• 한국환경보건학회지
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• 제32권2호
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• pp.179-185
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• 2006

Effect of organic loading rate on UASB performance was evaluated under the renditions of some surface area/reactor volume ratio and different reactor diameter. At the low leading rate of 0.4 kg $COD/m^3{\cdot}d$, reactor performance was not affected by reactor diameter. At the organic loading rate of 6 kg $COD/m^3{\cdot}d$, however, volatile acid accumulation and low COD removal efficiency is observed in reactor having 6.4 cm diameter, while volatile acid is not accumulated at all and high COD removal efficiency is observed in reactor having 3 cm diameter. Such a difference of reactor performance depending on reactor diameter can be explained that sludge bed can be fluidized by evolved gas bubble in narrow reactor, while sludge bed ran not be fluidized by evolved gas bubble only in wide reactor. At a high organic loading rate of 20 kg $COD/m^3{\cdot}d$, it can be judged that there is no relation between reactor configuration and reactor performance because all reactors showed very low COD removal efficiencies regardless of reactor diameter. Narrow and tall type reactor is favorable condition for making sludge bed fluidization at a constant surface area/reactor volume ratio. Thus, it can be judged that reactor configuration and sludge bed fluidization have great influence to reactor performance.

• 에너지공학
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• 제12권4호
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• pp.289-301
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• 2003

매체순환식 가스연소기의 개발을 위해 산화반응기와 환원반응기가 연계된 2탑 가압순환유동층 조건의 50kWth 매체순환식 가스연소기에 대해 물질수지와 에너지수지를 통한 개념설계를 수행하였다. 매체순환식 가스연소기의 물질수지를 통해 산화반응기는 상승관 형태의 고속유동층 조건으로, 환원반응기는 기포유동층 조건으로 반응기 형태를 결정하였다. 물질수지와 에너지수지에 의해 계산된 층내 고체량, 고체순환량 및 반응기 크기는 장치제작 및 실제조업에 적당한 범위의 값을 나타내었으며 산소공여입자의 반응속도는 만족할 만한 수준에 도달하는 것으로 확인되었다. 본 연구의 개념설계 결과에 의하면 매체순환식 가스연소기의 조업조건은 상용 순환유동층의 조업조건과 유사하였으며 실제공정에 적용하기에 무리가 없는 것으로 사료되었다. 본 연구에서 개발된 설계 tool을 이용하여 시스템의 용량, 조업압력, 산소공여입자 중의금속산화물의 함량, 수증기 주입량, 기체유속 및 고체층 높이 등의 변화에 따른 설계 값의 변화를 해석하였으며 이를 통해 조업조건 변화에 따른 시스템의 성능변화를 예측할 수 있었다.

• 한국재료학회지
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• 제27권2호
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• pp.63-68
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• 2017

A black nickel oxide powder, one of the commercial nickel oxide ores, was reduced by hydrogen gas in a batch-type fluidized-bed reactor in a temperature range of 350 to $500^{\circ}C$ and in a residence time range of 5 to 120 min. The hydrogen reduction behavior of the black nickel oxide was found to be somewhat different from that of green nickel oxide ore. For the black nickel oxide, the maximum temperature (below which nickel oxide particles can be reduced without any agglomeration) was significantly lower than that observed for the green nickel oxide. In addition, the best curve fittings of the Avrami model were obtained at higher values of the overall rate constant "k" and at lower values of the exponent "m", compared to those values for the green nickel oxide. It may be inferred from these results that the hydrogen reduction rate of the black nickel oxide is faster than that of the green nickel oxide in the early stages, but the situation reverses in the later stages. For the black nickel oxide ore, in spite of the low temperature sintering, it was possible to achieve a high degree fluidized-bed reduction at lower temperatures and at lower gas consumption rates than was possible for the green nickel oxide. In this regard, the use of black nickel oxide is expected to yield a benefit if its ore price is sufficiently lower than that of the green nickel oxide.

• 한국구조물진단유지관리공학회 논문집
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• 제22권5호
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• pp.119-126
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• 2018

최근 화력발전소에서는 순환유동층 연소방식의 발전소가 증가하는 추세이다. 순환유동층 보일러애시는 탈황 효과를 위해 석회석을 첨가함에 따라 애시 중에 포함되는 CaO, $SO_3$성분이 증가하여 일반적인 플라이애시 보다 free-CaO 함량이 높다. 또한 순환유동층 보일러애시는 기존의 플라이애시와 다르게 자기수경성 특성과, 높은 free-CaO함량에 의해 물과 만나면 높은 반응성을 갖는다. 본 연구는 순환유동층 보일러애시의 자기수경성 특성을 이용하여, 시멘트를 대체할 수 있는 비소성 결합재로써 활용 가능성에 대해 분석하였다. 순환유동층 보일러 애시의 함량에 따른 역학적 및 수화특성에 대해 검토하였다. 또한 석고의 종류 및 함유량에 따른 순환유동층 보일러애시 활용 비소성 결합재에 대한 압축강도 및 미세구조에 미치는 영향을 분석하였다.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.884-894
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• 2011

Effects of temperature, volatile content, particle diameter and solid input weight were investigated in the batch fluidized bed reactor using OCN703-1100 particle as oxygen carrier and Roto coal and char as fuels. Two solid fuels represented the best reactivity at different temperature, $900^{\circ}C$ for Roto coal and $950^{\circ}C$ for char, respectively. However, we selected $900^{\circ}C$ as the best operating temperature because the improvement of reactivity of char at $950^{\circ}C$ was negligible. Char represented better reactivity than Roto coal because char contains low volatile than Roto coal. For both solid fuels, reactivities were improved with increasing of the particle diameter. These results were explained by solid mixing tests in a transparent fluidized bed using two char particles having different particle size ranges and OCN703-1100 particle. The bigger particle showed better solid mixing with OCN703-1100 particle, and therefore, represented better reactivity. For both solid fuels, reactivities were improved with increasing of the solid input weight within the experimental conditions of this study because the weight of coarse particles increased with the solid input weight increased, and therefore, these coarse particles can mix well with the oxygen carrier.

• 한국재료학회지
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• 제26권2호
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• pp.79-83
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• 2016

A commercial NiO (green nickel oxide, 86 wt% Ni) powder was reduced using a batch-type fluidized-bed reactor in a temperature range of 500 to $600^{\circ}C$ and in a residence time range of 5 to 90 min. The reduction rate increased with increases in temperature; however, agglomeration and sintering (sticking) of Ni particles noticeably took place at high temperatures above $600^{\circ}C$. An increasing tendency toward sticking was also observed at long residence times. In order to reduce the oxygen content in the powder to a level below 1% without any sticking problems, which can lead to defluidization, proper temperature and residence time for a stable fluidized-bed operation should be established. In this study, these values were found to be $550^{\circ}C$ and 60 min, respectively. Another important condition is the specific gas consumption rate, i.e. the volume amount ($Nm^3$) of hydrogen gas used to reduce 1 ton of Green NiO ore. The optimum gas consumption rate was found to be $5,000Nm^3/ton$-NiO for the complete reduction. The Avrami model was applied to this study; experimental data are most closely fitted with an exponent (m) of $0.6{\pm}0.01$ and with an overall rate constant (k) in the range of 0.35~0.45, depending on the temperature.

• Journal of the Korean Wood Science and Technology
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• 제34권6호
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• pp.36-43
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• 2006

유동형 급속열분해기 (fluidized bed type fast pyrolyzer, 용량 400 g/h)를 이용하여 너도밤나무와 침엽수 혼합재(독일가문비나무/전나무, 50:50) 에서 바이오오일을 생산하였다. 목질바이오매스의 열분해는 약 $470{\pm}5^{\circ}C$에서 1~2초 동안 진행되었다. 목질바이오매스의 열분해 생성물의 조성은 너도밤나무의 경우 바이오오일 60%, 탄 9% 그리고 가스가 31% 정도 생산되었으며, 침엽수 혼합재는 바이오일 49%, 탄 9%, 그리고 42% 가량의 가스가 생성되었다. 두 종류의 목질바이오매스에서 생산된 바이오오일의 수분함량은 약 17~22%이었으며, 밀도는 수종에 관계없이 $1.2kg/{\ell}$이었다. 바이오오일의 원소 조성은 탄소 45%, 산소 47%, 수소 7%, 그리고 질소 1%로 일반적인 목질바이오매스와 큰 차이는 없는 것으로 나타났다. 그러나 화석자원에서 생산되는 오일류와 비교하여 바이오일은 산소함량이 매우 높았고 황은 전혀 포함되어 있지 않았다. 바이오오일의 GC 분석 결과 총 90여종의 방향족(aromatic) 또는 비방향족(non-aromatic) 저분자량 화합물이 검출되었으며 이들의 함량은 바이오오일 전건중량의 31~33%로 분석되었다.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.209-217
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• 2014

To enhance the performance of SEWGS system by holding the WGS catalyst in a SEWGS reactor, a spring type bed insert was developed. In this study, effects of operating variables such as steam/CO ratio, gas velocity, syngas concentration on CO conversion were investigated in a fluidized bed reactor using the spring type bed insert to hold the WGS catalyst as tablet shape. CO conversion increased initially as the steam/CO ratio increased. But further increment of the steam/CO ratio caused decreasing of CO conversion because of increment of gas velocity and decrement of syngas concentration. Moreover, CO conversion decreased as the gas velocity increased and the syngas concentration decreased at the same steam/CO ratio. Continuous operation up to 48 hours (2 days) was carried out to check reactivity decay of WGS catalyst supported by spring type bed insert. The average CO conversion was 99.04% and we could conclude that the WGS reactivity at those conditions was maintained up to 48 hours.

• 한국환경과학회지
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• 제8권4호
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• pp.525-532
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• 1999

This study was conducted to evaluate capability of dyeing wastewater treatment for 3 type reactors. These reactors were Packed Bed Reactor(PBR), Fluidized Bed reactor(FBR) and Moving Media Complete Mixing Activated Sludge reactor(MMCMAS). Experiments of PBR and FBR were performed by various packing ratios and organic loading rates, experiments of MMCMAS were performed by various organic loading rates. In order to obtain ${SBOD}_5$ removal efficiencies of more than 90%, the F/Mv ratios of PBR, FBR, MMCMAS were 0.11 kgBOD/kgMLVSS$\cdot$d, 0.12 kgBOD/kgMLVSS$\cdot$d, and 0.37 kgBOD/kgMLSS$\cdot$d, respectively. So MMCMAS system which has more active microorganisms showed better capability of organic removal and also stronger dynamic and shock loadings than those of PBR and FBR. In PBR and FBR, the media packing ratio of 20% showed better performance of organic matters removal effciencies than 10% and 30%, but sludge production rate at media packing ratio of 30% was relatively lower than that of 10% and 20%. When more than 90% organic matters removal efficiency was obtained, the ratios of attached biomass to total biomass at PBR, FBR, MMCMAS were 89~99%, 87~98%, and 54~80%, respectively. The ratio of attached biomass to total biomass was low in MMCMAS. This was formation of thin biofilm due to shear force between rotaing disc and water. The average sludge production rates(kgVSS/kgBODrem.) of PBR, FBR and MMCMAS were 0.20, 0.29 and 0.54, respectively.

• 한국식품과학회지
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• 제25권3호
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• pp.210-213
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• 1993

본 실험의 목적은 공극률과 상향유속의 관계에서 세입자의 유동특성을 고찰하는 데 있다 Column 내경은 유동층의 유속과 공극률과의 관계에 큰 영향을 미치지 못했으며 유속과 공극률과의 관계는 다음과 같다. $\frac{u}{u_t}={\varepsilon}^{3.703}$----모래$\frac{u}{u_t}={\varepsilon}^{3.5665}$----이온 교환수지$\frac{u}{u_t}={\varepsilon}^{4.066}$---GAC 또 유동층 매질입자는 구형을 사용하는 것이 일정유속에서 공극률을 낮게 유지할 수 있어 좋았고 실제로 미생물막 유동층 반응기에서는 미생물막이 매질에 부착되면 비중이 감소하므로 매질의 비중이 높을수록 유동층을 유지하기가 쉽다.