Longitudinal dispersion coefficient of liquid in three-phase fluidized bed for gas-liquid-solid systems.

Kato, Yasuo; Morooka, Shigeharu; Koyama, Makoto; Kago, Tokihiro; Yang, Shou-Zhi

doi:10.1252/jcej.18.313

Cited by 15 publications

(5 citation statements)

References 1 publication

(2 reference statements)

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“…It is seen that the experimental values of E z (for probe 1, at H/W = 0.95) are close to those calculated by the correlations of Deckwer et al 75 (with AARE = 16.114%), Miyauchi et al 76 (with AARE = 16.073%), and Towell 77 (with AARE = 15.016%). It is also noticed that the E z values obtained from the correlation of Deckwer et al, 78 Dobby and Finch, 79 Laplante et al, 80 Kato et al, 81 and Miyauchi et al 76 are higher than the present experimental values, while the values obtained by correlations of Shawaqfeh, 82 Shah et al, 7 Cruz, 83 Muroyama et al, 84 Nedeltchev et al, 85 Lim et al, 86 Kang and Kim, 87 and Wadaugsorn et al 31 underpredict the E z . The deviation of the values of the present experiment and the other correlations is due to different experimental conditions, operating variables, physical properties of the system, geometric variables, and operating modes.…”

Section: Variation Of the Transverse Slurry Dispersionsupporting

confidence: 81%

Dispersion Characteristics in a Counter-Current Microstructured Slurry Bubble Column and Its Analysis Based on the Turbulence and Circulation

Prakash

Majumder

Singh

2020

Ind. Eng. Chem. Res.

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The slurry bubble column has gained the attention of researchers over the years because of its wide application in various processes in the chemical and mineral industries. This work aims to quantify the degree of axial and transverse slurry dispersion in a counter-current microstructured slurry bubble column within the ranges of particle concentration of 0.5–3.0 wt %, particle size of 63–408 μm, superficial gas velocity of 0.011–0.074 m/s, and slurry velocity of 0.018–0.058 m/s. The residence time distribution (RTD) technique by online conductivity measurement was used to study the dispersion phenomena at different axial and transverse positions in the column. The axial and transverse slurry dispersion coefficients were found within the ranges of 9.12–137.23 and 12.63–141.83 cm2/s, respectively. Both the coefficients increase with the superficial gas and slurry velocities and the particle diameter but decreases with the particle concentration. The transverse slurry dispersion coefficient was 3.35–38.79% higher than the axial slurry dispersion coefficient. A model was developed to interpret the intensity of the dispersion based on liquid turbulence and circulation. The dispersion due to circulation strongly depends on the slurry velocity relative to the superficial gas velocity. The degree of dispersion was also analyzed by the velocity distribution model. The present study gives insight into process intensification and modeling of the counter-current slurry bubble column.

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Section: Variation Of the Transverse Slurry Dispersionsupporting

confidence: 81%

Dispersion Characteristics in a Counter-Current Microstructured Slurry Bubble Column and Its Analysis Based on the Turbulence and Circulation

Prakash

Majumder

Singh

2020

Ind. Eng. Chem. Res.

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“…air-surfactant fluidized beds of nylon and glass beads with the porous distributor exhibit similar heat-transfer behavior.The heat-transfer coefficient initially decreases with the liquid velocity and then either increases or remains constant with U, at higher liquid velocities. The initial decrease in the heat-transfer coefficient with increasing liquid velocity corresponds to the transition from incipient to fully fluidized state Kato and Morooka (1982). reported similar heat-transfer be-Variation of heat-transfer coefficient with the gas velocity in an air-surfactant fluidized bed of nylon beads with the porous distributor.…”

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confidence: 78%

Heat transfer in three‐phase fluidization and bubble‐columns with high gas holdups

1993

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Bubble column and three-phase fluidized bed reactors have wide applications in biotechnological and petroleum processes (Deckwer, 1985;Fan, 1989). In such biotechnological processes as fermentation and waste water treatment, small bubbles of oxygen and/or nitrogen are introduced in the column to enhance oxygen transfer and to ensure the stability of immobilized cell particles. In addition, tiny bubbles are formed by such gases as C02, H2, and CHI, which are produced during the biological process due to the production of surface active compounds. The presence of these small bubbles causes an increase in the gas holdup of the system. High gas holdups are also characteristics of industrial processes such as coal liquefaction and hydrotreating of residual oils. Tarmy et al. (1984) studied high gas holdup behavior in pilot-and large-scale coal liquefaction reactors and reported gas holdup as high as 50 ~0 1 % .Such high gas holdups were attributed to the formation of small rigid bubbles with noncoalescing tendencies due to high-pressure and high-temperature operations. Blum and Toman (1977) reported a maximum gas holdup of 0.5 in a hightemperature (100 to 350"C, 6.9 MPa) three-phase fluidized bed methanator. Thus, good understanding of the transport properties of three-phase fluidized beds with high gas holdups is essential to the design, control and optimum operations of the commercial reactors employed in the above-mentioned processes.High gas holdups in laboratory scale under ambient conditions can be obtained by the addition of surfactants in airwater and air-water-solid systems. Such high gas holdups in the presence of a surfactant simulate the conditions commonly encountered in coal liquefaction and petroleum resids hydrotreating operations. Levich (1962) reported that the presence of surfactants induces a noncoalescing tendency in the gasliquid flow and reduces the bubble rise velocity significantly by creating surface tension gradients that cause tangential stresses along the bubble surface. The addition of surfactants to pure water systems, however, increases the system complexity by altering the average bubble size, gas holdup, and bubble-particle interactions. This causes the flow regime transition which affects the heat-transfer behavior of the system. In addition to the dependence on liquid properties, operating

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“…The axial dispersion coefficient D ax, i was calculated based on the Chung and Wen correlation P e = L ε e d p ( 0.2 + 0.011 R e 0.48 ) …”

Section: Models and Theorymentioning

confidence: 99%

“…The axial dispersion coefficient D ax,i was calculated based on the Chung and Wen correlation 39 − , due to the presence of the Donnan potential between the solution and the resin phase. 40,41 However, the saturation adsorption Q M (1.7527 mmol/g) of HSO 4 − was higher than that of SO 4 2− (0.5653 mmol/g), which illustrated that HSO 4 − had a significantly higher adsorption capacity compared to that of SO 4 2− on the Gel-Sax resin.…”

Section: Dissociation Equilibriamentioning

confidence: 99%

Exploration of the Mechanism of Acid Tailing on Strong-Base Ion Exchangers: Modeling and Experiment

Kou,

Chen,

Zhang

et al. 2023

Ind. Eng. Chem. Res.

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A new DTSD-S model (combining the ion-exclusion chromatography-Donnan model and two-step dissociation of sulfuric acid) was developed herein to predict C P,SOd 4 2− and C P,HSOd 4 − in the resin pores during the adsorption and desorption processes. A comparison of C P,SOd 4 2− and C P,HSOd 4 − during the desorption process showed that the tailing phenomenon was affected by the acid concentration. When C H + was lower than 0.9 mol/L, the predominant species in the resin pores was SO 4 2− instead of HSO 4 − , which verified that the sulfuric acid tailing was caused by SO 4 2−. The results of energy-dispersive spectroscopy and X-ray photoelectron spectroscopy of the resins after adsorption showed the existence of extra S element, which further verified that the existence of SO 4 2− was the main factor that caused the acid tailing. Finally, we concluded that the acid tailing was inevitable and suggested that one could recover a high H 2 SO 4 concentration by using a high feed acid concentration.

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Longitudinal dispersion coefficient of liquid in three-phase fluidized bed for gas-liquid-solid systems.

Cited by 15 publications

References 1 publication

Dispersion Characteristics in a Counter-Current Microstructured Slurry Bubble Column and Its Analysis Based on the Turbulence and Circulation

Dispersion Characteristics in a Counter-Current Microstructured Slurry Bubble Column and Its Analysis Based on the Turbulence and Circulation

Heat transfer in three‐phase fluidization and bubble‐columns with high gas holdups

Exploration of the Mechanism of Acid Tailing on Strong-Base Ion Exchangers: Modeling and Experiment

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