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단일노즐을 사용한 내부순환 공기리프트 반응기에서 수력학과 액체의 흐름특성
김종철,장서일,손민일,김태옥 ( Jong Chul Kim,Sea Il Jang,Min il Son,Tae Ok Kim ) 한국공업화학회 1997 공업화학 Vol.8 No.5
기체분산기로 단일노즐을 사용한 내부순환 공기리프트 반응기에서 수력학과 액체의 흐름특성을 해석하였다. 실험은 공기-물계에서 기체속도와 반응기의 높이를 변화시키면서 국부지역의 기체체류량과 추적자의 충격-응답곡선을 측정하였다. 실험결과, 약 8 cm/s이상의 기체속도에서 상승관은 기포가 강한 합체를 일으키는 난류흐름을 나타내었고 하강관에서는 균일한 크기의 큰 기포들이 분산된 지역까지의 축방향 높이가 기체속도의 증가에 따라 감소하였다. 그리고 국부지역과 반응기 전체의 평균 기체체류량은 기체속도가 증가할수록 증가하였고 반응기 상부지역의 높이가 증가할수록 감소하였다. 또한 혼합시간은 기체속도보다 반응기 상부지역의 높이에 크게 영향을 받으며 이들이 증가할수록 감소하였다. 상승관과 하강관에서 액체의 흐름은 플러그흐름에 근접하였고 완전혼합흐름으로 볼 수 있는 반응기 상부지역의 크기에 따라 반응기 전체의 액체흐름특성이 크게 변화하였다. 이때 액체의 순환속도는 기체속도가 증가할수록 증가하였고 다른 기체분산기에서 보다 상당히 큰 값을 나타내었다. The hydrodynamics and the liquid flow characteristics were investigated in an internal circulation airlift reactor with a single nozzle as a gas distributor. In an air-water system, the gas holdup in the individual flow zone and the impulse-response curve of tracer were measured at various gas velocities and reactor heights. Experimental results showed that for the higher gas velocity(>about 8 cm/s), the flow behavior of bubbles in the riser was turbulent flow due to strong bubble coalescences and the axial height of dispersion zone of large bubbles having uniform sizes in the downcomer was decreased with increasing gas velocity. And mean gas holdups in the individual flow zone and the reactor were increased with increasing gas velocities and were decreased with increasing heights of the top section of the reactor. Also, the mixing time was larger effected by the height of the top section of the reactor and it was decreased with increasing the height of the top section and gas velocity. Flow characteristics of liquid in the riser andthe downcomer was tend to access to plug flow and the overall flow behavior ofliquid was mainly varied with the size of the top section which it was assumed to beperfect mixing zone. In these conditions, liquid circulation velocities were increased with increasing gas velocities and they were higher than those by using other gas distributors.
다공성 충전층반응기에서 기-액흐름양상의 전이와 액체체류량
손민일,함병호,조지훈,김태옥,장영준 明知大學校 産業技術硏究所 1996 産業技術硏究所論文集 Vol.15 No.-
For both downward and ward cement gas-liquid flow in a porous packed bed reactor the transition of gas-liquid flow pattern and liquid holdup were investigated experimentally in an air-water-Zeolite particle system. Experimental results showed that gas velocity at trickle-to-pulse flow transition boundary in the downflow system was decreased with increasing liquid velocity and that gas velocity at bubble-to-pulse flow transition boundary in the upflow system was nearly constant for lower liquid velocity, however, it was increased with increasing liquid velocity for turbulent flow region. We also found that the dynamic liquid holdup in the upflow system was higher than that in the downflow system and it was increased with increasing liquid velocity and with decreasing gas velocity. Furthermore,the dynamic liquid holdup was sensitively affected by liquid velocity at trickle flow in the downflow system while it was sensitively affected by gas velocity at bubble flow in the upflow system and at pulse flow in the downflow and upflow systems. For the porous particle system fluid velocities at gas-liquid flow transition boundaries and dynamic liquid holdup had nearly same that for the nonporous particle(glass bead) system.
조지훈,손민일,박용성,함병호,김태옥 明知大學校 産業技術硏究所 1993 産業技術硏究所論文集 Vol.12 No.-
For upward cocurrent gas-liquid flow in a packed column, holdup and axial mixing characteristics of liquid were investigated. In an air-water-glass bead system. liquid holdup and residence time distribution(RTD) were measured and Peclet number based on axial dispersion model was evaluated from experimental RTD. We found that liquid holdup was increased with increasing liquid velocity and size of packing material, and it was decreased with increasing gas velocity. Also, liquid holdup for the cocurrent up flow system was larger than that for the downflow system at the same experimental conditions. As increasing gas velocity, the in fluence of packing size and operation method on liquid holdup was reduced. The calculated Peclet number was not affected by gas velocity, and it was increased with increasing liquid velocity and with decreasing packing size. Furthermore, the effect of liquid velocity on Petlet number for higher liquid Reynolds number(Re1>70) was larger than that for lower Re1. In these conditions, correlations of the dynamic liquid holdup and the Bodenstein number were obtained.
기 - 액병류상향 충전탑에서 기 - 액흐름양상과 액체의 흐름 및 축방향혼합특성
김태옥,조지훈,함병호,손민일 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.4
기-액흐름이 병류상향으로 흐르는 충전탑에서 기-액흐름양상과 액체의 흐름 및 축방향혼합특성을 연구하였다. 실험은 공기-물계에서 기-액흐름양상의 전이조건과 액체의 체류시간분포(RTD)를 측정하였다. 측정된 RTD로부터 제시된 3가지 혼합모델, 즉 축방향분산모델(ADM), 정체지역이 존재하는 플러그흐름모델(PFM)과 정체지역이 존재하는 축방향분산모델 (DSM)을 사용하여 혼합모델의 매개변수들을 산출하였다. 그리고 조업조건에 따른 각 혼합모델의 적용성과 매개변수들을 해석하였다. 실험결과, 기포흐름에서 맥동흐름으로 전이되는 기체속도는 액체속도가 증가할수록, 그리고 충전물인 유리구슬의 직경이 작을수록 증가하였으며 액체의 흐름과 혼합특성은 모델 DSM으로 잘 해석할 수 있었다. 또한 곡선맞춤법으로 산출된 정체지역의 분율은 액체속도가 증가할수록 감소하였으나 유동지역과 정체지역간의 물질전달계수는 기체 및 액체속도의 증가에 따라 증가하였다. 그리고 모델 ADM과 모델 DSM으로 산출된 유통지역에서의 Peclet수는 액체속도가 증가할수록, 그리고 충전물의 직경이 작을수록 증가하였다. 이때 조업조건에 따른 이들 매개변수에 대한 상관식을 얻었다. For upward cocurrent gas-liquid flow in a packed column, the gas-liquid flow pattern, liquid flow, and axial mixing characteristics were investigated. The transition boundary of gas-liquid flow pattern and residence time distribution (RTD) of liquid phase were measured in an air-water system. Based on experimental RTDs, parameters of mixing models were evaluated with three proposed mixing models: axial dispersion model(ADM), plug flow model with stagnant zone (PFM), and axial dispersion model with stagnant zone(DSM). Accordingly, the applicability and parameters of each mixing model were analyzed for various operating conditions. We found that the gas velocity at bubble-pulse flow transition boundary was increased with increasing liquid velocity and decreasing diameter of glass bead as a packing material, and that the flow and mixing characteristics of liquid phase could be well analyzed by DSM. Also, the fraction of stagnant zone estimated by the curve fitting method was decreased with increasing liquid velocity, while the mass transfer coefficient between dynamic and stagnant zones was increased with increasing gas and liquid velocities. In dynamic zone, the calculated Peclet numbers in both ADM and DSM were increased with increasing liquid velocity and decreasing diameter of glass bead. In these conditions, correlations of these parameters were obtained for various operating conditions.
기-액병류상향 고정층반응기에서 액체의 흐름과 축방향분산
함병호,조지훈,편무실,김태옥,손민일 明知大學校 産業技術硏究所 1996 産業技術硏究所論文集 Vol.15 No.-
For upward cocurrent gas-liquid flow in a fixed bed reactor, the flow and axial dispersion of liquid were investigated in an air-water-Zeolite particle system. Based on experimental residence time distributions, parameters of mixing models were evaluated with two proposed liquid mixing models: axial dispersion model with stagnant zone(DSM) and plug flow model with stagnant zone(PFM). Accordingly, the applicability and parameters of each mixing model were analyzed for various operating conditions. We found that the flow and axial mixing characteristics of liquid could be analyzed well by DSM and parameters were well estimated by curve fitting using trial and error method. Also, the fraction of stagnant zone was decreased with increasing liquid velocity, while the dimensionless mass transfer coefficient between dynamic and stagnant zones was increased, and these parameters estimated by DSM were lower than those by PFM. In dynamic zone, calculated Peclet number were increased with increasing liquid velocity and axial mixing characteristics of liquid tended to access to plug flow for the high liquid Reynolds number(about Re1>50). For the porous catalyst particle system the flow and axial mixing characteristics of liquid had nearly same tendency that for the nonporous particle(glass bead) system, while dimensionless mass transfer coefficient was lower value than that for it. In these conditions, correlations of these parameters were obtained for various operating conditions.