분말 활성탄재생의 기초연구로써 기 고병류유동층에서, 고체입자의 크기, 기체유속, 금망충전이 mesh크기, aspect ratio（유동층에서 층고와 직경의 비） 등을 변수로 하여 고체입자의 혼합유형을 고체의 체류시간을 정함으로써 연구하였다. 실험결과에 의하면 기체유속과 aspect ratio가 크게 영향을 미쳤으며, aspect ratio가 감소할수록 또 기체유속이 증가할수록 고체입자들은 완전혼합에 가깝게 되었다. 또한 유동입자의 크기가 클수록 충전물 mesh크기가 클수록 완전혼합에 가까워지며, 이들에 대한 관계는 다음과 같은 실험식으로 표시할 수 있었다.
（S-1）⁤6.6×10^-2․((L/D)^0.56/(u_g/u_mf-1)^1.73(dҥ_p)^0.68(dҥ_m0)^0.2)

The mixing pattern of solids in a co-current gas fluidized bed with screen packings was studied by measuring the residence time distribution （RTD） for a basic research on the thernal 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 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 these results, the following empirical equation was obtained.
（S-1）⁤6.6×10^-2․((L/D)^0.56/(u_g/u_mf-1)^1.73(dҥ_p)^0.68(dҥ_m0)^0.2)