The effect of temperature on solid mixing rate was investigated both qualitatively and quantitatively for the application of the data to the activated carbon regeneration system. The mixing rate of solid was determined by measuring the residense time distribution (RTD) in a co-current gas-solid fuidized bed.
The variables selected for investigation of temperature effect on RTD of solids were temperature, flow rate of fluid and aspect ratio which is the length to diameter ratio of the fluidized bed.
The experimental results showed that the onset of fluidization occured earlier than the expected velocity as the temperature rise. And the temperature correction equation for minimum fluidizing velocity was
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It was founded from the study that the air flow rate and aspect ratio had a marked influence on mixing pattern of solids, but temperature elevation increased the mixing effect slightly.
The tendency to perfect mixing of solids increases with decrease of aspect ratio and increase of gas flow rate.
From these observations, the following empirical equation between efficiency of solids mixing and respective variables was derived.
$[(η-1) = 0.898 (ν_o/ν{mf})^{-1.411} (L/D)^{0.897} (T/T_o)^{-0.270}]$
분말 활성탄의 열재생에대한 기초연구로서 co-current qas-solid fluidized bed에서 solid의 체류시간분포를 측정함으로서 salid mixing에 대한 온도의 영향을 다른변수와 함께 정량적 및 정성적으로 열구하였다.
결과에 의하면 Erqun's $Eg^(9)$을 도입한 umf 추정식에 의한 예상보다 빨리 fluidization되기 시작했으며, 이식의 온도에 대한 보정식은 $Umf = \frac{(φdp)^2}{150}ㆍ\frac{ρ_s - ρ_g}{μ}g \frac{εmf^3}{1-εmf} (T/To)^{-0.113}, Rep ＜ 20$ 으로 표시되었다.
기체유속과 Aspect ratio가 solid mixing pattern에 상당한 영향을 미쳤으며, 기체유속이 증가할수록, Aspect ratio가 감소할수록 solid mixing이 좋아졌다.
minimum fluidization velocity에 온도보정을 하여 온도 효과를 살펴본 결과 온도의 증가가 약간의 혼합효율을 증가시켰다.
이와같은 결과를 plotting하여 solid mixing efficiency (η - 1)에 대하여 다음과 같은 실험식을 얻었다.
$(η-1) = 0.898(U_o/U_{mf})^{-1.41} (L/D)^{-0.897} (T/T_o)^{-0.270}$
