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Type transition in onset condition of turbulent fluidization
최정후,Ho-Jung Ryu,이창근 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.10
The type transition in onset condition of turbulent fluidization in gas fluidized beds was investigated to obtain the relation representing more precise roles of physical properties of gas and solid particles. The type transition in onset condition of turbulent fluidization occurs at Archimedes number of 20.87 by type transition of bubble breakup. The maximum stable bubble diameter (d_bmax) is greater than the equilibrium bubble diameter (d_beq) in the region, Ar<20.87, but d_(beq)>d_(bmax) in the region, Ar>20.87. Therefore, the onset of turbulent fluidization is determined in the region,Ar<20.87, by dbeq and in the region, Ar>20.87, by d_(bmax) as the limit of bubble growth. The u_c decreases in the region,Ar<20.87, but increases in the region, Ar>20.87 as temperature increases.
A model on an entrained bed-bubbling bed process for CO_2 capture from flue gas
최정후,이창근,Sung-Ho Jo 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.4
A simplified model has been developed to investigate effects of important operating parameters on performance of an entrained-bed absorber and bubbling-bed regenerator system collecting CO_2 from flue gas. The particle population balance was considered together with chemical reaction to determine the extent of conversion in both absorber and regenerator. The calculated CO_2 capture efficiency agreed with the measured value reasonably well. Effects of absorber parameters - temperature, gas velocity, static bed height, moisture content of feed gas on CO_2 capture efficiency - have been investigated in a laboratory scale process. The CO_2 capture efficiency decreased as temperature or gas velocity increased. However, it increased with static bed height or moisture concentration. The CO_2 capture efficiency was exponentially proportional to each parameter. Based on the absolute value of exponent of the parameter,the effect of gas velocity, static bed height, and moisture content was one-half, one-third, and one-fourth as strong as that of temperature, respectively.
Simulation of a bubbling fluidized bed process for capturing CO2 from flue gas
최정후,이창근,Sung-Ho Jo,Ho-Jung Ryu,Young Cheol Park 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.2
We simulated a bubbling bed process capturing CO2 from flue gas. It applied for a laboratory scale processto investigate effects of operating parameters on capture efficiency. The adsorber temperature had a stronger effectthan the regenerator temperature. The effect of regenerator temperature was minor for high adsorber temperature. Theeffect of regenerator temperature decreased to level off for the temperature >250 oC. The capture efficiency was ratherdominated by the adsorption reaction than the regeneration reaction. The effect of gas velocity was as appreciable asthat of adsorber temperature. The capture efficiency increased with the solids circulation rate since it was ruled by themolar ratio of K to CO2 for solids circulation smaller than the minimum required one (Gs, min). However, it leveled offfor solids circulation rate >Gs, min. As the ratio of adsorber solids inventory to the total solids inventory (xw1) increased,the capture efficiency increased until xw1=0.705, but decreased for xw1>0.705 because the regeneration time decreasedtoo small. It revealed that the regeneration reaction was faster than the adsorption reaction. Increase of total solids inventoryis a good way to get further increase in capture efficiency.
최정후,김규종,김병채 한국화학공학회 1994 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.32 No.3
공기 분배기로부터 0.2 m 높이에 2차 공기가 공급되는 상온 유동층(직경 0.1 m, 높이 2.4 m)에서 입자 비산 속도를 측정 및 고찰하였다. 층물질로는 체규격 0.5 ㎜ 이하의 모래가 사용되었다. 실험변수로는 입도(0.128-0.363 ㎜), 총괄유속(0.76-2.77 m/s), 2차 공기분율(0-0.5), 고정층 높이(0.1-0.3 m)가 변화되었다. 입자 비산속도는 유속이 증가할수록 입경이 감소할수록 증가하였다. 고정층 높이의 영향은 미약하였다. 2차 공기분율의 증가는 입자 비산속도를 감소시켰다. 이 영향은 2차 공기의 주입위치에 따라 다르며, 층내부일 경우에는 작으나, 프리 보드일 경우에는 두드러졌다. The particle entrainment rate was measured and discussed in a cold model fluidized bed(0.1 m-ID, 2.4 m-height) which employed a secondary air injection at a height of 0.2 m above the distributor plate. Sand particles of mixed sizes under 0.5 ㎜ in screen size were used as bed materials. The particle size(0.128-0.363 ㎜), the overall superficial gas velocity(0.76-2.77 m/s), the secondary air fraction(0-0.5), and the static bed height(0.1-0.3 m) were considered as experimental variables. The entrainment rate increased with the gas velocity, but with a decrease of particle size. The effect of static bed height was negligible. The entrainment rate decreased with an increase of the proportion of secondary air. The effect of secondary air fraction was appreciable for over-bed injection and was reduced as the location of second gas inlet moved toward in-bed.
최정후,선도원,김상돈,김병채,최광배 한국화학공학회 1995 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.33 No.5
전기로 가열되는 직경 0.1 m, 높이 2.1 m의 유동층에서 혼합입도(0-0.425㎜)의 또래를 총물질로 사용하여 층온도의 변화에 따른 고체입자의 비말동반특성을 고찰하였다. 실험변수로는 입도(0.075-0.425㎜), 기체유곡(0.65-2.3 m/s), 유동층온도(20-600℃)가 고려되었다. 입자비산속도에 대한 층온도의 영향은 유동과속도 0.8 m/s 이하에서는 온도가 증가함에 따라 아주 완만하게 증가하는 경향을 보였다. 유동화속도 1 m/s 이상에서는 온도가 증가함에 따라 감소하다가 최소값을 보인후 다시 증가하는 경향을 나타내었으며, 최소값의 위치는 유속이 증가함에 따라 더 높은 온도로 이동하였다. 이와 같은 경 향은 유동화속도가 종말속도인 입 경이 온도에 따라 변화하는 경향과 일치하였다. The effect of temperature en the particle entrainment rate was measured and discussed in a gas fluidized bed(0.1m in diameter, 2.1m high) which used sand as a bed material and was equipped with an electric heater. The particle size(0.075-0.425㎜), gas velocity(0.65-2.3 m/s) and bed temperature(20-600℃) were varied as experimental variables. The particle entrainment rate increased very slowly with the bed temperature at the gas velocity less than 0.8 m/s. At the gas velocity greater than 1 m/s, the particle entrainment rate decreased with increasing the bed temperature until a certain temperature above which the particle entrainment rate increased with the bed temperature. The minimum point of particle entrainment rate shifted to higher temperature with increasing gas velocity. The change of the particle entrainment rate along the bed temperature was same as that of the particle size whose terminal velocity was equal to the gas velocity.