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

Abstract

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.

Mixing Characteristics of a Liquid–Liquid Dispersion in a Jet-Driven Mixing Column: Developed for the Separation of Organic Pollutants

“…The analysis of the ADC is done using the mechanistic model. 52 The present system assumes constant circulation of a liquid mixture for each operating condition in the column. The difference in upward and downward velocity results in a radial exchange between the phases.…”

“…Liquid recirculation is attributed to the dynamic variable (jet velocity) and the system’s physical properties. The analysis of the ADC is done using the mechanistic model . The present system assumes constant circulation of a liquid mixture for each operating condition in the column.…”

“…A mass balance equation for a tracer at any point l in downward flow is expressed as where C df , u df , and a df are the concentration of the tracer, the jet velocity, and the area of the downward flow regime, respectively. The mass balance for upward flow tracer concentration is expressed as where “uf” refers to the upward flow regime and the parameter λ represents the liquid–liquid exchange between the upward flow and the downward flow. If the upward flow and the downward flow of the liquid–liquid phase interaction are significant, the difference in concentration ( C uf – C df ) is negligible.…”

Prediction of intensity of dispersion in surfactant solutions in vertical sparged bubble column

“…The enhancement of velocity distribution parameter with turbulence is also reported. 22,24,25 There is no general trend in literature for velocity distribution parameter. It may be due to the fact that the distribution of velocity is complex in different bubble column and other parameters like column diameter, phase velocity, types of gas distributor, range of gas liquid and gas flow influence the value of velocity distribution parameter.…”

“…The velocity distribution model has been also solicited for three-phase bubble column. 23 Prakesh et al 24 applied velocity distribution approach to predict the intensity of dispersion by the degree of phase exchange in three phase system. Sangtam et al 25 implemented velocity distribution model to interpret dispersion due to the phase circulation inside the jet-driven mixing column.…”