Gautam Kundu

Modeling of a novel multi-stage bubble column scrubber for flue gas desulfurization

Abstract Desulfurization of flue gases from various chemical industries in a techno-econo-enviro manner is a demanding technology. The concentrations of sulfur dioxide in and around these plants overshoot the danger point. In the present investigation, an attempt has been made for wet flue gas desulfurization using water as the absorbing medium in a newly developed scrubber. Prediction of SO 2 removal efficiency is very important for selection of pollution control equipment. The present paper reports on both the modeling and detailed experimental investigations on the scrubbing of SO 2 in the modified multi-stage bubble column scrubber (MMSBCS) using water. Experimental results show that almost 100% removal efficiency of SO 2 , can be achieved in the present system without additives or pre-treatment. A comparison has been made between the predicted and experimental percentage removal efficiency of SO 2 . Experimental results are in excellent agreement with the predicted values from the model.

Experimental studies on a co-current gas-liquid downflow bubble column

Abstract Two-phase co-current vertical downflow systems offer some distinct advantages, like uniform and finer bubbles, greater residence time, negligible coalescence of the bubles etc. In the present work the hydrodynamics of a vertical downflow bubble column fitted with an ejector have been evaluated. Experimental studies have been carried out to evaluate the total pressure gradient and gas holdup. Similarity analysis was used for analysing the data in order to overcome the complex flow behaviour in the system. Correlations have been developed to predict pressure drop and holdup of gas as a function of different physical and dynamic variables.

Gas holdup and entrainment characteristics in a modified downflow bubble column with Newtonian and non-Newtonian liquid

Abstract Gas entrainment and holdup characteristics have been studied in a downflow bubble column with both Newtonian and non-Newtonian liquid. Aqueous CMC solutions at different concentration were used as a non-Newtonian and water as Newtonian liquid. In the present system, use of plunging liquid jet and ejector were synchronized to obtain significant entrainment and dispersion of gas into liquid. The effects of operating variables such as liquid flowrate, nozzle diameter, separator pressure, etc. on gas entrainment and holdup were investigated. Flow behaviours of non-Newtonian liquids were compared with that of Newtonian liquid. Furthermore, gas holdup data were analysed by slip velocity and drift flux model and found to be in good agreement with other reported results. The gas holdup of the present system was also correlated by some dimensionless groups of the independent parameters.

Mass Transfer in High-Pressure Bubble Columns with Organic Liquids

Oxygen desorption from organic liquids (ethanol (96%), 1-butanol, toluene) and water into nitrogen gas has been studied with an optical sensor. Gas hold-ups and volumetric mass transfer coefficients have been determined in the pressure range of 1-10 bar. In this range both quantities are found to increase with the gas density to the power of 0.24. However, by comparison with literature data and on theoretical grounds, the gas density effect can be shown to depend on the gas velocity and on gas density itself. The effect becomes negligible at gas velocities below 0.01 m/s and at gas densities below about 0.1 kg/m 3 .

A NOVEL MODIFIED MULTI-STAGE BUBBLE COLUMN SCRUBBER FOR SO2 REMOVAL FROM INDUSTRIAL OFF GASES

The emission of SO2 from various chemical industries, always occur in association with particulate and most of the time the concentrations of sulfur dioxide in and around these plants overshoot the danger point. In the present investigation, an attempt has been made for wet flue gas de-sulfurization using water as the absorbing medium in a newly designed scrubber. Prediction of SO2 removal efficiency is very important for selection of a pollution control equipment. The present paper reports on the detailed experimental investigations on the scrubbing of SO2 in the modified multi-stage bubble column scrubber (MMSBCS) using water. Experimental results show that almost 100% removal efficiency of SO2, can be achieved in the present system. A correlation has been developed for predicting the percentage removal efficiency of sulfur dioxide. Experimental results are in excellent agreement with the correlation. *Patent pending.

Development of Manufacturing Technology for Cab Front Using Resin Transfer Molding Process

The development of a new composite product through resin transfer molding (RTM) process requires the identification of an effective injection strategy and optimization of the process variables and raw material parameters of the manufacturing process. This article presents an effective manufacturing technology for a cab front model using RTM isothermal mold-filling simulation technique. The simulations performed were based on the finite element method for which a commercial RTM simulation package was utilized. A number of isothermal mold-filling simulations using different injection strategies and process variables were carried out. Injection strategy using constant flow or pressure was executed to find optimum locations for injection ports and air vents requiring minimum mold -fill time. The effect of process variables, such as injection pressure, and raw material parameters, such as resin viscosity and mat permeability, on the mold-filling time was also studied. The simulation results show that the injection strategy of four injection points on the front face and four vents at the corners of the cab front with constant pressure of 5 atm delivers an optimum mold-fill time of 32 min without dry spots.

Gas-Newtonian and Gas-Non-Newtonian Slug Flow in Vertical Pipe, Part I: Gas Holdup Characteristics

Studies on two-phase gas-liquid co-current flow with non-Newtonian liquid system has attracted the attention of researchers over the years due to its wide-spread applications and importance in various different processes in chemical and biochemical industries, such as the process of two-phase in oil and gas wells, transportation systems of crude and refined products, and food processing in biochemical engineering and bio-reactors. This article examines the sole objective of experimental studies on gas holdup in Newtonian and non-Newtonian liquid slug flow within a range of gas and liquid flowrate of 0.5×10-4 to 1.92×10-4 m3/s and 1.6×10-4 to 6.7×10-4 m3/s, respectively. The present data was analyzed with different models. To predict gas holdup, correlations have been developed for individual system with Newtonian and non-Newtonian liquid. A general correlation was also developed to predict the gas holdup combing both the Newtonian and non-Newtonian liquid systems. The study of the gas holdup characteristics in gas-Newtonian and non-Newtonian liquid systems may give insight into a further understanding and modeling of this slug flow characteristics in industrial applications.

Stoffübergang in Druckblasensäulen mit organischen Flüssigkeiten

Der Gasgehalt und der Stoffubergang in Blasensaulen wurden experimentell untersucht. Die Blasenstruktur wurde mit dynamischen Entgasungsmessungen ermittelt. Dazu wird die Begasung der Blasensaule gestoppt und die Druckdifferenz im unteren Saulenabschnitt mittels Drucktransmittern verfolgt. Der Stoffubergangszahl wurde mittels Desorption von Sauerstoff ermittelt. Dabei kam eine optische Messmethode zum Einsatz, die auf Fluoreszenzloschung eines angeregten Farbstoffes beruht. Der Farbstoff wurde direkt in der Flussigkeit gelost, um die Ansprechzeit des Sensors zu minimieren. Als Flussigkeiten wurden Decalin, Ethanol, 1-Butanol, Ethylenglycol, Toluol sowie Wasser eingesetzt. Gemessen wurde in einem Temperaturbereich von 10°C bis 80°C. So konnten die Stoffparameter in folgenden Bereichen variiert werden: Viskositat: 0,401 – 31,5 mPas; Oberflachenspannung: 19,9 – 74,2 mN/m und Dichte 793 – 1117 kg/m³. Als Gase wurden Stickstoff und Helium im Druckbereich 1 – 51 bar eingesetzt. Damit kamen Gasdichten im Bereich von 0,174 – 59,47 kg/m³ zur Anwendung. Es kamen zwei Blasensaulen mit unterschiedlichen Fullhohen und Durchmessern zum Einsatz. Als Begaser wurden Einzellochbegaser, Lochplatten und Sinterplatten eingesetzt. Die Ergebnisse werden mit Korrelationen aus der Literatur verglichen.

Gas holdup characteristics in a flotation column with different solids

ABSTRACT This paper presents the effect of process variables on gas holdup. It was measured by volume expansion method in a continuously operating flotation column using coal and sphalerite. It was observed that addition of both solids reduced gas holdup. Increase in solid concentration and particle size reduced gas holdup. Also, increase in gas velocity and frother concentration increased the gas holdup as amount of gas increased and bubble surface property favored the formation of small bubbles. An empirical mathematical model was developed to predict gas holdup. The predicted results were in good agreement with the experimental and available published data.

Prediction of Gas Holdup in a Flotation Column by Artificial Neural Network

Flotation column is one of the separation technologies investigated for removal of gangue mineral from coal fines. The effect of process variables, such as gas flow rate, feed flow rate, and frother dosage on gas holdup, were investigated. In this study, the measurement of gas holdup in presence of coal fines was carried out in a laboratory flotation column by a phase separation method. Detailed parametric study was performed to observe the effect of slurry concentration, gas flow rate, slurry flow rate, and frother concentration on gas holdup. An artificial neural network approach with three layers was systematically employed to predict gas holdup using some of the experimental results. The rest of the experimental results were successfully compared with the model predictions with less than 5% average error. In this work, emphasis was made on random selection of training data and small network. The developed trained network was also able to capture the non-linear prediction of gas holdup with new operating conditions that were not used in the training process and enhanced the physical understanding of the process.