bluuebunny/crossref_metadata_2025_split huggingface dataset:
From hygroscopic single particle to batch fluidized bed drying kinetics
Authors: Burgschweiger Jens , Groenewold Hans , Hirschmann Carola , Tsotsas Evangelos 
Published: March 2009

AbstractA new normalization concept for convective drying of hygroscopic particulates is introduced. Both, intraparticle drying kinetics and sorption equilibrium are considered separately, and integrated into a new heterogeneous fluid bed model for coupled heat and mass transfer. Experiments were carried out using spherical γ‐Al2O3 particles. Sorption isotherms, as well as drying curves, for single particles and fluidized beds have been measured. Batch fluid bed drying curves appear to be predictable on the basis of single particle and material equilibrium data and with the help of the model. All model parameters are directly taken, or estimated from fluidization literature, without any fitting.
MTBE synthesis in a novel riser simulator
Authors: De Lasa Hugo , Fournier Pierre , Prakash Anand , Solh Tarek El 
Published: March 2009

AbstractMTBE synthesis, from methanol and iso‐butylene, is studied in a novel Riser Simulator using a ZSM‐5 catalyst. Conditions selected for the operation of the Riser Simulator unit are as follows: 1‐5 catalyst/reactant ratios, 80 to 160°C temperatures, 1.09 methanol/iso‐butylene mol ratio, 25 to 34 kPa methanol partial pressures and 10 to 120 s reaction times. Injection of methanol, with enough time for the methanol to reach adsorption equilibrium, followed by an isobuty‐lene injection is found to be the best operating mode to achieve 100% iso‐butylene selectivity toward MTBE with 4 to 6.8% isobutylene conversions. With the gathered experimental data, a reaction rate model based on the Rideal‐Eley kinetic model is successfully developed.
Preparation of the Mn/γ‐Al2O3 acceptor for high temperature regenerative H2S removal
Authors: Liang Bin , Korbee Rob , Gerritsen Albert W. , Van Den Bleek Cor M. 
Published: March 2009

AbstractAn alumina supported manganese acceptor can be used for high temperature regenerative removal of hydrogen sulfide. Such an acceptor was prepared by a wet impregnation method on a 10 kg scale. A porous alumina carrier with a size of 50 to 70 microns was impregnated with a manganese acetate solution. The impregnation slurry was centrifuged and dried in a microwave oven. The impregnation parameters and drying conditions were investigated. It is shown that this impregnation process is dominated by the solution penetrating the pores. The manganese loading of the acceptor was estimated based on the concentration of the impregnating solution. This showed a good agreement with the results of AAS (Atom Absorption Spectrometer) measurements. The microwave drying time needed was calculated by a heat balance over the drying system. The preparation exhibited a good reproducibility and the acceptors prepared have better dispersion and less initial deactivation.
A sporulation kinetic model for batch growth of B. thuringiensis
Authors: Rivera David , Margaritis Argyrios , de Lasa Hugo 
Published: March 2009

AbstractB. thuringiensiscells evolve from vegetative cells to sporulated cells during batch growth. As a result, the classical model based on an exponential binary fission and the Monod equation has intrinsic limitations to describe the biomass concentration. A new kinetic model accounting for the spore formation process is presented in this study. This model considers that only the cells without a spore are able to contribute to the cell growth. This model also incorporates the spore formation process using a spore formation step and a specific spore formation rate constant. Classical and new model predictions are compared with batch experimental data. Results demonstrate that the classical model is unable to predict the experimental data and this is particularly true from the middle of the transition stage on. In contrast, the new sporulation kinetic model is able to predict the experimental data more accurately for the complete time span of the batch culture.
Thermal deactivation studies of coconut shell pyrolysis
Authors: Bandyopadhyay Swati , Chowdhury Ranjana , Biswas Gopal Krishna 
Published: March 2009

AbstractThe kinetics of pyrolysis of predried coconut shell sample has been investigated in the temperature range of 523 K to 1023 K in an inert atmosphere by captive sample technique. A kinetic scheme has been proposed where two parallel reactions are given for the production of volatiles and char. The reaction rate constants are found to decrease with high temperatures above 673 K due to chemical and physical changes of the reactant during devolatilisation reaction. Several deactivation models have been proposed to give good agreement with the experimental data.
Correlations for the particle deposition rate accounting for lift forces and hydrodynamic mobility reduction
Authors: Adomeit Philipp , Renz Ulrich 
Published: March 2009

AbstractA numerical procedure is presented which allows one to predict the deposition rate of microparticles suspended in a liquid flow onto the confining walls. Particle transport is not only diffusive but also affected by hydrodynamically induced lift force and reduced particle mobility. An appropriate expression for the lift‐induced migration is introduced into the numerical procedure. Its results agree quanititatively with previously published experimental data showing a significant effect of lift‐induced particle transport. Based on the numerical results algebraic correlations are obtained, which enable to calculate the particle deposition rate in situations where lift forces and mobility reduction diminishes the particle deposition rate.
Thermal resistance of steam‐generator tube deposits under single‐phase forced convection and flow‐boiling heat transfer
Authors: Turner Carl W. , Klimas Stan J. , Brideau Mike G. 
Published: March 2009

AbstractMeasurements were made of the thermal resistance of porous deposits of various thicknesses under both single‐phase forced convection and flow‐boiling conditions. Both synthetic deposits and deposits on tubes removed from operating steam generators were used in this investigation. The thermal resistance was modeled as the sum of two components: one associated with conduction through the porous deposit and a second associated with the effect of surface roughness. The conductive component of the thermal resistance was always positive, whereas surface roughness made a negative contribution to the thermal resistance, i.e., roughness enhanced the rate of heat transfer. Thermal conductivity of the porous deposits was higher for single‐phase forced convection, whereas the effect of deposit roughness on thermal resistance was higher under flow‐boiling conditions. The results are discussed in terms of the effect of composition, morphology, surface roughness, and the mode of heat transfer on the thermal resistance of porous deposit.
Kinetic modelling of oxygen dependence in oxidative dehydrogenation of propane
Authors: Creaser Derek C. , Hudgins Robert R. , Silveston Peter L. , Andersson Bengt 
Published: March 2009

AbstractSeveral Mars—Van Krevelen‐type redox kinetic models were developed for the catalytic oxidative dehydrogenation of propane and examined for their ability to predict high propene yields at low oxygen/propane feed ratios. The intent in this study was to use modelling as a means of extracting further mechanistic insight from experimental data rather than to identify the best model. Thus, a conventional redox model with a consecutive reaction mechanism and a single pathway for the production of carbon oxides predicts higher propene selectivity but only at the expense of low propane conversion. Experimental data indicated, however, that even at the same propane conversion, propene selectivity increased as the oxygen partial pressure was lowered. Models that successfully describe the data had an additional carbon oxide production path involving the reaction of propane with deeply oxidizing surface oxygen species. Kinetic models and experimental data examined do not fully resolve how these deeply oxidizing surface oxygen species are formed. However, they do reflect the accepted view that lattice oxygen selectively produces propene whereas more weakly bound surface adsorbed oxygen reacts to completely oxidize propane.
Degradation of solvolysis lignin using Lewis acid catalysts
Authors: Hepditch Mona M. , Thring Ronald W. 
Published: March 2009

AbstractAlcell‐derived lignin was depolymerized in a batch reactor using the Lewis acid catalysts NiCl2 and FeCl3. The objective was to investigate the use of Lewis acids in the production of useful liquid products directly from solvolysis lignin. The effects of reaction temperature, time and catalyst were studied on the conversion of this lignin to gas, solid and liquid products. Also, selected monomeric compounds in the ether solubles were monitored in terms of the variation in their yields with different reaction conditions. The highest conversions, 30% and 26% from Ni and Fe, respectively, were both attained at the reaction conditions of 305°C and 1 h reaction time. The Ni produced a somewhat higher yield of ether solubles, reflecting its slightly higher performance. Under the reaction conditions studied, both catalysts apparently favour condensation reactions leading to the formation of insoluble reactor residue from solvolysis lignin. Low quantities of monomeric compounds were produced, with phenols dominating over ketones and aldehydes for both catalysts.
New image analysis methods for the study of mixing patterns in stirred tanks
Authors: Guillard Fabrice , Trägårdh Christian , Fuchs Laszlo 
Published: March 2009

AbstractA method of treating data acquired with the planar laser‐induced fluorescence technique has been developed to visualize the topology of two‐dimensional concentration fields and to describe the dynamics of the coherent mixing structures identified. This method is based on a conditional binary transformation of the local concentration data, combined with a joint probability calculation. The methodology has been used to investigate the mixing in a stirred tank, at two injection port locations (in the bulk and in the impeller stream region). With bulk injection, a “folding phenomenon” of the coherent mixing structure was detected. Away from this port, large‐scale spatially periodic motion was identified, with a characteristic time of oscillation of the order of 2 to 3 s. With injection in the impeller stream region, no spatial instabilities of the coherent structure were detected. Local oscillations of the coherent mixing structure were found both on short and long time‐scales (i.e., ˜1 and ˜80 s).
Gas hold‐up in bubble columns: Operation with concentrated slurries versus high viscosity liquid
Authors: Krishna Rajamani , Urseanu Maria I. , De Swart Jeroen W. A. , Ellenberger Jürg 
Published: March 2009

AbstractThe hydrodynamics of bubble columns with concentrated slurries of paraffin oil (density, ρL = 790 kg/m3; viscosity, μL = 0.0029 Pa·s; surface tension, σ = 0.028 N·m1) containing silica particles (mean particle diameter dp = 38 μm) has been studied in columns of three different diameters, 0.1, 0.19 and 0.38 m. With increasing particle concentration, the total gas hold‐up decreases significantly. This decrease is primarily caused by the destruction of the small bubble population. The hold‐up of large bubbles is practically independent of the slurry concentration. The measured gas hold‐up with the 36% v paraffin oil slurry shows remarkable agreement with the corresponding data obtained with Tellus oil (ρL = 862 kg/m3; μL = 0.075 Pa·s; σ = 0.028 N·m−1) as the liquid phase. Dynamic gas disengagement experiments confirm that the gas dispersion in Tellus oil also consists predominantly of large bubbles. The large bubble hold‐up is found to decrease significantly with increasing column diameter. A model is developed for estimation of the large bubble gas hold‐up by introduction of an wake‐acceleration factor into the Davies‐Taylor‐Collins relation (Collins, 1967), describing the influence of the column diameter on the rise velocity of an isolated spherical cap bubble.
A new model for the propagation of jets in dilute gas‐solid crossflows
Authors: Indenbirken Matthias , Schneider Torsten , Siepmann Volker , Strauss Karl 
Published: March 2009

AbstractThe three‐dimensional propagation of a horizontal gas jet injected into a gas‐solid crossflow is described by a model based on the mass and momentum balances for both phases. The potential core close to the nozzle, the kidney‐shaped cross‐section of the jet and the region of rapidly increasing jet volume are taken into account. Viscous and turbulent stresses within the gas phase as well as the momentum exchange with the solid phase are considered. Several parameters are determined empirically by experimental data obtained by measurements in a dilute circulating fluidized bed. The comparison of calculated with experimental data shows good agreement concerning the shape of the jet axis and the solid phase concentration.
A rate—controlling step in langmuir—hinshelwood kinetic models
Authors: Belohlav Zdenek , Zamostny Petr 
Published: March 2009

AbstractLangmuir‐Hinshelwood models with and without rate controlling step assumptions have been compared. Hydrogenations of toluene, cinnamaldehyde and mixture of methylesters of fatty acids were used as model systems. Integral data were obtained in semibatch reactors. The proposed models have been simplified by neglecting statistically insignificant parameters. The predicted mixture composition and surface coverages have been compared and the reliability of parameter estimates tested.
Heat and mass transfer in granular potash fertilizer with a surface dissolution reaction
Authors: Pen Shi‐Wen , Besant Robert W. , Strathdee Graeme 
Published: March 2009

AbstractPotash is a widely used granular fertilizer and when exposed to high humidities it readily adsorbs water vapour forming a liquid electrolyte solution on each particle. Heat and mass transfer due to air flow through granular potash beds is studied experimentally and numerically. A one dimensional experimental setup is used to measure the temperature and air humidity response and mass gain of a potash bed subjected to a change in air flow. A porous media mathematical model is developed to predict the transient temperature and moisture content distributions. The processes are modelled as nonequilibrium heat and mass transfers between the porous solid and air flow gaseous phases. The state of the surface electrolyte solution is modelled by the thermodynamics of electrolyte solutions. Experimental and numerical results show non‐equilibrium internal moisture and heat transfer processes exist with significant differences in the pore air and particle temperature and surface relative humidity.
High temperature desulphurization by fine limestone during staged fluidized‐bed combustion
Authors: Khan Wasi Z. , Gibbs Bernard M. 
Published: March 2009

AbstractThis paper reviews the SO2 emission from a 0.3 m2 stainless‐steel fluidized‐bed combustor. Fine coal was premixed with fine limestone and fed pneumatically under the bed. The SO2 emission was found to depend largely on air staging ratio and bed temperature, which agrees with previous observations. The SO2 emission observed in sorbent‐free tests (reported earlier by Khan and Cibbs, 1995) was found to be proportional to the sulphur content of the fuel when limestone was added, the sulphur capture at a fixed Ca/S molar ratio was dependent on oxygen stoichiometry and bed temperature. Finely sized limestone enhanced the effectivity of the sorbent at low bed temperature and air staging ratio. During staged combustion, the combustion efficiency depended largely on primary air to coal ratio. Around 90% combustion efficiency was observed at 1 m/s fluidizing velocity which was reduced when fluidizing velocity was increased to 1.5 and 2 m/s. This reduction is due to increased elutriation of finer coal particles from the combustor.
A fluidized bed kinetic model for the fluorination of dissociated zircon
Authors: Moolman Francis Sean , Heydenrych Michael David 
Published: March 2009

AbstractA reaction kinetic model for the fluorination of plasma dissociated zircon (PDZ, or ZrO2.SiO2) with hydrogen fluoride was developed. The model uses reaction as rate‐limiting step, with a shrinking core of PDZ in a porous matrix of zirconia (ZrO2). This model was used to develop models for a multi‐stage fluidized bed reactor. These models facilitated the determination and design of an optimally configured multi‐stage fluidized bed reactor for the fluorination of PDZ. It was shown that a combination cross‐/countercurrent multi‐stage fluidized bed reactor could yield significant improvement over the conventional countercur‐rent multi‐stage fluidized bed reactor for certain reaction kinetic conditions.
Application of apdc coupled polyurethane foam sorbent for the removal and recovery of toxic heavy metals Hg, Cd and Pb from industrial effluents
Authors: Anjaneyulu Yerramilli , Rao Rachakulla Venkata Sambasiva 
Published: March 2009

AbstractA novel, highly stable, selective and efficient sorption medium was synthesized for the removal of toxic metals from industrial effluents by coupling a chelating agent Ammonium pyrrolidine dithiocarbamate (APDC) with flexible open cell polyether polyurethane foam. The performance efficiency of the new sorbent was evaluated by static and dynamic methods for removing toxic heavy metals Hg, Cd and Pb from effluents. In fixed bed downflow column studies, a quantitative uptake of Hg (II) 400 mg/L, Cd (II) and Pb (II) 60 mg/L was attained at flow rates of 3.68 L/m2s. The design parameters using the APDC‐PUF as sorption material for a batch reactor and for column reactor and cost effectiveness of the process were evaluated. The sorption potential of the APDC‐PUF was demonstrated for the treatment of real industrial wastes from a common effluent treatment plant, Chloro alkali industry and municipal sewage.
Comparison of experimental results and numerical predictions of drop diameter from a single submerged nozzle in a liquid‐liquid system
Authors: Hamad Faik A. , Khan Mohammed K. , Pierscionek Barbara K. , Bruun Hans H. 
Published: March 2009

AbstractThis paper presents a comparison of experimental results and numerical predictions of drop formation from a single submerged nozzle for a liquid‐liquid system. The theoretical model is a modification of previous models used for a two‐stage drop formation mechanism. The model has been tested against experimental data for kerosene drop formation in distilled water using a range of different nozzle diameters. In addition, our liquid‐liquid model has been compared with both experimental and predicted results from published literature. These comparisons demonstrate that for liquid‐liquid systems, the present predictions of drop diameter versus dispersed phase nozzle velocity are in overall agreement with both the present and previous experimental results. In addition, the present model predictions are more accurate than those of previous models for liquid‐liquid systems.
Scale‐up of single phase axial dispersion coefficients in batch and continuous oscillatory baffled tubes
Authors: Ni Xiongwei , De Gélicourt Yann Sommer , Baird Malcolm H. I. , Rao Nadella V. Rama 
Published: March 2009

AbstractThis note presents the development of a scale‐up correlation of single‐phase axial dispersion coefficients in both batch and continuous oscillatory baffled flow systems. A hydraulic diameter is introduced to relate axial dispersion coefficients for various baffle geometry, including close‐fit and loose‐fit baffles, Karr plate and multiperforated plate, and various scales. The significance of this note is that the mixing characteristic in oscillatory flow devices is linear.
A feasibility study of adaptive plasma‐assisted incineration, Part 2: Techno‐Economic potential assessment
Authors: Filion Julie , Munz Richard J. , Salin Eric D. 
Published: March 2009

AbstractThis work assesses the techno‐economic potential of using an adaptive d.c. thermal plasma afterburner in hazardous waste incineration. Preliminary cost estimates were developed for soil incineration, soil desorption and liquid waste incineration. In general, the annual operating costs of plasma‐assisted processes (including depreciation of capital) exceed the costs of fuel combustion processes by 50%. However, a qualitative examination of environmental, legal and technical factors suggests that plasma treatment offers significant benefits in terms of effectiveness, safety and regulatory compliance.
Complex integration of processes
Authors: Glavič Peter 
Published: March 2009

AbstractPinch analysis is nowadays a practical tool for designing heat exchanger networks in chemical and process industries. Rules for integrating process units have also been worked out in the last decade or two. Process units can be described as different types of energy unit operations, donors and acceptors. Yet, heat integration alone is not sufficient for process integration. The largest savings are achieved when simultaneously optimizing enthalpy and mass flows — energy and material recycling is required to save the natural resources and protect the nature. Mathematical programming is increasingly used to optimize the problems both in continuous and batch operations. Task integration is spreading out: multifunctional units lower the capital investment, thus, the total annual cost Recent development of the complex integration with examples and reasonable forecast of the future development is presented in the paper.
Simultaneous isolation of keratinocytes and fibroblasts from a human cutaneous biopsy for the production of autologous reconstructed skin
Authors: Rochon Marie‐Hélène , Gauthier Marie‐Josée , Auger Francois A. , Germain Lucie 
Published: March 2009

AbstractThe key step In the reconstruction of skin by the self‐assembly approach is to use fibroblasts capable of secreting a mature extracellular matrix and keratinocytes that can associate with one another to form a stratified, differentiated epidermis. To determine the most efficient way to extract both cell types from a single cutaneous biopsy, five different enzymatic combinations were tested. The yield, viability and morphology of the recuperated cells were compared. The length and temperature of the enzymatic treatments influenced the number and the type of cells recuperated. The cells were then cultured in appropriate media in monolayers and reconstructed skin were produced using the self‐assembly approach. No difference was observed between the different strains of cells.
Survey of heat transfer mechanisms in a slurry bubble column
Authors: Li Hanning , Prakash Anand 
Published: March 2009

AbstractHeat transfer mechanisms in the bulk and distributor regions of a slurry bubble column are investigated based on the measurements of local heat transfer in a 0.28 m diameter Plexiglas column. The gas, liquid and solid phases used are oil‐free compressed air, tap water and 35 μm glass beads. The slurry concentration and superficial gas velocity are varied from 0 to 40 vol% and 0.05 to 0.30 m/s respectively. Measurements have been made with a fast response heat flux probe which provided local instantaneous heat transfer coefficients. The time‐averaged heat transfer coefficients in the bulk region were on average about 50% higher than the distributor region of the column. The wall region heat transfer coefficients are well predicted by the correlation of Deckwer et al. (1980). Heat transfer mechanism in column centre can be adequately described by the consecutive film and surface renewal model.