Ranjeet P. Utikar

Hydrodynamic Simulation of Cyclone Separators

Cyclone separators are commonly used for separating dispersed solid particles from gas phase. These devices have simple construction; are relatively inexpensive to fabricate and operate with moderate pressure losses. Therefore, they are widely used in many engineering processes such as dryers, reactors, advanced coal utilization such as pressurized and circulating fluidized bed combustion and particularly for removal of catalyst from gases in petroleum refinery such as in fluid catalytic cracker (FCC). Despite its simple operation, the fluid dynamics and flow structures in a cyclone separator are very complex. The driving force for particle separation in a cyclone separator is the strong swirling turbulent flow. The gas and the solid particles enter through a tangential inlet at the upper part of the cyclone. The tangential inlet produces a swirling motion of gas, which pushes the particles to the cyclone wall and then both phases swirl down over the cyclone wall. The solid particles leave the cyclone through a duct at the base of the apex of the inverted cone while the gas swirls upward in the middle of the cone and leaves the cyclone from the vortex finder. The swirling motion provides a centrifugal force to the particles while turbulence disperses the particles in the gas phase which increases the possibility of the particle entrainment. Therefore, the performance of a cyclone separator is determined by the turbulence characteristics and particle-particle interaction.

Kafirin adsorption on ion-exchange resins: Isotherm and kinetic studies

Kafirin is a natural, hydrophobic and celiac safe prolamin protein obtained from sorghum seeds. Today kafirin is found to be useful in designing delayed delivery systems and coatings of pharmaceuticals and nutraceuticals where its purity is important and this can be obtained by adsorptive chromatography. This study is the first scientific insight into the isotherm and kinetic studies of kafirin adsorption on anion- and cation-exchange resins for practical applications in preparative scale chromatography. Adsorption isotherms of kafirin were determined for five anion- and two cation-exchange resins in batch systems. Isotherm parameters such as maximum binding capacity and dissociation constant were determined from Langmuir isotherm, and adsorptive capacity and affinity constant from Freundlich isotherm. Langmuir isotherm was found to fit the adsorption equilibrium data well. Batch uptake kinetics for kafirin adsorption on these resins was also carried out and critical parameters including the diffusion coefficient, film mass transfer coefficient, and Biot number for film-pore diffusion model were calculated. Both the isotherm and the kinetic parameters were considered for selection of appropriate resin for kafirin purification. UNOsphere Q (78.26 mg/ml) and Toyopearl SP-650M (57.4 mg/ml) were found to offer better kafirin binding capacities and interaction strength with excellent uptake kinetics under moderate operating conditions. With these adsorbents, film diffusion resistance was found to be major governing factor for adsorption (Bi<10 and δ<1). Based on designer objective function, UNOsphere Q was found be best adsorbent for binding of kafirin. The data presented is valuable for designing large scale preparative adsorptive chromatographic kafirin purification systems.

Solid oxide fuel cell reactor analysis and optimisation through a novel multi-scale modelling strategy

The simulation of a solid oxide fuel cell (SOFC) that incorporates a detailed user-developed model was performed within the commercial flowsheet simulator Aspen Plus. It allows modification of the SOFCs governing equations, as well as the configuration of the cells fuel-air flow pattern at the flowsheet level. Initially, the dynamic behaviour of single compartment of a cell was examined with a 0D model, which became the building block for more complex SOFC configurations. Secondly, a sensitivity analysis was performed at the channel (1D) scale for different flow patterns. Thirdly, the effect of fuel and air flow rates on the predominant distributed variables of a cell was tested on a 2D assembly. Finally, an optimisation study was carried out on the 2D cell, leading to a robust, optimal air distribution profile that minimises the internal temperature gradient. This work forms the foundation of future stack and system scale studies.

Reverse phase HPLC method for detection and quantification of lupin seed γ-conglutin

A simple, selective and accurate reverse phase HPLC method was developed for detection and quantitation of γ-conglutin from lupin seed extract. A linear gradient of water and acetonitrile containing trifluoroacetic acid (TFA) on a reverse phase column (Agilent Zorbax 300SB C-18), with a flow rate of 0.8ml/min was able to produce a sharp and symmetric peak of γ-conglutin with a retention time at 29.16min. The identity of γ-conglutin in the peak was confirmed by mass spectrometry (MS/MS identification) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The data obtained from MS/MS analysis was matched against the specified database to obtain the exact match for the protein of interest. The proposed method was validated in terms of specificity, linearity, sensitivity, precision, recovery and accuracy. The analytical parameters revealed that the validated method was capable of selectively performing a good chromatographic separation of γ-conglutin from the lupin seed extract with no interference of the matrix. The detection and quantitation limit of γ-conglutin were found to be 2.68μg/ml and 8.12μg/ml respectively. The accuracy (precision and recovery) analysis of the method was conducted under repeatable conditions on different days. Intra-day and inter-day precision values less than 0.5% and recovery greater than 97% indicated high precision and accuracy of the method for analysis of γ-conglutin. The method validation findings were reproducible and can be successfully applied for routine analysis of γ-conglutin from lupin seed extract.

Heat Transfer and Dynamics of Impinging Droplets on Hot Horizontal Surfaces

Abstract In fluidised bed olefin polymerisation reactors, a liquid monomer is added for enhancing heat removal (super-condensed mode). This broadens the operating window and can substantially increase the capacity of a given reactor hardware. Design and location of liquid injection nozzles play a key role in dictating the performance of condensed mode operations. An understanding of the fundamental characteristics of droplet impingement onto solid particles is critical for proper design. In this paper, we study the interactions between liquid droplets and hot solid surfaces across various boiling regimes. High-speed digital imaging is used to capture the droplet vaporisation process. Water droplets impacting on a solid wall with different Weber numbers are investigated. The effect of various parameters such as surface and initial droplet diameter, liquid velocity and surface tension is studied. Experimental data of dynamic drop impact on a flat hot surface are reported. A phenomenological model is developed to describe the droplet vaporisation phenomena in single phase and nucleate boiling regimes. The results from the phenomenological model are compared with the experimental data presented here and the experimental results reported in the literature. The study provides useful clues for understanding the real case when solid particles are much larger than the injected liquid droplets.

Lupin seed hydrolysate promotes G-protein-coupled receptor, intracellular Ca2+ and enhanced glycolytic metabolism-mediated insulin secretion from BRIN-BD11 pancreatic beta cells

Lupin seed proteins have been reported to exhibit hypoglycaemic effects in animals and humans following oral administration, however little is known about its mechanism of action. This study investigated the signalling pathway(s) responsible for the insulinotropic effect of the hydrolysate obtained from lupin (Lupinus angustifolius L.) seed extracts utilizing BRIN-BD11 β-cells. The extract was treated with digestive enzymes to give a hydrolysate rich in biomolecules ≤7 kDa. Cells exhibited hydrolysate induced dose-dependent stimulation of insulin secretion and enhanced intracellular Ca2+ and glucose metabolism. The stimulatory effect of the hydrolysate was potentiated by depolarizing concentrations of KCl and was blocked by inhibitors of the ATP sensitive K+ channel, Gαq protein, phospholipase C (PLC) and protein kinase C (PKC). These findings reveal a novel mechanism for lupin hydrolysate stimulated insulin secretion via Gαq mediated signal transduction (Gαq/PLC/PKC) in the β-cells. Thus, lupin hydrolysates may have potential for nutraceutical treatment in type 2 diabetes.

Simulation and Analysis of Carbon-in-Leach (CIL) Circuits

Abstract Carbon in leach (CIL) is an important process in gold processing involving simultaneous leaching and adsorption. The process holds the key to profitability in gold extraction. While the mechanism of leaching and adsorption are well known, the effect of different operating and design parameters on the CIL circuit performance is still empirical. The focus of this paper is to study the effect of parameters like cyanide concentration, oxygen concentration and mean particle diameter on the overall efficiency of CIL circuit. A dynamic model based on first principles is developed for the entire CIL circuit. Suitable kinetic models for both leaching and adsorption are adopted from the literature. Customizable simulator is written in MATLAB to simulate the model. Simulation results are first validated using previously published results. The validated model is then used to perform sensitivity studies on different parameters that affect the gold extraction process. The model can be used for controlling the operating parameters and to optimize the CIL circuit in order to achieve higher efficiency.