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분리기술 , 열역학 : 호기성 삼상 역 유동층의 물질전달 특성
송평섭(Pyung Seob Song),강용(Yong Kang),김상돈(Sang Done Kim),김상우(Sang Woo Kim),김현태(Hyun Tae Kim) 한국화학공학회 2002 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.40 No.4
Gas holdup, axial dispersion coefficient of liquid phase and gas-liquid mass transfer characteristics have been investigated in a aerobic three-phase inverse fluidized bed whose diameter and height are 0.152m and 2.5m, respectively. Effects of gas and liquid velocities and particle density(particle kind) on the gas holdup, axial dispersion coefficient of liquid phase and volumetric gas-liquid mass transfer coefficient have been determined. Tap water, filtered compressed air and low density polypropylene particle(p_s=877.3㎏/㎥, d_p=0.004m) or polyethylene particle(p_s=966.6㎏/㎥, d_p=0.004m) have been used as a liquid, gas and fluidized solid phase, respectively. The gas holdup has been obtained from the pressure drop profiles by means of static pressure drop method, and the axial dispersion coefficient of liquid phase and volumetric gas-liquid mass transfer coefficient have been determined by means of axial dispersion model from the knowledge of axial profile of dissolved oxygen concentration. It has been found that the gas holdup, axial dispersion coefficient and volumetric gas-liquid mass transfer coefficient have increased with increasing gas and liquid velocities, but the effects of gas velocity have been dominant in aerobic three phase inverse fluidized beds. In the beds of polyethylene particle(relatively heavier particle) the values of ε_G, Dz and k_L a have exhibited higher than those in the beds of polypropylene particles(relatively lighter particle). The values of gas holdup, axial dispersion coefficient and gas-liquid mass transfer coefficient have been well correlated in terms of gas and liquid velocities and particle density.
송평섭,최왕규,민병연,김학이,정종헌,오원진,Song Pyung-Seob,Choi Wang-Kyu,Min Byung-Youn,Kim Hak-I,Jung Chong-Hun,Oh Won-Zin 한국방사성폐기물학회 2005 방사성폐기물학회지 Vol.3 No.2
Effects of the aluminum melting temperature, melting time and a kind of flux agents on the distribution of surrogate nuclide were investigated in the electric furnace at the aluminum melting including surrogate radionuclides(Co, Cs, Sr) in order to establish the fundamental research of the melting technology for the metallic wastes from the decommissioning of the TRIGA research reactor. It was verified that the fluidity of aluminum melt was increased by adding flux agent but it was slightly varied according to the sort of flux agents. The results of the XRD analysis showed that the surrogate nuclides move into the slag phase and then they were combined with aluminum oxide to form more stable compound. The weight of the slag generated from aluminum melting test increased with increasing melting temperature and melting time and the increase rate of the slag depended on the kind of flux agents added in the aluminum waste. The concentration of the cobalt in the ingot phase decreased with increasing reaction temperature but it increased in the slag phase up to 90$\%$according to the experimental conditions. The volatile nuclides such as Cs and Sr considerably transferred from the ingot phase to the slag and dust phase.
민병연,송평섭,안준형,최왕규,정종헌,오원진,강용,Min, Byung-Youn,Song, Pyung-Seob,Ahn, Jun-Hyung,Choi, Wang-Kyu,Jung, Chong-Hun,Oh, Won-Zin,Kang, Yong 한국방사성폐기물학회 2006 방사성폐기물학회지 Vol.4 No.1
The characteristics of the aluminum waste melting and the distribution of the radioactive nuclides have been investigated for the estimation on the volume reduction and the decontamination of the aluminum wastes from the decommissioning of the TRIGA MARK it and III research reactors at the Korea Atomic Energy Research Institute(KAERI). The aluminum wastes were melted with the use of the fluxes such as flux $A:NaCl-KCl-Na_3AlF_6$, flux B:NaCl-NaF-KF, flux $C:CaF_2$, and flux $D:LiF-KCl-BaCl_2$ in the DC graphite arc furnace. For the assessment of the distribution of the radioactive nuclides during the melting of the aluminum, the aluminum materials were contaminated by the surrogate nuclides such as cobalt(Co), cesium(Cs) and strontium(Sr). The fluidity of aluminum melt was increased with the addition of the fluxes, which has slight difference according to the type of fluxes. The formation of the slag during the aluminum melting added the flux type C and D was larger than that with the flux A and B. The rate of the slag formation linearly increased with increasing the flux concentration. The results of the XRD analysis showed that the surrogate nuclide was transferred to the slag, which can be easily separated from the melt and then they combined with aluminum oxide to form a more stable compound. The distribution ratio of cobalt in ingot to that in slag was more than 40% at all types of fluxes. Since vapor pressures of cesium and strontium were higher than those that of the host metals at the melting temperature, their removal efficiency from the ingot phase to the slag and the dust phase was by up to 98%.
순환유동층에서 기체-고체 흐름 거동의 Stochastic 해석
강용(Yong Kang),송평섭(Pyung Seob Song),우광재(Kwang Jae Woo),정의영(Yi Yeong Jeong),김상돈(Sang Done Kim) 한국화학공학회 1997 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.35 No.6
Pressure fluctuations in the riser of a circulating fluidized bed have been analyzed by means of stochastic analysis such as fractal analysis and phase space portrait, to analyze the characteristics of gas-solid contact and flow behavior in the riser. Polyethylene whose mean diameter is 0.454 ㎜ and density is 920 ㎏/㎥ has been used as a solid. The diameter and height of the riser are 0.102 m and 3.5 m, respectively. Effects of superficial gas velocity and solid circulation rate on the hydrodynamic characteristics such as solid interstitial velocity, slip velocity between gas and solid, and solid holdup have been determined. Effects of operating variables on the Hurst exponent and phase space portrait have been also examined. The values of the Hurst exponent have been recovered from the Pox diagram obtained by the rescaled range analysis of the data. The phase space portraits have been obtained by means of the rearrangement of the data by the multidimensional phase space portrait method. As a result of this study, the concept of choking velocity is very similar to that of transportation velocity in the riser. The Hurst exponent has exhibited its maximum value and the phase space portrait has focused its tracing within the limited boundary at the transition regime of gas-solid flow.
생물화공 , 에너지 / 환경 : 삼상 순환 유동층 생물반응기에서 열전달 계수
강태규(Tae Gyu Kang),송평섭(Pyung Seob Song),최길수(Gill Soo Choi),조용준(Yong Jun Cho),강용(Yong Kang),최호석(Ho Suk Choi),김상돈(Sang Done Kim) 한국화학공학회 2002 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.40 No.5
Heat transfer characteristics have been investigated in the riser of gas-liquid circulation and three-phase circulating fluidized-bed bioreactors whose diameter and height are 0.102m and 1.0m, respectively. Effects of gas and liquid velocities and holdup of fluidized biofilm media on the heat transfer coefficient between the immersed vertical heater and the bed have been determined. The heat transfer coefficient in the gas-liquid circulation reactor increases with increasing gas velocity, but increases only slightly with increasing liquid velocity. The h(heat transfer coefficient) value in the three-phase circulating fluidized-bed bioreactor also increases with increasing gas velocity or holdup of fluidized biofilm media, but it increases only slightly with liquid velocity. The value of heat transfer coefficient has been well correlated in terms of operating variables.
김현태 ( Hyun Tae Kim ),송평섭 ( Pyung Seob Song ),최길수 ( Gill Soo Choi ),김상우 ( Sang Woo Kim ),조용준 ( Yong Jun Cho ),강용 ( Yong Kang ) 한국공업화학회 2002 공업화학 Vol.13 No.7
직경이 0.152 m이고 높이가 2.5m인 삼상 역 유동층에서 전기저항 탐침법을 이용하여 기포특성인 기포수직길이와 상승속도 그리고 빈도수에 대해 고찰하였다. 기체와 액체 유속 그리고 유동입자의 종류가 기포크기, 기포상승속도 및 빈도수에 미치는 영향을 결정하였다. 물과 여과된 압축공기를 각각 액체와 기체상으로 사용하였으며, 유동 고체상으로는 밀도가 각각 877.3 kg/㎥, 966.6 kg/㎥인 직경이 0.004 m인 구형의 폴리프로필렌 입자와 폴리에틸렌 입자를 사용하였다. 삼상 역 유동층에서 기포의 크기와 빈도수는 기체유속과 액체유속이 증가함에 따라 증가하는 경향을 나타내었으며, 기포의 상승속도는 기체유속이 증가함에 따라 증가하나 액체유속의 증가에 따라서는 감소하는 경향을 나타내었다. 기포의 크기와 상승속도는 같은 유동조건에서 고체밀도가 작은 폴리프로필렌 입자의 경우가 폴리에틸렌을 입자로 사용할 경우에 비해 큰 값을 나타내었으며, 유동입자의 밀도가 큰 경우에 기포의 빈도수는 큰 값을 나타내었다. 삼상 역 유동층에서 기포의 수직길이, 상승속도 그리고 빈도수는 본 연구의 실험 범위에서 무차원군의 상관식으로 각각 나타낼 수 있었다. Bubble characteristics such as size, rising velocity and frequenc have been investigated in a three-phase inverse fluidized bed (0.152 m ID and 2.5 m in height) by employing electric resistivity probe method. Effects of gas and liquid velocities as well as types of particles on the size, the rising velocity and the frequency of bubbles have been determined. Water and filtered compressed air have been used as the liquid and the gas pahses, respectively. 4 mm polypropylene (PP) and polyethylene (PE) particles, with densities of 877.3 kg/㎥ and 966.6 kg/㎥, respectively, have been used as the fluidized particles. It has been found that the size and the frequency of bubbles increased with increasing the gas and liquid velocities, while the bubble rising velocity increased with increasing the gas velocity but decreased with increasing the liquid velocity in the three-phase inverse fluidized bed. The bubble size and rising velocity exhibited higher values in the bed of polypropylene particles than in the bed of polyethylene. But, the frequency of bubbles showed a higher value in the bed of polyethlene than in the bed of polypropylene. Using dimensionless groups, the size, the rising velocity and the frequency of bubbles were correlated well within the experimental conditions.
아크 용융로에서 Stainless steel의 용융 시 방사성 핵종의 분배특성에 대한 연구
민병연(Byung Youn Min),송평섭(Pyung Seob Song),안준형(Jun Hyung Ahn),최왕규(Wang Kyu Choi),정종헌(Chong Hun Jung),오원진(Won Zin Oh) 대한환경공학회 2005 대한환경공학회 학술발표논문집 Vol.2005 No.12
연구용 원자로(TRIGA) 및 우라늄 변환시설을 포함한 원자력 시설의 해체 시 발생되는 방사성 금속 폐기물의 효과적인 처리기술 개발을 위해 아크로에서 SUS 304에 Surrogate nuclides(Co, Cs, Ce, Sr) 500ppm을 오염시켜 다양한 슬래그를 사용하여 실험실 규모의 용융실험을 수행하였다. 용융 시료들의 결정상 구조를 규명하기 위해 X선 회절분석기(XRD)를 이용하였으며, 고화체 표면의 특성을 살펴보기 위해 주사현미경(SEM)을 사용하였고, 주괴와 슬래그 내에 포함되어 있는 성분들의 조성비는 ICP를 사용하여 핵종의 분배특성을 고찰하였다. 온도와 시간은 가장 중요한 변수이며 효과적인 방사성 핵종의 제거를 위해서는 최소 1500℃가 필요하였다. 용융체에서 발견된 Co-60의 양은 처음 아크로에 첨가되어 측정되어질 것이라고 예상된 양과 거의 일치하였다. 비록 약간의 Co-60이 슬래그로 이동하거나 산화된 금속 미립자가 기체 정화 시스템으로 이동될 것이라고 예상했지만, 용융로 분진에서는 발견되지 않았다. 분석 결과 Co는 슬래그에서 약간 검출되었으며 배기가스에서는 거의 발견할 수가 없었고, 거의 대부분이 금속에 전체적으로 균일하게 희석되어 존재하였다. 일부 실험에서는 Co-60의 약 90% 이상이 주괴에서 회수된 반면에 높은 증발압력을 가지고 있는 Cs은 용융체로부터 휘발되어 배기체로 휘발 또는 비말동반되어 SUS 304 주괴에서 아주 미미하게 검출되었다. Cs은 슬래그에서 Cs2SiO₃와 같은 안정한 화합물로 슬래그 상에 존재할 것으로 사료된다. 오염된 surrogate nuclide의 효과적인 제거를 위해 적절한 Slag 사용이 필요함을 결과를 통해 알 수 있었으며 Al₂O₃-CaO-SiO₂의 주 구성 슬래그에 산화력 및 전기전도도 등의 슬래그 물성을 변화시키는 플럭스를 첨가하였을 때 비방사성 동위원소가 슬래그 쪽으로 이동하여 효과적으로 제거됨을 알 수 있었다. 결론적으로 Co는 슬래그에 의한 제거보다는 균질화에 의한 희석효과에 Sr, Cs, Ce은 적절한 슬래그 조성과 종류에 의해 효과적인 제염이 이루어 짐을 볼 수 있었다.