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Received August 21, 2018
Accepted September 27, 2018
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고체 수송관이 있는 2 단 기포 유동층에서 붕괴 속도에 대한 하단 층 높이의 영향
Effect of Lower Bed Height on Collapse Velocity in the Two-Stage Bubbling Fluidized-Bed with a Standpipe for Solid Transport
Department of Chemical Engineering COMSATS Institute of Information Technology, Defence Road, Lahore 54000, Pakistan 1건국대학교 화학공학과, 05029 서울시 광진구 능동로 120
Department of Chemical Engineering, COMSATS Institute of Information Technology, Defence Road, Lahore 54000, Pakistan 1Department of Chemical Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul, 05029, Korea
choijhoo@konkuk.ac.kr
Korean Chemical Engineering Research, December 2018, 56(6), 864-870(7), 10.9713/kcer.2018.56.6.864 Epub 4 December 2018
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Abstract
고체 수송관(standpipe, 내경 0.025 m)으로 연결된 2단 기포 유동층(내경 0.1 m, 높이1.2 m)에서 붕괴 속도에 대한 하단 층 높이의 영향을 조사하였다. 기체로는 공기를 사용하였고, 고체로는 입도가 큰 입자(<1000 μm, 겉보기 밀도 3625 kg/m3)와 입도가 작은 입자(<147 μm, 겉보기 밀도 4079 kg/m3)를 혼합한 입자를 사용하였다. 작은 입자의 혼합비, 하단 유동층의 층 높이, 상단 유동층 분산판을 실험 변수로 고려하였다. 붕괴 속도는 하단 유동층의 정체 층 높이가 증가할수록 증가하였다. 그러나 작은 입도의 혼합비가 증가하면 이 효과가 감소하였다. 이 효과는 층 높이 증가에 따른 고체 수송관 압력 강하의 증가 때문이 아니라, 수송관 출구를 막는 농후상 굵은 입자 층 높이의 증가 때문으로 보였다. 상단 유동층 분산판 압력 강하의 증가는 붕괴 속도를 조금 감소시켰다. 붕괴 속도를 예측하는 개선된 상관식을 제안하였다.
The effect of lower bed height on the collapse velocity was investigated for a two-stage bubbling fluidizedbed (0.1 m in diameter, 1.2 m high) connected with a standpipe (0.025 m in diameter) for solid transport. Air was used as fluidizing gas and mixture of coarse (<1000 μm in diameter and 3625 kg/m3 in apparent density) and fine (<147 μm in diameter and 4079 kg/m3 in apparent density) particles as solid particles. Mixing ratio of fine particles, height of the lower bed and the distributor of the upper bed were considered as experimental variables. The collapse velocity increased with static height of the lower bed. However, the effect decreased as the mixing ratio of fine particles increased. The effect seemed to be attributed to the increase in height of the dense layer of coarse particles that prevented the gas from flowing into the standpipe, not in pressure drop for the standpipe, as the bed height increased. The collapse velocity decreased a little as the pressure drop of the distributor of the upper bed increased. An improved correlation was proposed for predicting the collapse velocity.
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