 모델을 개발하였다. 개발된 모델은 실험 데이터를 제공한 Knochen의 연구 결과와 비교하여 모델의 우수성을 검증하였다. 이 모델을 이용하여 반응기의 길이와 단면이 반응기 내부 왁스 hold-up 현상에 어떻게 영향을 미칠 수 있는지 분석해 보았다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.312-315
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• 1993

Optimal control theories based on the maximum principles have been evolved and applied to distributed parameter systems(DPSs) represented by partial differential equations (PDEs) and integral equations (IEs). This paper intends to show that an optimal control of a tubular reactor described by a one-dimensional partial differential equation was obtained using the distributed parameter control method for parabolic PDEs. In develping an algorithm which implements the calculation, the method of lines (MOL) was adopted through using a package called the DSS/2. For the tubular reactor system chosen for this paper, the optimal control method based on PDEs with the numerical MOL showed to be more efficient than the one based on IEs.

• Journal of Advanced Marine Engineering and Technology
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• 제31권1호
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• pp.84-94
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• 2007

As a reactor coolant pump(RCP) is operated in the nuclear power system for a long time. so its surface is continuously contaminated by radioactive scales. In order to perform regular or emergency repair about RCP internals a special decontamination process should be used to reduce the radiation from the RCP surface by means of chemical cleaning. In this study, applicable possibility in chemical decontamination for RCP was investigated on the various materials. The STS 304 showed the best electrochemical properties for corrosion resistance than other materials. However, the pitting corrosion was slightly generated in both STS 415 and STS 431 with the increasing numbers of cycle and intergranular corrosion were sporadically observed. The size of their pitting corrosion and intergranular corrosion were also increased with increasing cycle numbers.

• Korean Chemical Engineering Research
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• 제56권5호
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• pp.738-751
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• 2018

The effect of the reaction temperature and reaction time on the thermal oxidative purification quality of detonation nanodiamond (NDsoot) was investigated in a gas-solid fluidized bed reactor of a $0.10m-ID{\times}1.0m$-high stainless steel column with zirconia beads ($d_{SV}=99.2{\mu}m$). The carbon conversion increased with increasing the reaction temperature; however, when the reaction temperature was greater than 773 K, the carbon conversion did not increase. The content of $sp^3$-hybridized carbon at the reaction temperature of 703 K barely changed when the reaction time was more than 30 minutes, but at 773 K, the content decreased as preferred. At 703 K, the purification quality increased with the increasing reaction time; however, at 773 K, the purification quality increased up to 30 minutes and then decreased rapidly.

• 청정기술
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• 제21권4호
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• pp.229-234
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• 2015

현재 국내에서 수소 관련 연구에 대한 관심이 매우 크나 수소원으로 사용하는 디젤 등 연료 내 존재하는 황 화합물을 제거하는 흡착 시스템 개발 관련 연구는 매우 미흡한 실정이다. 따라서 본 연구에서는 수치해석을 통해 연료전지용 디젤 흡착 탈황반응기에 대한 기초 디자인 연구를 수행하였다. 유량에 따른 반응기 내부의 유동 변화와 출구에서의 황 화합물의 농도를 반응기의 지름 및 길이를 변화시켜가며 해석하여, 출구에서의 황 화합물의 기준 농도 (1 ppm)를 맞추기 위한 탈황 촉매의 성능을 예측하였으며 반응기의 길이 증가가 지름 증가보다 효율적임을 확인하였다. 또한, 충전된 탈황 촉매의 투과율에 따른 내부 유동 및 농도 변화를 살펴보았다. 본 연구 결과는 선박 연료전지용 디젤의 흡착 탈황 반응기 디자인 기초 자료로 활용될 것으로 기대된다. 또한, 연료전지뿐 아니라 일반적으로 정유사에서 생산되는 디젤유의 황 함유량을 감소시키는 저황 시스템 디자인에 활용할 수 있으며 이러한 의미에서 석유화학 산업의 청정화 기술 확보에 이바지할 것으로 기대된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.538-543
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• 2006

A packed bed reactor (PBR) was fed with nitrate containing synthetic wastewater or effluent from a sequencing batch reactor used for nitrification. The C source introduced into the PBR consisted of volatile fatty acids (VFAs) produced from anaerobic acidogenesis of food wastes. When nitrate loading rates ranged from $0.50\;to\;1.01\;kg\;N/m^{3}{\cdot}d$, the PBR exhibited $100{\sim}98.8%\;NO_{3}^{-}-N$ removal efficiencies and nitrite concentrations in the effluent ranged from $0\;to\;0.6\;NO_{2}^{-}-N\;mg/L$. When the PBR was further investigated to determine nitrate removal activity along the bed height using a nitrate loading rate less than $1.01\;kg\;N/m^{3}{\cdot}d$, 100% nitrate removal efficiency was observed. Approximately 83.2% nitrate removal efficiency was observed in the lower 50% of the packed-bed height. When reactor performance at a C/N ratio of 4 and a C/N ratio of 5 was compared, the PBR showed better removal efficiency (96.5%) of nitrate and less nitrite concentration in the effluent at the C/N ratio of 5. VFAs were found to be a good alternative to methanol as a carbon source for denitrification of a municipal wastewater containing 40 mg-N/L.

• Journal of Microbiology and Biotechnology
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• 제17권2호
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• pp.320-324
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• 2007

The removal of hydrogen sulfide ($H_2S$) from aqueous media was investigated using Thiobacillus novellas cells immobilized on a $SiO_2$ carrier (biosand). The optimal growth conditions for the bacterial strain were $30^{\circ}C$ and initial pH of 7.0. The main product of hydrogen sulfide oxidation by T. novellus was identified as the sulfate ion. A removal efficiency of 98% was maintained in the three-phase fluidized-bed reactor, whereas the efficiency was reduced to 90% for the two-phase fluidized-bed reactor and 68% for the two-phase reactor without cells. The maximum gas removal capacity for the system was 254 g $H_2S/m^3/h$ when the inlet $H_2S$ loading was $300g/m^3/h(1,500ppm)$. Stable operation of the immobilized reactor was possible for 20 days with the inlet $H_2S$ concentration held to 1,100 ppm. The fluidized bed bioreactor appeared to be an effective means for controlling hydrogen sulfide emissions.

• Korean Chemical Engineering Research
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• 제50권6호
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• pp.952-959
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• 2012

환형 광촉매반응기 외경지지체의 반사막에 의한 광촉매반응기시스템의 광도를 제고함으로써 개선된 광촉매반응기에 의한 악취성분 및 휘발성 유기화합물을 동시 포함한 폐가스의 처리를 수행하였다. 그리고 광도 제고가 각 운전조건에서의 폐가스처리효율에 미치는 영향을 조사하였다. 광촉매 코팅된 nonporous glass bead 담체와 porous silica-based 담체를 각각 광촉매반응기에 충전하였을 때에 반사필름이 부착된 개선된 광촉매반응기 외경에서 측정한 광도는, 반사필름이 부착되지 않아서 광도가 제고되지 않은 광촉매반응기보다 각각 30.1%와 28.5% 증가하였다. Porous silica-based 담체를 충전한 개선된 광촉매반응기의 제거효율에 대한 제고효과는 약 2~3%이었다. 그러나 glass-bead 담체를 충전했을 때에 개선된 광촉매반응기의 제거효율 제고효과는 미미하였다. Porous silica-based 담체가 충전된 개선된 광촉매반응기인 최적화 광촉매반응기의 경우의 황화수소 및 톨루엔 제거효율은 nonporous glass bead가 충전되고 반사막이 없는 광촉매반응기 경우의 제거효율인 각각 19%와 53%보다 각각 약 26%와 약 60%의 증가율을 보였다. 반사막 필름표면의 roughness가 종래의 상업용 거울의 roughness보다 4배 정도 컸으나, 향후 개선된 광촉매반응기의 반사막의 roughness를 개선할 경우에 광도 개선효과가 더욱 커져서 이에 따른 악취 및 VOC를 함유한 광촉매 처리효율이 더욱 제고되리라 예상된다.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.62-74
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• 2002

The tracking of a reference temperature trajectory in a polymerization batch reactor is a common problem and has critical importance because the quality control of a batch reactor is usually achieved by implementing the trajectory precisely. In this study, only energy balances around a reactor are considered as a design model for control synthesis, and material balances describing concentration variations of involved components are treated as unknown disturbances, of which the effects appear as time-varying parameters in the design model. For the synthesis of a tracking controller, a method combining the input-output linearization of a time-variant system with the parameter estimation is proposed. The parameter estimation method provides parameter estimates such that the estimated outputs asymptotically follow the measured outputs in a specified way. Since other unknown external disturbances or uncertainties can be lumped into existing parameters or considered as another separate parameters, the method is useful in practices exposed to diverse uncertainties and disturbances, and the designed controller becomes robust. And the design procedure and setting of tuning parameters are simple and clear due to the resulted linear design equations. The performances and the effectiveness of the proposed method are demonstrated via simulation studies.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.227-234
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• 2004

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion(CLC) may yield great advantages of savings of energy to $CO_2$ separation and suppressing the effect on environment. In chemical-looping combustor, fuel is oxidized by metal oxide medium (oxygen carrier particle) in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. The purpose of this study is to demonstrate inherent $CO_2$ separation and no NOx emission and to confirm high $CO_2$ selectivity, no side reaction (i.e., carbon deposition, hydrogen generation) by continuous reduction and oxidation experiment in a 50kWtb chemical-looping combustor. NiO/bentonite particle was used as a bed material and $CH_4$ and air were used as reacting gases for reduction and oxidation respectively.