Korean Chemical Engineering Research, Vol.54, No.5, 678-686, October, 2016
CPFD 시뮬레이션을 통한 Shroud 노즐 및 수직 구조물이 설치된 기포 유동층 반응기내에서의 기포 흐름 해석
CPFD Simulation of Bubble Flow in a Bubbling Fluidized Bed with Shroud Nozzle Distributor and Vertical Internal
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초록
본 연구에서는 내경 0.3 m, 높이 2.4 m인 기-고 유동층 반응기 내에서 수직 방향의 내부 구조물과 shroud 노즐 분산판이 기포 흐름에 미치는 영향을 CPFD (Computational Particle-Fluid Dynamics)를 이용하여 모델링을 수행하였다. 층물질로는 Metal-grade 실리콘 입자(MG-Si)가 사용되었으며 dp= 149 μm, ρp = 2,325 kg/m3, Umf = 0.02 m/s이다. 전체층물질의 양은 75 kg이며 정적층(static bed) 높이는 0.8 m이다. 수직 내부 구조물이 기포 상승속도에 미치는 영향을 파악하였다. 내부 구조물이 분산판으로부터 0.45 m 높이에 설치되었을 때 기포의 분쇄가 일어났다. 유동층의 압력강하 및 수직 고체체류량 분포는 내부 구조물의 영향을 크게 받지 않는 것으로 나타났다. 하지만 내부 구조물이 제트에 너무 가까운 경우 기포가 분쇄되지 않고 내부 구조물을 우회하여 상승하였으며 내부 구조물이 없는 경우나 0.45 m 높이에 설치된 경우에 비해 더 빠른 속도로 상승하였다.
The effect of internal and shroud nozzle distributor to bubbling fluidized beds which has the size of 0.3 m-ID × 2.4 m-high column was modeled by CPFD (Computational Particle-Fluid Dynamics). Metal-grade silicon particles (MG-Si) were used as bed materials which have dp = 149 μm, ρp = 2,325 kg/m3 and Umf = 0.02 m/s. Total bed inventory and static bed height were 75 kg and 0.8 m, respectively. Effect of vertical internal on the bubble rising velocity was investigated. Bubbles were split by internal when the axial position of the internal from the distributor, z = 0.45 m. Bed pressure drop and axial solid holdup were not affected by internal. However, in the case that axial distance of internal from distributor was too close to jet penetration length, bubbles were not separated and bypassed internal, and faster than without internal or z = 0.45 m.
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