Spouted Bed Research Articles

Evaluation of Mixing and Mixing Rate in a Multiple Spouted Bed by Image Processing Technique

Abstract Mixing efficiency is one of the most significant factors, affecting both performance and scale-up of a gas-solid reactor system. This paper presents an experimental investigation on the particle mixing in a multiple spouted bed. Image processing technique was used to extract the real-time information concerning the distribution of particle components (bed materials and tracer particles). A more accurate definition of the tracer concentration was developed to calculate the mixing index. According to the visual observation and image analysis, the mixing mechanism was revealed and the mixing rate was evaluated. Based on these results, the effects of operation parameters on the mixing rate were discussed in terms of the flow patterns. It is found that the detection of the pixel distribution of each component in RGB images is not affected by the interference of air void, thus maintaining good measurement accuracy. Convective transportation controls the particle mixing in the internal jet and spout, while shear dominants the particle mixing in the dense moving region. Global mixing takes place only when the path from one spout cell to the other is open. This path can be formed either by the bubbles or particle circulation flows. The mixing rate is linked to the bubble motion and particle circulation. Provided that there are interactions between the spout cells, any parameters promoting the bubble motion and circulation can increase the mixing rate. Finally, a mixing pattern diagram was constructed to establish the connection between the flow structure and mixing intensity.

Simulasi Pengeringan Gabah pada Pengering Spouted Bed Dua Dimensi

Simulasi Pengeringan Gabah pada Pengering Spouted Bed Dua Dimensi

CFD‐DEM Modeling of Liquid Injection for Spray Coating in a Prismatic Spouted Bed

Chemie Ingenieur TechnikVolume 88, Issue 9 p. 1360-1360 Vortrag CFD-DEM Modeling of Liquid Injection for Spray Coating in a Prismatic Spouted Bed S. Pietsch, Corresponding Author S. Pietsch swantje.pietsch@tuhh.de Technische Universität Hamburg, Institut für Feststoffverfahrenstechnik und Partikeltechnologie, Denickestraße 15, 21073 Hamburg, GermanyTechnische Universität Hamburg, Institut für Feststoffverfahrenstechnik und Partikeltechnologie, Denickestraße 15, 21073 Hamburg, GermanySearch for more papers by this authorProf. Dr. S. Heinrich, Prof. Dr. S. Heinrich Technische Universität Hamburg, Institut für Feststoffverfahrenstechnik und Partikeltechnologie, Denickestraße 15, 21073 Hamburg, GermanySearch for more papers by this authorK. Karpinski, K. Karpinski BASF SE, GCP/TT – L540, 67056 Ludwigshafen, GermanySearch for more papers by this authorM. Müller, M. Müller BASF SE, GCP/TT – L540, 67056 Ludwigshafen, GermanySearch for more papers by this authorDr. M. Schönherr, Dr. M. Schönherr BASF SE, GCP/TT – L540, 67056 Ludwigshafen, GermanySearch for more papers by this authorProf. Dr. F. Kleine Jäger, Prof. Dr. F. Kleine Jäger BASF SE, GCP/TT – L540, 67056 Ludwigshafen, GermanySearch for more papers by this author S. Pietsch, Corresponding Author S. Pietsch swantje.pietsch@tuhh.de Technische Universität Hamburg, Institut für Feststoffverfahrenstechnik und Partikeltechnologie, Denickestraße 15, 21073 Hamburg, GermanyTechnische Universität Hamburg, Institut für Feststoffverfahrenstechnik und Partikeltechnologie, Denickestraße 15, 21073 Hamburg, GermanySearch for more papers by this authorProf. Dr. S. Heinrich, Prof. Dr. S. Heinrich Technische Universität Hamburg, Institut für Feststoffverfahrenstechnik und Partikeltechnologie, Denickestraße 15, 21073 Hamburg, GermanySearch for more papers by this authorK. Karpinski, K. Karpinski BASF SE, GCP/TT – L540, 67056 Ludwigshafen, GermanySearch for more papers by this authorM. Müller, M. Müller BASF SE, GCP/TT – L540, 67056 Ludwigshafen, GermanySearch for more papers by this authorDr. M. Schönherr, Dr. M. Schönherr BASF SE, GCP/TT – L540, 67056 Ludwigshafen, GermanySearch for more papers by this authorProf. Dr. F. Kleine Jäger, Prof. Dr. F. Kleine Jäger BASF SE, GCP/TT – L540, 67056 Ludwigshafen, GermanySearch for more papers by this author First published: 29 August 2016 https://doi.org/10.1002/cite.201650255AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume88, Issue9Special Issue: ProcessNet-Jahrestagung und 32. DECHEMA-Jahrestagung der Biotechnologen 2016September, 2016Pages 1360-1360 RelatedInformation

Hydrodynamics of pulsed spouted beds: Effects of pulsation waveform, amplitude, and frequency

ABSTRACTThe effect of flow pulsations is studied via a discrete element model on hydrodynamics of spouted bed, which is being used in many important industries like drying processes. Decreased horizontal air percolation and preserving upward momentum, increased particle circulation, increased particle traverse distance, and better homogeneity are resulted from flow pulsations in spouted beds. Among the waveforms studied, square and triangular waveforms differ most and least from steady spouting, respectively. The predictions indicate that the pulsed spouted bed has the potential to enhance both gas and particle motion, hence being useful in drying and other operations.

Physicochemical Characterization and Bioactive Value of Tropical Berry Pomaces after Spouted Bed Drying

AbstractThis study addressed the physicochemical characteristics and selected bioactive compounds of tropical fruit pomaces acerola (Malpighia glabra L.), red pitanga (Eugenia uniflora) and jambolan (Syzygium cumini) obtained by spouted bed drying. The dried pomaces presented attractive colors, acidic pH, moisture between 8.3 and 9.7 g/100g, water activity lower than 0.5 and solubility around 40%. The water and ethanol extracts of these fruit powder samples showed high concentration of phenolics (10.1–30.7 mg GAE/g) with relevant DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) antioxidant activity (30.1–36.3 μmol Trolox equivalent/g). Dried jambolan also proved to be an outstanding anthocyanin‐rich product (377.0–478.7 mg cyanidin 3‐glycoside equivalent/100g). In addition, all extracts presented intermediate α‐amylase inhibitory activity (23.9–76.6%) and remarkable in vitro effect against α‐glucosidase (up to 99.3%). Overall, our results show the bioactive and technological potentials of dried acerola, red pitanga and jambolan pomaces as high quality food ingredients with functional attributes.Practical ApplicationsAcerola, red pitanga and jambolan are bioactive‐rich tropical fruits. The fruit processing generates a considerable amount of low‐value fruit pomaces. The motivation for this research was to propose the spouted bed drying as an appropriate strategy to produce food ingredients using the abundant residues of these selected fruits. A relevant concentration of residual bioactive compounds, antioxidant activity and inhibitory activities against key enzymes relevant to the management of early stages of type 2 diabetes were detected in the final dried products. Overall, our results present the spouted bed drying as a promising eco‐friendly process that can be successfully applied to produce value‐added fruit co‐products with potential health benefits. The data presented here constitute the biochemical rationale for the better exploitation of these tropical fruit pomaces.

Spouting Characteristics of Wet Particles in a Conical-Cylindrical Spouted Bed

Spout characteristics, such as flow pattern, minimum spouting velocity, and maximum spoutable bed height, are investigated in a wet conical-cylindrical spouted bed. Water and glass beads (Geldart D type) are adopted as the liquid and solid phases, respectively. The evolution of flow pattern of a wet spouted bed is captured by a CCD camera. The experimental results indicate that the minimum spouting velocity decreases when increasing the liquid saturation. The increase of initial bed height, particle size, or spout nozzle size leads to increased minimum spouting velocities. A correlation is formulated based on the experiments results for the prediction of minimum spouting velocities of wet spouted beds. Moreover, it is found that the maximum spoutable bed height Hmax decreases as particle size or spout nozzle diameter increases. However, Hmax is almost constant, approximately 1.5 times higher than that of its corresponding dry spouted bed, when increasing the liquid saturation.

Experimental Tests with Rice Straw on a Conical Square-Based Spouted Bed Reactor

Abstract A spouting bed reactor using rice straw as feedstock for further gasification purposes was studied in the present work. Experimental fluid dynamic tests were carried out in a conical square-based spouted bed reactor using a mixture of straw and silica, the latter acting as inert material. The influence of the initial bed of particles and the presence of coarse particles in the mixture on the pressure drop and minimum spouting velocity were evaluated. As a result, lower values of pressure drop along the bed were found compared to conventional fluidisation processes. Higher initial bed heights and higher percentage of straw in the mixture resulted in higher values of pressure drop and minimum spouting velocity. A new correlation for a cross section spouted bed reactor was proposed for the prediction of the minimum spouting velocity.

Hydrodynamic and Mixing Characteristics of Gas–Solid Flow in a Pulsed Spouted Bed

The flow behavior and particle motion in a pulsed gas–solid spouted bed was investigated using the Eulerian-Lagrangian approach. The computational fluid dynamics-discrete element method (CFD-DEM) was used to evaluate the gas flow field and particle trajectories. The model was four-way coupled to account for fluid–particle, particle–fluid, and particle–particle interactions. A column of 150 × 15 mm cross-section and height 750 mm containing 24500 particles of diameter 2.5 mm was investigated. Gas entered through a 10 × 15 mm slot at the base of the bed. Steady spouting was compared with pulsed spouting at frequencies of 1, 4, and 10 Hz, with superficial velocity amplitude of 0.5 and 1 m/s and a mean superficial spouting velocity of 2 m/s. In addition to comparing the bed pressure drop versus time and its Fourier decomposition, the hydrodynamics in the spout and annulus regions were examined. A new procedure was introduced to assess spouted bed mixing and homogeneity. Flow pulsation was shown to provide stronger upward air momentum, less horizontal gas percolation, better circulation, higher downward particle flux near the sidewalls, better mixing, and greater homogeneity.

Study on the Hydrodynamic Characteristics of a Biomass Fast Pyrolysis Conical Spouted Bed Reactor using the Pressure Fluctuations Analysis

Study on the Hydrodynamic Characteristics of a Biomass Fast Pyrolysis Conical Spouted Bed Reactor using the Pressure Fluctuations Analysis

Impact of Sodium and Sulfur Species on Agglomeration and Defluidization during Spouted Bed Gasification of South Australian Lignite

Transformations of inorganic elements during steam gasification of a high-sodium, high-sulfur lignite were investigated in a 77 mm i.d. spouted bed reactor. The role of sodium and sulfur in agglomeration and defluidization of the bed material is assessed by analysis of inorganics in the bed char, in cyclone dust, in any agglomerates formed, and in deposits formed at the gas inlet to the reactor. It was found that a sodium disilicate-quartz eutectic was the key species in causing stickiness of the surface of mineral particles within the coal. The present data indicate that sodium and silica from the coal are reacting to form sodium silicate species, which forms the “glue” causing solid ash particles to cohere, initiating particle growth and agglomeration. This finding agrees with a fundamental study conducted by other authors. Sodium–calcium–sulfur eutectics, which have been found by other authors to cause agglomeration for similar coals under combustion conditions in a fluidized bed, were only found to form near the steam–air inlet to the reactor and thus do not play a significant part in agglomerate chemistry under the reducing conditions which exist throughout the majority of the bed under gasification conditions.

A Study of CFD Modeling on Variation of Solid Fraction in a Batch Fluidized Bed

Two-dimensional gas–solid batch fluidized bed is simulated in transient conditions using the Eulerian–Eulerian two-fluid model. The grid independent test has been carried out for three different mesh sizes, and the courant number in the range of 0.2–0.4 has been used. The simulated results are compared with the experimental observations. The study is conducted for different sizes of Geldart group D solid particles, different bed heights, and different air velocities in the bubbling regime of fluidization. Two different models, such as the Gidaspow model and the Wen-Yu drag model, have been tested to model the drag at the phase interaction for Geldart group D solid particles. On comparison with experimental results the Gidaspow drag model matches well with experimental results and hence is used for simulation. At the initial stage of fluidization (where a fountain like phenomena was observed), the bed behaves like a spouting bed, and then the bubbling bed behavior follows. These predictions are compared with the experimentally observed bed height of particles of different sizes and air velocities. It is observed that the Gidaspow drag model predictions are in good accordance with the experimental results for particles of different sizes, both in the initial stage and in the bubbling regime of fluidization.

Bed Pressure Drop in a Draft‐Tube Conical Spouted Bed for Thermal Treatment of Wastes

AbstractAn experimental study of operating bed pressure drop was performed in thermal treatment of coarse waste particles of different size, density, and sphericity in conical spouted beds by introducing a nonporous draft tube. The influence of introducing a nonporous draft tube as well as of operating conditions on bed pressure drop was determined. Bed pressure drop in conical spouted beds with a nonporous draft tube was found to be lower than that without any device, which allows for saving operating costs. The most important factor influencing the bed pressure drop was the stagnant bed height. The bed pressure drop was reduced when stagnant bed height, particle density, particle sphericity or inlet gas temperature were decreased. Likewise, the bigger the particle diameter, the lower was the bed pressure drop.

Numerical investigation of the time-related properties of solid phase in a 3-D spout-fluid bed

Numerical simulation of the two-phase flow in a 3-D spout-fluid bed is carried out to investigate the time-related properties of solid phase based on the In-house code by CFD–DEM coupling approach. The mixing time, distribution properties of the cycle time, global residence time and local residence time of solid phase are explored. Moreover, the influences of spouting gas velocity, background velocity, particle diameter and bed thickness on these properties are discussed. The results illustrate that the mixing time is lowered with the increase of spouting velocity or the decrease of background velocity. Cycle time shows a log-normal distribution behavior and grows with the increase of the particle diameter but decreases with the increase of spouting velocity or background velocity. Moreover, nearly 60% of the total particle time elapses in the annulus and 34% of that in the fountain while only 6% of that is paid in the spout. The solid residence time (SRT) in the spout or annulus diminishes with increasing spouting velocity or background velocity and also the decrease of particle diameter. However, the SRT in the fountain region shows the opposite response behavior. The scale-up of the bed thickness enlarges the cycle time and SRTs in three regions of the bed. Besides, small local SRT appears in the spout while large value exists in the annulus especially the corners of the bed bottom. The geometrical configuration of the bottom leads to the opposite distribution of local SRT near walls in the annulus and fountain. Moreover, the local SRTs in different regions of the system show distinct distribution properties.

Slot-Rectangular Spouted Bed: Hydrodynamic Stability and Effects of Operating Conditions on Drying Performance

A new spouted-bed configuration (rectangular cross-section with air entry through two bottom slots) was investigated as a dryer of milk and a paste mixture of milk and blackberry pulp. The aim was to analyze hydrodynamic stability and the effects of operating conditions on powder production efficiency. For the best conditions of paste-feeding flow rate, air temperature and inert type, hydrodynamic was stable and powder production efficiency was greater than 75%. The slot-rectangular spouted bed allowed for tripling of the paste-feeding flow rate at a lower air velocity compared to the conventional geometry, showing its potential for process scale-up.

Protein quality of dried enzymatic hydrolysate from anchovy produced in a spouted bed of inert particles

SummaryThe anchovy (Engraulis anchoita) is a pelagic fish and due to its abundance in South America shows a sustainable exploitation. The enzymatic hydrolysis of anchovy protein associated to the drying technique in spouted bed was analysed in order to obtain products with the best characteristics. The drying conditions were inlet air temperature, concentration and flow rate of suspension. The degree of hydrolysis of the anchovy suspension was of 3.8%, and its available lysine and specific antioxidant activity were of 86 g kg−1protein and 4.31 mmDPPH kg−1 min−1, respectively. In spouted bed drying, the lowest reduction in available lysine (9%) and loss of specific antioxidant activity (8%) were found at 90 °C, and suspension concentration and flow rate of 65 g L−1 and 200 mL h−1, respectively. The dried product was characterised as a protein source of high biological value due to the essential amino acids profile.

Comparison of Three Blanching Treatments on the Color and Anthocyanin Level of the Microwave-Assisted Spouted Bed Drying of Purple Flesh Sweet Potato

Browning and a serious drop in anthocyanin level occur during microwave-assisted spouted bed drying (MWSB) of purple-flesh sweet potato (PFSP) cubes. Blanching pretreatment inhibits browning and also affects the drying behavior. Effects of microwave blanching (MWB), hot water blanching (HWB), and steam blanching (SB) were examined experimentally. The results showed that MWB leads to rapid peroxidase (POD) degradation, reduces the drying time, and yields highest anthocyanin level after MWSB drying. However, the color of the dried product was not as bright and purple as those obtained by HWB and SB treatments. Microwave blanching can improve the MWSB drying process to maintain the anthocyanin level in dried products while reducing the drying time.

Drying of Burdock Root Cubes Using a Microwave-Assisted Pulsed Spouted Bed Dryer and Quality Evaluation of the Dried Cubes

Burdock cube samples were dried using hot air and microwave pulsed spouted bed drying (MPSBD). Hot air drying was carried out at three temperatures (70, 80, and 90°C). MPSBD was carried out at three microwave power levels (1.0, 2.0, and 3.0 W/g). The results showed that MPSBD samples dried at 2.0 W/g for 30 min and at 1.0 W/g for 40 min had desirable color, flavor, and textural attributes. Gas chromatography–mass spectrometry results showed that the samples dried using MPSBD were richer in flavor compounds, especially in esters, compared to the hot air–dried samples.

Effects of Ultrasound and Microwave Pretreatments of Apple Before Spouted Bed Drying on Rate of Dehydration and Physical Properties

Pretreatments of fruits before drying have been proposed as alternative way to improve the quality of dried fruits and reduce drying time. In the present study, the effects of different pretreatments (ultrasound and microwave) on apple cubes prior to spouted bed drying were investigated. Ultrasound pretreatment resulted in a great loss of sugars (25.7% for 15 min) compared to microwave pretreatment, where little rise in sugar content was observed (1.6% at 300 W). Ultrasound pretreatment improved the drying rate more than microwave pretreatment. Nevertheless, microwave-pretreated dried apples were harder and had lower water activity than ultrasound-pretreated ones. Low-frequency nuclear magnetic resonance (LF-NMR) analysis was used to study the water state and revealed that all pretreatments promoted redistribution of water among apple cell compartments and showed that most of the water lost was from the vacuoles. If dried low-calorie fruits are required then ultrasound pretreatment would be preferred.

Development of a dual conical spouted bed system for heat integration purposes

This paper describes preliminary studies carried out to develop a system made up of two interconnected spouted beds for heat integration in highly endothermic processes, such as pyrolysis and gasification. Four different configurations of a dual spouted bed system have been studied depending on the location of the feeding and discharging points in the interconnection pipes, i.e., annulus–annulus, annulus–spout, fountain–spout and fountain–annulus. Fountain–annulus configuration has been determined to be the optimum option based on its stability, solid transfer rate (around 120kgh−1) and gas bypassing from one contactor to the other (below 1.5%). Once the optimum system has been established, the viability of the dual spouted bed system has been assessed for heat integration in the biomass pyrolysis, with the minimum temperature difference between the pyrolyser and combustor being 280°C for attaining allothermal operation. Furthermore, studies have been carried out on the solid circulation rate (energy balance), gas bypassing from one contactor to the other and system stability against different perturbations, which have allowed determining the optimum configuration

Particle Cycle Times in Draft Tube Conical Spouted Beds

A hydrodynamic study of conical spouted beds equipped with draft tube has been carried out for glass beads. Runs have been carried out in conical spouted beds of different geometry according to a factorial design of experiments. The purpose of this design has been to study the effect on particle cycle times and solid circulation rate of the following: the insertion of a draft tube, draft tube configuration, and the different factors of the contactor and particle system. Particle cycle times (average, maximum, and minimum) have been measured in draft tube conical spouted beds for different geometric factors of the contactor (angle and gas inlet diameter), draft tubes (diameter, height of the entrainment zone, and width of the faces) and under different operating conditions. It can be concluded that the hydrodynamics of conical spouted beds with draft tube is influenced by the geometric factors of the draft tube, contactor and operating conditions.