bluuebunny/crossref_metadata_2025 huggingface dataset:
New Photocatalytic Reactors for Destruction of Toxic Water Pollutants
Authors: Ray A. K.
Published: August 2010

Recent literature has established the potential of semiconductor photocatalysis technology to completely destroy toxic pollutants dissolved or dispersed in water into harmless substances. However, to date no viable pilot plant exists using this technology. In this paper, designs of two new photocatalytic reactors for water treatment are presented. One reactor consists of several hollow tubes employed as a means of light delivery to the catalyst present on the outside surface of the tubes, while the other design uses new extremely narrow diameter lamps. Experiments performed in both reactor configurations showed very promising results.
An Assessment of Hybrid Combined Cycle Power Generation Systems Based on a Coal Fired Pressurised Fluidised Bed Combustor
Authors: Evans R. H. , Mcmullan J. T. , Williams B. C.
Published: August 2010

A hybrid combined cycle electrical power generating scheme burning coal and natural gas is examined using the ECLIPSE chemical process simulator. The technical, environmental and economic performance of this system is presented and comparisons are made with conventional power generation technologies. These comparisons show that the hybrid combined cycle offers improvements in efficiency, CO2 emissions and cost.
Investigation into the Use of Copper‐Loaded Natural Zeolite for the Reduction of NO Using Methane
Authors: Headon K. A. , Zhang D. K.
Published: August 2010

The suitability of a copper‐loaded natural zeolite for the selective reduction of NO using methane was examined in a packed‐bed tubular reactor. The natural zeolite was found to decompose NO to nitrogen with a maximum conversion of30% achieved at 420 °C when 2% NO, 1% CH4 and 2% O2 were used with a contact time of 0.9 gscm−3. Exchange of the zeolite to the H‐form prior to copper ion‐exchange was essential for catalytic activity to be promoted by the presence of oxygen. The catalytic nature of the decomposition reaction was confirmed through experiments in the absence of any catalyst. Calcination of the zeolites after ion‐exchange resulted in no discernible effect on catalytic activity, and the use of Mg as a cocation also did not promote the activity. For a H‐exchanged sample, activity was significantly decreased.
Crossing Reaction Equilibrium in an Adiabatic Reactor System
Authors: Nicol W. , Hildebrandt D. , Glasser D.
Published: August 2010

The work presented in this paper looks at maximizing the conversion of an exothermic reversible reaction that is adiabatic overall, i.e. only allowing for internal heat exchange between streams. In a single adiabatic reactor the highest possible conversion is the equilibrium conversion. It is shown that an improvement can be made on this equilibrium conversion by using two reactors with two heat interchanging units. The heat interchange system can be further optimized by adding more reactors and heat interchangers. The optimum theoretical conversion for an adiabatic system was found to be the equilibrium conversion at the original feed temperature. This is achieved by operating a simultaneous heat interchanging and reactor structure. The work was extended to find a maximum conversion for a more practical system where account is taken of minimum temperature driving forces and incomplete conversions.
A Kinetic Investigation of the Copolymerization of Acrylonitrile and Vinyl Acetate in Bulk
Authors: Mcmanus N. T. , Penlidis A. , Rempel G. L.
Published: August 2010

The free radical copolymerization, initiated by 2, 2′ azo‐bis‐isobutyronitrile (AIBN), of acrylonitrile (AN) and vinyl acetate (VAc) in bulk has been examined. Reactivity ratios were evaluated using the error in variables model (EVM). In addition, full conversion range experiments were undertaken, which examined polymerization rate, molecular weight development and copolymer composition with respect to the effects of feed composition, initiator concentration and temperature.
A New Design Parameter ‐ “the Fit Factor” for the Retrofit Design of Heat Recovery Systems
Authors: Al‐Fakih N. , O'Neill B. K. , Roach J. R.
Published: August 2010

Retrofit design of heat recovery networks is an increasingly significant industrial problem. Such concern is driven by two factors ‐ the old and non‐optimal designs of many existing process plants coupled with increased economic and environmental pressures to improve their energy efficiency. In this paper, a new evaluation technique for the retrofit design of heat exchanger networks is presented. The ‘block design’ philosophy proposed by Zhu et al. (1) provides the basis for development of the method The retrofit situation differs considerably from the design of green‐field networks. A clear objective of the designer in the retrofit situation is to optimise the incremental investment expended in changing the existing network. To aid in achieving this goal, a new parameter “K” is defined to enable the engineer to identify well‐placed existing units and to highlight areas that would benefit from change. The new method identifies all of the available options and indicates the candidate exchangers for retention within the network together with situations likely to benefit from modification. Examples are provided to demonstrate the effectiveness of the proposed method.
Holdup in Vertical Three Phase Flow
Authors: Woods G. S. , Spedding P. L. , Watterson J. K. , Raghunathan R. S.
Published: August 2010

Vertical three phase air‐water‐oil data in a. 0.026 m i.d. pipe were presented. The liquid holdup data presented as a complex pattern against f0 the oil liquid volumetric ratio for annular flow at one value of total superficial liquid velocity. The form of the pattern was explained in qualititive terms depending on the nature of the flow pattern present. Generally for the water dominated regime below f0 = 0.5 the overlying oil annular film protected the water annular from the momentum effects of the gas. Above f0 = 0.5 the opposite took place and the water annulus film thinned until inversion to oil dominated flow occurred. This was a region of intense mixing of the liquid phases and the hold‐up rose dramatically.
Options for Small and Medium Scale Power Generation from Biomass
Authors: McIlveen‐Wright D. , Williams B. C. , Mcmullan J. T.
Published: August 2010

The technical and economic performance of a variety of options for producing electric power from woody biomass are assessed using the ECLIPSE suite of computer programs. The studies have included both fixed and fluidised bed combustion and gasification of the biomass with power generation from a range of small and medium scale steam turbines, gas engines, fuel cells or gas turbines in conventional, STIG and ISTIG modes.

For the small‐scale systems, gasification integrated with a gas engine was found to be the most appropriate of the current technologies, and gasification integrated with Molten Carbonate Fuel Cells the most promising technology for future development.

For medium‐scale systems, the IGCC systems were found to be the most efficient, but the less efficient combustion systems were competitive on cost. STIG and ISTIG systems offer promise for the future.
NOx Reduction Technology in PF Boilers
Authors: Mccahey S. , Mcmullan J. T. , Williams B. C.
Published: August 2010

Technical, environmental and economic assessments were performed, using the ECLIPSE process simulator, for a supercritical coal fired PF power station to investigate the impact of NOx reduction technologies. The study was modelled upon the Amer 9 Power Station at Geertruidenberg, The Netherlands, and both combustion and post‐combustion NOxreduction technologies were evaluated. SCR gave the largest reduction in NOx emissions to below 50mg/Nm3, but at an electricity cost of 2.44p/kWh, compared with 2.23p/kWh for the reference case and 2.26p/kWh for coal‐over‐coal reburning. The latter produced a 50% reduction in NOx emissions to below 200mg/Nm3. Use of a microniser, to reduce coal particle size, in coal‐over‐coal reburning is not justified, unless its absence produces excessive unburnt carbon losses or requires a reburn coal 50% more expensive than the main coal. With natural gas‐over‐coal reburning, an unrealisable natural gas price of £0.98/GJ is required to make it competitive with coal‐over‐coal reburning and natural gas prices between £1.76/GJ and £1.93/GJ are required for it to compete with SCR.
Viscosity of Reconstituted Milk Protein Concentrate Solutions as a Function of Shear, Temperature and Concentration
Authors: O'Donnell S. , Butler F.
Published: August 2010

The viscosity of reconstituted milk protein concentrate solutions was determined at various shear rates, (50‐1000 s−1), temperatures, (20‐60°C) and concentrations, (200‐260 g/kg). For a given temperature and concentration, the solutions were shear thinning and the effect of shear was adequately described by the Ostwald power law model. Viscosity increased with concentration and decreased with temperature. The effect of temperature on the consistency index followed an Arrhenius type relationship. The effect of concentration on the consistency index was modelled with both a power and an exponential relationship. The flow behaviour index was independent of temperature and concentration. The combined effects of shear rate, temperature and concentration on viscosity were modelled using an extended power law model.
Theoretical Investigations of Rotating Instabilities
Authors: Bowen P. J. , O'Doherty T. , Lucca‐Negro O.
Published: August 2010

This paper collates recent theoretical work which sets out to model the characteristics of rotating instabilities often generated by industrial swirl generators such as swirl burners and cyclone dust separators. Results generated from three modelling approaches are discussed: a perturbation analysis about an axisymmetric viscous flow; a two‐dimensional variational approach of incompressible inviscid flow; and numerical solutions of the three‐dimensional Navier‐Stokes equations using contemporary turbulence models. Each modelling approach can predict some of the features of the complex flowfield associated with these rotating instabilities.
The Impact of Scaling Criteria on the Characteristics of Pulverised Coal Flames
Authors: Smart J. P. , Van Kamp W. L. De
Published: August 2010

Results are presented of a series of experiments where a 12 MW, large‐scale swirl stabilised burner is compared with two 2.5 MW, geometrically similar burners designed around a constant‐velocity and constant‐residence‐time scaling criterion. High and low NOx flames were produced from all burners and selected flames were extensively probed to determine in‐flame thermo‐chemical structures. Results show that complex differences exist between flames. Results are also presented on the effect of scale on the ignition properties of axial turbulent jet flames. Experimental findings show an important effect of ignition distance on NOx that has important implications with respect to scaling effects on these flame types. The results detailed in the text are interpreted with reference to the effect of scale on turbulent mixing, two‐phase interactions and ignition properties. Results confirm that, regardless of the scaling criterion selected, similarity of the in‐flame thermochemical features is almost impossible to maintain as burner scale is changed irrespective of the scaling approach employed.
Research on the Properties of A Novel Granular Filter in Fluidized‐Bed
Authors: Zhang Shihong , Liu Dechang , Lu Jidong , Zheng Chuguang
Published: August 2010

A novel granular filter in fluidized‐bed is under developing in National Laboratory of Coal Combustion (NLCC) which can be applied in advanced coal‐fired power conversion systems. The characteristics of the filter, the parameters of a 3‐dimension lab‐scale filter facility in NLCC are analyzed in this paper. The results of preliminary investigation on the properties of the filter are also presented, which suggest that the novel filter can effectively clean the fine particles from gas streams, the mean size of the permeated particle is about 5 micron in diameter, the permeated particle volume flux is about 0.0000908cm3/sec/cm2 when sand is served as bed material. The filter unit immersed in fluidized bed is found to be a key factor which influences the fluidizing features of the filter.
Modeling of a Low Temperature Pyrolysis Process Using ASPEN PLUS
Authors: Yan H. M. , Zhang D. K.
Published: August 2010

An ASPEN PLUS based simulation model has been developed for a low temperature pyrolysis process, incorporating triple fluidised beds with solid circulation, for both valuable fuel oil production and power generation from low‐rank coal. This paper reports preliminary simulation results using a Loy Yang brown coal as the feed. Simulations indicate that, for the coal modelled, combustion of char and remaining volatiles after pyrolysis not only provide enough energy required for the endothermic pyrolysis reactions and the wet coal drying, but also can supply extra energy for power generation. About 2.7 MW power and 0.26 kg s−1 fuel oil can be produced from 1 kg s−1 dry coal feed to the process. Simulation also shows that the initial moisture content in the coal does not affect the tar yield in the pyrolyser but has an effect on the power generation from the process. Fraction of the non‐condensable fuel gas burnt in the combustor does not have significant effects on the power generated from the process.
Fundamental Principles of Incinerator Design
Authors: Swithenbank J. , Nassezadeh V. , Goh R. , Siddall R.G.
Published: August 2010

Waste management has become a major concern world‐wide and incineration is now being increasingly used to treat waste which cannot be economically recycled. The combustion of conventional well specified fossil fuels is a very complex process since it involves two‐phase turbulent reacting flow including radiant heat transfer. Incineration is even more complex since the waste is poorly specified and its composition varies from moment to moment. In the past, the design of incinerators has not been based on fundamental understanding and modelling of the process, and empirical rules have had to be used.

Over the last few years, computational fluid dynamics (CFD) has provided a means to model the freeboard region in a conventional municipal solid waste incinerator but the open literature contains no rigorous fundamentally based model of the bed region. The prediction of the flow composition emerging from this region is particularly important since it provides the “upstream” boundary condition for the flow calculations in the freeboard. For example, the calculation of the subsequent history of heavy metals requires knowledge of their emission rate from the burning bed.

The processes in the bed include drying, pyrolysis, oxidative burning, and gasification of the char. Furthermore, the movement of the grate is designed to mix the waste as it burns. Indeed, the existence of a rigorous bed model would also permit the grate design to be optimised, and, if immediate data on the feed were available, a rational combustion control strategy could be devised. A preliminary model of combustion in the bed is proposed herein based on governing equations for the burning of individual “regions” of waste in the upward gas flow, their motion, and radiant heat transfer within the bed. The emissions of gases from the surface of the bed is very non‐uniform with oxygen emitted from either end of the bed, organic compounds from the one‐third region, and carbon monoxide from the centre. The surface layer of this central part of the bed consists of char with gases coming up from the oxidising layer below containing NOx derived from the fuel nitrogen. The char region therefore acts as an important reburn zone and it is suggested that this reduces some of the NOx to nitrogen. This is important since the minimisation of NOx by optimising the basic combustion process is likely to be environmentally preferable to subsequent control of NOx by the injection ofreactants such as ammonia.

The calculation of flow and combustion in the freeboard using CFD can quantify the consequences of design concepts, however guidelines are needed to devise specific design concepts which are worthy of investigation. Thus the computer cannot “invent” a design but it can quantify the results of ideas.

Incinerator design thus requires a judicious combination of fundamental combustion science, ingenious engineering guided by an understanding of the mixing process, and last but not least, practical experience of previous failures and successes.
Technological Risk Assessment in the Process Industry: Recent Advances in Applications and Future Directions
Authors: Haddad S. , Mullins D. P.
Published: August 2010

Qualitative and quantitative risk assessment techniques have been applied in Australia and elsewhere in the process and related industries since the early 1980s. Technological, methodological, policy and regulatory regimes have progressively evolved and been developed, as have the scope and range of applications. Risk assessment has developed from being a hesitant complementary tool to engineering codes and standards, into an established component of integrated decision‐making processes covering such areas as: strategic land use safety planning, development approvals, risk communication, safety management, fire protection and emergency planning and response. This paper focuses on recent experience in implementing risk assessment within the NSW planning framework. Recent developments in policy, methodology and applications are highlighted, in particular: multi‐level approaches to risk assessment; contaminated water containment and treatment; and ecological risk assessment. Future directions may witness the strengthening of technological risk assessment as a living tool in on‐going operational and organisational safety.
Radiative Properties of Residual Char and Its Effects on Radiative Heat Transfer in Pulverized Coal Fired Furnaces
Authors: Liu Z. H. , Zheng C. G. , Xing H. W.
Published: August 2010

This paper gives a comprehensive modelling analysis of the radiative properties of residual char and its effect on radiative heat transfer in pulverised coal furnaces. Firstly, the effective optical constant is introduced into the model of the radiative properties of unburned char. Three structure models of unburned char are considered, i.e. constant diameter model, shrinking core model, and a transient model. The result shows that regardless of the structure of residual char, the absorption in the initial stage of combustion of large char particles (D>10μm) does not decrease, while a sharp decrease occurs near the burnout (B>0.9). Then radiative property models of particles were incorporated into a CFD code to investigate its effect on overall radiative heat transfer in pulverized coal furnaces. The numerical results of a 300 MW tangentially fired furnace show that residual char shields radiative heat transfer along the radial direction in the upper zone of the furnace, and thus the temperature at the exit of the furnace is higher. By ignoring the additional absorption of residual char, it will lead to a lower predicted radiant heat flux to the area of platen superheater
Dynamic Simulation and Control of an MTBE Catalytic Distillation Column
Authors: Lin H. , Douglas P. L.
Published: August 2010

A dynamic model of an MTBE (methyl tert butyl ether) catalytic distillation column was developed using the SpeedUp simulation package. Experimental kinetic rate data, rigorous thermodynamics, vapour‐liquid nonidealities and tray hydraulics were incorporated in the simulation. The steady state results from the dynamic model were compared with the steady state results from a steady state model developed using the AspenPlus simulation package. The steady state results from the two simulations were in perfect agreement with each other.

Open hop step tests were performed on the dynamic model of this process and the process model indicated a non‐linear, self‐regulating behaviour and did not exhibit any multiplicities. Multiloop linear control systems were designed and PI, PID and Dynamic Matrix Control (DMC) controllers were tested on the simulation for load disturbances and setpoint changes.

All controllers performed adequately; the DMC controller consistently resulted in better dynamic control performance than the other two controllers.
Efficient Simultaneous Dry Removal of SO2 and NOx from Flue Gas over Copper‐Based Catalytic Materials
Authors: Centi Gabriele , Perathoner Siglinda
Published: August 2010

The combined removal of SO2 (DeSOx) and NOx (DeNOx) from flue gas of power plants can be efficiently realized with a dry process using copper‐based sorbent‐catalysts which oxidize‐adsorb SO2 in the form of an easily regenerable copper‐sulphate and catalyze the reduction of NO in the presence of NH3/O2. This contribution reviews the results on this topic, discussing in particular the following main aspects: (i) Sorption and catalytic chemistry of the process, (ii) Development and features of the copper‐based sorbent‐catalyst. (iii) Optimization of the reaction conditions. (iv) Kinetic models of the sorption and catalytic behavior and role of the textural properties of the catalyst, (v) Flowsheet and economics of the process, (vi) Behavior in extended operations and life time cycles. The key features of the technology and its fields of application are also discussed.
Catalytic Destruction of Dioxins
Authors: Clark David M.
Published: August 2010

Dioxins are toxic and by many considered to be carcinogenic and mutagenic, hence control of dioxin emissions is now mandated by many governments. There are many technologies, which remove dioxins from flue gas streams, such as active carbon adsorption. However, these technologies only transfer the hazard associated with dioxins from the gas phase to the solid phase. This leaves the problem of disposing safely of dioxin containing waste, such that later release of dioxins from the adsorbent does not occur. To overcome these limitations a system has been developed which converts, rather than removes, dioxins to CO2, H2O, HCl and hydrocarbon fragments which are environmentally benign. This paper looks at the development of the technology from lab scale testing to commercial applications both in the Asia Pacific region and throughout the World.
The Role of Ammonium‐Sulfur Aerosols on Nitrogen Oxides Removal by Pulsed Corona Enhanced Wet Electrostatics Precipitation with Ammonia and Ozone Injection
Authors: Tseng C.‐H. , Keener T.C. , Khang S.‐J. , Lee J.‐Y.
Published: August 2010

The removal of nitrogen oxides (NO and NO2) has been investigated in a bench‐scale pulsed‐corona enhanced wet electrostatic precipitator (wESP). The 70 Hz pulsed voltage is applied up to 60 kV. Simulated flue gases with NOx concentration up to 1200 pp m have been used to determine the feasibility of NOx removal in the wESP. NO must be oxidized to NO2 before any removal takes place. NOx removal efficiency increased with gas residence time, inlet NO concentration and applied corona power. In the air stream with 10 seconds gas residence time, up to 20% of 1000 pp m NO (22% of NOx) was removed at a 20 watt pulsed corona. The amount of in‐situ ozone was not enough to be considered as a major NOx removal mechanism in this wESP. Ozone injection improved the NOx removal for both the corona and non‐corona cases by oxidizing NO. With 300 pp m of ozone, the removal of 750 pp m NO was increased from 18% to 50% by oxidation, but total NOx removal was improved only to 25%.

However, very high NOx removals were measured in simulated flue gas that contained ammonia, sulfur dioxide and ozone. For instance, in a 3% oxygen, 11% CO2 simulated flue gas with 800 pp m NO and 70% relative humidity at 8.6 sec of gas residence time, 30 kV corona discharge, the removal efficiency of NO was only 5%. Injecting NH3 only (NH3/NOx ratio 1) at 32 watts corona power, NO removal was increased to 10%. With the co‐presence of 2400 pp m SO2, 200 pp m ozone injection (no ammonia) increased NO removal to 36% by oxidation, but total NOxremoval only to 17%. After co‐injecting 312 pp m ozone and 2900 pp m NH3 (stoichiometry ratio 0.53), total N0X removal was increased to 79%. It was determined that the ammonium salt aerosols produced from the reaction of ammonia and sulfur dioxide enhanced the NOx removal substantially. The significance of this catalyzing effect by the in‐situ ammonium salt aerosols is addressed in this paper.
Applications of Mathematical and Computer Models for the Evaluation of Novel Catalytic Reactors
Authors: Moustafa T.M. , Fahmy M. , Elnashaie S.S.E.H.
Published: August 2010

A pseudo‐homogeneous model is used to explore the possibility of using a membrane reactor for the industrial production of styrene. This novel catalytic reactor consists of two compartments separated by a hydrogen selective membrane. The first compartment is the reaction side, in which the dehydrogenation of ethylbenzene to styrene is taking place, while the other compartment is the permeation side in which an inert sweep gas is used to remove the hydrogen permeated through the membrane. Different configurations of sweep gas flow were tested namely the co‐current and counter‐current flow. Partial blinding was also tested in the counter‐current flow case. The effect of vacuum in the permeation side was also investigated. Superior performance in terms of ethylbenzene conversion and styrene yield using this novel reactor was obtained in comparison with the conventional industrial reactor. The counter‐current sweep gas with optimal partial blinding gave the most superior performance.
Crystallization of Calcium Sulfate Dihydrate from Phosphoric Acid
Authors: Jamialahmadi M. , Müller‐Steinhagen H.
Published: August 2010

Knowledge of the kinetics of calcium sulfate dihydrate crystallization from phosphoric acid solutions is essential for design and operation of the dihydrate process, which is frequently used in fertilizer industries for the production of phosphoric acid A continuous crystallizer was used to investigate the effect of operating parameters on nucleation and growth rates, and ultimately on the crystal size distribution of calcium sulfate dihydrate. It is shown that growth rate increases with the square of supersaturation and that the effect of temperature on the growth rate constant follows an Arrhenius relationship with an activation energy of 65.2 kJ/mol. The predictions of the suggested kinetic models are verified against plant data.
Cross‐directional Estimation and Predictive Control of Paper Machines Using DWT
Authors: Song Zhihuan , Li Ping , Lou Yiming
Published: August 2010

This paper proposes a novel approach for cross‐directional (CD) estimation, modeling and control on paper machines based on discrete wavelet transforms (DWT). The CD basis weight variations are approximated at various resolutions using wavelet multiresolution analysis (WMRA). The controllable component of CD variations can be extracted from the original samples by choosing a suitable threshold resolution. An acceptable response model describing the relationship between the settings of the slice‐screws to the basis weight profile is obtained. The controller synthesis, model prediction, optimization and parameter estimation are all performed in the DWT domain. The size of optimization and control problems associated with such large dimensions can be significantly reduced.
Data Compression for Types of Nopaper Recorders Based on Some Wavelets
Authors: Jin Jiangxiang , Zhu Jianxin
Published: August 2010

In this paper, an efficient compression algorithm based on some wavelets for types of nopaper recorders is provided. Numerical results demonstrate that the algorithm is better applied to the compression of historical data, for example, temperature, liquid level, flow rate and pressure. Therefore, the algorithm reduces the need for storage of these data and improves the functions of the recorders to a maximum.
Output Feedback Stabilization of Uncertain Time‐Delay Systems Containing Saturating Actuators
Authors: Su Hongye , Hu Jianbo , Chu Jian , Lam James
Published: August 2010

The robust output feedback stabilization problem for a class of uncertain linear time‐delay systems containing a saturating actuator is studied in this paper. The systems are described by state differential equations with bounded time‐varying uncertain parameters and unknown constant delay in the state. New criterion for robust stabilizability of the uncertain time‐delay systems is presented and the corresponding observer‐based robust output feedback controller is derived in terms of the solutions of linear matrix inequalities (LMIs). Simulation results show that the obtained method is feasible.
Variable Structure Control for a Class of Systems with Mismatched Uncertainties
Authors: Hu Jianbo , Liang Ximing , Wu Jun , Su Hongye , Chu Jian
Published: August 2010

The problem of Variable Structure Control (VSC) for a class of systems with mismatched uncertainties is studied in this paper. The systems considered in this paper can be transformed into two staged sub‐systems. The first subsystem is a linear system with uncertainties U1, and its inputs are the state variables of the second subsystem. The second sub‐system, having the same dimension as the inputs, is a nonlinear system with uncertainties U2 and its inputs are the control inputs for the original system. In fact, U1 and U2 are the mismatched uncertainties and matched uncertainties of the original system, respectively. Based on the quadratic stabilization for the first sub‐system, the desired values of the second state variables are synthesized by Linear Matrix Inequality (LMI) technique, and the switching function vector is constructed based on the errors between the values of the second state variables and their desired values. Furthermore, the variable structure controller is derived by the reachable condition for the sliding‐mode such that the closed‐loop system can enter and retain the sliding‐mode. Meanwhile, the closed‐loop system has the stable sliding‐mode motion.
Burnout Behaviour of Bituminous Coals in Air‐Staged Combustion Conditions
Authors: Kluger F. , Spliethoff H. , Hein K. R. G.
Published: August 2010

In order to determine the influence on burnout by the combustion conditions and the coal preparation, three bituminous coals sold on the world market, from three different locations, in Poland, South Africa, and Australia, were studied more closely. For this purpose, the coals were ground in two different particle size ranges, which, besides the influence of the combustion conditions, such as temperature, residence time, and stoichiometry, made it possible to also investigate the impact on burnout by the coal preparation. The experiments were carried out in an electrically heated entrained‐flow reactor with a thermal input of 8.5 kW. The parameters for the experiments are wall temperature (1000 ‐ 1350d̀C), air ratio (0.6–1.15), and two particle sizes (70% < 75m̈m, 90% < 75m̈m). The results show that in general, for increasing temperatures, the burnout quality will improvel. For the Australian Illawara coal, another outcome is increased NOx emissions. Lowering the air ratio in the reduction zone leads to less NOx emission but to increased unburnt matter in ash. For the smaller particle size fraction, the analysis of the different particle sizes shows an improvement of the burnout without a change in NOx emissions.
A Study of the Reactivity and Formation of the Unburnt Carbon in CFB Fly Ashes
Authors: Li Yong , Zhang Jiang‐Sheng , Liu Qing , Lu Ji‐Ling , Yue Guang‐Xi , Sarofim Adel F. , Beér Janos M. , Lee Yam Y. , Eliasson Baldur
Published: August 2010

A comprehensive study was conducted on the reactivify and the turbostratic structure of the unburnt carbon in the CFB fly ashes. The observed deactivation of the unburnt carbon and the pyrolysis chars prepared under various conditions was studied and found to be due to the combination of the loss of catalytic effect of the minerals and the crystalline growth of carbon. Various forms of morphology of the residual carbon particles were examined under a microscope. Both inertinite and vitrinite seem to be possible sources of the unburnt carbon. The formation of the unburnt carbon in the CFB fly ashes was likely caused by the deactivation of char particles and the insufficient residence time of the corresponding fuel particles.
Mineral Matter Transformation During Pulverized Coal Combustion
Authors: Eddings Eric G. , Davis Kevin A. , Heap Michael P. , Valentine James R. , Sarofim Adel F.
Published: August 2010

Significant progress has been made in understanding and quantifying the processes governing the transformation of the inorganic constituents of fuels, leading to the promise of being able to predict the behavior of mineral matter in real systems. In addition, modern computational models have progressed to the point that combustion simulations can be now be realized for industrial‐scale systems. The combination of current understanding of mineral matter transformations with state‐of‐the‐art computational fluid dynamics (CFD) models provides a powerful tool for analyzing utility boilers. A case study is presented illustrating how knowledge of the transformation of pyrites coupled with CFD models can be used to explain problems of corrosion that have been encountered in some utility boilers as a result of modifications to reduce emissions of nitrogen oxides.
Rapid Solution of Stiff Differential Equations and Accurate Numerical Laplace Inversion of Steep and Oscillatory Functions using IMN Approximants
Authors: Taiwo O. , King R.
Published: August 2010

IMN approximants are a fast and convenient method of solving initial value problems in linear stiff differential algebraic equations as well as obtaining the numerical inversion of Laplace transforms In the past it was impossible to use them to obtain sufficiently accurate inversions of certain steep and highly oscillatory responses as useable values of N had to be relatively small not only to ensure reliable evaluation of IMN constants but also in order to avoid undue rounding errors in the computed results However, the development of computer algebra systems such as Mathematica which permit infinite precision computation has provided greater latitude for the application of the method This work is an exposition of the potency of IMN approximants in accurately and cheaply inverting functions in the Laplace domain whose time functions are steep, oscillatory or stiff Previous applications of the method to some examples in the literature led to wrong conclusions as the capabilities of the method were not fully explored We show how to obtain very accurate results in these circumstances using both the global and step‐by‐step methods The results of using IMN step‐by‐step technique to rapidly solve stiff differential equations of a large staged process are also presented As Matlab gives inaccurate results, Mathematica has been used to compute both the transfer function and the analytical expression for the time response of the plant Extended values ofM and N as well as the ranges of the corresponding IMN constants are tabulated for IMN approximants of full grade.
Applying Dynamic Neutron Radiography in In‐Situ Monitoring of the Drying Processes of Apple
Authors: Balaskó M. , Kőröusi F. , Farkas I.
Published: August 2010

A novel technique of Dynamic Neutron Radiography (DNR) was applied for identifying and visualizing the dewatering paths and patterns in apple slices at three thicknesses, to the best of our belief for the first time in this field. By analyzing the DNR images obtained, the iso‐distribution of water (dewatering paths) and fractals (patterns) were obtained. Having the images geometrically calibrated and bileveled, the surface changes of apple slices were described by an exponential model in the course of a dewatering study period of 1500 min, with the velocity of the shrinkage of surfaces being estimated.
An Investigation on Sulfation Mechanisms of Ca‐based Sorbent Modified by Sodium Salt
Authors: Wang Chunbo , Shen Xianglin , Li Daji
Published: August 2010

This paper discusses the calcination and sulfation characteristics of a limestone modfied by Na2CO3, in order to find the causes of enhanced sulfation capacity of the modfied sorbent. It is shown by the experiments that the decomposition rate of modified limestone is quicker than for the original sample, and the CaO formed by the modified limestone (abbreviated as M‐CaO) has higher calcium conversion in sulfation than that formed by the original sample (abbreviated as N‐CaO). Although the sulfur capture capability of M‐CaO is in excess of that of N‐CaO, pore structure measurements showed that specific surface area and porosity of the former are less than that of the latter Therefore, the M‐CaO sulfation phenomena cannot be explained based only on the pore structure. The crystal structure parameters of CaO were measured and require further investigation. According to solid‐state ions diflusion theory, a new sulfation mechanism is proposed. More lattice defects are formed in M‐CaO, which reduces the resistance of ion diffusion in the product layer and increases the calcium conversion.
The Effect of Extrusion Processing Conditions on the Properties of Blown and Cast Polyolefin Packaging Films
Authors: Billham M. , Clarke A.H. , Garrett G. , Mcnally G.M. , Murphy W.R.
Published: August 2010

Thin mono‐layer films of metallocene catalysed polyethylene, linear low density and conventional low density polyethylene, as well as polypropylene, were produced from a 38mm extruder through a 75mm diameter blown film die and a 600mm cast film die. By using the same die gap on each die to achieve equal draw‐down ratios, the influence of orientation from the two processes on the mechanical properties of each firm was investigated. Tensile strength at break, Young's Modulus, percentage elongation at break, tear propagation resistance, in both machine and transverse direction all gave significant differences in properties with cast film when compared to different blow‐up ratios for blown film. Differential Scanning Calorimetry was used to measure the percentage of crystallinity in each film. Differences were found to show that the cooling process as the melt exits the die has a significant effect on the percentage of crystallinity.
The Effect of Cooling Processing Conditions on the Crystallinity and Mechanical Performance of Pigmented Polypropylene Extruded Film
Authors: Marks A.F. , Leathern M. , Mcnally G.M. , Murphy W.R.
Published: August 2010

The mechanical properties of semi‐crystalline polymers will be dependant to a great extent on the overall crystalline morphology of these materials. These morphological structures are developed during cooling of the polymer melt during plastic fabrication processes such as extrusion. Control of this crystalline development is therefore a very important processing requirement in order to ensure optimum mechanical performance of products manufactured by extrusion processes. The nucleating effect of phthalocyanine‐based pigments on the processing and properties of semi‐crystalline polymers has also been a challenge to polymer processors for many years. These effects are ever more pronounced during in‐line, post extrusion processes such as elevated temperature drawing of polypropylene slit film tapes, for rope and twine applications. A range of polypropylene films containing levels of 2% phthalocyanine based pigments and inorganic iron (II) oxide based pigments were manufactured using the chill roll cast extrusion process, using a range of quench temperatures and die to chill roll gaps. Analysis of the tensile properties of the films showed significant increase in modulus for the phthalocyanine pigmented films by up to 25% in comparison to the iron (II) oxide pigmented and non‐pigmented films. DSC analysis showed the crystallinity of phthalocyanine‐pigmented films to be less affected by quench roll temperatures than the iron (II) oxide pigmented and non‐pigmented films. However polarized light microscopy analysis of the films showed the spherulite sizes for the phthalocyanine pigmented films to be significantly smaller than the iron (II) oxide pigmented films and non‐pigmented films.
The London Communiqué May be the Answer, but What was the Question?
Authors: Peet J.
Published: August 2010

How to achieve Sustainable Development (SD) is probably the most important policy question facing us. Most conventional approaches, however, fail to get to grips with the totality of the issue. In this paper I propose that SD be addressed from a wider perspective that acknowledges systemic complexity as the central issue. To address complexity properly requires that policymakers acknowledge that no single tool can answer the question — and also that the question should never be simplified in order to fit with the tools on offer. In order to integrate approaches from a number of disciplines, it is critically important to enunciate an ethic that will guide the process. Such an ethic should come out of a process involving stakeholders from all sectors of the community.
Direct Numerical Simulation of Open Channel Flow with Buoyancy
Authors: Honda Itsuro , Kanagawa Naotaka , Kawashima Yosuke
Published: August 2010

Free surface flow is important in chemical reactions, heat exchange, atmospheric science and industrial technology. In terms of fundamental research, turbulence near a free surface is important in transport phenomenon. However, free surface effects exhibit some nonlinear behavior, so that numerical methods are usually employed instead of analytical approaches. In this investigation, direct numerical simulation is applied to turbulent channel flow with a free surface. The Navier‐Stokes equations are solved using a finite difference method, and an interpolation scheme is applied to the convective term. Grid resolution is 128x65x128 and Reynolds number based on the friction velocity and channel elevation is 150. Slip wall approximations have been used extensively. This means that the free surface has no stress, velocity or deformation. In order to solve such problems, low Froude number approximations have recently been presented and these are used to calculate the free surface flow. In turbulent flow, dissipation and production are essential qualities, Reynolds‐stresses balances and pressure‐strain correlations are examined numerically. It is shown that the main difference between free surface and slip wall approximations is in pressure‐strain correlations near the surface.
Solvent Extraction of Metal Picrates with Oligoethylene Glycol Glyme Derivatives
Authors: Ouchi Mikio , Konda Makoto , Nagamune Satoshi , Yoneda Akio , Hakushi Tadao , Mishima Kenji
Published: August 2010

The cation‐binding by a series of oligoethylene glycol glyme derivatives has been performed by the solvent extraction of alkali metal picrates between water and dichloromethane. The effect of the length of the oligoethylene unit and the substituents at the terminal group on the cation binding ability is discussed. The results are compared with those of commercially available crown ethers and it was found that the compounds have lower cation binding ability.
The Processing and Performance of PVC Blends
Authors: Mcconnell D.C. , Mcnally G.M. , Murphy W.R.
Published: August 2010

Two grades of ethyl‐vinyl acetate copolymers (EVA), containing 26% vinyl acetate (VAc) (unmodified with 1.2% methacrylic acid), and 27% VAc (unmodified) respectively, and an ethylene‐vinyl acetate‐carbon monoxide terpolymer (EVA‐CO), were independently blended with two grades of polyvinyl chloride (PVC). The performance of these blends were also compared to several conventional plasticised PVCs (pPVCs), to determine the advantages of using these polymer‐modified PVCs as potential alternatives to the traditional plasticized PVCs for medical device and healthcare applications. Mechanical analysis of the EVA and EVA‐CO blends showed that the tensile and flexural modulus decreased significantly and impact strength greatly improved, with increasing copolymer and terpolymer content respectively. DMTA showed a shift in glass transition temperatures (Tg) of the PVC and EVA components for the PVC/EVA blends, suggesting partial miscibility over the range of concentrations studied. DMTA for the PVC/EVA‐CO blends showed a single Tg between that of the PVC and EVA‐CO components indicating complete miscibility. Rheological analysis gave only slight changes in shear viscosity with increasing copolymer and terpolymer content. The properties of most of the PVC/EVA‐CO blends were similar to those of commercially available plasticised PVCs suggesting these blends may be suitable alternatives to pPVCs, where improved impact strength is required particularly in medical film applications.
Effect of Coupling Agents and Weathering on the Mechanical Properties of Wood‐Polymer Composites
Authors: Douglas P. , Murphy W. R. , Billham M. , Mcnally G. M.
Published: August 2010

Polyvinylchloride (PVC), polypropylene (PP), and low density polyethylene (LDPE) were used to prepare a range of wood‐polymer blends containing 20, 40, and 60% w/w medium density fibreboard sawdust (90–150 microns and 212–850 microns). The blends were melt compounded using a Killion single‐screw extruder with a barriertype screw design. Two couplings agents (maleic anhydride and a titanate‐based compound) were incorporated into the blends during compounding at levels of 1 and 2 wt%. Mechanical analysis illustrated improved impact and break strength and tensile modulus for blends containing PP and LDPE with 1% maleic anhydride. During a weathering time of 49 days, the mechanical properties decreased in all composites with water retention evident when the composites were “dry.”
Leachability of Lead and Cadmium from Cementitious Wastes
Authors: Halim C. E. , Amal R. , Beydoun D. , Scott J. A. , Low Gary K.‐C.
Published: August 2010

In this paper, the leachability of lead and cadmium from cementitious waste was investigated to determine the leaching mechanism of these heavy metals from a cement matrix so that a more appropriate leaching test can be designed. The leaching studies were carried out using a modified Toxicity Characteristic Leaching Procedure (TCLP), and variations in leaching parameters such as leachate pH, the duration of agitation, the particle size, and the liquid to solid ratio were investigated. The main finding of these studies was that the leachability of Pb and Cd in cementitious waste was highly dependent on the pH of the leachate. Other findings included: (i) the leachability of metals initially decreased with increasing leaching duration but increased after the leachate pH reached equilibrium; (ii) the particle size of the cementitious waste affected the rate of leaching of alkalinity from cement and hence the leachability of the heavy metal ions; and (iii) the total metals in the leachate, increased with increasing liquid to solid ratio. Overall, the TCLP was found to be inappropriate for assessing the leachability of heavy metals from cementitious waste due to the high buffering capacity of the calcium ions in the cement. This maintained the pH of the leachate at a value where heavy metals are insoluble. The test was found to underestimate the concentration of heavy metal ions leached from cementitious waste relative to the concentration in the actual landfill environment.
Breakage can Cause Mean Size to Increase
Authors: Neumann L. , Howes T. , White E. T.
Published: August 2010

Breakage of particles in a distribution, under quite reasonable conditions, can result in the low order mean sizes of the distribution unexpectedly increasing. The conditions under which this occurs are given in general, and for a binary mixture.