bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation and design of membrane plants with AspenPlus
Authors: Rautenbach Robert , Knauf Rüdiger , Struck Alexander , Vier Jens 
Published: August 2005

AbstractIn this paper the simulation of hybrid processes containing membrane units will be discussed. For this purpose a user‐defined module for simulation and design of membrane processes was implemented into the simulation program AspenPlus.The advantages can be summarized as follows:–any combination of membrane processes with all other units already implemented in AspenPlus is possible, including internal recycle streams–utilization of the physical property models and data bases of AspenPlus is possible– cost and sensitivity analysis can be performed.These benefits are demonstrated in detail for a membrane vapor recovery unit for the treatment of tank farm off ‐gas, for a two‐stage reverse osmosis plant for organic/‐organic separations and for a combination of distillation and pervaporation for the separation of a dimethylcarbonate/methanol mixture.
Design of affinity membrane bioseparations
Authors: Sridhar P. 
Published: August 2005

AbstractAffinity separations rely on the highly specific binding between a protein in solution and an immobilized ligand to achieve a high degree of protein purification. A mathematical model including convection, diffusion, and rate kinetics is formulated to analyze the design and operation of affinity membrane bioseparation. The model equations are solved by orthogonal collocation method. Danckwerts' boundary conditions are used. The results obtained from model simulation show that the breakthrough of the protein is significantly influenced by Péclet number, feed protein concentration, Ligand number, Damköhler number, membrane thickness, and flow rate. Breakthrough profiles are quantitatively discussed in terms of protein recovery efficiency, ligand utilization efficiency, thickness of unused membrane, and width of the mass transfer zone.
Mathematical modeling and experimental validation of an absorption‐driven multiple‐effect evaporator
Authors: Yanniotis Stavros , Pilavachi Peter A. 
Published: August 2005

AbstractA mathematical model has been developed to simulate the operation of an absorption‐driven multiple‐effect evaporator. The model is based on mass and enthalpy balances and heat transfer rate equations of the various components of the system. The model has been validated by comparing model predictions to experimental results from the operation of a four effect absorption‐driven falling film evaporator coupled with a two‐effect regenerator which operated using solutions of sodium hydroxide as an absorptive medium. The model predictions are in satisfactory agreement with the experimental results.
Interfacial tension measurements between α‐tocopherol and carbon dioxide at high pressures
Authors: Moser Micro , Pietzonka Werner , Trepp Christian 
Published: August 2005

AbstractThe interfacial tension of the binary system α‐tocopherol/carbon dioxide was measured using the pendant drop method in the pressure range between 10 and 37 MPa at nine different temperatures: 313, 333, 343, 353, 363, 373, 383, 393, and 402 K. At every interfacial tension measurement, densities of both the liquid and the supercritical gas phase were also determined as the knowledge of these values is essential for calculating interfacial tension from the shape and size of drops. The interfacial tension decrease with rising pressure at a constant temperature and increases with increasing temperature at a constant pressure. The interfacial tension was found to be mainly a function of the mutual solubility of the two system components and of the density of pure carbon dioxide.
Heat consumption and irreversibilities in rectification processes
Authors: Knoche Karl Friedrich 
Published: August 2005

AbstractChemical engineering analysis using entropy production has been proven to be an essential tool to identify areas in chemical plants, where degradation of energy occurs. Though, applied very extensively in the area of heat exchanger networks in the form of “pinch technology”, the method is rarely used with respect to processes with mass energy. Entropy productions in destillation columns have been evaluated and discussed with respect to feed introduction, sequences of columns and other technically important features.
Adaptation of hydrocyclone to varying solid load by air injection
Authors: Mittal Manju 
Published: August 2005

AbstractIn the Chemical and Process Industry, liquid streams having a variable concentration solids are not uncommon. The hydrocyclone has been found to be a useful unit for the removal of particulate matter from these streams. The function of a hydrocyclone gets disturbed by an increase in the solid load concentration beyond a specified limit, and it may even overload the underflow opening. A variation of the solid load calls for a change in the split ratio of the hydrocyclone, which in turn requires an adjustment to the diameter of the underflow opening. A new technique has been developed which can automatically adjust to the change in the solid load without changing the underflow opening diameter. The split ration of a hydrocyclone can be changed by varying the pneumatic injection rate at the hydrocyclone's axis. Experiments were conducted using three geometrically similar hydrocyclones, and equations have been evolved to size the underflow opening.
Models describing the behavior of new carbon fiber packings inn rectification processes
Authors: Becker Oliver , Steiner Rudolf 
Published: August 2005

AbstractMany rectification processes are used to separate corrosive substances with high boiling points. This reports deals with a new type of structured column pacing mode of corrosion‐resistant carbon fiber material. These column internals allows for low pressure drop at high throughput rated with reasonable column efficiency. Experiments in columns of 50 and 100 mm diameter have been carried out to investigated separation efficiency, pressure drop and liquid holdup of the packing even at low operation pressures. In the respective columns twp geometrical different types of packing have been tested using binary mixtures of chlorobenzene/ethylbenzene with a packing geometry similar to the Sulzer EX packing, the 100 mm diameter column was filled with elements of rougher structure and smaller specific surface. Basing on the experimental results, model equations are presented, which allow the calculation of the investigated performance characteristics.
Characterization of small‐ and intermediate‐pore zeolites by means of temperature‐programmed desorption of amines
Authors: Christoph Merz , Fetting Fritz 
Published: August 2005

AbstractThis paper presents results of temperature‐programmed desorption (TDP) as a method for studying the acid and shape‐selective properties of small‐ and intermediate‐pore zeolites.A combination of an in situ infrared spectrometer and a downstream gas chromatograph for analyzing the desorption products is used to detect the desorption process. This is followed by a separate, newly installed microbalance facility.The studies shows that a part of the amines, esp. dimethylamine (DMA) and trimethylamine (TMA), adsorbed on the zeolites undergo decomposition, disproportionation and carbonization reaction during the TDP measurements at elevated temperatures. Comparison of the microbalance measurements and the gas chromatographic results give a good picture of the extent of these reaction.
Tailor‐made additives to influence the habit of barite (BaSO4) obtained by precipitation
Authors: Kipp Stephan , Lacmann Rolf , Reichelt Michael , Schröder Wolfgang 
Published: August 2005

AbstractIn order to influence the habit of barite (BaSO4) single crystals obtained by precipitation, the tailor‐made additives 2‐aminomethanol, 3‐aminoproponal, 5‐aminopentanol, 4‐aminobutane sulfonic acid, and several other growth inhibitors have been tested. The crystallization experiments have been carried out in a fully automated crystallizer with reproducible educt feed rates. The kinetics of the reaction has been measured by means of the conductivity. Scanning electron microscopic analysis of the obtained crystal habits led to the raesult that most of the additives tested did not influence the growth form of the crystals, but the predicted, tailor‐made additives resulted in a more isometric crystal form.
Simulation of removal of HCI gas in a spray dry tower
Authors: Meazawa Akinori , Suzuki Harunobu , Seno Tadachika , Uchida Shigeo 
Published: August 2005

AbstractA mathematical model of the absorption of HCI gas in a spray dry tower has been proposed. The proposed model describes the mechanism of HCI removal talking into account atomized droplet size distribution and the change in the droplet state from “slurry droplet” to “dry particle”. It is found that the removal efficiency can be simulated by using the model with the constant mean diameter of droplet from the simulation results. Simulation results of the removal of HCI gas are in good agreement with the experimental data in a spray dry tower.
Relation of mechanical power to gas holdup and mass transfer in an agitated vessel
Authors: Benadda Belkacem , Ismaili Samir , Otterbein Michel 
Published: August 2005

AbstractTwo devices were developed, mechanical and electrical, to measure the mechanical power relative to superficial gas velocity and stirring speed in a mechanically agitated reactor. Two bubble regimes were demonstrated. The study of gas holdup, obtained from the residence time distribution, and the bubble size, determined by interfacial area measurement, confirm these two regimes of flow. Our results show that the gas holdup, the interfacial area, and the liquid‐side mass transfer coefficient are increasing functions of the energy dissipated in the solution.
The determination of multiple steady‐states for a family of catalytic reactions in an isothermal CFSTR
Authors: Li Hsing‐Ya 
Published: August 2005

AbstractThe Subnetwork Corollary provides some sufficient conditions for which a complex reaction network could be determined to have capacity of admitting multiple positive steady‐states, if it contains a subnetwork that also admit multiple positive steady‐states. A family of reaction networks, involving catalytic reactions in an isothermal continuous flow stirred tank reactor (CFSTR), is determined to have the capacity to exhibit steady‐state multiplicity by implementation of the Deficiency One Algorithm and the Subnetwork Corollary. A set of rate constants and two corresponding positive steady‐states are constructed for several cases.
A contribution to the evaluation of mass transfer trays
Authors: Billet Reinhard 
Published: August 2005

AbstractTo review mass transfer trays from a process point of view, the dependence of efficiency on the loadings, the loading range and the maximum loadings with an acceptable tray efficiency have to be known. Comparing the results taken from experiments on Dualflex trays and from other types of trays which have been in industrial applications for many years and which are recognized as “industrial standard”, has been evaluated in this review.
Determination of effective macropore diffusion coefficients by digital image processing
Authors: Meyerhoff Karsten , Hesse Diethard 
Published: August 2005

AbstractIn this contribution, a new method is proposed for determining effective macropore diffusion coefficients in porous media by digitized microphotographs of porous support materials and random walk simulations. The method introduced allows calculation of the effective diffusion coefficient as a function of the mean free path length over a wide variety of values. A versatile method for the preparation of porous substances for light microscopy is described.The frequently applied model of an active shell, which is used to model particle/solid collisions, was found to give incorrect results in conjunction with the application of the first passage time algorithm, which was applied to save computing time in the simulation of gas diffusion. It was possible to show that more realistic results are obtained if a Knudsen layer is used to model particle/solid collisions. Furthermore, in investigating diffusion in two‐ and three‐dimensional representations of capillary tubes, it was found that results of simulations performed to calculate transport properties of fluids in porous media, based on two‐dimensional model systems, cannot in any case be transferred to the corresponding three‐dimensional systems.
Mathematical modeling and simulation studies of scale‐down fermentation systems
Authors: Özbek Belma 
Published: August 2005

AbstractIn this study, a scale‐down approach has been used for the simulation of the imperfect mixing on the growth processes by considering several configurations of continuous stirred tank reactor (CSTR, aerated) and plug flow tubular reactor (PFTR, not aerated). The steady‐state concentrations of biomass and enzyme in a continuous culture were calculated as a function of dilution rate using modified Monod growth kinetics. A mathematical model for each combination of two bioreactors was developed to account for growth, substrate utilization (oxygen and glucose) and enzyme synthesis and decay. The model was then used to investigate biomass production and enzyme expression in relation to the volumetric fraction Uf = VPFTR/(VCSTR + VPFTR) and the recirculation ratio R = fr/(f + fr) of the fermentation system. These two mixing parameters were found to be significant factors in the biomass and enzyme production from the fermentation system. This model was also compared with some of the existing models.
Optimization of a process for the synthesis of a sperm whale oil analogue
Authors: Bautista L. Fernando , Martínez Mercedes , Aracil José 
Published: August 2005

AbstractThe development and optimization of the synthesis of an analogue of sperm whale oil have been carried out. The product is an ester with characteristics similar to those of natural sperm whale oil. A central composite design was applied in the synthesis of this fine chemical. The variables selected for the present study are reaction temperature, initial concentration of catalyst and working pressure. Temperature is the most significant factor in the esterification process, and its influence is positive. Pressure influence can be neglected, and the catalyst concentration has a positive influence on the process. Depending on the temperature value, the influence of the interactions can be more important than that of the other two main effects, pressure and catalyst concentration. Response surface models have been found adequate to represent the yield of ester. The commercial quality of the synthesized product is very similar to that of natural spermaceti. Because of its low cost, this synthesis process is considered, from an economical point of view, very attractive.
The impact of fluid dynamics on the regeneration of automotive fiber coil filters I. Prediction of soot distribution
Authors: Schnitzlein Klaus 
Published: August 2005

AbstractThe detailed knowledge of the soot distribution is an indispensible prerequisite for a study of the impact of fluid dynamics on the regeneration behaviour of ceramic fiber coil filters. As shown by experiments and simulation calculations the soot distribution can be reliably predicted with a mathematical model formulated in terms of the structural parameters as well as of the operating conditions. Furthermore, it is demonstrated that besides its effect on the regeneration behaviour the impact of fluid dynamics on the soot distribution must be considered, too.
Catalytic oxidation of anisole over titanium silicalite‐1
Authors: Vayssilov Georgi N. , Popova Zdravka , Tuel Alain 
Published: August 2005

AbstractThe reaction of anisole hydroxylation with hydrogen peroxide to form methoxyphenols over TS‐1 was studied. Four C1‐C3 alcohols and the two aprotonic solvents acetone and acetonitrile were used. Product conversion was almost proportional to the titanium content of the catalyst sample. The highest conversion and p‐selectivity were observed in ethanol. Some speculations, based on the formation of substrate‐solvent or titanium‐solvent‐oxidant complexes, about the role of the solvent are presented. It was found that in all the solvents studied the p/o ratio increased with time.
Correlation and prediction of synthesis gas solubility in n‐paraffin systems
Authors: Campanella Enrique A. 
Published: August 2005

AbstractFluctuation solution theory relates thermodynamics partial derivatives to integrals of molecular direct correlation functions from statistical mechanics. This paper describes an application of that theory for correlating and predicting solubilities of light gases in heavy n‐paraffins. Two of the solvents are complex waxes. Equations from the theory represent the liquid phase, and additional hypothesis are adopted to build a model for the high pressure vapor‐liquid equilibrium. In the correlation mode, the model, based in the fluctuation solution theory, produces a molar fraction of the gas in the liquid phase with an average absolute relative deviation under 3% in a large number of cases. In the prediction mode, when binary parameters are used, errors are on the order of 10%. Overall for n‐paraffins solvents, the model presented in this paper shows a good capacity to correlate experimental solubility and an adequate power to extrapolate lower pressure data when a binary parameter value has been chosen.
Heterogeneously catalyzed oxidative dehydrogenation of isobutyric acid to methacrylic acid: A new application of periodic flow reversal
Authors: Seuffert Wolfgang , Laubersheimer Jürgen , Emig Gerhard 
Published: August 2005

AbstractThe heterogeneously catalyzed oxidative dehydrogenation of isobutyric acid in a fixed bed reactor using molybdenum (Mo) heteropoly acids as catalysts shows a loss of Mo into the gas phase due to the formation of volatile Mo‐complexes under reaction conditions. To avoid this loss of catalyst and to keep the catalytic material in the fixed bed and thus increase the catalyst's lifetime, the process has been performed under periodic flow reversal within the reactor. In this work, periodic flow reversal is tried in a semi‐pilot test reactor as a method to fix the Mo‐compounds in the catalyst bed. The influence of this mode of operation on the temperature profile in the reactor, on conversion, selectivity and yield of the product methacrylic acid is investigated in comparison with the process without periodic flow reversal.
A nonlinear observer for the iron‐catalysed hydrogen peroxide decomposition in a continuous stirred tank reactor
Authors: Neimeier Rolf , Schulz‐Ekloff Günter , Vielhaben Thomas , Thiele Georg 
Published: August 2005

AbstractThe H2O2 concentration for the nonlinear process of the iron‐catalysed hydrogen peroxide decomposition in a continuous stirred tank reactor is estimated using a time‐variant Extended Luenberger‐Observer. The asymptotic stability of the observer, designed by adequate pole‐placement, is demonstratéd by simulation and comparison of the transient behavior of the estimated concentration profiles with those of the nonlinear system. Comparison with measured H2O2 concentrations indicates satisfactory observer dynamics and accuracy with respect to a lower stationary state of the nonlinear process.
A new pigment disperser for high solids paper coating colors
Authors: Duquesnoy Jean‐Alain , Tanguy Philippe Anoré , Thibault Francis , Leuliet Jean‐Claude 
Published: August 2005

AbstractIn paper coating make‐down, a poor dispersion of pigments in coating colors may lead to coater runnability problems. This is manifested by coat defects at the paper surface, excessive coater blade wear, and an over‐consumption of pigments. For this reason, high shear impellers operated at high speed are used, yielding a high energy consumption. A new method to disperse high solids mix at low energy consumption is presented. This method based on the use of a rod impeller scraping the fluid surface in the vessel, is tested on a slurry composed of calcined and delaminated clays up to a solids content of 66.7 wt.% without dispersing aids.
Electronic Structure of the Ti1‐xScxNiSn and Zr1‐xScxNiSn Solid Solutions.
Authors: Romaka L. , Stadnyk Yu. , Horyn A. , Shelyapina M. G. , Kasperovich V. S. , Fruchart D. , Hlil E. K. , Wolfers P. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Investigation of Magnetic Phase Transitions in HfFe6Ge6‐Type Gd1‐xErxMn6Sn6 Intermetallics.
Authors: Cakir O. , Dincer I. , Elmali A. , Elerman Y. , Ehrenberg H. , Fuess H. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Highly Efficient KF/Al2O3‐Catalyzed Versatile Hetero‐Michael Addition of Nitrogen, Oxygen, and Sulfur Nucleophiles to α,β‐Ethylenic Compounds.
Authors: Yang Lei , Xu Li‐Wen , Xia Chun‐Gu 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Lewis Base Catalyzed Diastereoselective Strecker‐Type Reaction Between Trimethylsilyl Cyanide and Chiral Sulfinimines.
Authors: Takahashi Eiki , Fujisawa Hidehiko , Yanai Toshiharu , Mukaiyama Teruaki 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Fragmentation of Tertiary Cyclopropanol Compounds Catalyzed by Vanadyl Acetylacetonate.
Authors: Kirihara Masayuki , Kakuda Hiroko , Ichinose Motohiro , Ochiai Yuta , Takizawa Shinobu , Mokuya Asuka , Okubo Kumiko , Hatano Akihiko , Shiro Motoo 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of 1,2‐Diamino‐1‐phenylpropane Diastereoisomers from u‐N‐Trifluoroacetyl‐2‐amino‐1‐phenylpropan‐1‐ol.
Authors: Dufrasne Francois , Neve Jean 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
HNO3/Silica Gel Supported CAN; Oxidative Deprotection of Benzylic Tetrahydropyranyl Ethers under Solvent‐Free Conditions Using Microwaves.
Authors: Heravi Majid M. , Kazemian Pegah , Oskooie Hossein A. , Ghassemzadeh Mitra 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and Study of Some New N‐Substituted Imide Derivatives as Potential Anticancer Agents.
Authors: Jindal Dharam Paul , Bedi Vikas , Jit Birinder , Karkra Nalin , Guleria Sheetal , Bansal Ranju , Palusczak Anja , Hartmann Rolf W. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Derivatives of spiro‐Fused Cyclopropane‐Dibenzocycloheptatriene and ‐Dibenzocyclooctatriene. Synthesis and Properties.
Authors: Pop Mircea , Surugiu Nina Mirela , Pavel Claudia , Negoescu Mirela‐Alina , Razus Alexandru C. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Catalyzed Asymmetric Induction of Planar Chirality: Palladium‐Catalyzed Intramolecular Mizoroki—Heck Reaction of Prochiral (Arene)chromium Complexes.
Authors: Kamikawa Ken , Harada Kenji , Uemura Motokazu 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Cyanoacetylene and Its Derivatives. Part 32. Addition of Ammonia and Methylamine to 4‐Hydroxy‐4,4‐diphenyl‐2‐butynenitrile.
Authors: Mal'kina A. G. , Sokolyanskaya L. V. , Kudyakova R. N. , Sinegovskaya L. M. , Albanov A. I. , Shemyakina O. A. , Trofimov B. A. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
First Example of Base‐Promoted Tandem Alkylation—Bromination of 2‐Bromothiophene via Halogen Dance Process: A Remarkable Temperature Effect.
Authors: Peyron Corinne , Navarre Jean‐Michel , Van Craynest Nathalie , Benhida Rachid 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
A Base‐Catalyzed, Direct Synthesis of 3,5‐Disubstituted 1,2,4‐Triazoles from Nitriles and Hydrazides.
Authors: Yeung Kap‐Sun , Farkas Michelle E. , Kadow John F. , Meanwell Nicholas A. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and Biological Activities of Some 2‐(Substituted‐phenyl)‐2‐methyl‐4‐ (1,2,4‐triazole‐1‐yl)methane‐1,3‐dioxolane Derivatives.
Authors: Jian Fangfang , Xiao Hailian , Xu Liangzhong , Yu Guanping 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.