P. S. T. Sai

Bio: P. S. T. Sai is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Anhydrous & Sodium sulfate. The author has an hindex of 4, co-authored 6 publications receiving 93 citations. Previous affiliations of P. S. T. Sai include Council of Scientific and Industrial Research.

Flow pattern of the phases and liquid saturation in gas‐liquid concurrent downflow through packed beds

Abstract: Flow pattern was visually observed for non-foaming and foaming Newtonian and non-Newtonian liquids under concurrent downflow with air in packed beds using different configurations of column geometry and packins. Flow maps delineating the different flow regions were presented based on the present study as well as that of earlier investigations. The total and dynamic liquid saturation were experimentally measured and correlations were presented in terms of (i) the Lockhart-Martinelli parameter, χ, and (ii) the flow variables. On a observe de maniere visuelle les profils d'ecoulement pour des liquides newtoniens ou non newtoniens, moussants et non moussants, dans le cas d'un acoulement descendant de liquides et d'air dans un lit a garnissage. On a fait varier la gaomatrie de la colonne et le garnissage. Les diagrammes d'ecoulement delimitant les differentes regions d'ecoulement, presentes dans cette etude, s'appuient sur le travail actuel ainsi que sur des recherches anterieures. On a mesure de maniere experimentale la saturation du liquide dynamique et to tale, et les correlations sont presentes en fonction (i) du parametre Lockhart-Martinelli, χ, et (ii) des variables d'ecoulement.

Prediction of axial velocity profiles and solids hold‐up in a rotary kiln

Abstract: Axial bed depth profiles were experimentally measured in a rotary kiln containing ilmenite particles under steady state and transient conditions. The variables include feed rate of solids, inclination and rotational speed of the kiln. and dam height. The variation of the axial velocity with kiln axis was estimated. The semi-experimental model proposed by Perron and Bui (1990) was modified to include the effect of the variables of the present study. The mean residence time of solids was estimated from the fractional hold-up and expressed in terms of the process variables. The transients induced by a step change in any of the operating conditions were measured as variation of discharge rate of solids with time. On a mesure experimentalement les profils de profondeur d'un lit axial dans un four de regeneration contenant des particules d'ilmenite dans des conditions stationnaire et transitoire. Les variables incluent la vitesse d'alimentation des solides, l'inclinaison et la vitesse rotationnelle du four et la hauteur du serrement. On a mesure la variation de la vitesse axiale avec l'axe du four. Le modele semi-experimental propose par Perron et Bui (1990) a ete modifie de facon a inclure l'effet des variables precedentes. Le temps moyen de sejour des solides a ete estime a partir de la retention fractionnelle et exprimee en termes de variables de procede. Les transitoires induites par un changement en escalier de chacune des conditions de fonctionnement ont ete mesurees en termes de variation de la vitesse d'evacuation des solides en fonction du temps.

A Model for Residence Time Distribution of Solids in a Rotary Kiln

Abstract: A five-parameter model for residence time distribution of low-density particles in a bed of high-density particles in a rotary kiln is derived based on combinations of flow regimes in several sub-regions. The parameters of the model are the number of turnover stages, the cascade volume fraction, the Peclet number, the dead volume fraction in cascade region, and the cross-flow ratio. The effect of feed rate of solids, rotational speed and inclination of the kiln on the model parameters is evaluated. On a calcule d'apres des combinaisons de regimes d'ecoulement dans plusieurs sous-regions un modele a cinq parametres pour la distribution de temps de sejour de particules de faible masse volumique dans un lit de particules de masse volumique elevee dans un four rotatif. Les parametres du modele sont le nombre d'etages de rotation, la fraction volumique de l'etage, le nombre de Peclet, la fraction de volume mort de l'etage et le debit transversal. On a etudie l'effet du debit d'alimentation en solides, de la vitesse de rotation et de l'inclinaison du four sur les parametres du modele.

Esterification of ethanol with sulfuric acid: A kinetic study

Abstract: Experiments were conducted in a stirred batch reactor under isothermal conditions for obtaining kinetics of the esterification reaction between ethanol and sulfuric acid. Reactive adsorption technique was employed to enhance the conversion. Anhydrous sodium sulfate was used as an adsorbing agent to remove the water formed during the reaction. The variables include the mole ratio of ethanol to sulfuric acid, reaction temperature, purity of the reactants, and the amount of adsorbing agent. The reaction was found to be reversible and second order at low mole ratios, and irreversible and first order at high mole ratios. The kinetic parameters of the rate law were estimated. A possible reaction mechanism was proposed and validated with the experimental data. The effect of the mole ratio of reactants, anhydrous sodium sulfate loading, and purity of the reactants on the yield of ethyl hydrogen sulfate was studied, using full-factorial search and optimized conditions were obtained by the method of steepest ascent. More precise optimum conditions were obtained using the Box-Wilson composite method.

Transient response of granular bed motion in rotary kiln

Abstract: A non linear model proposed by Perron and Bui (1994), which focuses on the dynamics of slow mode to predict the transient response induced by step changes in operating variables in the motion of the granular bed in a rotary kiln, was validated for different experimental conditions. The variables include feed rate of solids, inclination and rotational speed of the kiln, and dam height. The validity of the model for step changes in two or more variables at a time was also verified. On a valide pour differentes conditions experimentales, un modele non lineaire propose par Perron et Bui (1994), reposant sur la dynamique du mode lent, dans le but de predire la reponse transitoire induite par des changements de phases dans les variables de fonctionnement dans le deplacement du lit granulaire dans un four rotatif. Ces variables comprennent la vitesse d'alimentation des solides, l'inclinaison et la vitesse rotationnelle du four et la hauteur de la digue. La validite du modele pour les changements de phases en deux ou plusieurs variables en meme temps a egalement ete verifiee.

Hydrodynamics in a cocurrent gas-liquid trickle bed at elevated pressures

Abstract: Data on design and operation of trickle beds at elevated pressures are scarce. In this study the influence of the gas density on the liquid holdup, the pressure drop, and the transition between trickle and pulse flow has been investigated in a tricklebed reactor operating up to 7.5 MPa and with nitrogen or helium as the gas phase. Gas-liquid interfacial areas have been determined up to 5.0 MPa by means of CO2 absorption from CO2/N2 gas mixtures into amine solutions. A comparison of the results from nitrogen as the gas phase to those of helium shows that at equal gas densities the hydrodynamic states are the same. The gas-liquid interfacial area increases when operating at higher gas densities. When the determined dimensionless interfacial areas agl/as are all within the range 0.25-0.8, the trickle-bed reactor is suggested to operate in the trickle-flow regime. The gas density has a strong influence on the liquid holdup. Due to the higher pressure gradients at elevated gas densities, the liquid holdup decreases noticeably. Besides, the boundary between the trickle-flow and pulse-flow regime shifts toward higher liquid throughputs: the region for trickle-flow operationg becomes larger. For the liquid holdup and the pressure gradient in the trickle-flow regime, correlations derived based on dimensionless numbers can be applied to high-prssure trickle beds.