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상온 2단 선회류 유동층에서 상단으로의 입자 유입속도
Entrainment Rate of Particles from the Lower Stage to the Upper Stage in a Cold Model Two-Stage Swirl-Flow Fluidized Bed
HWAHAK KONGHAK, June 1996, 34(3), 327-333(7), NONE
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Abstract
상온 2단 선회류 유동층에서 하단 유동층으로 공급된 연료 입자 중 하단 가스공탑속도 변화에 따른 상단으로의 입자 유입속도를 파악하였다. 하단 가스공탑속도 증가에 따라 단위시간당 입자의 상단 유입량은 증가하는 경향을 보였으며, 본연구의 하단 가스공탑속도 범위(Uol=0.9_1.3m/s)내에서 상단으로의 입자 유입량은 하단 유동층으로 공급되는 전체 입자량의 약 35-48% 범위에 해당되었다. 입경별 상단으로의 입자 유입속도를 측정한 결과, 입자의 종말속도가 하단 가스공탑속도보다 큰 입자들은 거의 상단으로 유입되지 못하였다. 그러나 입자의 종말속도가 하단 가스공탑속도보다 작은 입자들의 경우에는 하단으로 공급된 시료입자 중 상단으로 유입된 입자의 분율은 하단 가스공탑속도가 증가하고 입경이 감소할수록 증가하였으며, 무차원 slip velocity가 1에 접근하게 되면 하단으로 공급된 연료입자 중 거의 대부분이 상단으로 유입되는 경향을 보였다. 또한 하단으로 공급된 연료입자 중 상단으로 유입되는 입자의 분율은 아래 식과 같이 무차원 slip velocity에 대하여 지수함수적인 상관관계를 가졌으며, 이 때 상관계수는 0.89이었다.
Emi / Foi = 1 - 189.1 exp[-8.377(Uol - Uti / Uol)0.17]
Emi / Foi = 1 - 189.1 exp[-8.377(Uol - Uti / Uol)0.17]
The rate of particles entrained from the lower stage to the upper stage according to the primary superficial air velocity are investigated in a cold model two-stage swir-flow fluidized bed combustor. The total entraimment rate increases with the primary superficial air velocity and ranges from 35 percent to 48 percent of particles fed into the lower bed under the operating conditions(Uol=0.9-1.3m/s). The particles whose terminal velocity is higher than the primary superficial air velocity may not be entrained from lower stage to the upper stage. However, in the case of particles whose terminal velocity is lower than the primary superficial air velocity, the entraiment rate of particles increases as the particle size becomes smaller and/or the primary superficial air velocity increases. Further, the particles whose dimensionless slip velocity approaches to unity are almost entrained. The entrainment rate can be correlated with the dimensionless slip velocity as follows:
Emi / Foi = 1-189.1 exp[-8.377(Uoi-Uti/Uoi)0.17]
Emi / Foi = 1-189.1 exp[-8.377(Uoi-Uti/Uoi)0.17]
Keywords
References
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Radovanovic M, "Fluidized Bed Combustion," Chap. 1, Hamisphere Publishing Co., New York (1986)
Taylor TE, Proc. of the 2nd Eng. Found. Conf. on FBC, 258 (1978)
Anthony EJ, Becker HA, Code RK, Liang DT, Stephenson JR, Proc. of the 8th Int. Conf. on FBC, 32 (1985)
Chen TP, Saxena SC, Proc. of the 2nd Eng. Found. conf. On FBC, 151 (1978)
Korenberg J, Proc. Int. Conf. on Fluidization, 491 (1983)
Lee JK, Hu CG, Shin YS, Chun HS, Can. J. Chem. Eng., 68(5), 824 (1990)
Lee JK, Lee KH, Lee KH, Chun HS, HWAHAK KONGHAK, 28(4), 470 (1990)
Lee JK, Lee KH, Jang JG, Lim JH, Lim JS, Chun HS, HWAHAK KONGHAK, 30(4), 499 (1992)
이제근, 장정국, 여석준, 허철구, 임준혁, 전해수, 한국폐기물학회지, 9(1), 45 (1992)
Lee JK, Lee KH, Jang JG, Shin Ys, Chun HS, J. Chem. Eng. Jpn., 24(6), 703 (1991)
Lee JK, Lee KH, Chun HS, J. Chem. Eng. Jpn., 26(2), 179 (1993)
Lee JK, Lee KH, Jang JG, Chun HS, J. Chem. Eng. Jpn., 26(4), 368 (1993)
Gong JH, Lim JH, Shin YS, Lee JK, Chun HS, Proc. 1st Asian Conf. on Fluidized Bed and 3-Phase Reactors, Tokyo, Japan, 253 (1988)
Lim JH, Lim JS, Shin YS, Chun HS, Proc. of 2nd Asian Conf. on Fluidized Bed and 3-Phase Reactors, Kenting, Taiwan, 202 (1990)
Horio M, Shibata T, Muchi I, Proc. 4th Int. Conf. on Fluidization, 307 (1984)
Kunii D, Levenspiel O, "Fluidization Engineering," 2nd Ed., Ch. 1, Ch. 7, Butterworth-Heinemann Inc., New York (1991)
Zenz FA, Weil NA, AIChE J., 4(4), 472 (1958)
