Showing papers in "Chemical Engineering Science in 1996"

TL;DR: In this paper, a discrete particle model of a gas-fluidized bed was developed and in this the two-dimensional motion of the individual, spherical particles was directly calculated from the forces acting on them, accounting for the interaction between the particles and the interstitial gas phase.

TL;DR: A new framework for the discretization of continuous population balance equations (PBEs) is presented and a numerical technique has been developed that is applicable to binary or multiple breakage, aggregation, simultaneous breakage and aggregation and yields excellent predictions in all cases.

TL;DR: In this paper, a hydrate formation mechanism is reviewed to suggest the new inhibition method and two apparatuses are presented for the best kinetic inhibitors among approximately 1500 chemicals, including poly(N-vinylcaprolactam) (PVCAP), poly(n)-vinylpyrrolidone (N-PVC), N-dimethylaminoethyl-methacrylate (VC-713), and N-vinYL-poly(nvinylpolymorphic acid) (VP/VC).

TL;DR: In this article, the state of micromixing at molecular scale in stirred reactors has been studied using the Dushman reaction between the iodide and iodate in an alkaline medium.

TL;DR: In this article, a coupled transport and reaction model is formulated to investigate the effects of various parameters on biomass pyrolysis, taking into account formation of chars, tars and gases through mechanisms including both primary reactions of virgin biomass degradation and secondary reactions of the primary tar.

TL;DR: The Karhunen-Loeve decomposition can be used in the control or parameter estimation of nonlinear distributed parameter systems defined on irregular domains, which are the cases with many practical engineering systems.

TL;DR: In this article, the authors provide an overview of the different polymerization processes and mathematical modeling approaches and also address the problems related with the computer-aided design, monitoring, optimization and control of polymerization reactors.

TL;DR: In this article, the existence, location, and size of segregated regions in the flow were observed for both unbaffled and baffled vessels stirred by either radial or axial flow impellers.

TL;DR: In this article, the reaction rate constants for the reaction between CO 2 and the sterically hindered amine, 2-amino-2-methyl-1-propanol (AMP), were determined from measurements of the rate of absorption of CO 2 into both aqueous and nonaqueous (1-Propanol) AMP solutions.

TL;DR: In this paper, the identity and composition of petroleum's countless molecular components is beyond the resolution of analytical techniques, and models of petroleum refining processes must have a molecular basis to be useful in predicting the molecular composition of products and their physical and quality properties required by industry specifications.

TL;DR: In this article, a system of parallel-competing reactions producing iodine was developed to study partial segregation in stirred tanks and the experimental results, obtained in 1 and 20 litre stirred tanks, were interpreted by the incorporation model, relating the micromixedness ratio, α, to the ratio of reaction time to micromixing time.

TL;DR: In this article, a review of gas-solid fluidization at elevated temperatures and pressures is presented, where the application of purely hydrodynamic fluid-bed stability criteria to account for the transition from non-bubbling to the bubbling state is described and compared with the expected effect of interparticle forces on this transition.

TL;DR: In this paper, the authors present a method for calculating the absolute exergy of multicomponent liquid, vapour or two-phase flows, which is different from those described by most authors in that it enables a clear division of the total exery of a material stream into three terms such that the exergy change of mixing is calculated separately from the chemical and the physical exergy.

TL;DR: In this article, an extended UNIQUAC model is used to describe phase behaviour (VLE, SLE) and thermal properties (heat of mixing, heat capacity) for aqueous solutions containing ions like (Na +, K +, H + ) (Cl −, NO 3 −, SO 4 2−, OH −, CO 3 2−, HCO 3 − ).

TL;DR: In this article, a differential particle model is applied to a single particle, which includes mass and heat transport, transport through a product layer and chemical kinetics, but heat transport and product layer diffusion are of minor importance.

TL;DR: In this paper, a study on the hydrodynamics of a two-dimensional slurry bubble column was carried out with air/paraffin oil slurries with solids concentrations of 0, 28.3 and 38.6 vol% of porous silica particles (mean diameter of 38 μm).

TL;DR: In this paper, a mathematical programming-based approach to computer-aided molecular design is presented using a set of structural groups, the problem is formulated as a mixed integer nonlinear program in which discrete variables represent the number of each type of structural group present in the candidate compound.

TL;DR: A critical review of information on heat transfer between the furnace and enclosing walls of a circulating fluidized-bed boiler is presented in this paper, where empirical correlation based on measurements in large commercial units are proposed for design calculations.

TL;DR: In this paper, the results about the esterification of acetic acid with ethanol on a highly cross-linked sulphonic ion-exchange resin (Amberlyst 15) in a continuous Simulated Moving Bed Reactor (SMBR) laboratory unit are reported.

TL;DR: In this paper, the effects of mixing factors (stirrer speed, feed time, feed location and viscosity) on particle size distribution (PSD) in the precipitation of BaSO4 conducted in a semi-batch stirred tank reactor were investigated.

TL;DR: In this paper, the three-dimensional turbulent flow field in unbaffled tanks stirred by radial impellers was numerically simulated by a finite-volume method on body-fitted, co-located grids.

TL;DR: In this paper, the phase distributions within the network are visualized and compared to numerical pore network simulations, and the influence of the viscous forces, which are not taken into account in the simulator, is discussed.

TL;DR: A strategy for synthesizing a reaction system to meet various business and technical objectives is outlined in this paper, which replaces the conventional paradigm of the sequential evolution of the micro-reactor, bench-scale reactor, pilot plant reactor and commercial reactor.

TL;DR: In this paper, the alkylation of isobutane with 2-butene is carried out using a zeolitic catalyst in a well stirred slurry reactor, and the authors show that the key elements to extend catalyst lifetime appear to be (i) a zeolite (e.g. Beta) with high activity/stability, and high acid site density (low Si/Al ratio) and (ii) a low olefin concentration throughout the reactor, which is achieved by intensive reactor mixing.

TL;DR: In this paper, a population balance modeling approach for modeling multistage olefin polymerization processes using catalyst residence time as the main coordinate is presented, where a variety of reactor systems can be modeled each with unique residence time distributions and having different internal and external residence time distribution.

TL;DR: In this paper, the current capabilities of CFD for chemical reactor engineering are illustrated by considering a series of examples from industrial practice, and a discussion of future needs and expectations of the chemical processing industry with respect to CFD modelling, mainly focussing on multiphase flow.

TL;DR: In this article, a simple one-dimensional model for a three-way catalytic converter is briefly described and solved, and the discrepancies are essentially attributed to the accuracy limit of the time-resolved input data, to the extreme sensitivity of the reactions about light-off temperature, to a possible internal diffusion limitation at high temperature, and to some transient state catalytic process which was neglected in the model.

TL;DR: In this article, a model was developed to predict the preferential movement of particles in the shearing active layer of a rotary kiln to determine the extent of fine particle segregation.

TL;DR: The results with industrially important biocatalysts underscore the advantages of this ‘evolutionary’ approach to protein engineering.