Latest issue

Home > Archives > Latest issue

International Review of Chemical Engineering (Rapid Communications) - November 2010 (Vol. 2 N. 6) - Papers

Problem, Failure and Safety Analysis of Ammonia Plant: A Review (Invited Paper)
Modeling Periodic and Aperiodic Behavior of Acetylcholine Hydrolysis
Characterization of Biocorrosion of Welded Tubes and Environment
Biodiesel Preparation from Jatropha Seeds by Enzymatic Reactive Reaction and Dimethyl Carbonate
Optimization of Cyclone Separators Using Genetic Algorithm
Semiconducting Properties of Thermally-Formed Films on Niobium Surfaces
Catalytic Wet Peroxide Oxidation of an Azo Dye Orange I Using Natural Clays
Producing Sulfur Coated Urea by Fluid Bed Wet Coating Method: Drying Kinetics and Product Quality

Special Section on "XIII Computational Modeling Meeting"

Preface to the Special Section
Improved Bees Colony Algorithm Applied to Chemical Engineering System Design
Computational Modeling of Photoacoustic Spectroscopy for Studies of Epoxy Resin Curing: T2F Method
Numerical Simulation of a Two-Phase Flow in a Porous Medium Employing the Finite Volume Method and a Semi-Implicit Approach
Experimental-Theoretical Analysis of a Transient Heat Conduction Setup via Infrared Thermography and Unified Integral Transforms
Kinetic Parameter Estimation of Calcium Phosphate Coating using Particle Swarm Optimization
Using Artificial Neural Networks to Generate Virtual Acoustic Reality Applied on Escape Training in Blind Conditions
Parameter Identification in Albear Channel with a Global Search Algorithm Based on an Analysis of Sensitivity
Study of the Influence of Casing and Liquid inside Oil Wells on the Response of Neutron Logging Tools
Numerical Simulation of Transport Phenomena by Diffusion, Convection and Surface in Chromatographic Columns

International Review of Chemical Engineering (Rapid Communications) - Papers

Problem, Failure and Safety Analysis of Ammonia Plant: A Review (Invited Paper)
by Madhusoodan Ojha, A. K. Dhiman

Vol. 2. n. 6, pp. 631-646

Abstract - Ammonia is produced on large scale mainly for production of fertilizers using steam reforming of natural gas. Capacity of single stream has gone upto 4000 tpd. Large release of ammonia due to accident and vessel failure etc. has decreased considerably in the last three decades. But problems and failures do occurs frequently in the ammonia plant even after following the inherently safer design philosophy and risk assessment. Major areas of failures are reforming and synthesis loop. This paper presents the information on various kinds of failures taken place in ammonia plant in the last three decades. It also includes large releases of ammonia from the storage vessel as well as important information which are generally applicable to chemical industries with focus on ammonia plant. The collected information has been critically reviewed and conclusions drawn.

Keywords: Ammonia, reformer, synthesis, failure, fire.

Modeling Periodic and Aperiodic Behavior of Acetylcholine Hydrolysis
by Ibrahim G, , Saleh O., Mustafa, I.H., ElAhwany A.H., Elnashaie S.S.E.H.

Vol. 2. n. 6, pp. 647-661

Abstract - A two compartments model with the acetylcholinesterase activity localized in one compartment only has been used to investigate the periodic and aperiodic behavior of acetylcholine hydrolysis process. The investigation based on a well established kinetic scheme and kinetic data. The model has accounts for the effects of hydrogen ions concentrations on the kinetics and its role in creating membrane potential assuming no other charged ions are exist. Both autonomous and non-autonomous cases are investigated considering the two common mechanisms of applying acetylcholine in practical physiological situations (constant and quantal). The investigation uncovered a wealth of static and dynamic bifurcations of the system including multiplicity of steady states, isola, periodic and aperiodic behavior. The periodic and aperiodic behavior characterized by different patterns of spikes . two spikes per cycle in membrane potential is the dominating pattern all over most of the considered range. Changing the feeding mechanism of acetylcholine from constant steady feeding to constant quantal feeding causes dramatic changes in the dynamic behavior of the system. This is an element of establishing a complete descriptive model for the neurocycle acetylcholinestrase/choline acetyltransferas biosystem.

Keywords: Acetylcholine hydrolysis – Bifurcation – Periodic and aperiodic – Chemical synapse – Membrane potential – pH effect – Neurocycle.

Characterization of Biocorrosion of Welded Tubes and Environment
by HANNACHI Mohamed Tahar, H. Djebaili

Vol. 2. n. 6, pp. 662-669

Abstract - The microorganisms have been identified like one vectors of the dissemination of the metallic pollutants in soils and promote the degradation of most of the materials in their natural environment, including metallic materials. The experiences of simultaneous transfer of metals and bacterial colloids showed an affinity more important of metals for the bio-colloidal fraction that for the porous environment coming with an acceleration of their transfer until an advanced factor. Thesis processes can be ominous of quoted it industrial heart the economic stake ace heart the pollution of soils heart conditions geo-chemical of the middle and one speaks of the environment and health. In other words, biocorrosion is not a form of corrosion, but a change in the kinetics under the influence of the presence of bacteria and products of their metabolism. Among industrial risks necessary to control, the phenomena of biodegradation represent a real danger, which is essential to characterize. So far, the mechanisms leading to the deterioration of materials by the bacterial microflora are not all fully explained. Indeed, the spread of knowledge requires has sustained interacts between metalworkers, microbiologists, biochemists, chemists and corrosionnistes. A second reason, no less important, is the lack of scientific studies from micro-organisms isolated from the industrial environment.

Keywords: Bacteria, Biofilm, corrosion, degradation, Sulphato Reducing (BSR).

Biodiesel Preparation from Jatropha Seeds by Enzymatic Reactive Reaction and Dimethyl Carbonate
by Gizine I. El Diwani, Shadia A. El Rafie, Salwa I.Hawash, Sohair Hefni

Vol. 2. n. 6, pp. 670-682

Abstract - Biodiesel is a fuel generally consisting of a mixture of fatty acid methyl esters (FAMEs) which is used as alternative or in combination with petroleum diesel for its environmental benefits. Biodiesel prepared by enzymatic catalyzed reactive reaction (in–situ extraction and transesterification) has become of much current interest for alternative fuel production. A novel biodiesel-like material was developed by reacting Jatropha curcas grinded seeds with dimethyl carbonate (DMC), which avoided the co-production of glycerol. In the present study three different Lipases, Lipase immobilized from Candida Antrctica, Hog pancreas Lipase and locally prepared lipase from fungal strain source (Asperigillus niger), were screend for the reactive reaction of Jatropha Seeds in (DMC) to produce biodiesel with novel characteristics. The maximum rate of conversion for biodiesel production were obtained from Lipase immobilized which after eight hours reaction reached 90.1%. Hog pancrease Lipase enzymatic reactive reaction gives 76.26% biodiesel content in eight hours, while fungus lipase produced 72.59 % biodiesel content for the same time reaction. The reusability test indicated that Lipase immobilized has the most stable activity through three cycles but Hog Lipase retained 77.98% of its initial activity through three cycles at the same conditions. The important parameters like reaction temperature, reaction time, enzyme load and effect of reusability of enzymes with and without regeneration were studied. The prepared biodiesel content and purity were studied by the Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectrum High Perphormance Liquid Chromatography (HPLC) and colorimetric determinations for triglycerides retained. Valuable antioxidants were obtained through the reaction and their activity was determined. The thermogravimetric analysis was used for studying and comparing the thermal properties of Bio-lipase(s). From the calculated enthalpy the fungal lipase gave the highest heat followed by> Bio-immobilized lipase > Bio-Hog Lipase.

Keywords: Fuel, immobilized enzyme, in-situ, Jatropha, transesterification.

Optimization of Cyclone Separators Using Genetic Algorithm
by S. I. Pishbin, M. Moghiman

Vol. 2. n. 6, pp. 683-691

Abstract - Several classical approaches for designing cyclone separators have been presented till today. Although these approaches have worked well in certain circumstances, they may not always lead to the best possible designs. This paper presents a robust performance optimization method for cyclone separators using genetic algorithm. The effects of seven geometrical design parameters on efficiency and pressure drop are investigated simultaneously. For calculating these performance characteristics, a gas- solid multiphase flow simulation is used to model the two-phase flow inside the cyclone. The proposed computational fluid dynamic model is employed to formulate the objective functions, which are the pre-requisite of genetic algorithm. The simultaneous optimizing of cyclone parameters reveals the profound effects of the conical height and slope, on both efficiency and pressure drop of cyclone separators. The results also show that by increasing the efficiency over 85 percent, pressure drop will be increased significantly.

Keywords: Cyclone, efficiency, genetic algorithm, pressure drop, weighting coefficient.

   Semiconducting Properties of Thermally-Formed Films on Niobium Surfaces
         by Irena Mickova
           Vol. 2. n. 6, pp. 692-700

Abstract - Using the photoelectrochemical methods, the semiconducting properties of oxide films obtained by heating niobium in the temperature range from 100 OC to 400 OC, have been studied. The photocurrent spectra were recorded in 1 M H2SO4 at various applied potentials ranging from -0.2 to 1.5 V sce. For all investigated temperatures of thermal treatment, the photoelectrochemical parameters such as: photocurrent peaks, band gap energies and flat band potentials were determined. It was found that the thickness, inhomogeneity and porosity of formed films increase with increasing temperature and the duration of the thermal treatment.
The nature and structural changes in the films have been investigated with Raman spectroscopy. At lower temperatures and shorter time of thermal treatments the films are amorphous. Beyond a certain critical temperature, the appearance of some Raman bands and change in their intensities indicated that the film transformed from amorphous to microcrystalline structure. Short theoretical background for application of photoelectrochemistry in investigations of semiconducting properties of metal oxide films is presented.

Keywords: Nb oxides, Thermal oxide films, Photoelectrochemistry, Raman spectroscopy.

Catalytic Wet Peroxide Oxidation of an Azo Dye Orange I Using Natural Clays
by Z. Omri, H. Ben Amor, M. R. Jeday

Vol. 2. n. 6, pp. 701-706

Abstract - The study deals with a catalytic wet peroxide oxidation of an azo dye Orange I (OI) in the presence of natural clays. Some important operating parameters such as pH value of solutions, oxidation rate of H₂O₂, catalyst dose and temperature, which influence the decolorization of OI in aqueous solution, have been investigated systematically. The results showed that suitable decolorization conditions were selected as initial pH 2.0, initial H₂O₂/OI concentration ratio 100 mol/mol and catalyst dose of 4g/L for initial dye concentration of 2.5 10^-4 M. The decolorization of OI enhanced with the increasing of reaction temperature. On the given conditions, the degradation efficiencies within 2hours were more than 84% without significant catalyst leaching. The solid can be used several times without any change of its catalytic properties. The mineralization efficiency reached 93.5% of chemical oxygen demand (COD) abatement after 6hours. Sulfur heteroatoms were converted into innocuous SO₄^2- ions (99%) and nitrogen atoms were transformed into NO₃^- ions (97%).The results can provide fundamental knowledge for the treatment of wastewater containing OI and/or other azo dyes by catalytic oxidation process.

Keywords: advanced oxidation, catalytic oxidation, hydrogen peroxide, natural clay, organic dyes.

Producing Sulfur Coated Urea by Fluid Bed Wet Coating Method: Drying Kinetics and Product Quality
by Suherman, Widayat, M. Djaeni

Vol. 2. n. 6, pp. 707-712

Abstract - This paper presents development in producing sulfur coated urea by fluid bed wet coating method. Firtsly, urea are mixed with sulfur, coconut oil, linear alkzl benzene sulfonate and water, then drying in fluid bed dryer. Three different drying temperature are investigated. The product quality are measured such as dissolution show that product has properties such as slow release fertilizer. In addition, the fluid bed model (FLUBED) was applied for derivation single particle drying kinetics curve. The derivation was successfully conducted by giving a good agreement of drying curve between measurements and prediction results.

Keywords: Coating, Fluid Bed, Urea.

Special Section on “XIII Computational Modeling Meeting” - Papers

Preface to the Special Section
by Gustavo Mendes Platt, Ivan Napoleão Bastos

Vol. 2. n. 6, p. 713

Improved Bees Colony Algorithm Applied to Chemical Engineering System Design
by José Alberto de Sousa, Fran Sérgio Lobato, Carla Eponina Hori, Valder Steffen Jr

Vol. 2. n. 6, pp. 714-719

Abstract - In the last decades, nature has been contributing to the development of new optimization algorithms. Among these ones, we can cite the Bees Colony Algorithm (BCA), which is based on the bees’ colony behavior in search for food to the honey production. That approach combines global randomly search (through the performance of scout bees) with local search (by accentuated exploration of promising regions of search space) to solve the optimization problem. However, due to the architecture of the canonical algorithm described in the literature, the stagnation of the population around a local optimal represents a limitation of the technique. In this context, the aim of this work is to propose a strategy to prevent the stagnation of the population and, consequently, to increase the capacity of escaping the local optima. The proposed algorithm is then applied to solve mathematical functions and to a problem related to chemical engineering systems design. The results obtained demonstrate that the inclusion of this operator helps the algorithm to find the global optimal.

Keywords: Bees Colony Algorithm, Refinement Strategy, Chemical Engineering, Optimization.

Computational Modeling of Photoacoustic Spectroscopy for Studies of Epoxy Resin Curing: T2F Method
by M. A. Pereira Neto, N. Cella

Vol. 2. n. 6, pp. 720-727

Abstract - In this work the method for determining thermal diffusivity of materials called Two-Beam Phase-Lag Technique (T2F), based on the photoacoustic effect, is numerically simulated. This simulation provides support to an experimental work, still ongoing, where a new method is proposed to monitor in real time epoxy resin curing. A designed cell with two photoacoustic chambers is expected to detect the phases of the photoacoustic signals due to front and rear illuminations, simultaneously. With this information, it is possible, by T2F technique, a continuous monitoring of the thermal diffusivity of an epoxy resin sample, under curing process. Therefore, the degree of crosslinking can also be monitored online. It is shown that the simulations are important for this study, especially to verify the adequacy of the experimental boundary conditions required by the theoretical model. As a result, it is found the set of allowed values for modulation frequencies, sample thickness and optical absorption coefficient, in which the experiments should be carried out. An experimental result of preliminary tests is shown, where the performance of the thermal diffusivity measurements with the proposed methodology is discussed.

Keywords: Materials characterization, Epoxy, Photoacoustic, Simulation, Thermal diffusivity.

Numerical Simulation of a Two-Phase Flow in a Porous Medium Employing the Finite Volume Method and a Semi-Implicit Approach
by J. A. T. Schulz, H. P. Amaral Souto

Vol. 2. n. 6, pp. 728-735

Abstract - A numerical method is proposed for the solution of a two-phase flow problem in petroleum reservoirs. The two-phase (water and oil) flow problem is governed by a pressure-velocity equation coupled to a saturation equation. The finite volume method with a semi-implicit formulation is used in the numerical solution of the velocity-pressure and mass transport problems. A Total Variation Diminishing (TVD) scheme with a flux limiter function is used for the numerical discretization of the advective terms while centered schemes are employed for the diffusion terms in the mass transport problem. In the validation of our numerical method we compared numerical and theoretical solutions for the one-dimensional Buckley-Leverett equation, and presented our two-dimensional numerical results for a two-phase flow in a heterogeneous fractal porous media.

Keywords: Two-phase Flow, Petroleum Reservoirs, Flux Limiter, Finite Volume Method.

Experimental-Theoretical Analysis of a Transient Heat Conduction Setup via Infrared Thermography and Unified Integral Transforms
by Diego C. Knupp, Carolina P. Naveira Cotta, João Vítor C. Ayres, Helcio R. B. Orlande, Renato M. Cotta

Vol. 2. n. 6, pp. 736-747

Abstract - The present work is aimed at demonstrating and covalidating the experimental and theoretical analysis via infrared thermography and unified integral transforms, respectively, of a partially heated sandwiched plate configuration, recently proposed and employed for space variable thermophysical property identification in heterogeneous media. The plates are heated at their contact with an electrical resistance of known dissipative power, exchanging heat by natural convection and radiation at the external faces. Infrared camera measurements are taken at the external face of one of the plates. Then, a novel open source computational code called UNIT (UNified Integral Transforms), which provides a development platform for finding solutions of partial differential equations by means of integral transforms, is employed in the comparative theoretical analysis. In the corresponding mathematical model, the equation dissipation term suffers an abrupt variation due to the partially applied heat flux (up to half of the plate’s height), with the resulting steep heat transfer coefficient at the external surface. The results obtained with the UNIT code show a reasonably good agreement with the experimental data, but also indicate the need for inverse analysis in the proper identification of the abrupt variations in the heat transfer coefficient and of the time lag in the interface heat flux behavior. Thus, a recently developed inverse problem analysis combining infrared thermography, integral transforms and Bayesian inference is here illustrated in simultaneously estimating the thermophysical properties, the applied heat flux, and the heat transfer coefficient functional behaviors. Finally, employing the estimated parameters, an excellent agreement is achieved between experimental and theoretical results.

Keywords: Heat Conduction, Integral Transforms, UNIT Code, Infrared Thermography, Inverse Problem, Bayesian Inference.

   Kinetic Parameter Estimation of Calcium Phosphate Coating using Particle Swarm Optimization
         by C. X. Resende, R. L. Pagano, V. M. A. Calado, I. N. Bastos, E. C. Biscaia, G. A. Soares
           Vol. 2. n. 6, pp. 748-753

Abstract - Metallic surface coated with calcium phosphate combines the excellent mechanical properties of metal with the calcium phosphate bioactivity. Therefore, these materials have been largely used for biomedical applications. The aim of this work was to study the biomimetic deposition process kinetics by using two solutions with different chemical compositions. The biomimetic process consists of substrate immersion into a Simulated Body Fluid (SBF). Many papers describe this process; however, few works have focused on the process of the kinetic parameter estimation. In the experimental procedure, titanium samples were soaked into solutions, called as Simulated Body Fluid (SBF) and Solution for Bioactivity Evaluation (SBE); calcium and phosphorous concentration were quantified during the biomimetic exposure. In the present work, Lagergren models were tested to fit the experimental data. In order to find the best model and consequently obtain the kinetic parameters, with confidence intervals, a computational package based on Particle Swarm Optimization (PSO) was used. Pseudo-first and second order kinetics were tested with experimental data. However, the best fit for both SBE and SBF was obtained with the first order. The estimated SBE deposition rate was higher than the SBF one and this result can be corroborated by more intense deposition of simplified fluid.

Keywords: Calcium Phosphate, Parameter estimation, PSO and Kinetic model.

Using Artificial Neural Networks to Generate Virtual Acoustic Reality Applied on Escape Training in Blind Conditions
by José F. L. Naranjo, Roberto A. Tenenbaum, Julio C. B. Torres

Vol. 2. n. 6, pp. 754-759

Abstract - This work presents a new approach to obtain the Binaural Impulse Responses (BIRs) to be applied in auralization systems, by using Artificial Neural Networks (ANN). The main goal is to implement the spectral modification of a Head-Related Impulse Response (HRIR) by using a neural network, instead of performing traditional signal processing such as convolution through Fourier transforms. The input data for the trained networks are acoustic rays carrying the power spectrum and the arriving direction. These rays were obtained with the hybrid method implemented at the acoustic simulation program RAIOS. The tests performed over a subset of HRIR directions show that the new method is capable to substitute with advantages the traditional procedure and to generate BIR's components with very small errors and much lower computational effort than the traditional method. Time and frequency domain results are presented and discussed. The results are applied to an industrial environment simulating the escape training route in blind conditions in an industrial plant.

Keywords: Artificial Neural Networks, Auralization, Binaural Impulse Responses, Escape training, Virtual Acoustic Reality.

Parameter Identification in Albear Channel with a Global Search Algorithm Based on an Analysis of Sensitivity
by Yoel Martínez González, Pedro P. G. Watts Rodrigues, David E. Marón Domínguez

Vol. 2. n. 6, pp. 760-766

Abstract - Albear Channel has more than a century of continuous operation with a contribution of 12.23% of the total volume of water consumed by the population of Havana. The channel had presented serious deterioration problems before a major restoration was completed in 2001. The impact of these problems in the hydraulic behavior of the channel could not be assessed at that time due to the lack of measurements and availability of computational tools that allow a robust way to estimate the channel efficiency, the channel roughness and auto-depuration capacity. In this work, the flow and transport equations were numerically solved for Albear channel, being coupled to the global search algorithm PCA (Particle Collision Algorithm) in order to achieve parameter estimations, through minimization of the error between observation and simulation.

Keywords: Albear Channel, flow, parameter estimation, PCA algorithm, transport.

Study of the Influence of Casing and Liquid inside Oil Wells on the Response of Neutron Logging Tools
by Edmilson M. Souza, Samanda C. A. Correa, Ademir X. Silva, Inaya C. B. Lima, Paula L. F. Rocha, Ricardo T. Lopes

Vol. 2. n. 6, pp. 767-771

Abstract - The influence of the casing and liquid inside the borehole in neutron porosity tool response is analyzed. For this, MCNPX simulation of neutron tool inside of a slim borehole was performed. The results showed that the presence of PVC casing and liquid inside the borehole reduces the tool response in about 73% for low porosities, and 90% for high porosities.

Keywords: Nuclear well logging, neutron porosity, MCNPX, casing influence, He-3 detector.

Numerical Simulation of Transport Phenomena by Diffusion, Convection and Surface in Chromatographic Columns
by Diego Pinto Costa, Flávio de Matos Silva, Kamilla Vogas Romualdo, Antônio José da Silva Neto, Leôncio Diógenes Tavares Câmara

Vol. 2. n. 6, pp. 772-777

Abstract - The mass transport phenomena are present in several and relevant industrial processes where the study can provide many benefits related to separation systems design. In this work we carried out the computational modeling of three different transport phenomena in chromatographic column, being evaluated the diffusion, the convection and the surface kinetic by adsorption and desorption. It was employed the finite difference and Runge-Kutta 4th order methods in the numerical solutions of the partial and ordinary differential equations, respectively. From the simulation results were observed that the axial dispersion coefficient, velocity and the kinetic constants of adsorption and desorption have significant influence on the separation process dynamic of molecules percolating the porous of the chromatographic column. In the case of diffusion the axial dispersion coefficient showed great influence on the time to reach the stead state regime of the column. The effect of the axial dispersion coefficient in the mass transport was lower in the case of advection in which the significant contribution comes from the field of velocity inside the column. The modeling of mass transport through the kinetic of molecules on the adsorbent surface showed simulations results in which the kinetic parameters of adsorption and desorption can influence significantly the maximum capacity of adsorption of the adsorbent material.

Keywords: Adsorption, Chromatography, Numerical Simulation, Transport Phenomena.