bluuebunny/crossref_metadata_2025 huggingface dataset:
Data Reconciliation Using AspenPlus
Authors: Piccolo M. , Douglas P. L. , Lee P. L.
Published: August 2010

Process measurements made in chemical plants generally do not satisfy material and energy balance constraints due to random or possibly gross errors in the measuring device readings. Data reconciliation is a method of adjusting random errors in the measurements in a weighted least squares sense in order to satisfy the process constraints. Linear data reconciliation involves solving a linear system of mass and energy balances as well as inequality constraints. Non‐linear data reconciliation, involving non‐linear mass and energy balances and constraints, is substantially more complex and requires a significant amount of work in developing the model and/or solution strategy.

Steady state simulation packages equipped with optimization routines can be used to perform data reconciliation and parameter estimation with existing models which automatically satisfy mass and energy balance constraints. The time required to develop a data reconciliation problem can be shortened by using these packages without sacrificing the quality of the results. Five examples are presented to illustrate this technique using the AspenPlus flowsheet simulation and Optimization system. The first four are simple problems taken from literature and are included to validate the method. The fifth example involves a nonlinear industrial distillation example included to illustrate the scope of the technique.

In the fist four cases, the solution to the data reconciliation problem war easily developed and quickly solved. The fifth example involved somewhat more work but was still relatively quickly developed and solved. Steady state process simulation systems can be used to perform non‐linear data reconciliation. The reduction in development time increases dramatically with the problem complexity involving staged separation and multiple units.
Kinetics of Adsorption of Pb (II) on Used Tea Leaves and Cr (VI) on Acacia Arabica Bark
Authors: Tiwari D. P. , Saksena D. N. , Singh D. K.
Published: August 2010

Adsorption of Pb (II) on used tea leaves and Cr (VI) on acacia arabica bark after chemical pretreatment exhibit nearly first‐order reversible reaction kinetics in wastewater treatment. Adsorption follows Langmuir and Freundlich isotherm models. Effective parameters such as initial metal‐ion concentration, adsorption dosage, and size of adsorbent particles have been correlated to enable prediction of the equilibrium adsorption of metal ions within a maximum deviation of ± 10% from experimental data.
Modelling and Dynamic Simulation of an Industrial Rotary Dryer
Authors: Duchesne C. , Thibault J. , Bazin C.
Published: August 2010

Rotary dryers are widely used in chemical and mineral processes due to their flexibility and simplicity of operation. Nevertheless, the comprehension of the basic phenomena taking place in this type of dryer is still of great interest. In order to better understand the phenomenological behaviour of the process and to assess product moisture control strategies, a complete dynamic simulator of a mineral concentrate dryer has been developed The simulator is calibrated with industrial data and consists of a furnace model, a solids transportation model and a gas model, including the heat and mass transfer phenomena. The dryer simulator was shown to adequately represent the dynamic behaviour of an industrial rotary dryer.
A Study of Two‐Phase Co‐current Flow in Inclined Pipe
Authors: Spedding P. L. , Ferguson M. E. G. , Watterson J. K.
Published: August 2010

Data are presented on horizontal and slightly inclined flows at +50 and ‐50 for a cocurrent air‐water system in α 0.0508 m i.d. pipe.

The predictive ability of existing flow regimes maps were shown to be inadequate. New maps were proposed for horizontal and slightly inclined up and downward flow. Several transitional criteria were shown to be useful in prediction for horizontal flow.

Both liquid holdup and pressure drop characteristics for inclined flows were different either side of a superficial gas velocity of 10 m s−1. Below this value upward flow had the greatest pressure loss and horizontal flow the least. Above the 10 m s−1 the opposite was the case. For holdup; Vsg < 10 m s−1 led to down flow having the lowest value but for Vsg > 10 m s−1 the horizontal condition had the lowest value. Upflow always possessed the highest liquid hold‐up value.

The Olujic [80] and Spedding‐Hand [71] models were successful in predicting most flow regimes for horizontal flow except stratified ripple and blow‐through‐slug, annular droplet and the intermittent regimes. The inclined flows proved more difficult to predict.
The Influence of Changes to Mixing on the Sooting and NOx Emission Characteristics of Unconfined Turbulent Jet Diffusion Flames
Authors: Newbold G. J. R. , Nathan G. J.
Published: August 2010

Results are presented from new measurements of vertically fired unconfined diffusion flames issuing from precessing jet nozzles and new calculations of existing data from simple jet flames. These results provide quantitative information about large‐scale mixing, NOx emissions and sooting tendencies of precessing jet flames. It is shown that a characteristic large eddy strain rate at the tip of a precessing jet flame is reduced by an order of magnitude when compared to that in simple jet flames. The reduction in large eddy strain rate correlates with an increased sooting tendency that is consistent with findings for simple jet flames presented elsewhere. The reduction in strain rate correlates with decreased NOx emissions and is found to be contrary to flamelet model predictions for simple jet flames.
The Effect of Particle Size and Heating Rate on the Transformation of Sulphur during Pyrolysis of a South Australian Low‐rank Coal
Authors: Telfer M. A. , Heidenreich C. A. , Zhang D. K.
Published: August 2010

Particle size and heat transfer effects on organic and inorganic sulphur transformations during pyrolysis are investigated using temperature‐programmed pyrolysis and fixed‐bed pyrolysis (700‐900°C) of pulverised Bowmans coal, and fluidised bed pyrolysis at 800°C of 6, 8 and 10mm diameter cylindrical coal pellets. Results are interpreted using a heat transfer model [8]. The pyrolysis experiments reveal that during the initial devolatilisation stage, organic and sulphate sulphur decomposition occurs at a rate directly proportional to heating rate and inversely proportional to particle size. Towards the end of the devolatilisation stage, the transportation of volatiles out of the coal decreases so that sulphate undergoes solid‐state transformations to form organic sulphur in the char. The reincorporation process is accelerated by higher reaction temperatures or heating rates which allows greater decomposition of sulphate and longer periods of slow devolatilisation to support the solid‐state reactions. Smaller particles in the fluidised bed reveal a similar effect due to faster internal heating rates. Larger particle sizes also facilitate organic sulphur increase due to slow internal heating rates and hence slow and extended devolatilisation and sulphate reincorporation.
Research on the Combustion of Lower Volatile Coal in PFBC
Authors: Zhang Mingyao , Sun Chenliang , Liu Qianxin , Tang Chuming , Jin Baosheng , Shen Xianglin
Published: August 2010

Up to now, five sets of P—200 PFBC—CC Commercial Demonstration Power Plant are operating in the world, in which the bituminous coal and lignite are used as fuel and the combustion efficiency can reach higher than 99%. But using lean coal or anthracite as fuel it will not be satisfied for the expected value. So the combustion characteristic of these lower volatile coals must be tested and the methods of solving problem will be supplied. This paper will discuss and analyze some results from tests as follows:

The investigation of the burning characteristic for different coals under pressure,

The comparison of the combustion efficiency in PFB combustor for different coals,

The research results with fly ash circulating technology for lower volatile coals.
Power Generation and Greenhouse Gas Abatement: The Effects of Generation Efficiency, Fuel Type and Renewables
Authors: Millar G. , Hessami M‐A.
Published: August 2010

Power generation in Australia is responsible for about 25% of the country's greenhouse gas emissions. Due to the abundance of coal, most power stations use this fuel as the primary source of energy. The high carbon content of coal combined with the relatively poor power generation efficiency of these facilities, explain the contributions which power generation make to Australia's greenhouse gas emissions. In this paper, the effects of these two parameters, ie, fuel type and generation efficiency, on greenhouse gas abatement is studied. It is shown that by controlling these two factors, there is a significant potential to reduce greenhouse gas emissions in Australia.

An analysis of the electricity market showed that renewable energy projects and natural gas fired power stations cannot compete on price with coal fired power stations. Carbon taxes and green energy programs are seen as the most likely ways to make renewable energy and natural gas competitive with coal, and thus reduce greenhouse gas emissions caused by power generation.
A Kinetic Study on the Production of Toxic Compounds in Enclosure Fires Under Suppression by Halon Replacement Extinguishing Agents
Authors: Moghtaderi B. , Dlugogorski B. Z. , Kennedy E. M.
Published: August 2010

This paper presents the results of a theoretical investigation designed to characterise the mechanism of formation of those toxic compounds which are produced when halon replacement extinguishing agents are released in the hot upper‐layer of typical enclosure fires. The present work was primarily motivated by the fact that in many building fires the extinguishing agent may not be directly applied to the flame but released in the hot layer. For this purpose, detailed chemical kinetic modelling techniques were used to predict the generation of combustion products and toxic byproducts within the hot layer. This can be justified based on the fact that recent studies in this field have shown that the production of major combustion products in the upper‐layer is kinetically controlled. Effects of the mixing phenomenon were investigated by considering two possible extremes using infinitely fast and infinitely slow mixing models. The heat loss variation was also studied under isothermal and adiabatic conditions. Calculations presented here show that the concentration of toxic compounds originated from halon replacement extinguishing agents are much higher than those of halons mainly because for such agents, due to the lack of significant chemical reaction inhibition, higher extinguishing concentration are required.
Uncertainty of an Environmental Risk Ranking Analysis
Authors: Hutchison R. B. , Witt H. H.
Published: August 2010

A semi‐quantitative PC tool to rank environmental risks and to assess the cost‐benefit of capital expenditure proposals for risk reduction has been developed by ANSTO Safety and Reliability. The ranking method, which is typical of semiquantitative techniques, is summarised. City Rail (the Sydney railway operator) has used the tool to rank the risks of undesired spillage at many of its sites. The results of this application of the tool were examined to determine the accuracy of the ranking. Such information is relevant to the ongoing development of the method and provides some assurance that the analysis is robust and providing useful information.

The methodology uses environmental science, engineering and site operations expertise. The operations are examined to generate a list of possible environment damaging scenarios and associated point estimates of the likelihood and the quantity of material released. For each material‐scenario combination, transfer effectiveness estimates are assigned based on the pathway to the receptors. Scenario risks are ranked using these estimates along with ratings for the impact of each hazardous material, and ratings for the ecological sensitivity of the sites.

Since the method is reliant on numerical judgements the uncertainty of the scenarios' ranking should be determined. Three techniques were used to assess the uncertainty of the parameter estimates. The accuracy implied by the number of significant figures assigned to estimates was examined and considered unrealistic.

The number of discrete values actually used in the results gives an indication of the analyst's implicit judgement. The third technique was subjective assessment of the parameter estimate's uncertainty by independent analysts. The subjective assessment of the uncertainty was significantly larger than the two other uncertainty estimates.

These uncertainty estimates were used to estimate the uncertainty of the calculated risk scores by using a Monte Carlo simulation. This technique enabled the uncertainty of the parameter estimates to be propagated to determine the uncertainty of the final calculated results. From the data used in the City Rail study and subjective estimates of the uncertainty of parameter values, risk scores from this model differing by at least two orders of magnitude can be confidently (95%) said to be different Conversely, when the risk scores differ only by a factor of two, there is only a 60% confidence that the relative ranking is correct
Monitoring of 2‐D Combustion Temperature Images in a 670 t/h Utility Boiler and Simulation of its Application in Combustion Control
Authors: Zhou H.‐C. , Zhang S.‐S. , Huang Y.‐L. , Zheng C.‐G.
Published: August 2010

A simple method of monitoring 2‐D temperature images from monochromatic gray images of flames captured from utility boilers, and reference temperatures measured by two‐color pyrometry, are presented in this paper. In a 670 t/h utility coal‐fired boiler furnace, the magnitude of the combustion temperature fluctuation can reach as high as 180 K under normal conditions. Furthermore, a two‐loop combustion control strategy was proposed with steam pressure as its outer‐loop control variable and the radiant energy signal as the inner‐loop control variable. Simulation on the single‐and two‐loop control strategies clearly indicates that the two‐loop control strategy can realize a more economical utilization of fuel. It also ensures steady steam pressure and safer conditions for the superheater surface tubes (not to be overheated) making the boiler respond quickly to the load change.
Sulfur‐RiteTM: A Big, New Answer to Small H2S Removal Problems
Authors: Cantrall Rosalind
Published: August 2010

US Filter's Gas Technology Croup (USF/GTP) is currently introducing a new H2S removal process named Sulfur‐RiteTM. Sulfur‐Rite is specifically designed to remove small quantities of H2S (≤ 125 kg/day) from all types of gas streams. The Sulfur‐Rite process can remove H2Sfrom gas streams at any pressure. For non‐hydrocarbon gas streams the temperature is limited to approximately 115° and for hydrocarbon gas streams the temperature is limited to approximately 82°C. The non‐hazardous, environmentally friendly Sulfur‐Rite media converts H2S to iron pyrite (fool's gold). In addition to H2S, the Sulfur‐Rite process can remove approximately 50% of methyl and ethyl mercaptans. The spent media may be disposed of in a non‐hazardous landfill or made into compressed blocks for structural use or in some instances used as a soil supplement. The Sulfur‐Rite Equipment Packages are designed and supplied by USF/GTP. Single vessel and lead/lag dual vessel systems are available. This paper will discuss in detail the gas streams that can be treated, the equipment available, the advantage of Sulfur‐Rite over certain types of scavenger processes, and the disposal of the spent media.
Application of Chaos in Chemical Process Optimization
Authors: Chenzhong Luo , Chunkai Zhang , Huihe Shao
Published: August 2010

Chaos has initial condition sensitivity, intrinsic irregular property and ergodicity, so it was applied to optimization problems. Two new methods were proposed for this kind of application: chaos search method combined with exact non‐differentiable penalty function for nonlinear constraint optimization, and chaos mutation operator for real‐coded evolutionary algoriths. Both are simple and easy to implement. Simulation with a chemical process optimization problem shows that the proposed methods are effective and reliable.
A Study in Advanced Control Application to an Azeotropic Distillation Column within a Vinyl Acetate Monomer Process Design
Authors: Olsen D.G. , Young B.R. , Svrcek W.Y.
Published: August 2010

Simulation of a Vinyl Acetate Monomer (VAM) process design is developed in this work to allow testing of two advanced control strategies within the base PI control scheme Specifically, the two schemes focus on improving the control performance of the azeotropic distillation column A detailed steady‐state and dynamic analysis of the distillation column has been performed to provide insight into the control behaviour of the two composition loops The possible benefits from this type of study include production increase, safer operation and lower operating cost To the authors' knowledge, this paper represents the first time a ratio control scheme and a model predictive controller (MPC) have been applied to the VAM process and presented in the open literature Simulation results are presented to illustrate the effectiveness of the new control strategies
Spray‐Dried Particle Morphologies
Authors: Walton D.E.
Published: August 2010

Particulate powders and particle morphologies produced by spray drying are discussed, along with factors that affect powder quality, e.g. process conditions, and particle properties. Structural categories of spray‐dried particles are demonstrated and related to various drying mechanisms. The methods of studying particle morphology are also outlined with particular reference to the single droplet drying method, reportedly analogous to industrial spray drying and possibly other particulate formation processes. The advantages and disadvantages of the method are discussed and the importance of particle morphology to powder technology emphasised.
A Model for the Approach to Solubility Equilibrium in Crystallizing and Dissolving Systems
Authors: Dalziel S.M. , White E.T. , Johns M.R.
Published: August 2010

Accurate equilibrium solubility data is important when studying the crystallization behavior of a compound. Measurements of solubility can be hindered by the length periods encountered during the approach to equilibrium. This is especially true for proteins and other compounds with relatively slow crystal growth rates. A new model curve fitting technique is developed and applied, which is equally applicable to crystallizing and dissolving systems. The curve fitting inputs are: (i) measurements of solute concentration as a function of time, taken during the dynamic approach to equilibrium; and (ii) the order of crystal growth or dissolution kinetics. The equilibrium solubility is an output parameter of the curve fitting. Where properly used, this curve fitting technique can give a more precise estimate of solubility equilibrium. The technique is applied to the measurement of solubility for glucose isomerase, an industrial enzyme.
The Structure and Interactions of Species in Supersaturated Caustic Aluminate Solutions
Authors: Addai‐Mensah Jonas , Li Jun , Prestidge Clive A.
Published: August 2010

The influence of akali metal ions (Na+ and K+), hydrogen isotope (H and D) and temperature on apparent hydrodynamic molar volumes, structure and interactions of species in synthetic, supersaturated caustic aluminate solutions (Bayer liquors) has been investigated. A strong dependency of structure, size and species interactions (ion‐ion and ion‐solvent) on the three primary variables was revealed. Sodium and deuterium‐based liquors displayed higher viscosities, reflected in greater attractive interactions, higher activation energies and entropies of viscous flow, than potassium and hydrogen‐based liquors. The apparent, hydrodynamic molar volumes of the viscosity modifying species were larger in sodium and hydrogenated than in potassium and deuterated aluminate liquors, and decreased with increasing temperature. Ionic strength‐independent average molar mass of Al(III)‐containing species close to 100 g mol1 and corresponding to monomeric, tetrahydroxo aluminate (Al(OH)) species was observed.
Co‐combustion of Municipal Solid Waste and Coal in a Circulating Fluidized Bed
Authors: Dong Changqing , Jin Baosheng , Lan Jixiang
Published: August 2010

Experiments on the co‐combustion of municipal solid waste (MSW) and coal were performed in a 0.2 MWth circulating fluidized bed and focused on the emissions of NO, N2O, HCl and SO2. The results show that the addition of MSW leads to lower NO, N2O, and SO2 emissions. However, hydrogen chloride concentrations increase with the amount of waste added. A feedforward neural network model was proposed to predict the variation of NO emission with the mixture composition.
Blood Flow Characteristics in a Femoral Artery Bypass Graft
Authors: Cole J.S. , Watterson J.K. , O'Reilly M.J.G.
Published: August 2010

The development of disease at sites where a bypass graft is attached to an artery is a major cause of graft failure. Localisation of this disease suggests that it may be promoted by the local disturbed flow field.

Computational Fluid Dynamics (CFD) simulations of the pulsatile, non‐Newtonian flow of blood through a life‐like femoral artery bypass configuration have been performed in order to further the understanding of bypass flows, and to identify aspects of the flow which encourage the progression of disease. It may then be possible to develop more effective bypass systems.

The graft/artery junction flow is characterised by extensive recirculation, flow separation and reversal, complicated flow paths, elevated fluid particle residence times, and an unusual wall shear stress distribution. It is believed that the occurrence of disease is related to high particle residence times and the unnatural shear stresses acting on the artery wall.
A Universal Flow Regime Map for Horizontal Two‐Phase Flow in Pipes
Authors: Spedding P.L. , Cooper R.K. , Mcbride W.J.
Published: August 2010

A new universal flow regime map has been developed for two‐phase co‐current pipe flow for the condition that the liquid viscosity μL < 0.02 kg m−1 s−1. The map has been successfully tested against a wide variety of data. Three flow regime transitions suggested by various other workers have been shown to be useful in prediction of regime transitions.

Six new models are proposed for certain transitions, namely the smooth stratified to stratified ripple and inertial wave; the stratified ripple to roll wave; the stratified roll wave to film plus droplet; the film plus droplet to annular type flows; the blow through slug to slug; and the slug to bubble flow regime changes.
Effect of Pigment Type and Concentration on the Rheological Properties of Polypropylene
Authors: Marks A.F. , Orr P. , Mcnally G.M. , Murphy W.R.
Published: August 2010

The rheological characteristics of a range of pigmented isotactic polypropylene (iPP) was investigated using dual capillary rheometry techniques, over the temperature range 190d̀C to 230d̀C and shear rate range of s−1 to 800 s−1. The iPP was compounded with pigment masterbatch concentrations ranging from 0.2% to 3.0%, using a 38 mm Killion compounding line. The pigment masterbatches investigated were iron oxide, titanium dioxide and phthalocyanine blue. The rheological data, showed that there were considerable increases in apparent viscosity of pigmented iPP even at relatively low pigment loadings. The increase in apparent viscosity was particularly from the rheological data showed large increases in Ea for pigmented iPP especially at lower shear rates, suggesting crystallization of the iPP melt.
The Effect of Cure Conditions on the Performance of Styrene Butadiene Rubber for Industrial Conveying Applications
Authors: Mcnally G. M. , Clarke J. L. , Small C. M. , Skelton W. J. , Mccall J.
Published: August 2010

A range of samples were prepared from a commercial styrene butadiene rubber (SBR), over a range of cure temperatures (140d̀C‐170d̀C) and cure times (30–120 min), using a high temperature moulding press held at a constant pressure of 5000 psi. Mechanical analysis of the various samples showed considerable increase in modulus, shore hardness and break strength with progressive increase in cure temperature, especially at lower cure times. Dynamic frictional analysis under different loadings, of the SBR samples with High Molecular Weight Polyethylene (HMWPE) and 90 Shore A Polyurethane (PU), showed a progressive decrease in frictional force with increase in SBR cure temperature and time. Some reversion of the SBR was shown to occur at higher temperatures and longer cure time
Urea From Underground Coal Gas
Authors: Williamson C.J.
Published: August 2010

New Zealand has a dwindling supply of natural gas currently used as both a petrochemical feedstock and as a fuel for thermal power stations. However, the country has large reserves of coal, much of it at depths that make it difficult to mine using conventional methods. It is possible to gasify the coal underground and produce a gaseous mixture of hydrogen, carbon dioxide, carbon monoxide and water that can be used as a replacement for natural gas as a feedstock or fuel. This paper describes a design study on the production of urea from underground coal gas in New Zealand.
Agglomeration of Fine‐Grained Petroleum Coke
Authors: Aly I.H.M. , Magdy Y.H. , Barakat N.A.M. , Madany A.B.
Published: August 2010

Fine‐grained petroleum coke cannot be used for industrial purposes, therefore pelletizing of fine petroleum coke (less than 200 μm) was achieved with addition of bentonite as inorganic binder. The effect of moisture content, inclination angle, residence time and bentonite percent on the crushing strength, as well as the average diameters produced were studied. From the experimental results obtained it was found that the optium working conditions were: inclination angle of 60d̀, moisture content of 32.5%, and residence time of 15 minutes. Several mathematical models were created using the experimental results. They were developed as two computer programs to calculate the crushing strength and the average pellet diameter of the produced pellets when bentonite was as binder. The validity of these programs was examined and acceptable results were obtained.
Deformation and Disintegration Behaviour of Single Water Drops in an Oil Phase in an Electric Field
Authors: Maruyama Morito , Ishii Hiroki , Yamaguchi Manabu
Published: August 2010

Deformation and disintegration behavior for single water drops in an oil phase in electric fields were studied experimentally. The experimental degree of deformation of the drops and their maximum degree just before their disintegration agreed approximately with the theoretical value proposed by Taylor. Two types of electrical disintegration for the drops were observed depending on the size of the drops: a small deformed drop was disintegrated by ejecting a series of smaller drops at its sharp pointed ends; while a large drop was elongated as a rod‐like shape and immediately disintegrated into several small drops.
Control of Polymorphism in Crystallization of Amino Acid
Authors: Kitamura Mitsutaka
Published: August 2010

The crystallization mechanism and the controlling factors in the crystallization of amino acid polymorphs were investigated. It was demonstrated that the effect of supersaturation (Ostwald's step rule) was not observed for systems of either L‐Glutamic acid (α, β) or L‐Histidine (A, B). The intensive effect of temperature was shown in the crystallization of L‐Glutamic acid (L‐Glu) polymorphs, however, no temperature effect was observed in the case of L‐Histidine (L‐Hist)polymorphs. It was suggested that such a difference could be related to the difference of the molecular conformation between the polymorphs, and the contribution of the conformers in the solutions to the nucleation process of L‐Glu polymorphs. The growth of both L‐Glu polymorphs (α and β) appeared to be due to the nuclei‐above‐nuclei mechanism. With these results, temperature and supersaturation appeared to be the basic important controlling factors (the primary factors) of polymorphism. Solvents and additives (the secondary factors) also have an influence on polymorphism. The influence of ethanol compositions on the crystallization of L‐His polymorphs (A and B) was observed, and demonstrated that the solvent effect is very kinetic, i.e. the nucleation and growth rate of the A form are suppressed with an increase in the ethanol composition. The effects of L‐Phenylalanine as an additive on the crystallization and transformation rates were shown in batch crystallization. The effect of L‐phenylalanine on the growth rate and morphology of L‐Glu polymorphs was also examined using the single crystal method in a flow system. The relationship between the additive concentration and the growth rate of each polymorph was expressed by the proposed equation. The importance of the kinetics of the crystallization for control of the polymorphic crystallization was demonstrated. The supersaturation needed for control of the selective crystallization of the polymorph was also calculated. From these results the controlling factors for the crystallization of polymorphs have been classified in order to clarify their complex interrelationship.
A Comparative Study of Numerical Methods for Solving Continuous Population Balance Models for Aggregation Processes
Authors: Balliu N.E. , Cameron I.T. , Newell R.
Published: August 2010

In this paper two discretization methods—Hounslow's fixed discretization method and Ramkrishna's adjustable discretization method—will be applied to population balance models in order to compare their performance under various modelling and simulation scenarios. The methods will be tested using an integrated dynamic modelling and simulation system for analysis of particulate processes in the case of agglomeration in a continuous granulation unit where the fresh feed and the recycle have different particle size distributions. In this comparison we will consider the accuracy of the results, the computational time required and the modelling effort.

The results show that Hounslow's method is able to give satisfactory predictions for small to medium particle size ranges but the quality of predictions for large size ranges is poor. The method of Kumar and Ramkrishna is slightly more complex than Hounslow 's method but is able to give good predictions for all particle size ranges. Both methods requires similar computational time when a geometrical grid with a size ratio equal to 2 is used while Kumar and Ramkrishna's technique requires more time to be implemented and solved for finer grids.
Catalytic Partial Oxidation of Propylene to Acrolein: The Activity of Bismuth Molybdate Catalysts under Oxygen‐Rich Conditions
Authors: Fansuri H. , Pham G.H. , Wibawanta S. , Radford R.D. , Zhang D.K.
Published: August 2010

The effect of Bi/Mo ratio, which varied between 1:3 and 2:1, on the activity of bismuth molybdate catalysts prepared by precipitation method for partial oxidation of propylene has been investigated. X‐ray diffraction analysis revealed that the catalysts contained a mixture of α‐Bi2Mo3O12 and molybdite (MoO3) for BI/Mo = 1:3, pure α‐Bi2Mo3O12, for Bi/Mo = 2:3, a mixture of β‐Bi2Mo2O9 and α‐Bi2Mo3O12 for Bi/Mo = ]:I, and pure γ.Bi2MoO6 for Bi/Mo = 2:l. The catalytic activity tests show that the catalysts achieved up to 56% conversion of C3H6, with up to 91% selectivity towards C3H40 production. The relative reactivity of the catalysts follow the order of Bi/Mo 2:3 = Bi/Mo 2:1> Bi/Mo 1.3 Bi/Mo 1:1.
Flocculation of silica by High Molecular Weight Polysaccharides
Authors: Foong K. K. , Amal R. , Doherty W. O. S. , Edye L. A.
Published: August 2010

Flocculation of colloidal silica particles by naturally occurring polysaccharides is of interest to soft drink and beer manufacturers. Compounds found in floc include polysaccharides, proteins, lipids, waxes and silica. These compounds may originate from the water, sugar, yeast, other beverage ingredients or additives used in the beverage manufacture. In this paper, the flocculation of silica particles by polysaccharide extracts of cane sugar was investigated. The change in the particle size with time was monitored by small angle light scattering. Studies were performed under both static and agitated conditions. Under static conditions, it was observed that faster flocculation kinetics were obtained at higher polysaccharide loadings as the time taken to form the floc network was reduced. Higher silica concentrations resulted in larger and denser flocs. The time lapse prior to the appearance of visible cottonball floc was reduced substantially when the solutions were agitated
Constructed Wetlands for Water Pollution Control ‐ Processes, Parameters and Performance
Authors: Greenway M.
Published: August 2010

constructed wetlands are now recognised as an ecologically sustainable option for water pollution control. Natural wetlands are biologically diverse ecosystem. They provide an array of physical, biological and chemical processes to facilitate the removal, recycling, transformation or immobilisation of sediment and nutrients. Most of these processes are facilitated by the wetland vegetation, associated biofilms and micro‐organisms. Wetland ecosystems are complex and the interactions between abiotic and biotic components are fundamental to an understanding of the treatment processes. Constructed wetlands must therefore be designed to have the attributes of natural wetland ecosystems.

The treatment efficiency of a wetland system requires a balance between pollutant loading rate and hydraulic retention time, which is also affected by the water quality and quantity of wastewater effluent or stormwater runoff: The size of a wetland will depend upon the volume of runoff, pollutant characteristics, desired level of treatment and the extent to which the wetland is expected to function as a flood retention basin. Water depth and extent of inundation will determine the types and species of aquatic plants. A combination of emergent, submerged and floating species should be selected.

Pretreatment and detention times are crucial parameters to maximise pollutant removal efficiency. Sedimentation ponds are important in stormwater wetlands to remove particulates, but dense vegetated macrophyte zones are essential to enhance the removal of suspended solids and nutrients.

Ecologists and engineers need to work together to maximise the treatment efficiency of constructed wetlands. Planners and landscape architects' must become involved to ensure that stormwater wetlands have a multi‐functional role in the urban setting.

Constructed wetlands offer the ideal challenge to environmental engineers allowing for the integration of engineering and ecological principles to find the technical solution to fit both nature and society.
Kinetic Model for the Water Oxidation Method for Treating Wastewater Sludges
Authors: Imteaz M.A. , Shanableh A.
Published: August 2010

A generalized kinetic model for the hydrothermal oxidation of organic matter in biological wastewater treatment sludge was developed using a simplified first‐order reaction scheme. The model was based on a series of experimental results obtained using a continuous‐flow hydrothermal reactor system used to destroy the organic component of the sludge. Forty‐eight hydrothermal treatment experiments using three sets of inflow conditions were performed. Using excess oxygen, the treatment involved sludge destruction under subcritical (<374d̀C) and supercritical (>374d̀C) water oxidation temperatures. The chemical oxygen demand (COD) was used to measure the organic content and progress of the oxidation reaction. The Arrhenius equation was used to model the reaction rate constant. In the Arrhenius equation, the pre‐exponential factor was fixed and the activation energy was found to vav with temperature. The activation energy increased up to approximately 263d̀C then stabilised at temperatures above 263d̀C. The variation of the activation energy with temperature reflected the complexity of the composition of the organic content of the sludge, which generally consists of proteins, lipids, carbohydrates and fibres. In hydrothermal oxidation, the various organic compounds oxidize at different rates, with the easily oxidized matter being removed first. As such, the activation energy reflected the changing composition of the remaining organic matter with the progress of the oxidation reaction. Above about 263d̀C, the activation energy became virtually independent of temperature. A functional relationship was established between activation energy and average temperature of the reactor. A mathematical model for the destruction of COD in the presence of excess oxygen was set using a kinetic equation having an average pre‐exponential constant and temperature dependent activation energy. With the new equation and known influent COD, efluent COD was simulated for the entire set of experiments and was compared with the actual measured effluent COD.
A Method for Measuring the Strength of Scale Deposits on Heat Transfer Surfaces
Authors: Chew J. Y. M. , Paterson W. R. , Wilson D. I. , Höufling V. , Augustin W.
Published: August 2010

The technique of fluid dynamic gauging has been successfully applied to assess the adhesion characteristics of thin (< 1 mm) layers of calcium sulphate deposits serving as mimics of mineral scales often found on heat transfer surfaces. The shear strength of the scale layers increased on ageing; layers aged for more than 14 hours could not be removed by the gauging fluid flow. The shear stresses imposed by the gauging flow have been shown to be reliably estimated by an analytical result, provided that the flow rate is measured.
Absorption Rate of Carbon Dioxide by K2CO3‐KHCO3 DEA Aqueous Solution
Authors: Takahshi K. , Nii S. , Kawaizumi F.
Published: August 2010

Gas absorption rates of carbon dioxide from CO2‐air mixtures into K2CO3, K2CO3‐KHCO3, DEA and K2CO3‐KHCO3‐DEA solutions have been measured by using a wetted wall column. The method to determine the enhancement factor of chemical absorption is confirmed by the absorption of carbon dioxide in NaOH solution. The enhancement factor was correlated with the potassium concentration [K+] (= 2[K2CO3 + [KHCO3]), the DEA concentration, and the CO2‐loading ratio of the absorbent. The chemical reaction for CO2, absorption has been expressed by an (m,n)th order irreversible‐reaction model, where the reaction orders are m = 1 for CO2, n = 1.35 for DEA, n = 0.6 for K2CO3, and n = 0.6 and 1.35 for K2CO3 and DEA respectively. Experimental values of the enhancement factor were successfully reproduced by the calculations, where the reaction rate constants reflected the effect of loading ratio of the absorbent with carbon dioxide.
A Soft Sensor Based on Orthogonal Nonlinear Principal Component Analysis
Authors: Zhao Yuhong
Published: August 2010

An accurate on‐line measurement of quality variables is essential for the successful monitoring and control tasks in chemical process operations. A soft sensor is developed based on orthogonal nonlinear principal component analysis, due to its ability to capture the linear and nonlinear features of the data. An orthogonal nonlinear principal component analysis network is utilized to retain a compact representation of the data optimally. Then the linear relationship between the scores and estimated variable is gained by robust linear regression based on M‐estimation. The proposed method is applied on an industrial crude oil atmospheric distillation tower, and illustrated by comparison with other familiar methods. The results have shown that the proposed method gives a better performance over the conventional PCA method and neural networks method.
A Dioid Linear Algebraic Model for a Class of Hybrid Event Graphs
Authors: Zhang Duan , Dai Huaping , Sun Youxian
Published: August 2010

Hybrid Event Graphs (HEGs), a subclass of Hybrid Petri Nets, are extensions of Timed Event Graphs and Timed Event Multi‐graphs. A set of dioid linear algebraic equations will be inferred as a novel method of analysis a special class of HEG, if we treat the numbers of firings for discrete transitions and the cumulated amount of consumed token for continuous transitions as state‐variables. As a new modelling approach, it clearly illustrates characteristics of both discrete events and continuous events. Based on the algebraic model, the analyses and controls of HEG are more convenient. An example of optimal control is demonstrated.
Removal of SO2 and NOx from Flue Gas by Pulsed Corona Discharges
Authors: Ning C. , Zheng C. G. , Li J.
Published: August 2010

A pulsed power supply set and a plasma reactor were designed to investigate the process of removal of SO2 and NO using pulsed corona discharge. It is shown that positive pulsed corona is more effective than negative pulsed in removing both SO2 and NO. Using positive pulsed corona, the energy yields for SO2 and NO removed are 64.3 SO2/kWh and 9.9 gNO/kWh, respectively. The amounts of SO2 or NO removed are independent of the initial concentration and primarily determined by the energy absorbed by flue gas. Removal efficiency of 95% of SO2 can be achieved only by ammonia addition (without pulsed voltage). The removal effectiveness and thermal stability of reaction products can be enhanced when exerting a pulsed voltage. Ammonia is critical to SO2 removal and pulsed corona discharge plays a decisive role in NO removal. Ash itself can only remove a small amount of SO2, but the presence of ash in the flue gas reduced the effectiveness of pulsed corona discharge in SO2 removal. Our results indicate that pulsed corona discharges should be operated at temperatures below 80 d̀C.
Modelling and Simulation of Enzymatic Membrane Reactor for Hydrolysis of Ibuprofen Ester: Separation of Products
Authors: Long Wei Sing , Kamaruddin Azlina Harun , Bhatia Subhash
Published: August 2010

The enzymatic hydrolysis of racemic ibuprofen ester by lipase from Candida rugosa using a hollow‐fiber membrane reactor was studied. The modeling and simulation of an enzymatic membrane reactor was based on the diffusion of (S)‐ibuprofen acid product which leaves the reactor from the lumen side of the capillary fibers. The mathematical model containing a set of nonlinear partial differential equations was solved using orthogonal collocation technique. Orthogonal collocation technique is a weighted residual method based on Jacobi polynomials incorporating orthogonal trial functions. This paper presents a numerical technique of high efficiency, based on the orthogonal collocation of weighted residuals in solving the nonlinear partial differential equations of product diffusion in the capillary fibers. The modelling simulation study provided a better understanding of the process dynamics and product separation in the integrated enzymatic membrane reactor. The simulation study shows that noticeable product diffusion and transport occurred throughout the region of the fiber length, with 63.0% of product concentration (solute concentration) obtained at the exit of the fiber. The input parameters investigated were Peclet number and weighing function parameters, α and β. The best simulation results were achieved at the optimal 10 collocation points.
Enzymatic Enantioselective Acylation of Sterically Aromatic Secondary Alcohol
Authors: Chua Lee‐Suan , Sarmidi Mohamad Roji
Published: August 2010

This study focused on the kinetic resolution of(R,S)‐1‐phenylethanol using lauric acid as acyl donor. The enantioselective esterification was catalysed by immobilised lipases in organic media. From exploratory experiments, several commercial immobilised lipases were screened for their efficiency in resolving the racemic alcohol. They were lipases from Pseudomonas cepacia, Candida antarctica and Candida rugosa (Candida cylindracea) with different immobilisation methods. The cross‐linked enzyme crystal of P. cepacia lipase (ChiroCLEC‐PC) and the carrier‐fixed lyophilised C. antarctica lipase B (Chirazyme L2, c.‐f., C3, lyo) showed the highest performance in term of enzyme activity as well as enzyme enantioselectivity. They were selective towards the R‐enantiomer of 1‐phenylethanol with enantiomeric ratio (E) above 200. The presence of S‐enantiomers in the racemic alcohol did not cause inhibition to the resolution. Kinetic studies were carried out by varying the substrates concentration at the determined reaction conditions. Both enzymes required three‐fold molar excess of lauric acid over (R,S)‐1–phenylethanol (50 mM) in order to achieve the highest initial reaction rate. When using the molar excess of (R,S)‐1–phenylethanol, equilibrium conversion dropped due to enzyme deactivation.
Decentralized Control for Multivariable Processes with Actuator Nonlinearities
Authors: Su S. W. , Bao J. , Lee P. L.
Published: August 2010

Decentralized control is the most widely used control strategy in the process industries because of the simplicity to design and implement the controller, and the potential to achieve failure tolerant control. Actuator nonlinearities are often encountered in many chemical processes. This paper presents a decentralized control method for processes which have static actuator nonlinearities, such as saturation and dead zone. The proposed decentralized integral controller is designed based on feedforward passivation, which can be applied to nonminimum phase processes and/or processes of high relative degree. The concept of marginally stable positive real systems is used to analyse the stability of a closedloop system. The feedforward system is constructed to attain dynamic performance on the basis of frequency based passivity analysis. The effectiveness of the proposed approach is demonstrated using an example of a quadruple tank control problem.
Monitoring, Forecasting and Simulation of the Steelmaking Process
Authors: Hong Xin , Chen Jia‐Ying , Zheng Shao‐Bo , Qiu Xiao‐Lei
Published: August 2010

This paper introduced the sonic level monitor for continuous detection of slag condition, forecasting end‐composition of molten steel using artificial neural network, dynamic modeling and computer simulation of the steelmaking process.
Mathematical Modeling of the Vacuum Chamber of RH‐KTB Process
Authors: Huang Zong‐Ze , Chen Yi‐Sheng , He You‐Duo
Published: August 2010

A mathematical model was developed for the simulation of gas flow, combustion and heat convection in the vacuum chamber of RH‐KTB process at Baosteel. Under different conditions, the model was used to predict the influence of the top oxygen blowing lance on the gas flow; chemical reactions and temperature distribution were calculated. The optimum position of the lance is suggested for the RH‐KTB process.
Hydrogel beads based on carboxymethyl cellulose for removal heavy metal ions
Authors: Yang Shaoping , Fu Shiyu , Liu Hao , Zhou Yiming , Li Xueyun
Published: August 2010

Environment‐friendly carboxymethyl cellulose (CMC) hydrogel beads were successfully prepared using epichlorohydrin (ECH) as a crosslinking agent in the suspension of fluid wax. There was an ether linkage formed between ECH and CMC, which was identified from bands in FTIR spectra of the prepared hydrogel. The prepared hydrogel beads with diameters about 4 mm were apparently spherical and fully transparent. The X‐ray diffraction (XRD) spectra indicated that the adsorption of metal ion onto the oxygen atom of carboxyl group led to change in crystallinity patterns of hydrogels. The scanning electron microscope (SEM) images clearly showed that the hydrogels had an internal porous structure. The adsorption capacity increased as initial concentrations of metal ions and the pH value of metal ion solution increased. Freundlich and Langmuir isotherm models were employed to analyze the data from batch adsorption experiments. There are vey good correlation coefficients of linearized equations for Langmuir model, which indicated that the sorption isotherm of the hydrogel beads for metal ions can be fitted to the Langmuir model. The maximum adsorption amount of hydrogel beads for metal ions is 6.49, 4.06, and 5.15 mmol/g for Cu(II), Ni(II), and Pb(II), respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011