The mixing pattern of solids which was known by measuring the residence time distribution (RTD) in a co-current gas-salid fluidized bed was studied for a basic research on the thermal regeneration of activated carbon. The variables selected for investigation of RTD of solids were aspect ratio(the length to diameter ratio of the fluidized bed), the flow rate of fluidizing gas, particle size, mesh size of screen packing and the flow rate of solid through the system.
The experimental results showed that the gas flow rate and the aspect ratio had a very marked effect on the mixing pattern of solids. The tendency to perfect mixing of solids increases with decrease of aspect ratio and increase of gas flow rate.
The results also showed that the tendency to perfect mixing increased with increase of mesh size of screen cylinder and particle size of solids. But within the range studied, the feed rate of solids had no effect on the mixing pattern. From this results, the following empirical equation was obtained.
$(S-1)=6.6×10^{-2}\frac{(L/D)^{0.56}}{(frac{Ug}{Umf}-1)^{1.73} (\bar{d}p)^{0.68} (dmo)^{0.20}}$
분말 활성탄의 열재생에 대한 기초연구로써 co-current gas solid fluidized bed 에서 solids의 체류시간을 정함으로써 solids 의 mixing patlern 을 정량적 및 정성적으로 연구하였다.
실험에 사용된 변수는 aspect ratio ( 유동층에서 bed height와 직경의 비), 기체유속, 고체입자의 크기, screen packing 의 mesh size, 고체의 유입속도 등이었다.
실험결과에 의하면 기체유속과 aspect ratio 가 solid의 mixing pattern에 크게 영향을 미쳤으며, aspect ratio가 감소할수록 또 기체유속이 증가할 수록 solids는 perfect mixing에 가깝게 되었다.
또한 영향은 그리 크지 않지만 screen packing의 mesh size가 클 수록 또 유동입자의 크기가 클 수록 perfect mixing 에 가깝게 되었다.
그런데 실험범위 내에서 solid의 feed rate는 solid의 mixing pattern에 거의 영향이 없었다.
이와같은 결과를 plotling 하여 다음과 같은 실험식을 얻을 수 있었다.
$(S-1) = 6.6 × 10^{-2} \frac{(L/D)^{0.56}}{(frac{Ug}{Umf}-1)^{1.73} (\bar{d}p)^{0.68} (dmo)^{0.20}}$
