내경이 0.105 m이고 높이가 2.5 m인 삼상(기체-액체-고체) 유동층에서 상대적으로 큰 기포와 작은 기포의 체류량 특성을 고찰하였다. 기체유속(0.01~0.07 m/s), 액체유속(0.01~0.07 m/s) 그리고 입자크기(0.5~3.0×10.3 m)가 상대적으로 큰 기포와 작은 기포의 체류량에 미치는 영향을 검토하였다. 삼상 유동층에서 이들 두 종류 기포들의 체류량은 동력학적 기체 유출 방법(Dynamic gas disengagement method)에 의해 측정된 각각 기포들에 의한 압력강하 정보로부터 정압강하법(static pressure drop method)에 의해 산출되었다. 기체조절기에 의해 조절되는 건조되고 여과된 공기와 물 그리고 밀도가 2,500 kg/m3인 유리구슬을 각각 기체, 액체 및 고체유동입자로 사용하였다. 삼상유동층에서 이들 두 종류의 기포, 즉 상대적으로 큰 기포와 작은 기포들은 유동층 탑에 유입되는 기체와 액체의 흐름을 정지시킨 후 경과시간에 따른 탑 내부의 압력강하를 측정함으로써 효과적으로 조사하고 분리할 수 있었다. 이들 두 종류의 기포들은 경과시간에 따라 증가하는 압력강하의 기울기가 서로 매우 다르게 나타났다. 실험결과 상대적으로 큰 기포들의 체류량은 기체의 유속이 증가함에 따라 증가하였으나 액체의 유속이 증가함에 따라서는 감소하였다. 그러나, 이들 큰 기포의 체류량은 유동입자의 크기가 변화함에 따라 국부_x000D_ 적인 최소값을 나타내었다. 상대적으로 작은 기포들의 체류량은 기체유속 또는 고체입자의 크기가 증가함에 따라 증가하였으나 액체의 유속이 증가함에 따라서는 약간 감소하였다. 이들 두 종류 기포들의 체류량들은 각각 본 연구의 실험 범위 내에서 조작변수들의 상관식으로 나타낼 수 있었다.

Phase holdup characteristics of relatively large and small bubbles were investigated in a three-phase(gasliquid-solid) fluidized bed of which diameter was 0.105 m(ID) and 2.5 m in height, respectively. Effects of gas(0.01~0.07 m/s) and liquid velocities(0.01~0.07 m/s) and particle size(0.5~3.0×10.3 m) on the holdups of relatively large and small bubbles were determined. The holdups of two kinds of bubbles in three phase fluidized beds were estimated by means of static pressure drop method with the knowledge of pressure drops corresponding to each kind of bubble, respectively, which were obtained by dynamic gas disengagement method. Dried and filtered air which was regulated by gas regulator, tap water and glass bead of which density was 2500kg/m3 were served as a gas, a liquid and a fluidized solid phase, respectively. The two kinds of bubbles in three-phase fluidized beds, relatively large and small bubbles, were effectively detected and distinguished by measuring the pressure drop variation after stopping the gas and liquid flow into the column as a step function: The increase slope of pressure drop with a variation of elapsed time was quite different from each other. It was found that the holdup of relatively large bubbles increased with increasing gas velocity but decreased with liquid velocity. However, the holdup showed a local minimum with a variation of size of fluidized solid particles. The holdup of relatively small bubbles increased with an increase in the gas velocity or solid particle size, while it decreased slightly with an increase in the liquid velocity. The holdups of two kinds of bubbles were well correlated in terms of operating variables within this experimental conditions, respectively.

Large Bubble Small Bubble Three-Phase Fluidized Beds

Fan LS, Gas-Liquid-Solid Fluidization Engineering, Butterworths, Stonehair, Ma. (1989)
Kim SD, Kang Y, Chem. Eng. Sci., 52(21-22), 3639 (1997)
Kim SD, Kang Y, Stud. Surf. Sci. Catal., 159, 103 (2006)
Kang Y, Lee KI, Shin IS, Son SM, Kim SD, Jung H, Korea Chem. Eng. Res. (HWAHHAK KONGHAK)., 45, 451 (2008)
Lefebvre S, Guy C, Chaouki J, Chem. Eng. J., 133(1-3), 85 (2007)
Kim SD, Kang Y, “Dispersion Phase Characteristics in t Hree-phase Fluidized Beds”, Mixed Flow Hydridynamics, Advanced Eng. Fluid Meckanics Series, Gulf Pub. Co. New York (1996)
Wild G, Saberian M, Schwarty J, Charpentier JE, Int’L Chem. Eng., 24, 639 (1984)
Lee KI, Son SM, Kim UY, Kang Y, Kang SH, Kim SD, Lee JK, Seo YC, Kim WH, Chem. Eng. Sci., 62(24), 7060 (2007)
Shin KS, Song PS, Lee CG, Kang SH, Kang Y, Kim SD, Kim SJ, AIChE J., 51(2), 671 (2005)
Lin TJ, Hung-Tzu C, Catal. Today, 79(1-4), 159 (2003)
Cho YJ, Song PS, Kim SH, Kang Y, Kim SD, J. Chem. Eng. Jpn., 34(2), 254 (2001)
Son SM, Kang SH, Kang Y, Kim SD, Korean Chem. Eng. Res., 44(5), 505 (2006)
Son SM, Shin HJ, Kang SH, Kang Y, Kim SD, J. Korean Ind. Eng. Chem., 15(6), 652 (2004)
Wan L, Alvaregcuenca M, Upreti SR, Lohi A, Chem. Eng. Processing : Process Intensification., Doi: 10. 1016/J. Cep. 2009. 10. (2009)
Ramesh KV, Raju GMJ, Sarma GVS, Sarma CB, Chem. Eng. J., 145(3), 393 (2009)
Jena HM, Roy GK, Meikap BC, Chem. Eng. Res. Des., 86(11A), 1301 (2008)
Deckwer WD, Bubble Column Reactors, John Wiley And Sons. Ny (1992)
Krichna R, Sie ST, Fuel Processing Technol., 64, 73