파일럿규모 슬러리 기포탑에서 기포체류량의 축방향, 반경방향 분포

임대호 ( Dae Ho Lim ),장지화 ( Ji Hwa Jang ),강용 ( Yong Kang ),전기원 ( Ki Won Jun ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.2

Axial and radial distributions of bubble holdup were investigated in a slurry bubble column with pilot plant scale(D=1.0 m). Effects of gas velocity, surface tension of continuous liquid medium and solid fraction in the slurry phase on the axial and radial distributions of bubble holdup were examined. The bubble holdup decreased with increasing radial dimensionless distance from the center of the column, while it increased with increasing dimensionless distance in the axial direction from the distributor, in all the cases studied. The radial non-uniformity of bubble holdup increased with increasing gas velocity but decreasing surface tension of liquid medium, while it was not dependent upon the solid fraction in the slurry phase. The axial non-uniformity of bubble holdup increased with increasing gas velocity, but it does not change considerably with variations of liquid surface tension or solid fraction in the slurry phase. The axial and radial distributions of bubble holdup were well correlated in terms of operating variables within this experimental conditions.

모사된 GTL공정의 점성액체 매체에서 wake의 특성

임대호 ( Dae Ho Lim ),장지화 ( Ji Hwa Jang ),강용 ( Yong Kang ),전기원 ( Ki Won Jun ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.5

Characteristics of bubble driven wakes were investigated in a simulated GTL process(0.102 m x 1.5 m in height) with viscous liquid medium. Effects of gas velocity(0.04~0.12 m/s) and liquid viscosity(0.001~0.050 Pa·s) on the wake characteristics such as rising velocity, frequency, size and holdup were determined by employing a resistivity probe method. The wake phase formed behind the rising multi-bubbles as well as single bubbles were detected effectively from the conductivity fluctuations measured by the probe. Compressed, filtered and regulated air and aqueous solutions of Carboxy Methyl Cellulose(CMC) were used as a dispersed gas phase and a continuous liquid medium, respectively. It was found that the rising velocity and size of wake phase increased with an increase in gas velocity or liquid viscosity. The holdup and frequency of wake phase increased with increasing gas velocity due to the increase of gas input into the process with increasing gas velocity. However, We values of holdup and frequency of wake phase decreased with increasing liquid viscosity, since the size of bubbles and thus that of wakes increased with increasing liquid viscosity. The ratio of wake holdup to that of gas phase, which was in the range of 0.25~0.48, increased with an increase in liquid viscosity but decreased with gas velocity. The wake characteristics were well correlated in terms of operating variables within this experimental conditions.

점성액체 기포탑에서 탑의 직경이 기포, wake 및 연속액상 체류량에 미치는 영향

임대호 ( Dae Ho Lim ),장지화 ( Ji Hwa Jang ),강용 ( Yong Kang ),전기원 ( Ki Won Jun ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.5

Holdup characteristics of bubble, wake and continuous liquid phases were investigated in bubble columns with viscous liquid media. Effects of column diameter(0.051, 0.076, 0.102 and 0.152 m ID), gas velocity(U(G)=0.02~0.16 m/s) and liquid viscosity(μL=0.001~0.050 Pa·s) of continuous liquid media on the holdups of bubble, wake and continuous liquid phases were discussed. The three phase such as bubble, wake and continuous liquid phases were classified successfully by adapting the dual electrical resistivity probe method. Compressed filtered air and water or aqueous solutions of CMC(Carboxy Methyl Cellulose) were used as a gas and a liquid phase, respectively. To detect the wake as well as bubble phases in the bubble column continuously, a data acquisition system(DT 2805 Lab Card) with personal computer was used. The analog signals obtained from the probe circuit were processed to produce the digital data, from which the wake phase was detected behind the multi-bubbles as well as single bubbles rising in the bubble columns. The holdup of bubble and wake phases decreased but that of continuous liquid media increased, with an increase in the column diameter or liquid viscosity. However, the holdup of bubble and wake phases increased but that of continuous media decreased with an increase in the gas velocity. The holdup ratio of wake to wake to bubble phase decreased with an increase in the column diameter or gas velocity, however, increased with an increase in the viscosity of continuous liquid media. The holdups of bubble, wake and continuous liquid media could be correlated in terms of operating variables within this experimental conditions as: εB=0.043D(-0.18)U(G)(0.56)μL(-0.13), εW=0.003D(-0.85)U(G)(0.46)μL(-0.10), εC=1.179D(0.09)U(G)(-0.13)μL(0.04).

삼상유동층 공정에서 수력학적 Similarity 해석

임호 ( Ho Lim ),임현오 ( Hyun Oh Lim ),진해룡 ( Hae Ryoung Jin ),임대호 ( Dae Ho Lim ),강용 ( Yong Kang ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.6

삼상유동층에서 수력학적 유사성을 규모인자(scaling factor)를 이용하여 해석하였다. 규모인자는 직경이 다른 두 종류의 삼상유동층간의 기체, 액체, 그리고 고체입자의 체류량과 단위면적당 유효부피흐름속도를 기준으로 정의하였다. 두 종류 삼상유동층의 직경은 각각 0.102 m와 0.152 m이었다. 여과된 압축공기, 물 그리고 밀도가 2,500 kg/m3인 유리구슬을 각각 기체, 액체 그리고 유동고체입자로 사용하였다. 각 삼상유동층에서 각 상들의 체류량은 정압강하법에의해 결정하였다. 기체 및 액체의 유속 그리고 고체유동입자의 크기가 각 상들을 기준으로한 규모인자와 유효부피흐름 속도를 기준으로한 규모인자에 미치는 영향을 검토하였다. 직경이 다른 두 삼상유동층에서 기체 체류량의 편차는 기체와 액체의 유속이 증가함에 따라 감소하였으나 유동입자의 크기가 증가함에 따라 증가하였다. 직경이 다른 두 종류 삼상유동층에서 액체 체류량 편차는 기체와 액체 그리고 고체유동입자의 크기가 증가함에 따라 감소하였다. 두 종류 삼상유동층에서 고체입자 체류량 편차는 기체유속과 유동입자의 크기가 증가함에 따라 증가하였으나 액체의 유속이 증가함에 따라 감소하였다. 직경이 다른 두 종류 삼상유동층에서 유효부피흐름속도를 매개로 한 규모인자는 기체유속과 유동입자의 크기가 증가함에 따라 감소하였으나 액체의 유속이 증가함에 따라 증가하였다. 본 연구에서 정의된 규모인자는 삼상유동층 공정의 수력학적 유사성을 해석하는데 효과적으로 사용될 수 있었다. Hydrodynamic similarity was analyzed by employing scaling factor in three phase fluidized beds. The scaling factor was defined based on the holdups of gas, liquid and solid particles and effectivity volumetric flux of fluids between the two kinds of fluidized beds with different column diameter. The column diameter of one was 0.102 m and that of the other was 0.152 m. Filtered compressed air, tap water and glass bead of which density was 2,500 kg/m3 were used as gas, liquid and solid phases, respectively. The individual phase holdups in three phase fluidized beds were determined by means of static pressure drop method. Effects of gas and liquid velocities and particle size on the scaling factors based on the holdups of each phase and effective volumetric flux of fluids were examined. The deviation of gas holdup between the two kinds of three phase fluidized beds decreased with increasing gas or liquid velocity but increased with increasing fluidized particle size. The deviation of liquid holdup between the two fluidized beds decreased with increasing gas or liquid velocity or size of fluidized solid particles. The deviation of solid holdup between the two fluidized beds increased with increasing gas velocity or particle size, however, decreased with increasing liquid velocity. The deviation of effective volumetric flux of fluids between the two fluidized beds decreased with increasing gas velocity or particle size, but increased with increasing liquid velocity. The scaling factor, which was defined in this study, could be effectively used to analyze the hydrodynamic similarity in three phase fluidized processes.

보문: 미립지공학·유동층·기후변화대응기술·연료전환기술 ; 삼상슬러리 기포탑에서 액상의 표면장력이 열전달 계수에 미치는 영향

임호 ( Ho Lim ),임대호 ( Dae Ho Lim ),진해룡 ( Hae Ryong Jin ),강용 ( Yong Kang ),정헌 ( Heon Jung ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.3

산업현장에서 자주 접하는 액상의 물성인 표면장력이 상대적으로 작은 액상으로 구성된 삼상슬러리 기포탑에서 총 괄 열전달 특성을 고찰하였다. 기포탑 내부의 열전달 현상은 기포탑 내부의 수직 열원과 기포탑 간의 열전달계를 구성 하여 고찰하였으며 열전달 계수는 정상상태에서 열원표면의 온도와 기포탑 내부의 평균 온도의 차를 측정하여 결정하 였다. 기체유속(UG), 슬러리 상에 포함된 고체입자의 분율(CS) 그리고 연속 액상의 표면장력(σ L)이 기포탑 내부의 총 괄 열전달 계수(h)에 미치는 영향을 규명하였다. 기포탑 내부 열원 표면과 기포탑 벌크영역 간의 온도차는 시간의 변 화에 따른 온도차 요동을 측정하여 그 평균값으로 결정하였다. 기포탑 내부 열원표면과 기포탑 벌크 영역 간의 온도차 요동은 연속 액상의 표면장력이 감소할수록 진폭이 감소하였으며 온도차의 평균값도 감소하였다. 내부 수직 열원과 기 포탑 간의 총괄 열전달 계수는 기체의 유속과 슬러리 상에 포함된 고체입자의 분율이 증가함에 따라 증가하였으며 연 속 액상의 표면장력이 증가함에 따라 감소하였다. 표면장력이 물보다 작은 연속 액상의 기포탑에서 측정된 총괄 열전 달 계수는 본 연구의 범위 내에서 실험변수와 무차원군의 상관식으로 나타낼 수 있었다. Characteristics of overall heat transfer were investigated in a three-phase slurry bubble column with relatively low surface tension media, which has been frequently encountered in the fields of industry. The heat transfer phenomena was examined in the system which was composed of a coaxial vertical heater and a proper of bubble column. The heat transfer coefficient was estimated from the measured mean value of temperature difference between the heater surface and the column proper at the steady state condition. Effects of gas velocity (UG), solid fraction in the slurry phase (CS) and surface tension (σ L) of continuous liquid media on the overall heat transfer coefficient (h) in the bubble column were determined. The mean value of temperature difference was estimated from the data of temperature difference fluctuations with a variation of time. The amplitude and mean value of temperature difference fluctuations with respect to the elasped time appeared to decrease with decreasing the surface tension of liquid phase. The overall heat transfer coefficient between the immersed heated and the bubble column increased with an increase in the gas velocity or solid fraction in the slurry phase, but it decreased with an increase in the surface tension of continuous liquid media, The overall heat coefficient in the slurry bubble column with relatively low surface tension media was well correlated in term of operating variables and dimensionless groups within this experimental conditions.

마이크로 액적/기포 유동반응기에서 ZnO 입자의 연속제조 특성

이승호 ( Seung Ho Lee ),양시우 ( Si Woo Yang ),임대호 ( Dae Ho Lim ),유동준 ( Dong Jun Yoo ),이찬기 ( Chan Ki Lee ),강경민 ( Gyung Min Kang ),강용 ( Yong Kang ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.5

직경이 0.03 m이고 높이가 1.5 m인 마이크로 액적/기포 유동반응기에서 ZnO 입자의 연속제조 특성을 검토하였다. 마이크로 액적을 운반하는 기체의 속도는 6.0 L/min, 전구체 중 Zn이온의 농도는 0.4 mol/L로 유지하였다. ZnO 입자의 합성을 위한 반응의 온도(973 K~1,273 K)와 마이크로 기포의 유속 (0~0.4 L/min)이 합성된 ZnO 입자의 기공 특성에 미치는 영향을 고찰하였다. 본 연구의 실험범위에서 ZnO 입자의 합성온도는 1,073 K가 합성된 ZnO 입자의 기공을 극대화하는데 최적이었다. 또한, 반응기에서 연속 제조되는 ZnO 입자의 평균크기는 반응온도가 증가함에 따라 감소하였으며 입자의 표면은 점점 매끄럽게 단순화되었다. 반응기 내부에 마이크로 기포를 유입함으로써 유입하지 않는 경우와 비교하여 합성된 ZnO 입자 내부에 기공을 효과적으로 형성시킬 수 있었으며, 평균 BET면적을 58%까지 증가시킬 수 있었다. 마이크로 액적/기포 유동반응기를 사용하여 연속 합성한 ZnO 입자의 평균입도는 반응온도에 따라 1.25~1.75 μm이었다. Characteristics of continuous preparation of ZnO powder were investigated in a micro drop/bubble fluidized reactor of which diameter and height were 0.03 m and 1.5 m, respectively. The flow rate of carrier gas for transportation of precursors to the reactor was 6.0 L/min and the concentration of Zn ion in the precursor solutions was 0.4 mol/L, respectively. Effects of reaction temperature (973 K~1,273 K) and flow rate of micro bubbles (0~0.4 L/min) on the pore characteristics of prepared ZnO powder were examined. The optimum reaction temperature for the maximum porosity in the ZnO powder was 1,073 K within this experimental condition. The mean size of ZnO powder prepared continuously in the reactor decreased but the surface of the powder became smooth, with increasing reaction temperature. The injection of micro bubbles into the reactor could enhance the formation of pores in the powder effectively, and thus the mean BET surface area could be increased by up to 58%. The mean size of prepared ZnO powder was in the range of 1.25~1.75 μm depending on the reaction temperature.

고점성 낮은표면장력 매체 기포탑에서 열전달

김완태 ( Wan Tae Kim ),임대호 ( Dae Ho Lim ),강용 ( Yong Kang ) 한국화학공학회 2014 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.52 No.4

고점성이며 낮은 표면장력 매체로 구성된 기포탑에서 축방향 국부 열전달 계수와 총괄 열전달 계수에 대해 고찰하였다. 기체공탑유속(0.02~0.10 m/s), 액체 점도(0.1~0.3 Pa·s) 그리고 액체 표면장력(66.1~72.9×10-3 N/m)이 국부 및 총괄 열전달 계수에 미치는 영향을 검토하였다. 열전달 영역은 기포탑 내부 열원과 기포탑 간의 열전달계로 구성하였다. 즉, 기포탑의 중앙에 수직 열원을 설치하여 내부 열원으로 하였다. 열전달 계수는 주어진 운전조건에서 열원에 제공되는 열량과 내부 열원과 기포탑 간의 온도차를 연속적으로 측정하여 결정하였다. 국부 열전달 계수는 기체공탑유속이 증가함에 따라 증가하였으나 기체 분산판으로 부터의 축방향 거리가 증가함에 따라, 액체의 표면장력이 증가함에 따라 감소하였다. 총괄 열전달 계수는 기체공탑유속이 증가함에 따라 증가하였으나 액상의 점도와 표면장력이 증가함에 따라서는 감소하였다. 총괄 열전달 계수는 기체공탑유속, 액상의 점도와 표면장력의 함수로 상관계수 0.91의 상관식을 얻을 수 있었으며 넛셀 수, 레이놀즈 수, 플란틀 수 그리고 웨버 수의 함수로 상관계수 0.92의 상관식으로 나타낼 수 있었다. Axial and overall heat transfer coefficients were investigated in a bubble column with relatively high viscous and low surface tension media. Effects of superficial gas velocity (0.02~0.1 m/s), liquid viscosity (0.1~0.3 Pa·s) and surface tension (66.1~72.9×10-3 N/m) on the local and overall heat transfer coefficients were examined. The heat transfer field was composed of the immersed heater and the bubble column; a vertical heater was installed at the center of the column coaxially. The heat transfer coefficient was determined by measuring the temperature differences continuously between the heater surface and the column which was bubbling in a given operating condition, with the knowledge of heat supply to the heater. The local heat transfer coefficient increased with increasing superficial gas velocity but decreased with increasing axial distance from the gas distributor and liquid surface tension. The overall heat transfer coefficient increased with increasing superficial gas velocity but decreased with increasing liquid viscosity or surface tension. The overall heat transfer coefficient was well correlated in terms of operating variables such as superficial gas velocity, liquid surface tension and liquid viscosity with a correlation coefficient of 0.91, and in terms of dimensionless groups such as Nusselt, Reynolds, Prandtl and Weber numbers with a correlation of 0.92;

가압 삼상슬러리 기포탑의 설계 및 Scale-up을 위한 수력학적 Similarity 해석

서명재 ( Myung Jae Seo ),임대호 ( Dae Ho Lim ),진해룡 ( Hae Ryong Jin ),강용 ( Kang Yong ),정헌 ( Heon Jung ),이호태 ( Ho Tae Lee ) 한국화학공학회 2009 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.47 No.6

실시간 박테리아 감지를 위한 정전용량방식의 MEMS 바이오센서

서혜경 ( Hye Kyoung Seo ),임대호 ( Dae Ho Lim ),임미화 ( Mi Hwa Lim ),김종백 ( Jong Baeg Kim ),신전수 ( Jeon Soo Shin ),김용준 ( Yong Jun Kim ) 한국센서학회 2008 센서학회지 Vol.17 No.3

가압 삼상슬러리 기포탑에서 직경변화에 따른 기체-액체 물질전달 특성

서명재 ( Myung Jae Seo ),임대호 ( Dae Ho Lim ),신익상 ( Ik Sang Shin ),손성모 ( Sung Mo Son ),강용 ( Yong Kang ) 한국화학공학회 2009 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.47 No.4