• Title, Summary, Keyword: Bubble Column

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Analysis of Acoustic Back Scattering from Bubble Columns in Water (수중 기포기둥에 의한 음파의 후방 산란특성 분석)

  • Park, K.-J.;Yoon, S.-W.;Roy, R.A.
    • The Journal of the Acoustical Society of Korea
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    • v.10 no.2
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    • pp.36-43
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    • 1991
  • Acoustic backscattering from a buble column in water was studied theoretically and experimentally. For theoretical analysis a general scattering theory was used by assuming the bubble column to be lumped element scatterer which can be characterized by its shape, void fraction and dimensions. When the void fraction is less than 1% and the incident frequency is higher than individual bubble resonance frequencies, the experimental results show that the acoustic backscattering from a bubble column depends mainly on the void fraction rather than the individual bubble sizes. It was also theoretically and experimentally observed that the acoustic backscattering levels were increased and their peaks moved to the lower frequency regin by raising the void fraction of bubble column.

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Continuous rapid Production of Soy Sauce by Coimmobilized Mixed Culture system of Zygosaccharomyces rouxii and Candida versatilis using Air Bubble Column Reactor (Zygosaccharomyces rouxii와 Candida versatilis의 동시 고정화에 의한 Air Bubble Column Reactor에서 간장의 연속적 속성 생산)

  • 류병호
    • KSBB Journal
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    • v.18 no.6
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    • pp.455-460
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    • 2003
  • This study was designed to find out the rapid fermentation of soy sauce from koji hydrolyzates using air bubble column reactor packed with coimmobilized mixed culture system. Continuous ripid production was performed by coimmobilized Z. rouxiii BH-90 and C. versatilis BH-91. Coimmobilized cells of Zygosaccharomyces rouxii BH-90 and Candida versatilis BH-91 mixture cells in the column reactor produced 2.8% ethyl alcohol and 18mg/L 4-ethylguaiacol over 96 hours under the optimal conditions. Coimmobilized cells produced 2.30∼2.4% ethyl alcohol during 30 days, and decreased gradually from 40 days to 70 days. Also coimmobilized cells produced 4-ethylguaiacol at the constant rate of 16∼18mg/L and decreased gradually after 40 days. Final product of soy sauce contained 2.4% ethyl alcohol and 18mg/L 4-ethylguaiacol. However, amino acid compositions of soy sauce were consisted of predominantly glutamic acid, leucin, arginine, aspartic acid, Iysine and valine, which were more than 50% of total amino acid.

The Experimental Study on Deflation of Air for Top-Down Joint area (역타기둥 이음부의 공기포 배출을 위한 실험적 연구)

  • 임형일;이동하;백민수;박병근;이영도;정상진
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.763-768
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    • 2001
  • The purpose of this study is to research a specific material characteristics of top down concrete at column joint and to reduce column joint opening. Based on the established top down study, the experiment to apply an real construction case is performed. When the concrete placed into joint of top down column, raised air bubble is left as opening. This study is examined the incomplete packing reason in the top down column and found to air deflation method. The result of study is below (1) As the method to minimize column opening caused from confined air, it is required that an air exhaust port installation in joint column. (2) From air exhaust port installation, most of air bubble in column part is exhausted. As the concrete placing height is going up, air bubble size is going smaller.

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Characteristics of Bubble Flow Behavior in a Gas-liquid Countercurrent Bubble Column Bioreactor (기-액 향류 흐름 기포탑 생물 반응기에서 기포 흐름 거동 특성)

  • Son, Sung-Mo;Kang, Suk-Hwan;Lee, Chan-Gi;Jung, Sung-Hyun;Kang, Yong;Kim, Sang-Done
    • Korean Chemical Engineering Research
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    • v.43 no.2
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    • pp.272-277
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    • 2005
  • Characteristics of bubbling behavior and bubble properties were investigated in a gas-liquid countercurrent bubble column of in diameter 0.152 m and 3.5 m in height, respectively. Effects of gas and liquid velocities and bubble distribution mode(even, wall-side, central or asymmetric distribution) on the bubble properties such as chord length, frequency, rising velocity and holdup in the reactor were measured and examined by means of dual resistivity probe method. The bubble size, frequency and holdup increased with increasing gas($U_G$) or liquid velocity($U_L$). The rising velocity of bubbles increased with increasing $U_G$, whereas decreased with increasing $U_L$. The uniformity of bubble size distribution and bubble holdup decreased when the distribution mode of bubbles at the gas distributor was changed from even to wall-side, central or asymmetric. The central distribution of bubbles was better than asymmetric mode but worse than wall-side distribution, in considering the bubble holdup and uniformity of distribution.

Enhancing Photon Utilization Efficiency for Astaxanthin Production from Haematococcus lacustris Using a Split-Column Photobioreactor

  • Kim, Z-Hun;Park, Hanwool;Lee, Ho-Sang;Lee, Choul-Gyun
    • Journal of Microbiology and Biotechnology
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    • v.26 no.7
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    • pp.1285-1289
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    • 2016
  • A split-column photobioreactor (SC-PBR), consisting of two bubble columns with different sizes, was developed to enhance the photon utilization efficiency in an astaxanthin production process from Haematococcus lacustris. Among the two columns, only the smaller column of SC-PBR was illuminated. Astaxanthin productivities and photon efficiencies of the SC-PBRs were compared with a standard bubble-column PBR (BC-PBR). Astaxanthin productivity of SC-PBR was improved by 28%, and the photon utilization efficiencies were 28-366% higher than the original BC-PBR. The results clearly show that the effective light regime of SC-PBR could enhance the production of astaxanthin.

Characteristics of Gas-liquid Mass Transfer and Interfacial Area in a Bubble Column

  • Lim, Dae Ho;Yoo, Dong Jun;Kang, Yong
    • Korean Chemical Engineering Research
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    • v.53 no.3
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    • pp.315-320
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    • 2015
  • Characteristics of gas-liquid mass transfer and interfacial area were investigated in a bubble column of diameter and height of 0.102 m and 2.5 m, respectively. Effects of gas and liquid velocities on the volumetric gas-liquid mass transfer coefficient ($k_La$), interfacial area (a) and liquid side true mass transfer coefficient ($k_L$) were examined. The interfacial area and volumetric gas-liquid mass transfer coefficient were determined directly by adopting the simultaneous physical desorption of $O_2$ and chemical absorption of $CO_2$ in the column. The values of $k_La$ and a increased with increasing gas velocity but decreased with increasing liquid velocity in the bubble column which was operated in the churn turbulent flow regime. The value of $k_L$ increased with increasing gas velocity but did not change considerably with increasing liquid velocity. The liquid side mass transfer was found to be related closely to the liquid circulation as well as the effective contacting frequency between the bubbles and liquid phases.

Analysis of Hydrodynamic Similarity of Pressurized Three-Phase Slurry Bubble Column for its Design and Scale-up (가압 삼상슬러리 기포탑의 설계 및 Scale-up을 위한 수력학적 Similarity 해석)

  • Seo, Myung Jae;Lim, Dae Ho;Jin, Hae Ryong;Kang, Yong;Jung, Heon;Lee, Ho Tae
    • Korean Chemical Engineering Research
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    • v.47 no.6
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    • pp.720-726
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    • 2009
  • Hydrodynamic similarity was investigated in pressurized three-phase slurry bubble columns by selecting the bubble holdup and pressure drop as objective functions, for the effective design and scale-up of it. In addition, effects of operating variables on the bubble holdup with variation of column diameter were also analyzed. Gas velocity($U_G$), viscosity(${\mu}_{SL,eff}$) and surface tension(${\rho}_{SL}$) of slurry phase, density difference between the slurry and gas phases(${\rho}_{SL}-{\rho}_G$) depending on the operating pressure, pressure drop per unit length(${\Delta}P/L$), column diameter(D) and gravitational acceleration(g) were chosen as governing parameters in determining the bubble holdup and pressure drop in the column. From the dimensional analysis, four kinds of dimensionless groups were derived from the 7 parameters and 4 fundamental dimensions. Effects of dimensionless groups such as Reynolds, Froude and Weber numbers on the bubble holdup in the column were discussed. The pressure drop and bubble holdup could be predicted from the correlation of dimensionless groups effectively, which could be used as useful information for the design and scale-up of pressurized slurry bubble columns.

Relationship between void fraction and mixing in bubble column flow (기포탑 유동에서의 기포분율과 혼합정도의 상관관계)

  • Zahidul, Islam MD;Lee, Jubeom;Park, Hyungmin
    • Journal of the Korean Society of Visualization
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    • v.15 no.1
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    • pp.41-46
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    • 2017
  • Control of mixing and transport processes are the key areas that can be benefited by understanding the hydrodynamics in gas-liquid two-phase flows. In particular, the enhanced bubble-induced liquid-phase mixing is known to be a function of void fraction distribution, gas phase velocity and so on. To further our insight on the characteristics of the liquid-phase mixing induced by the bubbles, in the present study, we experimentally investigate the mixing performance of a rectangular bubble column while changing the void fraction from 0.006 to 0.075%. A shadowgraphy technique is used to measure the gas-phase properties such as void fraction and size/velocity of bubbles. On the other hand, we use dye visualization with low diffusive buoyant dye to directly measure the level of mixing. Finally, we confirm that the time taken for full mixing scales with the inverse of volume void fraction.

Effects of Liquid Surface Tension on the Heat Transfer Coefficient in a Three-Phase Slurry Bubble Column (삼상슬러리 기포탑에서 액상의 표면장력이 열전달 계수에 미치는 영향)

  • Lim, Ho;Lim, Dae Ho;Jin, Hae-Ryong;Kang, Yong;Jung, Heon
    • Korean Chemical Engineering Research
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    • v.50 no.3
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    • pp.499-504
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    • 2012
  • 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 ($U_G$), solid fraction in the slurry phase ($C_S$) and surface tension (${\sigma}_L$) 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.

Axial and Radial Gas Holdup in Bubble Column Reactor

  • Wagh, Sameer M.;Ansari, Mohashin E. Alam;Kene, Pragati T.
    • Bulletin of the Korean Chemical Society
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    • v.35 no.6
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    • pp.1703-1705
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    • 2014
  • Bubble column reactors are considered the reactor of choice for numerous applications including oxidation, hydrogenation, waste water treatment, and Fischer-Tropsch (FT) synthesis. They are widely used in a variety of industrial applications for carrying out gas-liquid and gas-liquid-solid reactions. In this paper, the computational fluid dynamics (CFD) model is used for predicting the gas holdup and its distribution along radial and axial direction are presented. Gas holdup increases linearly with increase in gas velocity. Gas bubbles tends to concentrate more towards the center of the column and follows a wavy path.