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액체-고체 순환유동층의 상승관에서 액상의 점도가 고체체류량 및 열전달계수에 미치는 영향

Effects of Liquid Viscosity on the Solid Holdup and Heat Transfer Coefficient in the Riser of Liquid-Solid Circulating Fluidized Beds

이찬기 강석환 신광식 송평섭 강용^† 김상돈¹

Chan-Gi Lee Suck-Hwan Kang Kwang-Sik Shin Pyung-Seob Song Yong Kang^† Sang-Done Kim¹

충남대학교 화학공학과, 305-764 대전시 유성구 궁동 220 ¹한국과학기술원 생명화학공학과, 305-701 대전 유성구 구성동 373-1

School of Chemical Engineering, Chungnam National University, 220-Gung-dong, Yuseong-gu, Daejeon 305-764, Korea ¹Department of Chemical & Biomolecular Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea

HWAHAK KONGHAK, August 2003, 41(4), 524-529(6), NONE

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Abstract

직경이 0.102 m이고 높이가 3.5 m인 액체-고체 순환유동층에서 액체의 점도가 고체입자의 체류량과 열전달계수에 미치는 영향을 검토하였다. 밀도가 2,500 kg/m(3)인 유리구슬(dp=1.0, 1.7, 2.1 또는 3.0 mm)과 CMC 용액(μL=0.96-38 mPas)을 각각 고체상과 액체상으로 사용하였다. 액체-고체 순환유동층에서 고체입자의 체류량은 액체의 유속이나 점도가 증가함에 따라 감소하였고 유동입자의 크기나 입자의 순환속도가 증가함에 따라 증가하였다. 액체-고체 순환유동층에서 열전달계수는 액체의 점도가 증가함에 따라 감소하였고 유동입자의 크기나 순환속도가 증가함에 따라 증가하였으나, 액체의 유속이 증가함에 따라서는 큰 변화가 없었다. 액체-고체 순환유동층에서 고체입자의 체류량과 열전달계수는 다음과 같이 실험변수와 무차원군에 의해 상관식으로 얻을 수 있었다._x000D_ εS = 0.783UL(-0.100)GS(0.164)dp(0.302)μL(-0.036)_x000D_ h = 4349.3UL(0.010)GS(0.099)dp(0.151)μL(-0.015)_x000D_ (hdp/kL) = 1259(cpμL/kL)(-0.018)(GS/ULρS)(0.078)(dp/D)(1.229)

Effects of liquid viscosity on the solid holdup and heat transfer coefficient have been investigated in the riser of a liquid-solid circulating fluidized beds, whose diameter is 0.102 m and 3.5 m in height. Glass beads (dp=1.0, 1.7, 2.1 or 3.0 mm) whose density is 2,500 kg/m(3) and aqueous solutions of carboxymethy cellulose (CMC)(μL=0.96-38 mPas) have been used as the solid and liquid phase, respectively. It has been found that the solid holdup decreases with increasing liquid velocity or viscosity, but it increases with increasing solid particle size or solid circulation rate. The heat transfer coefficient decreases with increasing liquid viscosity but it increases with increasing particle size or solid circulation rate, however, it does not change considerablely with increasing liquid velocity. The solid holdup and heat transfer coefficient have been well correlated in terms of operating variables or dimensionless groups as fellow:_x000D_ εS = 0.783UL(-0.100)GS(0.164)dp(0.302)μL(-0.036)_x000D_ h = 4349.3UL(0.010)GS(0.099)dp(0.151)μL(-0.015)_x000D_ (hdp/kL) = 1259(cpμL/kL)(-0.018)(GS/ULρS)(0.078)(dp/D)(1.229)

Keywords

Liquid-Solid Circulating Fluidized Bed Viscous Liquid Medium Solid Holdup Heat Transfer Coefficient

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