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Abstract: The fluid–particle interaction and the impact of different heat transfer conditions on pyrolysis of biomass inside a 150g/h fluidised bed reactor are modelled. Two different size biomass particles (350μm and 550μm in diameter) are injected into the fluidised bed. The different biomass particle sizes result in different heat transfer conditions. This is due to the fact that the 350μm diameter particle is smaller than the sand particles of the reactor (440μm), while the 550μm one is larger. The bed-to-particle heat transfer for both cases is calculated according to the literature. Conductive heat transfer is assumed for the larger biomass particle (550μm) inside the bed, while biomass–sand contacts for the smaller biomass particle (350μm) were considered unimportant. The Eulerian approach is used to model the bubbling behaviour of the sand, which is treated as a continuum. Biomass reaction kinetics is modelled according to the literature using a two-stage, semi-global model which takes into account secondary reactions. The particle motion inside the reactor is computed using drag laws, dependent on the local volume fraction of each phase. FLUENT 6.2 has been used as the modelling framework of the simulations with the whole pyrolysis model incorporated in the form of User Defined Function (UDF). [Copyright &y& Elsevier]

Abstract: Tars and CH4 generated from biomass gasification processes contribute significantly to the energy content of the producer gas: catalytic tar and CH4 steam reforming allows to clean the gaseous fuel and improve the H2 yield; in addition, the use of a CO2 sorbent minimises carbon oxides. As a result of the whole process, a H2 rich fuel gas may be obtained. This experimental work is addressed to study the practical feasibility of such concepts, choosing CH4, toluene and 1-methyl naphthalene (1-MN) as biomass gasification key primary products. Ni is used as a catalyst for steam reforming, and dolomite as a sorbent for CO2 capture. Two kinds of catalytic systems are tested as bed material: a mixture of dolomite and commercial nickel catalyst, and a new Ni/dolomite combined catalyst and sorbent. The experimental investigations have been carried out in a fixed bed microreactor and a bench scale fluidised bed reactor rig. Both combinations of catalyst and sorbent are found to be very effective in tar removing, with conversion values near to 100% for the compounds tested; simultaneous CO2 sorption reveals itself as the key process step, improving significantly the performance of the catalytic system that may then decrease considerably after sorbent saturation. [Copyright &y& Elsevier]

Abstract: The rates of oxidation of CO to CO2 by particles of a co-precipitated mixture of CuO and Al2O3 (355–500μm) have been measured in a fluidised bed; these measurements were not affected by interphase mass transfer or the deposition of carbon. Efforts were made to minimise sampling problems by using a rapid-response mass spectrometer to analyse the gases from the hotter beds or those fluidised by gases with high [CO]. However, the base-line of the mass spectrometer drifted with time, so an infra-red analyser measured [CO2] and [CO] in the off-gases from cooler beds, in which CO was oxidised to CO2 more slowly. These techniques enabled rates of reaction to be measured from 250 to 900°C; the order of reaction in CO was always close to unity. It was established that above 500°C, the oxidation of CO by particles of CuO was controlled mainly by external mass transfer. At ∼250°C, it appears that CO reacts directly with solid CuO in: However, above ∼700°C, CuO particles seem to react by the shrinking core mechanism, predominantly involving the two consecutive steps: The activation energies and pre-exponential factors for reactions 1 and 4 were measured. [Copyright &y& Elsevier]

Abstract: The fluid–particle interaction inside a 150g/h fluidised bed reactor is modelled. The biomass particle is injected into the fluidised bed and the heat, momentum and mass transport from the fluidising gas and fluidised sand is modelled. The Eulerian approach is used to model the bubbling behaviour of the sand, which is treated as a continuum. Heat transfer from the bubbling bed to the discrete biomass particle, as well as biomass reaction kinetics are modelled according to the literature. The particle motion inside the reactor is computed using drag laws, dependent on the local volume fraction of each phase. FLUENT 6.2 has been used as the modelling framework of the simulations with the whole pyrolysis model incorporated in the form of user-defined function (UDF). The study completes the fast pyrolysis modelling in bubbling fluidised bed reactors. [Copyright &y& Elsevier]

Abstract: The pyrolysis of a freely moving cellulosic particle inside a continuously fed fluid bed reactor subjected to convective heat transfer is modelled. The Lagrangian approach is adopted for the particle tracking inside the reactor, while the flow of the inert gas is treated with the standard Eulerian method for gases. The model incorporates the thermal degradation of cellulose to char with simultaneous evolution of gases and vapours from discrete cellulosic particles. The reaction kinetics is represented according to the Broido–Shafizadeh scheme. The convective heat transfer to the surface of the particle is solved by two means, namely the Ranz–Marshall correlation and the limit case of infinitely fast external heat transfer rates. The results from both approaches are compared and discussed. The effect of the different heat transfer rates on the discrete phase trajectory is also considered. [Copyright &y& Elsevier]

Abstract: The fluidisation of partially-crystallised whey powder above the glass-transition temperature of lactose has been investigated, with the intent of crystallising the amorphous-lactose fraction in order to reduce the propensity of the powder to cake during storage. Partially-crystallised whey powder can be fluidised in a vibrated fluidised bed at temperatures of 25 to 40 °C above the glass-transition point of lactose, depending on the relative humidity of the air, before the powder becomes too sticky to fluidise. This temperature difference can be increased up to 80 °C by fluidising the powder with fine, relatively non-sticky, fully-crystallised whey powder in order to coat and protect the sticky partially-crystallised whey particulates during fluidisation. Despite this temperature-difference increase, the time required to crystallise the amorphous-lactose fraction in partially-crystallised whey powder is not reduced sufficiently for this process to be viable in industry. An amorphous whey powder crystallisation process is likely to be more feasible, because the reduced salt and protein concentrations in this powder would ensure that lactose crystallisation is faster. Finally, this work has highlighted the potential of using the phenomenon of lactose plasticization above the glass-transition temperature and fines coating to improve the instant properties of milk-based powders. [Copyright &y& Elsevier]

Abstract: The fluid–particle interaction inside a 150g/h fluidised bed reactor is modelled. The biomass particle is injected into the fluidised bed and the momentum transport from the fluidising gas and fluidised sand is modelled. The Eulerian approach is used to model the bubbling behaviour of the sand, which is treated as a continuum. The particle motion inside the reactor is computed using drag laws, dependent on the local volume fraction of each phase, according to the literature. FLUENT 6.2 has been used as the modelling framework of the simulations with a completely revised drag model, in the form of user defined function (UDF), to calculate the forces exerted on the particle as well as its velocity components. 2-D and 3-D simulations are tested and compared. The study is the first part of a complete pyrolysis model in fluidised bed reactors. [Copyright &y& Elsevier]

Abstract: In this paper, a mathematical model is developed for the simulation of a large-scale sewage sludge incineration plant. The model assumes the bed to consist of a fast gas phase, an emulsion phase and a fuel particle phase with specific consideration for thermally-thick fuel particles. The developed model is employed to predict the dynamic response of the bed combustion to fluctuations in sludge feeding-rate. Calculation results indicate that the bed combustion is sensitive to fluctuations with response times greater than 30min, but severe delays exist for both outlet oxygen level and bed temperatures; from 6 to 13min for O2 and 22–45min for temperatures. Depending on the fluctuation frequency, the corresponding phase shifts are 39–96° for outlet O2, 138–336° for bed temperature and 80–336° for freeboard temperature. [Copyright &y& Elsevier]

Galvanising is the most widely used process for zinc coating. However alternative methods exist with less environmental impact such as fluidised bed process. In this work the structure of Zn coatings formed with fluidised bed process technique at 400°C for 1 h holding time has been studied. The coated samples were observed with scanning electron microscopy and characterised with energy dispersive spectroscopy and X-ray diffraction. The as formed phases correspond to gamma and delta phases of the Fe–Zn system. Some of the as deposited coatings are likely to provide sufficient anticorrosive protection while others are of low quality, as many porous areas are present in their mass. [ABSTRACT FROM AUTHOR]

Abstract: Top-spray fluid bed coating scale-up experiments have been performed in three scales in order to test the validity of two parameters as possible scaling parameters: The drying force and the relative droplet size. The aim was to be able to reproduce the degree of agglomeration as well as the mechanical properties of the coated granules across scale. Two types of placebo enzyme granule cores were tested being non-porous glass ballotini cores (180–350 μm) and low porosity sodium sulphate cores (180–350 μm). Both types of core materials were coated with aqueous solutions of Na2SO4 using Dextrin as binder. Coating experiments were repeated for various drying force and relative droplet size values in three top-spray fluid bed scales being a small-scale (Type: GEA Aeromatic-Fielder Strea-1), medium-scale (Type: Niro MP-1) and large-scale (Type: GEA MP-2/3). The tendency of agglomeration was assessed in terms of particle size fractions larger than 425 μm determined by sieve analysis. Results indicated that the particle size distribution may be reproduced across scale with statistical valid precision by keeping the drying force and the relative droplet size constant across scale. It is also shown that none of the two parameters alone may be used for successful scaling. Morphology and microscope studies indicated that the coating layer is homogenous and has similar structures across scale only when both the drying force and the relative droplet size were fixed. Impact and attrition tests indicated that it is possible to produce granules with similar attrition and impact strength across scale and that the two types of mechanical properties are inversely related. [Copyright &y& Elsevier]

Abstract: An exploratory spray-zone modelling concept which uses energy of adhesion at the contact of particles has been incorporated in a fully-3D Discrete Element Method (DEM)-based granular dynamics fluidised bed model and applied to fluidised bed spray granulation. In this ‘proof-of-concept’ spray model, simple functional relationships are used to notionally model surface energy pick-up by particles traversing the spray zone and an increase in energy of adhesion at drying interparticle bonds. The formation and breakage of interparticle bonds is thus governed by theoretical contact mechanics. Early-stage granulation simulation results provide qualitatively realistic granule size evolution trends. [Copyright &y& Elsevier]

Abstract: Firing or co-firing of biomass in efficient power plants can lead to high-temperature corrosion of superheaters due to condensation of alkali chlorides into superheater deposits. Corrosion can be prevented if a significant portion of the alkali chlorides present in the flue gases is destroyed before reaching the superheaters. The alkali capturing power of aluminium and ferric sulphates was determined in a pilot-scale fluidised bed (FB) reactor. The reagents were added in solution, through a spraying nozzle, to the upper part of the freeboard. Both reagents, at economical dosages, fast and effectively destroyed the alkali chlorides by producing sufficient SO3 for the sulphation. Both the mass flow rate and type of sulphate affected the sulphation ability. Thus, the cation, too, plays a role in the reaction. The required chemical dosage is not directly proportional to the Sreagent/Cl2fuel ratio because alkali chlorides must compete with calcium and magnesium oxides and probably also with alkali oxides for the available SO3. [Copyright &y& Elsevier]

Abstract: Sewage sludge and its ashes after combustion are contaminated with metals in various concentrations. In the work described in this paper, the mobility of metals during recovery of phosphorus by acid leaching of fly ashes from co-combustion of sewage sludge with wood was investigated. The metal concentrations in two sewage sludges, fly ashes and leachates from acid phosphorus extraction, were compared with phosphorus rock and different fertilisers used in agriculture. The secondary cyclone ashes were found to be less contaminated with trace elements than the bag-filter ashes. The largest problem is cadmium, which in all ashes studied has a too high level to meet the legislative limits for the maximum dosage in Sweden and the proposed limits in the European Union. The legislation includes limits for cadmium (Cd), mercury (Hg), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) calculated for an amendment of X kg of fertiliser per year and hectare of land. The solubility of the trace metals in the cyclone ash, with Cd as an exception, is in general much lower than the solubility of phosphorus. A decrease in pH results in an increased release of Cd but has just a slight influence on the other metals analysed in this study. The Cd yield increases by 30% when pH is lowered from 2.5 to 1.0, whereas the Hg release is not affected at all. The trace element concentrations in the leachates are far below the European and Swedish limitations of metal concentrations in fertilisers. The leachates thus fit as fertilisers and also as raw material to the industry, if Cd is removed. In Part I of the project [Pettersson A, Åmand L-E, Steenari B-M. Leaching of ashes from co-combustion of sewage sludge and wood. Part I: recovery of phosphorus. Biomass and Bioenergy, 2007, accepted for publication [1]] focus was on the phosphorus recovery only. [Copyright &y& Elsevier]

Abstract: Three promising biomass fuels for southern Mediterranean regions were tested for their agglomeration tendency in an atmospheric lab-scale fluidised bed (FB) gasifier using quartz and olivine as bed materials. The defluidisation temperatures of the energy crops Giant Reed (Arundo donax L.) and Sweet Sorghum bagasse were respectively approx. 790 °C and 810 °C, in both bed materials, while the agro industrial residue olive bagasse caused defluidisation of the quartz bed at 830 °C and olivine bed at >850 °C. Agglomerates from these tests were analysed with SEM/EDS. Coatings and necks between bed particles were formed due to ash derived potassium silicate melt. For the first two fuels cluster-type agglomerates around remains of char particles were observed. Thermodynamic equilibrium simulations of each chemical system were performed to cross examine the predicted ash melting temperatures and chemistry with experimental findings. Predictions of potassium liquid compounds, like K2O·SiO2(l) were verified by EDS analyses on the particle coatings. FB gasification of olive bagasse resisted defluidisation up to higher temperatures because of its lower potassium and higher calcium content, especially in the case of olivine bed. The latter experimental finding coincided with thermodynamic predictions. [Copyright &y& Elsevier]

Abstract: Top-spray fluidised bed coating scale-up experiments have been performed in three scales in order to test and validate the Akkermans flux number as possible scale-up parameter. Coating operations were performed on low porosity sodium sulphate cores coated with aqueous solutions of using Dextrin as binder in three top-spray fluidised bed scales, i.e. a small-scale (type: GEA Aeromatic-Fielder Strea-1), medium-scale (type: Niro MP-1) and large-scale (type: GEA MP-2/3). Following the parameter guidelines adapted from the original patent description, the flux number was tested in the preferred range of 3.5–4.5 as well as with a value of 4.7 in a total of 24 experiments. The agglomeration tendency was observed to decrease with increasing flux number on an overall basis, but coating conditions with flux number values below 4.5 resulted in a complete collapse of the bed. Coating conditions with flux number values of 4.5 and 4.7 were however successful in terms of agglomeration tendency and match of particle size fractions, but indicated in addition a strong influence of nozzle pressure. The present paper suggests even narrower boundaries for the flux number compared to the patent descriptions, and adds further new guidelines for the successful scale-up of top-spray fluidised bed coating systems in terms of the flux number. [Copyright &y& Elsevier]

Abstract: Costs of biofuel production from energy crops can be reduced by applying the crop residues in heat and power production. Perennial herbaceous crops like Cynara cardunculus L. are challenging fuels because they tend to have high ash and chlorine contents. Coals, however, are often rich in aluminium silicates and sulphur, and co-firing of these biofuels with coal could be expected to reduce operational problems. In addition, CO2 emissions are lower than during coal firing alone. Blends of Cynara and two coals, South African bituminous and Spanish sub-bituminous coal, were combusted in a 20kW bubbling bed pilot reactor to ascertain the ability of the coals to reduce operational problems by alkali capture. The Cynara fuel sample contained almost 2wt% chlorine. The South African coal was rich in kaolinite capable of capturing alkalies from chlorides to produce alkali aluminium silicate and HCl. The Spanish coal was rich in sulphur (mostly present as FeS2), and produced high concentrations of SO2 that partially oxidised to SO3. The SO3 can capture alkalies from chlorides by sulphation. Up to 30% Cynara, on energy basis, could be co-fired with Spanish coal without operational problems, whereas the same percentage of Cynara with South African coal led to strong Cl deposition. Co-firing of Cynara with both coals resulted in high HCl emissions (up to 1500mg/Nm3 in 6% O2). In addition, co-firing of the Spanish coal led to very high SO2 emissions (up to about 16,000mg/Nm3 in 6% O2). Thus, a power plant capable of firing such blends must be equipped with flue gas cleaning equipment for effective SO2 and HCl capture in the flue gas channel after the superheaters, or else the quality of the Cynara must be markedly improved by changing the harvesting technology and fertilisers, which could be major sources of high ash and chlorine content in the fuel. [Copyright &y& Elsevier]

Abstract: The degree of agglomeration and impact strength of Na2SO4 cores (all in the size range of 200–300 μm) coated with aqueous solutions of sodium sulphate and dextrin as a function of several process and formulation variables have been investigated. The coating process was performed in a modified small-scale GEA Aeromatic-Fielder Strea-1 top-spray fluidised bed, and the impact strength was tested in bulks using a Pneumatic Impact Gun, in which granule samples of 0.5 g were exposed to ten repeated impacts at 10 m/s. Using an unreplicated double 24−1 fractional factor design, two regression models were derived from experimental data describing quantitatively the degree of agglomeration and impact strength respectively. The agglomeration model suggests in accordance with previous studies that increasing the nozzle pressure as well as coating-solution-dry-matter-concentration decreases the tendency of agglomeration. The consistency between the agglomeration model and new experimental data is concluded to be satisfactory. The impact strength model indicates increasing impact strength with increasing nozzle pressure, coating solution–dry-matter-concentration and bed temperature. These tendencies may be influenced by the large extent of droplet penetration, as observed in additional coating droplet penetration and coating layer morphology studies in the present paper. The validation of the impact strength model shows that the model clearly follows overall experimental tendencies. The derivation of these quantitative models may be seen as a first step towards the development of processes for production of unagglomerated enzyme granules with high mechanical strength and contribute to an improved understanding of fluid bed processes and products. [Copyright &y& Elsevier]

This study investigates a model system for potential pharmaceutical materials in fluidised bed processes. In particular, this study proposes a novel use of Raman spectroscopy, which allows in situ measurement of the composition of the material within the fluidised bed in three spatial dimensions and as a function of time. This is achieved by recording Raman spectra from specific volumes of space. The work shows that Raman spectroscopy can be used to provide 3D maps of the concentration and chemical structure of the particles in a fluidised bed within a relatively short (120s) time window. At the most basic level the technique measures particle density via the intensity of the Raman spectra, however this could be used. More importantly the data are also rich in spectroscopic information on the chemical structure of the fluidised particles which is useful either for monitoring a given granulation process or more generally for the analysis of the dynamics of the airflow if the data were incorporated into an appropriate model. The technique has the potential to give detailed in situ information on how the structure and composition of the granules/powders within the fluidised bed (dryer or granulator) vary with the position and evolve with time. [Copyright &y& Elsevier]

Phosphorus chemicals control key aspects of eutrophication and other environmental process. Hypophosphite (HP) originating from manmade and natural sources was evidenced as present in the environment and was investigated rarely. Recently, iron oxide has been used as a catalyst for oxidising organic contaminants with hydrogen peroxide (i.e. heterogeneous Fenton-like reaction). This study focused mainly on the oxidation of 1.0 mM HP by hydrogen peroxide in the presence of a novel iron oxide catalyst (B1 catalyst) which was prepared through a fluidised-bed Fenton reactor (FBR-Fenton). The background experiments including the oxidation experiment of HP by air only, by H2O2 only and adsorption of HP by B1 catalyst were first elucidated. It was found that HP could not be oxidised at all by air and H2O2 at pH 2.5-12 in 24 hours. On the other hand, it could be adsorbed by B1 catalyst with 89.8% removal at pH 2.5 in 5 hours and complete desorption at pH 11.0. Then, we investigated the effects of pH and Fe leaching from the catalyst on the oxidative efficiency of HP. We found that although the removal rate of HP at pH 2.5 is faster than that at pH 4.0, B1 catalyst has a higher HP oxidation efficiency at pH 4.0 than that at pH 2.5. We conclude that it is a major heterogeneous catalytic oxidation by our novel iron oxide catalyst to oxidise HP at pH 4.0. Also, B1 could be a useful and potential catalyst for the treatment of HP wastewater. [ABSTRACT FROM AUTHOR]

The investment casting technique has advantages in the production of quality components and key benefits of accuracy, versatility and integrity. The mechanical performance of the ceramic shell is fundamental to the quality of the finished component. Two main techniques are used in the casting industry for the application of stucco material: rainfall sanding and fluidised bed. Work was carried out to characterise the fundamental difference in physical structure and mechanical properties of shells produced by both techniques. Stucco application within samples prepared by fluidised bed showed a tendency for the particles to be parallel to the ceramic surface, while in samples prepared by rainfall sanding the particles were more random and embedded into the slurry layer resulting in a thinner total shell build. Stress–strain curves generated form fired samples prepared by fluidised bed demonstrated a certain degree of non-brittle fracture, where this is not the case for rainfall sanding produced material. It is suggested that this is related to the manner in which cracks propagate through in the fluidised bed structure during testing. A relatively larger proportion of through stucco fracture was found in rainfall sanding produced samples in comparison to that in fluidised bed produced samples. [ABSTRACT FROM AUTHOR]

The reduction of greenhouse gas emissions and replacement of fossil fuels by renewable energy sources are important national and international targets. Oxyfuel (oxygen combustion technology) is one of the most promising technologies enabling carbon capture and storage from flue gases. The aim of oxyfuel concept development is to study different oxygen production technologies, combustion processes, CO2 capture methods and integrate those to optimised concept. The goal is to create technical readiness for demonstration of oxygen combustion by using state of the art knowledge, experiments, modelling and simulation. Demonstration plan for oxygen combustion for an existing power plant(s) in Finland will be prepared. Main results will be an evaluation of oxygen combustion business potential for implementation in existing and new power plants, and improvement of competitiveness of Finnish companies in energy sector by developing CO2 free power production technologies. Before oxygen combustion can be demonstrated in full scale, small scale testing and model development must be done. Material exposure conditions in oxygen combustion will differ from any present day environment. Current high temperature steel grades have not been developed or tested for such aggressive conditions. VTT (Technical Research Centre of Finland) has in Jyväskylä unique small scale combustors applicable for oxygen combustion research. [ABSTRACT FROM AUTHOR]

Abstract: A review of air-suspension particle coating concluded that, in order to speed product and process development, a phenomenological approach is necessary to develop generic guidelines for the selection of coating materials and process variables. This paper identifies 10 fundamental phenomena (micro-level processes) that occur during an air-suspension particle coating process: particle motion, atomisation, droplet–particle collision, droplet impact and adherence, droplet impact and spreading, infiltration, drying, film formation, layering and inter-particle agglomeration. Their relevance to the coating objectives is discussed and from these four are identified as key micro-level processes: drying, droplet impact and spreading, and stickiness which encompasses the two key micro-level processes of droplet impact and adherence and inter-particle agglomeration. It is believed that significant advances in particle coating research can be made through examination of these key micro-level processes. [Copyright &y& Elsevier]

Abstract: As a medium to maximise the resources recovery from municipal solid waste, refuse-derived fuel (RDF) is considered as a priority solution in industrialised countries. RDF is a value added material with a higher calorific value and a homogeneous particle size. The main objective of this study was to investigate the RDF combustion characteristics and the associated pollutant emissions in a fluidised bed combustor. A series of combustion tests was carried out using three different RDF samples in two atmospheric fluidised bed combustors (AFBC). The temperature profiles, gas composition and the properties of fly ash residues were investigated for different RDF fuels and operating conditions. Bed temperatures (ranging from 754 to 906°C) were correlated with different air and RDF feed rates. It was shown that the overall combustion efficiency of the system improved when secondary air jets were introduced into the system. Only between 2.6% and 4.3% of the potential nitrogen in the fuel was converted to . A slight decrease in the concentration was observed upon injection of secondary air. The capture fractions of N, Cl and trace elements in the fly ash were evaluated from the elemental composition of the fuels and fly ashes. The ratios of between 1.6 and 2.2 proved to be very efficient in capturing Cl in the fly ash. The operating conditions of the AFBC system together with the physical characteristics of the ash allowed a full elutriation of the ash residues. [Copyright &y& Elsevier]

The quench sensitivity of Al–Si–Mg (D357 unmodified and Sr modified), and Al–Si–Mg–-Cu (354 and 319 Sr modified) cast alloys was investigated using a fluidised bed (FB). The average cooling rate of castings in the fluidised bed is lower than those quenched in water; the cooling rate first increases to a certain maximum and then decreases during quenching. The change in the cooling rate during quenching in water was more drastic, where the cooling rate varied from 0 to -80 K s-1 in less than 8 s, as compared with those quenched in FB, where the cooling rate varied from 0 to -14 K s-1 in 18 s. The FB quenching resulted in the formation of several metastable phases in Al–Si–Mg–Cu alloys; in contrast, no such transformation was observed during water quenching. The T4 yield strength of the FB quenched alloys was greater than water quenched alloys owing to the formation of a greater volume fraction of metastable phases in the FB quenched alloys. The tensile properties of T6 treated alloys show that Al–Si–Mg alloys (both unmodified and Sr modified) are more quench sensitive than Al–Si–Mg–Cu alloys. The high quench sensitivity of the Al–Si–Mg alloys is because GP zones are not formed, whereas GP zones are formed during quenching of the Al–Si–Mg–Cu alloys as predicted by time temperature transformation and continuous cooling transformation) diagrams. [ABSTRACT FROM AUTHOR]

Abstract: Because little information is available about sewage sludge gasification in a bubbling fluidised bed (BFB), further experiments are required to quantify the power generation potential of dried sewage sludge (DSS) as well as to evaluate the optimum conditions for its gasification. In this work, the influence of the bed height on the process was experimentally determined using a laboratory-scale BFB reactor. The gasification tests were performed at different values of equivalence ratio (λ) and at two values of constant bed height (150 and 300mm). Attention was focused on the effect of increasing bed height on the gas composition, average cold gas efficiency, and product distribution. Results obtained in this study show that a bed height increase improves the efficiency of the DSS gasification process. This fact could be explained because the high ash content of DSS represents an obstacle to the gas diffusion. [Copyright &y& Elsevier]

This work presents an experimental study of nickel (II), lead (II) and zinc (II) metallic ions removal by adsorption in zeolite Baylith WE984. The experiments were conducted in a fluidised-bed rig with 300 grams of zeolite particles having diameter in the range 1 - 4mm. The volumetric flow rate of the fluidizing solution was 4.1 lmin-1. Metal concentrations in the solution were measured by atomic absorption and the breakthrough curves were obtained for concentrations of metals ranging from 5 to 30 ppm (pH= 2). Experimental results obtained were fitted to the Renken model for analysis of the mass transfer resistance and the kinetic of adsorption. It was verified that the kinetic of adsorption was the limiting factor for the metallic ion retention in fluidised bed. Competitiveness of the metals adsorbed into Baylith zeolite were also analyzed being found the following order of preference for the metal removals: nickel > zinc > lead. The competitiveness was evaluated simultaneously in the combination of 2 × 2 and the three metals. [ABSTRACT FROM AUTHOR]

Abstract: In Parts I and II, the influence of molecular oxygen and substrate moisture on the formation of monomeric phenols was reported for the low-temperature, bubbling fluidised bed fast pyrolysis of Radiata pine (Pinus radiata). This study reports on the sensitivity of the molecular-oxygen-promoted decomposition process on certain fluid bed parameters. These parameters were bed mass (135 and 200g) and particle size range (150–210, 210–310 and 310–500μm). Pyrolysis experimentation was performed on a bench scale fluidised bed reactor, manufactured by RTI Ltd., which was externally heated to 290–295°C. The fluidising gas consisted of air. For all sand particle size ranges, the inclusion of molecular oxygen in the reaction system did not significantly effect yield or composition of the monomeric phenolic product when the bed mass was 135g. However, when the bed mass was increased to 200g, the inclusion of molecular oxygen in the reaction system resulted in a significant increase in the yield of the phenolic product for all sand particle size ranges. Moreover, the yield of individual phenols varied substantially with fluid bed particle size when the bed mass was 200g, reflecting the apparent dependency of the various decomposition processes on the characteristics of the fluidised bed for pyrolysis performed under such conditions. The maximum yield of monomeric phenols was 5.03% and occurred when the bed mass was 200g and the corresponding particle size range 310–500μm. [Copyright &y& Elsevier]

Abstract: In Part I, the influence of molecular oxygen on phenolic compound formation from the low-temperature fast pyrolysis of Radiata pine (Pinus radiata) was reported. This work is elaborated upon and includes the interaction, or dual effect, of molecular oxygen and substrate water on phenolic compound formation. Experimentation was performed on a bench scale fluidised bed system and gas chromatography/mass spectroscopy was used for product analysis. Oven-dried and ‘as received’ (9.7% moisture content) Radiata pine (150–250μm) was processed at 290–295°C using air, nitrogen and oxygen enriched nitrogen as the fluidising gases. The inclusion of both molecular oxygen, in the form of air, and substrate moisture in the reaction system resulted in an increase in the yield of monomeric phenols from 0.07 to 5.03% (m/m). However, the inclusion of either molecular oxygen or substrate moisture resulted in a phenolic compound yield of only 0.60 and 0.27% (m/m), respectively. It was proposed that the molecular oxygen promoted the homolytic, free radical induced, aryl ether cleavage through facilitation of free radical formation as well as through hydroperoxide formation on the aliphatic carbon associated with aryl ether linkages. This explanation was consistent with the significant increase in carbonyl content of the phenolic product when molecular oxygen was included in the reaction atmosphere. However, such carbonyl groups are quite reactive and may participate in cross-linking reactions at elevated temperatures. The positive influence of water on the yield of monomeric phenolic compounds was believed to be indirect. That is, under fast pyrolysis conditions, in which the residence time of both substrate and volatile decomposition products is short, the evaporation of water would have suppressed substrate temperature elevation, thereby suppressing the rate of cross-linking reactions, resulting in the increased preservation of carbonyl containing low molecular weight products. [Copyright &y& Elsevier]

Abstract: Process operations often involve the physical interaction of a gas and a solid phase. Fluidised bed heat transfer can be characterised by limited space–time (τ) on the basis of particle volume in the bed. As aimed in this study, a thermal inefficiency model (TIM) was developed using a pseudo-steady-state heat balance, i.e., equating the electrical power input to the rate of heat transfers from the bed to the gas. A bench-scale fluidised bed (105×200 mm) was operated for obtaining the gas temperature profiles. Temperature data were used for extracting the bed-to-gas heat transfer coefficients (h BG) with effectiveness factors (η) from the TIM. Fluidised bed experiments at low temperature range (290–473 K) were conducted avoiding excessive instrumentation and time. Compressed dry air entered the bed through a distributor of a 200-mesh brass sieve and fluidised the single charge of alumina particles (1.3 kg) with a mean diameter approximately 250 μm. The superficial gas velocity was changed from 0.085 to 0.469 m s−1. The bed-to-gas heat transfer coefficients (h BG0×η 0) at initial bed hight and thermal inefficiency constants (k I) were calculated from the intercept and slope of the linear form of the TIM, respectively. The agreement between the experimental and predicted values of gas temperatures confirmed by the TIM. The latter may be successfully used to design fluidised beds for, e.g., drying or combustion. [Copyright &y& Elsevier]

Abstract: Atmospheric bubbling fluidised bed coal combustion (ABFBCC) of a bituminous coal and an anthracite with particle diameters in the range 500–4000μm was investigated in a pilot-plant facility, with and without limestone addition. The experiments were conducted at steady-state conditions using three excess air levels (10, 25 and 50%) and bed temperatures in the range 750–900°C. Combustion air was staged, with primary air accounting for 100, 80 and 60% of total combustion air. During limestone addition, in general, the NO emission decreases with the decrease in excess air and the increase in air staging, for both coals (as also observed without limestone). The bed temperature does not influence the NO emission significantly (as also observed without limestone); however, it was observed that during bituminous coal combustion there is a slight trend for a decrease on the NO emission with temperature increase in the range 825–900°C, whereas for anthracite coal the trend is the opposite. On the other hand, the N2O emission increases with: the decrease in excess air, the increase in air staging (as opposed to what was observed without limestone), and the decrease in bed temperature (as also observed without limestone). Taking the coal combustion without limestone as reference, it was observed that the effect of limestone addition on the NO and N2O emission depends on the first stage stoichiometry: (1) under first stage fuel lean conditions the NO emission increases, while that of N2O decreases, (2) under first stage fuel rich conditions (for example, high air staging) the opposite trend is observed. [Copyright &y& Elsevier]

Abstract: Due to the ban on meat and bone meal (MBM) as an animal feed, combustion with energy recovery has been considered a viable alternative usage for the mounting stocks of MBM. The effects of the co-combustion of MBM and peat on flue gas emissions and fluidisation were studied using a bubbling fluidised bed (BFB) test facility (20kW). The dispersion of emissions such as nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), hydrogen chloride (HCl) and particulates was investigated for a proposed site and compared to the relevant national and international regulations. Concentrations of NO2, CO and HCl were less than 10% of legislative and guideline thresholds while ground level concentrations of SO2 were also below relevant EU and world guidelines. The results indicate the potential for using MBM as a co-fuel with peat in a BFB while maintaining high air quality standards. [Copyright &y& Elsevier]

Abstract: This paper is the first of a series to study the influence of operating conditions on the kinetics of fluidised bed melt granulation. First, we identify the rate processes responsible for the net growth in granule size in a top-sprayed fluidised bed granulator and propose a sequence of events based on these rate processes. The overall kinetics during the process is identified to be a combination of particle aggregation, binder solidification and granule breakage. By conducting experiments in a small-scale modified commercial fluidised bed granulator, the influence of various operating conditions (binder spray rate, bed temperature, atomising pressure, fluidising air velocity) on the granule growth behaviour was examined. The results indicate the granule growth rate to be directly dependent on the relative amount of binder sprayed into the bed, which essentially determines the speed of the aggregation process. The overall granule growth rate is observed to increase relatively with increased bed temperature for a more viscous PEG4000, while a maximum growth is seen for a lower viscosity PEG1500. A larger droplet size was also seen to have increased the overall growth rate, even though a smaller droplet seems to be able to induce a faster initial growth. The results also reveal the increase in fluidising air velocity to reduce the overall granule growth rate. The final granule size distribution was also observed to become narrower with increased bed temperature and fluidising air velocity. These observations are effectively explained using the proposed sequence of rate events. [Copyright &y& Elsevier]

Abstract: A bench-scale fluidised bed (105×200 mm) was set-up for studying bed-to-gas and wall-to-bed heat transfer. Low temperature (17–200 °C) experiments were conducted at steady state avoiding excessive instrumentation and time. Compressed dry air at ambient temperature entered the bed through a distributor of a 200-mesh brass sieve and fluidised the single charge of alumina particles with a mean diameter of approximately 250 μm. The superficial gas velocity ranged from 0.085 to 0.412 m s−1. A simple model was developed based on steady state energy balances, i.e. equating the electrical power input separately to the rate of heat transfer from the heater walls to the bed and from the bed to the gas. The bed-to-gas heat transfer coefficient was calculated from the model equations. Inserting this value into the relevant heat transfer equations then extracted the wall-to-bed and bed-to-gas heat transfer coefficients. The agreement between the experimental and predicted values of temperatures validated the model. The latter may be successfully used to design fluidised beds for e.g. drying or combustion. [Copyright &y& Elsevier]

Abstract: This paper describes measurements and modelling of the discharge of a pressurised bed of fluidised particles through a circular orifice. A simple one dimensional flow model is used to describe three stages of flow; radial convergence of flow towards the orifice, axial acceleration through the orifice, and continued acceleration of the free particle jet beyond the orifice. This model correctly predicts previously observed trends in the final velocity and voidage of particle jets discharging from low pressure beds. Experimental results reported here for discharge from higher pressure beds are also well predicted. Experimental results are described for discharge of particles with a mean diameter of 150 μm to atmosphere through 3 mm and 4 mm diameter orifices, from a fluidised bed at pressures up to 5 bar. For the larger orifice diameter, the solids mass flow rate increased with the square root of the pressure drop across the orifice, consistent with theory and observation described by other authors for lower pressure systems. For the smaller diameter orifice the solids flow rate had a dependency on the pressure drop to a power of 0.4. This is explained in terms of changes in the pressure profile through the orifice that occurs when the orifice diameter is small compared to the thickness of the orifice plate. Gas volumetric flow rates increased approximately linearly with pressure. [Copyright &y& Elsevier]

Abstract: The development of a simplified process for the simultaneous disruption and direct selective purification of intracellular proteins from unclarified yeast disruptate has been investigated. The recovery of glyceraldehyde 3-phosphate dehydrogenase (G3PDH) from baker''s yeast was selected as a potential demonstration of the generic applicability and practical feasibility of this integrated technique. The application of an adsorbent characterised by high density (UpFront steel-agarose; ρ =2.65gml−1) facilitated the combining of cell disruption operation (bead milling of 50% ww/v of yeast suspension at 7.2lh−1) with fluidised bed dye-ligand (Cibacron Blue 3GA) adsorption operated immediately downstream of the disrupter. The adoption of a polymer shielded, dye-ligand technique advanced recovery efficiency. It was demonstrated that G3PDH could be recovered with a yield of 67.5% bound activity and a specific activity of 40.2IUmg−1, after a single step elution with 0.15M NaCl. The generic application of this approach has been evaluated. [Copyright &y& Elsevier]

Abstract: The production of supported catalysts by impregnation method of porous supports can be carried out in a fluidized bed. This technique allows to obtain, in only one apparatus, catalysts which by the traditional way must successively undergo the stages of impregnation, filtration, drying and calcination/activation. This paper deals with the results of experiments related to the manufacture of traditional catalysts and new generation catalysts containing various metals (nickel, manganese, copper, palladium) deposited on a porous support such as alumina or silica gel. Moreover, it was shown that the reproducible synthesis of metallic nanoparticles of size, composition and controlled surface quality could be carried out under mild conditions with organometallic precursors. The principle of this technique consists in the spraying of a solution containing a metallic precursor into a hot fluidised bed of porous fine particles as chosen support. The adequate choice of operating conditions makes possible a uniform deposit of the metal precursor inside the porous matrix. After the impregnation step, the decomposition of the metallic precursor and metal activation can be operated in the same reactor. For organometallic complexes the decomposition/activation is achieved at low temperature (T <80 °C) under a reactive atmosphere (H2/N2 mixture) giving then rise to the synthesis of metal nanoparticles with controlled size and composition. Feasibility studies and optimisation of the operating conditions have been carried out, solid characterization and catalytic tests have been conducted to validate the process. In the case of asymmetric catalysts, Pd nanoparticles associated to cinchonidine as an asymmetric ligand inside silica particles have been prepared by this process for the ethyl pyruvate hydrogenation. [Copyright &y& Elsevier]

Abstract: Atmospheric Bubbling Fluidised Bed Combustion (ABFBC) of a bituminous coal and anthracite with particle size in the range 500–4000 μm was investigated in a pilot-plant facility, with and without limestone addition (particle size in range 710–1000 μm). The experiments were conducted at steady-state conditions using three excess air levels (10%, 25% and 50%) and bed temperatures in the 750–900 °C range. Combustion air was staged, with primary air accounting for 100%, 80% and 60% of total combustion air. Limestone addition is suitable for in-situ SO2 removal during ABFBC, with removal efficiencies in the range 25–85%. In general, the efficiency of SO2 removal by limestone decreases with an increase in air staging and a decrease in excess air. The increase in the bed temperature range 825–900 °C decreases the efficiency of SO2 removal by limestone, and in some situations a maximum can occur around 825 °C bed temperature. The reducing conditions at the first stage level, the secondary combustion, and the reductive decomposition of CaSO4 could be responsible for the low efficiency of SO2 removal by limestone during both high air staging and high bed temperatures. [Copyright &y& Elsevier]

Abstract: An adaptive algorithm for detecting process changes in a process monitored by acoustic emission is presented as an alternative to traditional modelling techniques based on fixed or static models. This approach significantly reduces the need to remodel the process as operating conditions change. The central idea is that two moving windows are moved through the data side by side. The signal variation in one of them is modelled by a principal component analysis (PCA) model, and the samples in the other window are compared to the critical borders of the PCA model. Significant differences are interpreted as a process change, i.e. the acoustic emission from the process has changed. In this work acoustic emission data from a fluidised bed is analysed. Optimal settings for the algorithm are proposed and the robustness towards noise and other signal degradations is shown to be good. The algorithm seems to be batch independent, which means that regular re-calibration (blank runs) which is needed by reference model approaches can be avoided. [Copyright &y& Elsevier]

Abstract: Atmospheric Bubbling Fluidised Bed Combustion (ABFBC) of a bituminous coal and anthracite with particle diameters in the range 500–4000μm was investigated in a pilot-plant facility (circular section with 0.25m internal diameter and 3m height). The experiments were conducted at steady-state conditions using three excess air levels (10, 25 and 50%) and bed temperatures in the 750–900°C range. Combustion air was staged, with primary air accounting for 100, 80 and 60% of total combustion air. The effect of limestone addition was also tested. Large CO concentrations were observed inside the bed, up to 8 and 6% (v/v) in the cases of anthracite and bituminous coals, respectively. These concentrations decreased sharply as the gases emerged from the bed, and the CO flue gas concentration observed was in general less than 2000 and 4000ppm, respectively. The CO flue gas concentration increased with air staging and with limestone addition, but decreased with either excess air or temperature increase. The observed results confirm the influence of sand particles (and probably of SO2) in the ‘quenching’ of the oxygenated free radicals (HO and HO2) reactions responsible for the CO oxidation inside the bed. [Copyright &y& Elsevier]

Experiments have been performed to test the efficiency with which a novel fluidised bed technique could separate different metallic powders in terms of size and density. The overall aim was to assess the potential of this technique for the commercial separation of defective powder fractions from mechanically alloyed (MA), iron based powders. Separation in terms of size was readily achieved, with the largest powder particles sinking to the bottom of the fluidised bed. In a simulated commercial process, density separation of defective Fe3Al powder could not be demonstrated as any differences in density were overshadowed by size and morphology differences. However, from a batch of iron based powder (ρ=8·02 g cm-3), seeded with six other metallic powders, aluminium powder (ρ=2·70 g cm-3) segregated strongly to the top of the bed from where samples containing 93 vol.-%Al were taken. The process is thought to be sensitive to differences in density of a factor of 1.1–3. [ABSTRACT FROM AUTHOR]

Abstract: Atmospheric Bubbling Fluidised Bed Coal Combustion (ABFBCC) of a bituminous coal and anthracite with particle diameters in the range 500–4000 μm was investigated in a pilot-plant facility (circular section with 0.25 m internal diameter and 3 m height). The experiments were conducted at steady-state conditions using three excess air levels (10%, 25% and 50%) and bed temperatures in the 750–900 °C range. Combustion air was staged, with primary air accounting for 100%, 80% and 60% of total combustion air. For both types of coal, virtually no N2O was found in significant amounts inside the bed. However, just above the bed-freeboard interface, the N2O concentration increased monotonically along the freeboard and towards the exit flue. The N2O concentrations in the reactor ranged between 0–90 ppm during bituminous coal combustion and 0–30 ppm for anthracite. For both coals, the lowest values occurred at the higher bed temperature (900 °C) with low excess air (10%) and high air staging (60% primary air), whereas the highest occurred at the lower bed temperature (750 °C for bituminous, 825 °C for anthracite) with high excess air (50%) and single stage combustion. Most of the observed results could be qualitatively interpreted in terms of a set of homogeneous and heterogeneous reactions, where catalytic surfaces (such as char, sand and coal ash) can play an important role in the formation and destruction of N2O and its precursors (such as HCN, NH3 and HCNO) by free radicals (O, H, OH) and reducing species (H2, CO, HCs). [Copyright &y& Elsevier]

Abstract: Ionic mass transfer from electrolyte to a plate cathode in liquid fluidised bed filled with spherical inert particles has been experimentally studied. The mass transfer rates were measured by using the limiting current diffusion technique (LCDT) in ferri- and ferrocyanide electrolyte systems. The effects of bed height and electrode location from the bottom of test chamber in different electrolyte concentrations and flow velocities on mass transfer coefficient were evaluated. Ranges of the variables used in the study are as follows: Reynolds number=78–300, Galileo number=282,000–298,000, density number=0.335–0.370 and Schmidt number=1831–1995. Experimental data are correlated as follows, by non-linear regression using Statistica Package Program: A comparison between the present data and related several literature correlation''s has been achieved by calculating absolute (σ A) and relative (σ R) deviations. The deviations in present study are less than those in the literature cited. [Copyright &y& Elsevier]

Four different tool steel materials, P20, H13, M2 and D2, were nitrocarburised at 570°C in a fluidised bed furnace. The reactive diffusion of nitrogen and carbon into the various substrate microstructures is compared and related to the different alloy carbide distributions. The effect of carbon bearing gas (carbon dioxide, natural gas) on carbon absorption is reported, as well as its influence on compound layer growth and porosity. Partial reduction of Fe3O4 at the surface resulted in the formation of a complex, ε-nitride containing oxide layer. In H13, carbon was deeply absorbed throughout the entire diffusion zone, affecting the growth of grain boundary cementite, nitrogen diffusivity and the sharpness of the compound layer: diffusion zone interface. When natural gas was used, carbon became highly concentrated in the compound layer, while surface decarburisation occurred with carbon dioxide. These microstructural effects are discussed in relation to hardness profiles, and compound layer hardness and ductility. The surfaces were characterised using glow discharge optical emission spectroscopy, optical and scanning electron microscopy and X-ray diffraction. [ABSTRACT FROM AUTHOR]

Nitrocarburised H13 disks were tested in dry, sliding wear against a stationary ruby ball (pin). Three different 4 h nitrocarburising treatments were compared, using N2/NH3/CO2, N2/NH3/natural gas and N2/NH3 gas mixtures, resulting in compound layers of varying thickness, hardness, porosity and oxide morphology. During mild, oxidative wear, with the formation of abrasive wear debris, the most brittle and oxidised surfaces performed poorly. Polishing to a bright, reflective finish greatly reduced wear. However, the N2/NH3/CO2 sample also frequently maintained a 'very mild' wear regime, owing to the formation of a protective film between the wear surfaces, and resulting in a lowering of the friction coefficient. This treated surface was porous and covered in a complex layer of coarse oxide+ε-carbonitride. Nitrocarburised samples and wear tracks were characterised by optical microscopy, SEM, atomic force microscopy and stylus profilometry. [ABSTRACT FROM AUTHOR]

Abstract: The performance of a particulate-biofilm, expanded-bed process for nitrification of activated sludge final effluent (ASFE) is reported for a plant receiving mixed industrial and domestic wastewater. The support material for the particulate-biofilms was glassy coke, to which the nitrifying bacteria attached and formed a highly active biofilm. An average nitrification rate of 1.7±0.6kgm−3 expanded bed d−1 was recorded during operation of the bioreactor, which had a hydraulic residence time of 15min. On average, the ASFE contained 12.6±3.7gm−3 NH3–N, which was reduced to 2.6±3.3gm−3 NH3–N. Furthermore, transfer of 10–12% of the oxygen in air was achieved using counter-current aeration. This investigation has demonstrated that a high rate of nitrification can be achieved with a particulate-biofilm, expanded-bed process. It has also demonstrated that the process can operate without backwashing and still remove particulate material from the ASFE feed. [Copyright &y& Elsevier]

Abstract: Many active components (anti-oxidants, aromas) are lipophilic substances, available in liquid form and have to be protected from the environment. Encapsulation of oil drops into a solid matrix is regarded as an efficient protection method and a means of formulating liquid compounds in a solid dosed form. The aim of this study is to investigate the feasibility of encapsulation of a vegetable oil (ISIO4®, 5% w/w dry matter) used as a model into a mixture of maltodextrin and acacia gum. Encapsulation was completed in three stages, i.e. emulsification, spray drying and fluid bed agglomeration. Optimal operating conditions for spray drying and agglomeration were identified. Powders were characterized before and after agglomeration in terms of oil content and protection (dispersion into the matrix, surface oil content, oxidation) and powder handling properties (flowability, wettability, friability). The proposed encapsulation method provided powders where oil droplets were well dispersed and protected (oil droplets diameter lower than 1 μm in reconstituted emulsions, less than 2% of the total oil content at the particle surface, oil oxidation lowered compared to unprotected oil). Agglomeration did not change oil encapsulation properties of the spray-dried powder but considerably improved its wettability. Industrial relevance: Encapsulation of active components finds many applications in food industry for aromas, vitamins, anti-oxidants, etc. used in powdered foods (soups, instant drinks and sauces), prepared meals and food complements with a market in constant increase. It is also widely used in pharmaceutical, chemical and cosmetics industries where products are different but techniques are similar. This study aimed to test the combination of spray drying and fluidised bed agglomeration to encapsulate sensitive lipid-based compounds into dosed powders to provide protection and storage stability and render their use easier. [Copyright &y& Elsevier]

A low external temperature method (LETM) of active electrode material synthesis for lithium ion batteries has been proposed. The method consists of a two-step process, which is comprised of drying fine droplets of a solution of the starting compound in a liquid drying agent at 200?°C, followed by calcination of the obtained precursor in a fluidised bed at a furnace temperature of 300?°C. The method prevents uncontrolled growth of particles during the initial thermal pre-treatment and the final firing process. Lithium manganese spinel has been selected for describing the proposed LETM of synthesis. The properties of the spinel obtained by LETM are compared with those of a spinel obtained by the classical immobilised solid state synthesis at 750 °C. On electrochemical cycling, the capacity loss after 100 cycles of the LETM spinel at 11% is significantly lower than that for the spinel prepared by solid state methods (21.5%). However, only 3% difference is seen in the total integral capacity over the 100 cycles between spinels prepared by the different methods. [ABSTRACT FROM AUTHOR]

Coating of powders is often used to protect particles and to modify surface properties such as lustre, catalytic activity, hardness, permeability, adhesion and conductivity. A fast circulating fluidised bed for combustion chemical vapour deposition (CCVD) and CVD is introduced for the production of particles coated with nanolayers of metal oxides and metals. The CCVD fluidised bed process involves Nanomiser device atomisation and controlled thermal decomposition of low cost metalorganic liquid precursors and nanocoating of particles with thin films or with nanoparticulates while suspended in a turbulent fluidised bed. This paper describes the production of mica and glass spheres uniformly covered with metal oxide (TiO2, Cr2O3) and metal (Ag) films. The coated powder morphology, surface composition and optical properties were characterised by electron and optical microscopy and elemental analysis. [ABSTRACT FROM AUTHOR]

Chemical recycling of poly(ethylene terephthalate) (PET) materials was carried out by pyrolysis with a fluidised bed reactor between 510 and 730°C. Several PET materials, with and without fillers, were successfully decomposed. Almost all products were gases and solids. The yield of gases was between 38 and 49wt%. Pyrolysis gas consisted chiefly of CO2 and CO. Other gases like methane, ethane and hydrogen occurred in small yields. The other major fraction was formed by solid products. Above all, the organic residues in the reactor increased strongly with temperature. Just 5wt% of organic residues were found in the reactor at a temperature of 510°C, but 40wt% at 730°C. The amount of oxygen containing compounds decreased with increasing temperature due to the decomposition of terephthalic acid and benzoic acid. The amount of liquid products was small. The aliphatic hydrocarbons in oil fraction were slight, but aromatic hydrocarbons were found between 2 and 5wt% of all organic products due to formation of benzene, benzene derivatives and naphthalene derivatives, respectively. [Copyright &y& Elsevier]