HWAHAK KONGHAK, Vol.31, No.1, 118-126, February, 1993
삼상유동층에서 기-액접촉면적과 물질전달 특성
Gas-Liquid Interfacial Area and Mass Transfer Characteristics in Three-Phase Fluidized Beds
초록
삼상유동층에서 기체(0.01-0.12m/s) 및 액체유속(0.02-0.10m/s)과 입자크기(1.0-8.0mm)가 기-액접촉면적과 물질전달계수에 미치는 영향을 내경 0.142m, 높이 2m인 Plexiglas column에서 연구하였다. 기-액접촉면적은 기상 및 액상 유속에 따라 증가하나 입자크기 증가에 따라 감소했다가 증가하는 경향을 나타내었다. 액상물질 전달계수는 기포합체영역에서는 기체상의 유속에 따라 증가하나 기포분쇄영역에서는 기상의 유속에 무관하였다. 액상의 유속에 따른 액상물질전달계수의 변화는 무시할 정도로 작었고 입자크기에 따른 액상물질전달계수의 변화는 감소했다가 증가하는 최소점을 나타내었다. 삼성유동층에서의 물질전달계수를 입자의 Sherwood 수의 함수로 표시하여 isotropic turbulence theory를 근거로 Schmidt와 Reynolds 수로 상관식을 제시하였다.
The effects of gas(0.01-0.12m/s) and liquid velocities(0.02-0.10m/s) and praticle size(1-8mm)on gas/liquid interfacial area(a) and mass transfer coefficient(kL) have been determined in a 0.142m-I.D.×2.0m-high Plexiglas column. Gas-liquid interfacial area increases with increasing gas and liquid velocities, but it exibits a minimum value in the bed of 6.0mm particle. In the bubble coalescing regime, kL is nearly independent of gas velocities. The effect of liquid velocity on kL is found to be negligibly small. A minimum value of kL exhibits the bed of 1.7mm particle. The liquid side mass transfer coefficient in terms of Sherwood number in three-phase fluidized beds have been correlated with Schmidt and particle Reynolds numbers related to the energy dissipation rate in the bed based on the local isotropic turbulence theory.
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