Juray De Wilde

Bio: Juray De Wilde is an academic researcher from Université catholique de Louvain. The author has contributed to research in topics: Fluidized bed & Fluidization. The author has an hindex of 23, co-authored 85 publications receiving 3969 citations. Previous affiliations of Juray De Wilde include United States Department of Energy & Council of Scientific and Industrial Research.

Chemical Reactor Analysis and Design

Abstract: CHEMICAL ENGINEERING KINETICS Elements of Reaction Kinetics Kinetics of Heterogeneous Catalytic Reactions Transport Processes with Reactions Catalyzed by Solids Noncatalytic Gas-Solid Reactions Catalyst Deactivation Gas-Liquid Reactions ANALYSIS AND DESIGN OF CHEMICAL REACTORS The Fundamental Mass, Energy, and Momentum Balance Equations The Batch and Semibatch Reactors The Plug Flow Reactor The Perfectly Mixed Flow Reactor Fixed Bed Catalytic Reactors Nonideal Flow Patterns and Population Balance Models Fluidized Bed and Transport Reactors Multiphase Flow Reactors Author Index Subject Index.

Dynamic methods for catalytic kinetics

Abstract: The application of various transient techniques in heterogeneous catalysis (TAP, step-response experiments, SSITKA, TEOM), with the aim to determine reaction kinetics for design purposes, is presented for several cases. These cases, comprising catalytic cracking, diffusion in zeolites, simultaneous NO, and SO, removal, syngas production from methane by chemical looping and selective catalytic reduction of NOx, show that transient techniques can be well used for the purpose of rapid determination of the reaction kinetics without the laborious classical approach of steady-state kinetic measurements and without the need of high levels of sophistication to interpret and process the experimental data. In this respect transient kinetics deserve, next to fundamental catalysis studies, more frequent application in design Studies for industrially relevant reaction systems. Topics and challenges for further developments in transient studies are indicated. (c) 2008 Elsevier B.V. All rights reserved.

Effect of Clustering on Gas−Solid Drag in Dilute Two-Phase Flow

Abstract: When coarse-grid calculations in two-phase flow are performed, mesoscale fluctuations, such as clusters, cannot be explicitly captured. Their impact on macroscale fluctuations, however, has to be taken into account by the introduction of an appropriate closure model. A new closure model to describe gas−solid drag is introduced. The effect of particle clustering on the interphase momentum-transfer coefficient is taken into account by introducing the concept of effective drag. Clustering results in a decreasing value of the interphase momentum-transfer coefficient because the contribution of particles in the cluster is considered to be negligible in dilute phase flow. For solids fractions greater than 1%, clustering phenomena become increasingly important, resulting in an important decrease of the interphase momentum-transfer coefficient. Calculation results for a riser reactor, both neglecting and including the effects of clustering on the gas−solid drag, are presented and validated with experimental data....

Advances in mathematical modeling of fluidized bed gasification

Abstract: Gasification is the thermochemical conversion of solid fuel into the gas which contains mainly hydrogen, carbon monoxide, carbon dioxide, methane and nitrogen. In gasification, fluidized bed technology is widely used due to its various advantageous features which include high heat transfer, uniform and controllable temperature and favorable gas–solid contacting. Modeling and simulation of fluidized bed gasification is useful for optimizing the gasifier design and operation with minimal temporal and financial cost. The present work investigates the different modeling approaches applied to the fluidized bed gasification systems. These models are broadly classified as the equilibrium model and the rate based or kinetic model. On the other hand, depending on the description of the hydrodynamic of the bed, fluidized bed models may also be classified as the two-phase flow model, the Euler–Euler model and the Euler–Lagrange model. Mathematical formulation of each of the model mentioned above and their merits and demerits are discussed. Detail reviews of different model used by different researchers with major results obtained by them are presented while the special focus is given on Euler–Euler and Euler–Lagrange CFD models.

Rotating fluidized beds in a static geometry: Experimental proof of concept

Abstract: The new concept of a rotating fluidized bed in a static geometry (RFB-SG) is presented. The rotating motion of the particle bed and the tangential fluidization of the solids are obtained by the tangential injection of the fluidization gas via multiple gas inlet slots in the outer cylindrical wall of the fluidization chamber. The solids experience a radially outwards centrifugal force. The gas, on the other hand, is forced to move radially inwards towards a chimney with one or more outlet slots, creating a radially inwards gas-solid drag force and fluidizing the solids radially. The new fluidization concept is experimentally investigated and proven using one and the same non-optimized fluidization chamber design with either large diameter, low density polymer particles or small diameter, higher density Alumina particles. The fluidization chamber is operated in continuous mode, at different solids loadings and in the vertical and horizontal position. (c) 2007 American Institute of Chemical Engineers.

Overview of the Fundamental Reactions and Degradation Mechanisms of NOx Storage/Reduction Catalysts

Abstract: Over the last several years, nitrogen oxide(s) (NOx) storage/reduction (NSR) catalysts, also referred to as NOx adsorbers or lean NOx traps, have been developed as an aftertreatment technology to reduce NOx emissions from lean‐burn power sources. NSR operation is cyclic: during the lean part of the cycle, NOx are trapped on the catalyst; intermittent rich excursions are used to reduce the NOx to N2 and restore the original catalyst surface; and lean operation then resumes. This review will describe the work carried out in characterizing, developing, and understanding this catalyst technology for application in mobile exhaust‐gas aftertreatment. The discussion will first encompass the reaction process fundamentals, which include five general steps involved in NOx reduction to N2 on NSR catalysts; NO oxidation, NO2 and NO sorption leading to nitrite and nitrate species, reductant evolution, NOx release, and finally NOx reduction to N2. Major unresolved issues and questions are listed at the end of ...

A review of the current state of biodiesel production using enzymatic transesterification

Abstract: Enzymatic biodiesel production has been investigated intensively, but is presently employed industrially only in a 20,000 tons/year pilot plant in China (Du et al. [2008] Appl Microbiol Technol 79(3):331-337). This review presents a critical analysis of the current status of research in this area and accentuates the main obstacles to the widespread use of enzymes for commercial biodiesel transesterification. Improved results for enzymatic catalysis are seen with respect to increased yield, reaction time and stability, but the performance and price of the enzymes need further advances for them to become attractive industrially for biodiesel production. Critical aspects such as mass transfer limitations, use of solvents and water activity are discussed together with process considerations and evaluation of possible reactor configurations, if industrial production with enzymes is to be carried out. Results of published studies on the productivity of enzymes are also presented and compared to the use of chemical catalysts.

Insight into the adsorption kinetics models for the removal of contaminants from aqueous solutions

Abstract: The past decade has seen a boom in environmental adsorption studies on the adsorptive removal of pollutants from the aqueous phase. A large majority of works treat kinetic modeling as a mere routine to describe the macroscopic trend of adsorptive uptake by using common models, often without careful appraisal of the characteristics and validity of the models. This review compiles common kinetic models and discusses their origins, features, modified versions (if any), and applicability with regard to liquid adsorption modeling for both batch adsorption and dynamic adsorption systems. Indiscriminate applications, ambiguities, and controversies are highlighted and clarified. The appropriateness of linear regression for correlating kinetic data is discussed. This review concludes with a note on the current scenario and the future of kinetics modeling of liquid adsorption.