Subrata Kumar Majumder

Knowledge of mixing phenomena is of great value in the mineral and other chemical and biochemical industries. This work aims to analyze the quality of mixedness (QM), the intrinsic mass transfer (MT) number, and the MT efficiency based on information entropy theory in the counter-current microstructured slurry bubble column. A thorough analysis is conducted to assess the effects of particle loading, gas and slurry velocity, and axial variation on the QM. The range of gas velocity, slurry velocity, particle size, and particle loading was 0.011–0.075 m/s, 0.018–0.058 m/s, 242.72–408.31 μm, and 15.54–88.94 kg/m³, respectively. QM is a time-dependent parameter, and the concept of contact time has been used for scale-up purposes. The maximum QM was achieved at dimensionless times of 0.40 × 10⁻³, 0.15 × 10⁻³, and 0.85 × 10⁻³ for the maximum superficial gas velocity, particle loading, and axial height, respectively. The gas velocity positively influenced both the intrinsic MT number and its efficiency. In contrast, the slurry velocity and particle loading had a negative effect. The present theoretical analysis will pave the path for industrial process intensification in counter-current flow systems.

The formation of gas hydrates in surface production equipment is common and poses a significant loss to the oil and gas industry sectors. It arises primarily in the pipeline located beneath sea level, and this causes equipment blockages, increasing the operational cost. Most drilling processes incorporate thermodynamic inhibitors such as methanol, ethylene glycol, and triethylene glycol to address these issues. One method to study this relationship is by developing an empirical correlation to predict the hydrate equilibrium condition. In the current work, new empirical correlations for organic and inorganic gas hydrates in pure water and thermodynamic inhibitors are developed. It was observed that the overall mean deviation between the experimental data and the predicted correlations for organic and inorganic gas hydrates in pure water was 5.61% and 3.27%, respectively. Similarly, the overall mean deviation for CO₂ in MeOH, EG, and TEG was 5.77%, 8.90%, and 2.09%, respectively. In the case of CH₄ and C₂H₆ in TEG, the overall mean deviation was 2.03% and 2.16%, respectively. The developed correlations are in good agreement with the experimental data in the literature. The present work may be helpful in predicting the various gas hydrate equilibrium conditions, especially in natural gas production.

The recovery of coal particles in a flotation column was investigated to determine its dependency on the type of frother, particle size, and gas and feed velocities. The kinetics of the cumulative recovery was established. The induction time and flotation rate constant were analyzed based on the recovery, incorporating the stability, attachment, and collision efficiencies of the particles with the bubbles. An inverse relationship between recovery and induction time was observed. Recovery of the particles was noticed to increase with superficial air velocity and frother dose, while it decreased with increasing particle size and feed circulation velocity. The induction time decreases with increasing superficial air velocity and frother dose but increases with increasing particle size and feed circulation velocity. Low induction time and high recovery were observed in the cationic frother. Small particles with low induction time can be captured with ease and have excellent selectivity. A generalized correlation for the induction time was proposed based on experiments under different operating conditions. The presented research will be beneficial in terms of increasing the transport efficiency of flotation systems.

The flow of bubbles in a two-phase system has great implications in chemical, petrochemical, and biochemical applications. This work enunciates the measurement of bubble size distribution and bubble aspect ratio in three-different axial zones in the countercurrent flow mode with a gas and liquid velocity range of 0.044–0.321 and 0.019–0.058 m/s, respectively. Bubble size is measured by the photographic technique. The bubble aspect ratio and bubble size distribution results reveal that the impact of gas and liquid velocities is significant on the Sauter mean bubble size. The Sauter mean bubble size increases as the gas velocity increases, whereas it decreases with the liquid velocity. The Sauter mean bubble diameter ranges from 2.65 to 6.16 mm. The distribution of bubble sizes follows the LogLogistic probability density function. In addition, a correlation is also proposed for the interpretation of bubble diameter in terms of Reynolds number and Froude number. The bubble aspect ratio changes with axial zones and gas and liquid velocities. Experiments reveal that the bubble aspect increases with liquid velocity while decreasing with gas velocity and axial zones. The bubble aspect ratio correlations are developed in terms of Eötvös and Reynolds numbers. The present results will be helpful for the process intensification of bubble-aided two-phase flow applications.