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Marcus Ohman - One of the best experts on this subject based on the ideXlab platform.
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Time-Dependent Crack Layer Formation in Quartz Bed Particles during Fluidized Bed Combustion of Woody Biomass
Energy & Fuels, 2017Co-Authors: Nils Skoglund, Marcus OhmanAbstract:Bed Agglomeration during combustion and gasification of woody biomass fuels in quartz Beds has been frequently studied, and chemical mechanisms responsible for Bed Agglomeration have been suggested. However, few studies have focused on the Bed material deposition on walls, in cyclones, and return legs in fluidized Bed combustion. Part of these Bed material depositions originates from sticky fragments of alkali-rich silicates formed after crack formation in older quartz Bed particles. The crack layer formation in quartz Bed particles in fluidized Bed combustion of woody biomass was therefore investigated by collecting Bed material samples of different ages from full-scale bubbling and circulating fluidized Bed facilities. Scanning electron microscopy/energy-dispersive spectroscopy was used to analyze the crack morphology and composition of the layer surrounding the cracks. For quartz Bed particles with an age of some days, a crack in the quartz Bed particle was observed in connection to the irregular inter...
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Time Dependence of Bed Particle Layer Formation in Fluidized Quartz Bed Combustion of Wood-Derived Fuels
Energy & Fuels, 2014Co-Authors: Dan Boström, Marcus OhmanAbstract:Formation of sticky layers on Bed particles has been considered as a prerequisite for Bed Agglomeration in fluidized Bed combustion of wood-derived fuels. The present investigation was undertaken t ...
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Bed Agglomeration Characteristics in Fluidized-Bed Combustion of Biomass Fuels Using Olivine as Bed Material
Energy & Fuels, 2012Co-Authors: Alejandro Grimm, Marcus Ohman, Therese Lindberg, Andreas Fredriksson, Dan BoströmAbstract:The Bed Agglomeration characteristics during combustion of typical biomass fuels were determined in a bench-scale bubbling fluidized-Bed reactor (5 kW) using olivine and quartz sand as Bed material. The fuels studied include willow, logging residues, wheat straw, and wheat distiller’s dried grain with solubles (wheat DDGS). Bed material samples and agglomerates were analyzed by means of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), for morphology and elemental composition. Furthermore, Bed ash particles were separated by sieving from the Bed material samples and analyzed for elemental composition by SEM–EDS and for determination of crystalline phases by powder X-ray diffraction (XRD). Chemical equilibrium calculations were performed to interpret the experimental findings of layer formation and reaction tendencies in both Bed materials. Significant difference in the Agglomeration tendency between olivine and quartz was found during combustion of willow and loggin...
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Fluidized-Bed Combustion of Mixtures of Rapeseed Cake and Bark: The Resulting Bed Agglomeration Characteristics
Energy & Fuels, 2012Co-Authors: Patrycja Piotrowska, Marcus Ohman, Alejandro Grimm, Nils Skoglund, Dan Boström, Christoffer Boman, Maria Zevenhoven, Mikko HupaAbstract:The Bed Agglomeration characteristics resulting from the combustion of 11 mixtures of rapeseed cake and spruce bark were studied in a bench-scale bubbling fluidized-Bed reactor (5 kW). The objectiv ...
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Bed Agglomeration characteristics during fluidized olivine Bed combustion of typical biofuels
2011Co-Authors: Alejandro Grimm, Dan Boström, Therese Lindberg, Andreas Fredriksson, Marcus OhmanAbstract:Controlled combustion and Agglomeration experiments were conducted during eight hours in a bench– scale bubbling fluidized Bed (5 kW) to determine the Bed Agglomeration tendencies of four different ...
Evangelos Tsotsas - One of the best experts on this subject based on the ideXlab platform.
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Influence of operating parameters on process behavior and product quality in continuous spray fluidized Bed Agglomeration
Powder Technology, 2020Co-Authors: Gerd Strenzke, Andreas Bück, Robert Dürr, Evangelos TsotsasAbstract:Abstract The present work investigates continuous spray fluidized Bed Agglomeration with internal separation using glass primary particles and sprayed solution of cellulosic binder. Different fluidization and thermal parameters were investigated with respect to their influences on process behavior and product quality. Product quality is characterized with respect to particle size, sphericity and porosity. Trends between operation parameters and product characteristics are established, especially in view of the drying potential of the fluidization gas. In addition to the successful identification of the parameter influences, this study has detected general relationships between drying potential and agglomerate porosity, as well as between agglomerate size and porosity.
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Stochastic model to simulate spray fluidized Bed Agglomeration: a morphological approach
Powder Technology, 2019Co-Authors: Abhinandan Kumar Singh, Evangelos TsotsasAbstract:Abstract Constant volume Monte Carlo (CVMC) method is a stochastic method used to describe the agglomerate growth during spray fluidized Bed Agglomeration (SFBA). The methodology overcomes the difficulties of expressing and solving multivariate population balance equations (PBE). It enables to account for micro-scale events and processes involved in the Agglomeration process, especially for binder addition and drying. Previous CVMC models assume that all agglomerates have the same porosity. This simplistic assumption is replaced in the present paper by given fractal dimension, which means that porosity can change with agglomerate size and process conditions. Evaluation of measured morphological descriptors and the Agglomeration rates shows that this leads to more realistic results.
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Bifurcation analysis of process stability of continuous fluidized Bed Agglomeration with external product classification
Computer Aided Chemical Engineering, 2016Co-Authors: Andreas Bück, M. Wegner, Christoph Neugebauer, Stefan Palis, Evangelos TsotsasAbstract:Abstract This contribution discusses the process behaviour of continuous fluidised Bed Agglomeration with external product screening and milling. The stability behaviour is tracked in the parameter plane (aggregation efficiency and milling diameter) by parameter continuation methods. It is shown that for EKE and gravitational kernels, loss of stable operation with onset of oscillatory behaviour has to be expected.
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A new framework for population balance modeling of spray fluidized Bed Agglomeration
Particuology, 2015Co-Authors: Mubashir Hussain, Jitendra Kumar, Evangelos TsotsasAbstract:Abstract Previous work (Hussain et al. (2013). Chemical Engineering Science, 101, 35) has pointed out that the conventional, one-dimensional population balance equation for aggregation can be expanded to accurately reproduce the results of discrete simulations of spray fluidized Bed Agglomeration. However, some parameters had to be imported from the discrete simulation (Monte-Carlo). The present paper shows how the expanded population balance can be run without importing parameters from the Monte-Carlo simulation. The expanded population balance still reproduces the results of Monte-Carlo simulations accurately, taking into account key micro-scale phenomena (sessile droplet drying, efficiency of collisions), but with much lower computational cost. Required input parameters are just the drying time of sessile droplets (calculated in advance), and the pre-factor of an equation that correlates particle collision frequency with fluidized Bed expansion. In this way, the expanded population balance is, apart from autonomous, also (nearly) predictive. Its performance is demonstrated by comparisons with both Monte-Carlo results and experimental data for various operating conditions (binder mass flow rate, gas temperature). Despite formally being a one-dimensional expression, the expanded population balance captures additional properties, such as the number of wet particles and the number of droplets in the system, which are even difficult to measure in experiments.
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Modeling of aggregation kernel using Monte Carlo simulations of spray fluidized Bed Agglomeration
AIChE Journal, 2014Co-Authors: Mubashir Hussain, Evangelos Tsotsas, Mirko Peglow, Jitendra KumarAbstract:The present work attempts to consider the microscopic mechanisms of spray fluidized Bed Agglomeration while modeling the macroscopic kinetics of the process. A microscale approach, constant volume Monte-Carlo simulation, is used to analyze the effects of micro-processes on the aggregation behavior and identify the influencing parameters. The identified variables, namely the number of wet particles, the total number of particles, and the number of droplets are modeled and combined in the form of an aggregation kernel. The proposed kernel is then used in a one-dimensional population balance equation for predicting the particle number density distribution. The only fitting parameters remaining in the population balance system are the collision frequency per particle and a success fraction accounting for the dissipation of kinetic energy. Predictions of the population balance model are compared with the results of Monte-Carlo simulations for a variation of significant operating parameters and found to be in good agreement. © 2014 American Institute of Chemical Engineers AIChE J, 60: 855–868, 2014
Pimon Jamnong - One of the best experts on this subject based on the ideXlab platform.
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Production of instant soymilk powders by ultrafiltration, spray drying and fluidized Bed Agglomeration
Journal of Food Engineering, 2008Co-Authors: Nakarin Jinapong, Manop Suphantharika, Pimon JamnongAbstract:Production of instant soymilk powders was completed in three stages - ultrafiltration, spray drying, and fluidized Bed Agglomeration. Ultrafiltration increased total solids, protein, and fat contents, but decreased carbohydrate and ash contents of soymilk, leading to an increase in particle size, wettability, and dispersibility of the resultant spray-dried powders. However, all the spray-dried soymilk powders were very small (
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production of instant soymilk powders by ultrafiltration spray drying and fluidized Bed Agglomeration
Journal of Food Engineering, 2008Co-Authors: Nakarin Jinapong, Manop Suphantharika, Pimon JamnongAbstract:Production of instant soymilk powders was completed in three stages - ultrafiltration, spray drying, and fluidized Bed Agglomeration. Ultrafiltration increased total solids, protein, and fat contents, but decreased carbohydrate and ash contents of soymilk, leading to an increase in particle size, wettability, and dispersibility of the resultant spray-dried powders. However, all the spray-dried soymilk powders were very small (<25 μm) and very cohesive leading to their poor flowability. Agglomeration of the spray-dried powders with maltodextrin as an aqueous binder solution using a fluidized Bed agglomerator improved the handling and reconstitution properties of the powders. The optimum binder concentration was found to be 10% w/v maltodextrin which resulted in the largest particle size of the agglomerated powder (260 μm) having a good flowability and low cohesiveness. The wettability of this agglomerated powder (wetting time = 42 s) was good but its dispersibility (61%) could be improved.
Nakarin Jinapong - One of the best experts on this subject based on the ideXlab platform.
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Production of instant soymilk powders by ultrafiltration, spray drying and fluidized Bed Agglomeration
Journal of Food Engineering, 2008Co-Authors: Nakarin Jinapong, Manop Suphantharika, Pimon JamnongAbstract:Production of instant soymilk powders was completed in three stages - ultrafiltration, spray drying, and fluidized Bed Agglomeration. Ultrafiltration increased total solids, protein, and fat contents, but decreased carbohydrate and ash contents of soymilk, leading to an increase in particle size, wettability, and dispersibility of the resultant spray-dried powders. However, all the spray-dried soymilk powders were very small (
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production of instant soymilk powders by ultrafiltration spray drying and fluidized Bed Agglomeration
Journal of Food Engineering, 2008Co-Authors: Nakarin Jinapong, Manop Suphantharika, Pimon JamnongAbstract:Production of instant soymilk powders was completed in three stages - ultrafiltration, spray drying, and fluidized Bed Agglomeration. Ultrafiltration increased total solids, protein, and fat contents, but decreased carbohydrate and ash contents of soymilk, leading to an increase in particle size, wettability, and dispersibility of the resultant spray-dried powders. However, all the spray-dried soymilk powders were very small (<25 μm) and very cohesive leading to their poor flowability. Agglomeration of the spray-dried powders with maltodextrin as an aqueous binder solution using a fluidized Bed agglomerator improved the handling and reconstitution properties of the powders. The optimum binder concentration was found to be 10% w/v maltodextrin which resulted in the largest particle size of the agglomerated powder (260 μm) having a good flowability and low cohesiveness. The wettability of this agglomerated powder (wetting time = 42 s) was good but its dispersibility (61%) could be improved.
Christelle Turchiuli - One of the best experts on this subject based on the ideXlab platform.
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Fluidised Bed Agglomeration of particles with different glass transition temperatures
Powder Technology, 2015Co-Authors: Carlos Aviles, Elisabeth Dumoulin, Christelle TurchiuliAbstract:Fluidised Bed Agglomeration of particles consists in spraying liquid drops (water or binder solution) on the surface of particles, fluidised by hot air, in order to create sticky regions to allow formation of agglomerates when the sticky particles collide. Many parameters influence agglomerate growth, especially those controlling the particle circulation, and the water and temperature conditions within the Bed that determine drying and particle stickiness linked to the glass transition of amorphous components and to the viscosity of moist zones at the particle surface. Maltodextrin DE12 and DE21 particles with different glass transition temperature domains were agglomerated in a batch bench scale fluidised Bed, under constant mechanical constraints, changing the sprayed water feed rate and the fluidisation air temperature in order to investigate the influence of particle stickiness on agglomerate growth kinetics and mechanism. The two powders showed a different sensitivity to the water and temperature constraints applied. Whilst for maltodextrin DE12, the size and growth rate increased significantly with the sprayed water flow rate, only a small variation was observed for maltodextrin DE21. In both cases, Agglomeration occurred in two stages: firstly, the association of initial particles and secondly the Agglomeration of intermediate agglomerates into larger and more porous structures. The change from one growth mechanism to the other depended on the conditions, and influenced the size distribution and structure of agglomerates.
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Aroma encapsulation in powder by spray drying, and fluid Bed Agglomeration and coating
2013Co-Authors: Christelle Turchiuli, Elisabeth DumoulinAbstract:Aroma encapsulation in powder by spray drying, and fluid Bed Agglomeration and coating
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Milk powder agglomerate growth and properties in fluidized Bed Agglomeration
Dairy Science & Technology, 2013Co-Authors: A. Barkouti, Christelle Turchiuli, J. A. Carcel, Elisabeth DumoulinAbstract:Fluidized Bed Agglomeration is used to produce large and porous dry agglomerates with improved instant properties. Water (or binder solution) is sprayed in the fluidized Bed of particles to render their surface sticky. The agglomerate growth results from the repetition of different steps (wetting of the particle surface, particles collision and bridging, and drying) and depends on the processing conditions and product properties. In this work, skim and whole milk powders were fluidized in hot air and agglomerated by spraying water in a bench-scale batch fluidized Bed. The aim was to study the impact of the sprayed water flow rate (0-5.5 g.min(-1)), particle load (300-400 g), initial particle size (200-350 mu m), and composition (skim-whole milk) on the growth mechanisms and on the properties of the agglomerates obtained. Powder samples were regularly taken in the fluidized Bed during Agglomeration and characterized for the size, size distribution, and water content. Whatever the conditions tested, the size increase and the evolution of the particle size distribution during Agglomeration were found to mainly depend on the relative amount of water sprayed in the particle Bed. Agglomeration occurred in two stages, with first the rapid association of initial particles into intermediate structures, and second, the progressive growth of porous agglomerates. In any case, Agglomeration allowed improving instant properties of the milk powder.
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Fluidised Bed Agglomeration: Agglomerates shape and end-use properties
Powder Technology, 2005Co-Authors: Christelle Turchiuli, Zouheir Eloualia, Noureddine El Mansouri, Elisabeth DumoulinAbstract:Abstract Agglomerated powders properties depend on the process used and on the operating conditions during Agglomeration. Fluidised Bed Agglomeration in one of the suitable processes to produce instant powders. Agglomerates obtained exhibit different shapes, structures and therefore end-use properties depending on the type of binder used, its amount, the way it is introduced…. In this study physical (size, shape) and end-use properties (wettability, friability, flowability) of zein particles agglomerated with maltodextrin introduced as a liquid solution (A) or as a powder (B) were compared. (A) type agglomerates were larger, more irregular and more fragile than (B) type ones. In case (A) the use of less concentrated binder solutions was found advantageous for the properties of agglomerates. In case (B), better agglomerates properties were obtained using binder particles smaller than the solid ones and limiting the duration of the operation by spraying limited amount of water.
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Oil encapsulation by spray drying and fluidised Bed Agglomeration
Innovative Food Science and Emerging Technologies, 2005Co-Authors: Christelle Turchiuli, M Fuchs, M Bohin, Marieelisabeth Cuvelier, C Ordonnaud, Marie-noëlle MaillardAbstract: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 (R), 5% w/w dry matter) used as a model into a mixture of maltodextrin and acacia guru. 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 mu m 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.