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기계적 교반유동층에서 미세입자의 최소유동화속도에 미치는 교반속도와 온도의 영향

Effects of Agitation Speed and Temperature on Minimum Fluidization Velocity of Cohesive Particles in a Mechanically Agitated Fluidized Bed

배달희 류호정^† 선도원 진경태 이동규¹ 최정후²

Dal-Hee Bae Ho-Jung Ryu^† Dowon Shun Gyoung-Tae Jin Dong-Kyu Lee¹ Jeong-Hoo Choi²

한국에전지기술연구원 유동층기술연구센터, 대전 305-343 ¹충북대학교 공업화학과, 대전 361-763 ²건국대학교 화학공학과, 대전 361-763

Fluidization Research Center, Korea Institute of Energy Research, Daejeon 305-343, Korea ¹Department of Industrial Chemistry Engineering, Chungbuk National University, Chongju 361-763, Korea ²Department of Chemical Engineering, Konkuk University, Seoul 143-701, Korea

HWAHAK KONGHAK, April 2002, 40(2), 237-245(9), NONE

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Abstract

응집성이 있는 Geldart 분류 C 입자계의 최소유동화속도에 미치는 교반속도와 온도의 영향을 고찰하기 위해 층물질로 벤토나이트 입자(평균입경 3.7 μm, 입자밀도 1,681 kg/m(3))를 사용한 고온교반유동층(내경 0.05 m, 높이 1.31 m)에서 교반속도(rpm)와 층온도의 변화에 따른 층내압력강하 및 압력요동신호를 측정하여 최소채널링속도 또는 최소유동화속도를 측정 및 고찰하였다. 기계적 교반이 없는 경우에는 채널링이 일어났으며 교반에 의해 미세입자의 유동화가 가능하였다. 측정된 최소채널링속도와 최소유동화속도는 온도가 증가함에 따라 증가하는 경향을 나타내었으며 교반속도가 증가함에 따라 감소한 후 다시 증가하는 경향을 나타내었다. 기존의 최소유동화속도 상관식을 수정하여 본 실험에서 측정된 온도변화에 따른 최소유동화속도의 변화경향을 예측할 수 있는 상관식을 제시하였다.

To interpret the effects of agitation speed and temperature on the minimum fluidization velocity, bed and distributor pressure drop and pressure fluctuation signal have been measured in a high temperature mechanically agitated fluidized bed(0.05 m i.d. and 1.31 m high) using bentonite(mean particle diameter: 3.7 μm, apparent density: 1,681 kg/m(3)) as bed material._x000D_ Fluidization of very fine cohesive powder is possible if mechanical energy is introduced into the bed by agitation. Measured minimum channeling velocity and minimum fluidization velocity increased with increasing bed temperature, however, increased after an initial decrease with increasing agitation speed. The empirical correlation, considering the temperature effect but no effects of agglomerate size and density, on the minimum fluidization velocity of cohesive particles has been proposed on the basis of the experimental data of present study.

Keywords

Fluidization Channeling Cohesive Powder Minimum Fluidization Velocity

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