Fluidized Bed Research Articles

Synergizing sugarcane waste valorization: Optimization of two-stage anaerobic co-digestion for enhanced methane recovery and organic matter removal

Multiple strategies have been used in anaerobic digestion of effluents aiming to enhance the efficiency of the methane (CH4) recovery process, where co-digestion and the two-stage process emerge as prominent methods. In this context, this study aimed at evaluating the co-digestion of sugarcane vinasse and molasse in a two-stage process using anaerobic fluidized bed reactors (AFBR), verifying the effect of increasing the organic loading rate (OLR) (5–22.5 kg COD.m−3.d−1) and temperature in the second stage methanogenic reactor. Regarding the two-stage process, sugarcane vinasse and molasses fermentation demonstrated the maximum energy potential (E.P) of 57.08 kJ.d−1 (7.5 g COD.L−1). Regarding the methanogenic sequential reactors, organic matter removal reached high values (up to 84.5 % in a thermophilic sequential reactor (TSR); up to 84.5 % in a mesophilic sequential reactor (MSR)). The highest CH4 yield (MY) of 306.77 ± 38.84 mL CH4.g−1 COD rem was observed in MSR (9 kg COD.m−3.d−1). Meanwhile, the maximum value of MPR (3.8 ± 0.5 L CH4.L−1.d−1) was observed in TSR (21 kg COD.m−3.d−1). Regarding the Archaea domain, a predominance of hydrogenotrophic microorganisms could be identified, in which the genera Methanobacterium and Methanothermobacter were the most abundant in MSR and TSR, respectively. This study demonstrates that anaerobic digestion of sugarcane vinasse and molasses enhances anaerobic treatment using two-stage AFBRs. It not only produces CH4 but also generates hydrogen and high-value products through an acidogenic reactor. This research marks a significant advancement in managing sugarcane processing by-products, offering promising approaches to maximize biogas production and improve pollutant removal efficiency.

Experimental investigation and CFD study of direct reduction of iron ore in the conical fluidized bed

The reduction behavior of iron ore is the fundamental process in ferrous metallurgy. Considering the gas–solid interface-structure relationship, heterogeneous transfer-reaction behavior, and multiple reaction kinetics, this work provides an effective analytical tool to investigate the fluidized reduction of iron ore. The conical fluidized bed is numerically examined to be capable of preventing de-fluidization induced by the sticking behavior, due to the steady circulation of flow pattern and full fluidization of coarse agglomerates. Compared with the hydrogen concentration, the gas velocity shows a stronger influence on the agglomerate reduction rate for the more efficient gas–solid contact. For the simulated transitions of Fe2O3 → Fe3O4 → Fe(1-x)O → Fe are assumed to overlap each other, there exist discrepancies between computed and theoretical reduction degrees. The experimental and numerical findings can be used to develop a methodology for optimizing the operational complexity and economic benefits of the fluidized reduction of iron ore.

Wall-scaling prevention in cryogenic external cooler of ammonium chloride solution by liquid-solid fluidization

A double-tube cooler with liquid-solid circulating fluidization operation and corresponding parameter measuring system are developed to avoid fouling of inner walls of heat exchange tubes in a cryogenic temperature external cooler of ammonium chloride solution in soda ash production. Wall-scaling prevention performance of the cooling process is experimentally evaluated using convection and overall coefficients, enhancement factor, wall temperature and fouling resistance. Effects of different volume fractions of added particles, particle size, superficial liquid velocity, and cooling medium temperature on heat transfer are examined. Under present conditions, convection coefficient of liquid-solid flow inside the tube of external cooler is higher than that of the liquid phase flow, increased by 0.7–2.8 times, enhancing cooling performance obviously. Convection coefficient initially increases and then decreases as the volume fraction of added particles increases, reaching its maximum value at a volume fraction of 2.0%. The wall-scaling prevention effect of glass beads mainly depends on the volume fraction of added particles; optimal anti-fouling effects are achieved when adding particles at a volume fraction of 2.0%, regardless of changes in superficial liquid velocity or cooling medium temperature. This study lays a foundation for industrial applications of this new technique of fluidized bed external coolers.

Hydrogen Production from Natural Gas Using Hot Blast Furnace Slag: Techno-economic Analysis and CFD Modeling

A process for thermal decomposition of methane to hydrogen and solid carbon is presented and examined. It utilizes the high-temperature heat from the slag by-product of blast furnace ironmaking to drive a thermal decomposition reaction, making it a waste-heat-to-hydrogen technology. This is accomplished via dry granulation of molten slag that feeds a fluidized bed reactor to effect methane–slag contact. First, the proposed process and the heat and mass balances are presented. It is found that it could produce an amount of hydrogen that is equivalent to about 20% of the reductant, depending on the iron-to-slag ratio. Then, a techno-economic analysis investigates the capital and operating costs of the process, compares the hydrogen production cost to that of other processes, and examines cost sensitivity to the prices of process inputs and outputs. This analysis suggests that the process would be suitable for on-site hydrogen production and use within a plant. In addition, using the hot slag to drive the methane decomposition would reduce hydrogen production cost by 15% compared to combusting a portion of the natural gas itself. Finally, a computational fluid dynamics (CFD) modeling study of the fluidized bed reactor examines the thermal decomposition of methane and its dependence on reaction kinetics as well as reactor design and operation. The bed operated in the bubbling regime at an average temperature between 1020 and 1060 °C and resulted in as high as 82% conversion of the methane to hydrogen, with additional optimization still possible.Graphical

Sensitivity analysis of a dense discrete phase model for 3D simulations of a tapered fluidized bed

This study aims to conduct a sensitivity analysis of closure models and modeling parameters for the Dense Discrete Phase Modeling (DDPM) approach in order to investigate the hydrodynamics of a 3D lab-scale Tapered Fluidized Bed (TFB). The closure models and model parameters under investigation include the gas-solid drag force, viscous models, particle-particle interaction models, restitution coefficient, specularity coefficient, and rebound coefficient. The primary objective of this sensitivity analysis is to optimize the numerical model's performance. The numerical results, in terms of axial and lateral Solid Volume Fraction (SVF) profiles obtained from the sensitivity analysis, indicate that the drag force and restitution coefficient significantly influence the hydrodynamics of the TFB. Properly selecting these parameters could result in the improved performance of the numerical model. However, the sensitivity of turbulence models, particle-particle interaction models, specularity coefficient, and rebound coefficient has a lesser impact on the hydrodynamics results. This work concludes with the recommendation of a set of closure models and modeling parameters that offer the most accurate prediction of the hydrodynamics of the TFB.

Machine learning and physics-driven modelling and simulation of multiphase systems

We highlight the work of a multi-university collaborative programme, PREMIERE (PREdictive Modelling with QuantIfication of UncERtainty for MultiphasE Systems), which is at the intersection of multi-physics and machine learning, aiming to enhance predictive capabilities in complex multiphase flow systems across diverse length and time scales. Our contributions encompass a variety of approaches, including the Design of Experiments for nanoparticle synthesis optimisation, Generalised Latent Assimilation models for drop coalescence prediction, Bayesian regularised artificial neural networks, eXtreme Gradient Boosting for microdroplet formation prediction, and a sub-sampling based adversarial neural network for predicting slug flow behaviour in two-phase pipe flows. Additionally, we introduce a generalised latent assimilation technique, Long Short-Term Memory networks for sequence forecasting mixing performance in stirred and static mixers, active learning via Bayesian optimisation to recover coalescence model parameters for high current density electrolysers, Gaussian process regression for drop size distribution predictions for sprays, and acoustic emission signal inversion using gradient boosting machines to characterise particle size distribution in fluidised beds. We also offer perspectives on the development of a shape optimisation framework that leverages the use of a multi-fidelity multiphase emulator. The results presented have applications in chemical synthesis, microfluidics, product manufacturing, and green hydrogen generation.

Desi chickpea flaking: Impact of processing parameters on flake quality

This study explores the novel production dependent characteristics of ready-to-eat whole pulse flakes from desi chickpea splits. The research investigates a three-stage process: minimal live steam conditioning, precise rolling, and rapid fluidised bed drying. Effects of steam time (1, 3, 5 min), roller gap (0.5–0.8 mm, 0.8–1.3 mm), and drying temperature (150 °C, 200 °C) on flake quality were examined. These conditions altered flake appearance, with optimal roller settings maintaining the aspect ratio within 10% of the original split. Steam time increased starch gelatinisation by 21–31%, while longer steaming and wider roller gaps decreased water absorption, improving bowl life. Drying at 200 °C accelerated moisture loss, reducing durability of 5-min steamed flakes. The study demonstrates that tailored processing can yield viable chickpea flakes comparable to whole grain cereals. These findings have significant implications for the food processing industry, offering a pathway to develop nutritious, pulse-based ready-to-eat products.

Commercialization of the Xalkori Pediatric Multiparticulate Product Using Quality-by-Design Principles.

A pediatric dosage form for crizotinib (Xalkori) was commercialized using quality-by-design principles in a material-sparing fashion. The dosage form consists of spherical multiparticulates (microspheres or pellets) that are coated and encapsulated in capsules for opening. The crizotinib (Xalkori)-coated pellet product is approved in the US for pediatric patients 1 year of age and older and young adults with relapsed or refractory, systemic anaplastic large cell lymphoma (ALCL) and unresectable, recurrent, or refractory inflammatory myofibroblastic tumor (IMT) that is ALK-positive. The product is also approved in the US for adult patients with non-small cell lung cancer (NSCLC) who are unable to swallow intact capsules. The lipid multiparticulate is composed of a lipid matrix, a dissolution enhancer, and an active pharmaceutical ingredient (API). The API, which remains crystalline, is embedded within the microsphere at a 60% drug loading in the uncoated lipid multiparticulate to enable dose flexibility. The melt spray congealing technique using a rotary atomizer is used to manufacture the lipid multiparticulate. Following melt spray congealing, a barrier coating is applied via fluid bed coating. Due to their particle size and content uniformity, this dosage form provides the dosing flexibility and swallowability needed for the pediatric population. The required pediatric dose is achieved by opening the capsules and combining doses of different encapsulated dose strengths, followed by administration of the multiparticulates directly to the mouth. The encapsulation process was optimized through equipment modifications and by using a design of experiments approach to understand the operating space. A limited number of development batches produced using commercial-scale equipment were leveraged to design, understand, and verify the manufacturing process space. The quality by design and material-sparing approach taken to design the melt spray congeal and encapsulation manufacturing processes resulted in a pediatric product with exceptional content uniformity (a 95% confidence and 99% probability of passing USP <905> content uniformity testing for future batches).

The Influence of Gas Pulsed Flow on Hydrodynamic Behaviors of Refined Standard Sugar

The influence of gas-pulsed flow when supplied in the perpendicular direction to the refined standard (RS) sugar layer has been studied in this article. Some hydrodynamic parameters of the RS sugar in the gas-pulsed fluidized bed have also been determined. The research results have been applied in the design of the RS sugar dryer using the modern pulsed fluidized bed drying method. The bed porosity in the static particle layer (e0) was 0.44 while the bed porosity in the minimum fluidized bed (emg) was 0.484 and the minimum fluidized bed velocity (Umg) was 0.65 m/s. The bed porosity in the homogeneous fluidization bed (ehg) was 0.67, and the homogeneous fluidization velocity (Uhg) of 1.63 m/s has been calculated. The critical velocity (Ucg) of 2.7 m/s and the bed porosity (ecg) of 0.8 in the circulating particle bed were determined. The pressure drop through the layer of RS sugar with a thickness of 300 mm was 3808 N/m2.

Synthesis and characterization of breast milk analogue structured triacylglycerols by immobilized lipase using magnetic fluidized bed

Structured triacylglycerols with 1,3-dioleoyl-2-palmitoylglycerol (OPO) have many health benefits for infants. In this paper, tripalmitin (PPP) and oleic acid (OA) were used as raw materials, the method of magnetic fluidized bed and immobilized lipase was used in the synthesis reaction of OPO. Reaction parameters in the fluidized bed were simulated by computer. The results showed that flow rate of 0.0023 m/s and magnetic field strength of 0.021 T were the optimal conditions for the synthesis of OPO in the magnetic fluidized bed. Under the same conditions, OPO content in the magnetic fluidized bed was 45.79%, which was 3.11% higher than batch reaction. After 7 times of reuse, the enzyme activity in fluidized bed was 81.75%, which was 10.7% higher than that of the batch reaction. This study may provide an efficient and more economical method for OPO production in the future.

Ideal performance assessment of non-recirculating anaerobic fluidized bed reactors treating low to high strength organic loads with low retention time

This study investigated the ideal performance of non-recirculating Anaerobic Fluidized Bed Reactors (AnFBRs) for treating organic wastewater of varying strengths under low Hydraulic Retention Time (HRT). Four 4.58 L AnFBRs were used to treat synthetic wastewater with an Organic Loading Rate (OLR) ranging from 4.50 to 40.11 gCOD/L-d, and HRT between 1.1 and 4.4 hours. The AnFBRs achieved high removal efficiencies ranging from 83 % to 96 % at steady state, except during the organic shock load, which reduced removal performance to 12 %. Shortened HRT conditions led to a decreasing trend in reactor pH due to an incomplete anaerobic cycle. The modified Stover-Kincannon model estimated the maximum substrate utilization rate of AnFBR's to be 196.08 gCOD/L-d, with a correlation coefficient of 0.98. Under shortended HRT, microbial diversity analysis identified predominant non-filamentous bacterial families, such as Streptococcaceae and Veillonellaceae, which collaborate during biofilm development in anaerobic environments. It was suggested that the porous media provided secure attachment sites for the biomass growth and biofilm formation under shock load and high shear force conditions. While these results offer valuable insights, further studies are needed to confirm these findings and enhance the understanding of the use porous media in non-recirculating AnFBRs.

Experimental study and correlation analysis for the effect of hydrogen pressure on biomass fluidized hydropyrolysis under N2-H2 mixed atmosphere

The utilization of fluidized bed reactors for the biomass hydropyrolysis vapor upgrading is essential in the conversion of biomass into liquid fuels. Conducting pyrolysis experiments in fluidized bed reactors with a N2-H2 mixed atmosphere is advantageous for system operation as it allows for lower minimum operating velocities, enhances pyrolysis efficiency, and reduces heat loss. This research examines the impact of hydrogen pressure in a bubbling fluidized bed reactor using a N2-H2 mixed carrier gas, with poplar wood as the feedstock and Ni-Moγ/Al2O3 as the catalyst. Through experimental and correlation analyses, significant relationships are observed between hydrogen pressure and the production of liquid and gas-phase products, with varying effects attributed to changes in hydrogen ratio and reaction pressure. Elevated hydrogen ratios facilitate secondary reactions such as the CO2 hydrogenation, resulting in a decline in CO2 production and an elevation in the yields of light hydrocarbons and aqueous phase products. Augmenting the reaction pressure to enhance hydrogen pressure aids in promoting hydrogen saturation and cracking, and amplifying the hydrogen pressure through an increase in the reaction pressure at a specific hydrogen ratio proves more efficacious in enhancing both the quantity and quality of bio-oil produced. In the context of poplar hydropyrolysis vapor upgrading utilizing a Ni-Moγ/Al2O3 catalyst, a hydrogen ratio of 50 % at a reaction pressure of 1.5 MPa emerged as the preferred option for achieving a 12 % bio-oil yield with a moderate average bio-oil carbon number and satisfactory hydrogenation levels. This comprehensive investigation examines the influence of hydrogen pressure on biomass hydropyrolysis, highlighting variations in the impacts of changes in hydrogen ratio and reaction pressure on pyrolysis results. These results offer a theoretical framework for discerning distinctions between hydropyrolysis investigations carried out in pure hydrogen atmospheres versus mixed N2-H2 atmospheres.

Small-scale fluidised bed flotation device for ore amenability testing

Fluidised bed flotation, such as with Eriez’s HydroFloat®, has demonstrated the ability to recover coarse particles up to 600 µm in size during sulphide flotation. The ability to perform flotation at coarse particle sizes provides significant benefits to the minerals processing industry, including energy savings in comminution and increased plant throughput.However, the smallest available fluidised bed flotation units require between 15 and 20 kg of sample for a single test and upwards of 100 kg of sample to conduct initial scoping studies for new ore feed material. This high sample requirement often prohibits the execution of small-scale flotation optimisation tests using this technology.The development of a small-scale fluidised bed flotation device is therefore vital to enable rapid and efficient testing for essential operations such as ore amenability and geometallurgical evaluation, circuit modelling and design, and routine metallurgical assessment.This work presents the design and development of a small-scale fluidised bed flotation device that uses 1–2 kg of sample per test. The work further outlines the testing methodology to achieve both reasonable and reproducible flotation results. Both the device and test methodology were demonstrated using two copper ore samples, and the flotation results generated were similar in form to laboratory batch testing using conventional flotation cells.

Reduced-Order Modeling of Indirect Fluidized-Bed Particle Receivers with Axial Dispersion

Oxide particles present a heat transfer and thermal energy storage (TES) media for next-generation concentrating solar power (CSP) plants where the high-temperature particle TES can provide dispatchable solar power [1]. Transferring heat to flowing particles can be a challenge and bubbling fluidization is a promising method for increased heat transfer between the oxide particles and confining walls. Using experimentally calibrated correlations for particle-wall heat transfer coefficients [2], this study explores in a quasi-1D model of a narrow-channel counterflow fluidized bed how the high heat transfer coefficients from bubbling fluidization enable cavity-based indirect particle receivers. Particle-wall heat transfer coefficients exceeding 800 W m-2 K-1 support angled solar fluxes &gt; 200 kW m-2 from high normal fluxes &gt; 1200 kW m-2 with wall temperatures &lt; 900 oC. Parametric studies identify how gas flows, solar fluxes, and receiver heights impact receiver solar efficiency for a CSP plant. These modeling studies provide a basis for the development of an indirect narrow-channel fluidized particle receiver that has the potential to operate at normal solar fluxes over 1000 kW m-2 and solar efficiencies above 85%.

Experimental study on reactivity and inorganic component transformation of activated fuels in a fluidized bed

The gasification and combustion of activated fuels produced from fluidized bed are beneficial for achieving clean and efficient coal utilization. In this study, a high-calcium coal was used for the activation process, carried out in a high-temperature vertical fluidized bed. The carbon and ash characteristics of activated fuels were studied. The reactivity of activated fuels was characterized using Raman test, and scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS). Inorganic components were characterized using X-ray diffraction (XRD), and X-ray fluorescence spectrometry (XRF). With the increase of temperature and equivalence ratio (ER), the graphitization degree of activated fuels decreases, and a higher proportion of active sites leads to, a better activation effect. The activation effect is optimized at the equivalence ratio of 0.45. As the temperature rises, the calcium-containing minerals in the raw coal are gradually transformed into anorthite (CaAl2SiO7), and the anhydrite (CaSO4) reacted with the reducing gas (CO) to produce oldhamite (CaS); Fe2O3 as a fluxing agent, is prone to melting with silica-aluminates at high temperature. As the particle size of activated fuel increased, the relative enrichment index (REI) of heavy metals decreases.

Aspek Gizi dan Fungsional Tepung Bawang Dayak (Eleutherine palmifolia (L) Merr) : Kajian Pengeringan Menggunakan Fluid Bed dan Cabinet Dryer

Dayak onion is a type of medicinal plant that grows in several areas and has been used for generations to cure various diseases in Kalimantan, Indonesia. Dayak onion contains bioactive compounds such as phenolic, flavonoids, saponins, tannins and naphtoquinones which can act as antioxidants, anti-microbials, and anti-inflammatories. Currently the application of Dayak onions is still rare even though it has many benefits. This study aims to characterize nutritional and functional aspects of dayak onion flour with various drying temperature using fluidized bed dan cabinet dryer. The research design used is factorial design. The characterization of Dayak onion flour carried out was yield, moisture content, ash, protein, fat, concentration of IC50, WHC and OHC. Microbial contamination tests carried out included ALT, E.coli, and mold. In the research results, the best nutrition and functional aspect of Dayak onion flour was drying with temperature 40? in the cabinet and fluidized bed dryer. Determination of the best results is taken based on the De Garmo test where the two samples have the highest value of effectiveness in each method. The best concentration of IC50 is Dayak onion flour using the cabinet dryer with a temperature of 35? that was 3703,43 ppm. In addition, no growth of E.coli and mold bacteria was found and the number of bacterial colonies was still classified as safe when compared to the SNI for cassava flour so that dayak onion flour was safe against microbial contamination.

Adsorptive removal of microplastics from aquatic environments using coal gasification slag-based adsorbent in a liquid–solid fluidized bed

Microplastics (MPs) are emerging pollutants in aquatic environments that threaten ecological health. This study investigated the adsorption process and mechanism of a coal gasification slag-based adsorbent in a liquid–solid fluidized bed to remove MPs from an aquatic environment. The results showed that the coal gasification slag-based adsorbent had high MP adsorptive removal efficiency of up to 1400 mg/g and adsorption-removal efficiency of 99.2 %. The adsorption process was mainly dominated by electrostatic attraction, π-π absorption, and surface complexation, supplemented by partial physical adsorption. The adsorbent dosage mo was the dominant factor affecting the adsorption performance of the liquid–solid fluidized bed for the continuous adsorption of MPs, followed by the initial MP concentration co and ascending water velocity vt. At a suitable combination of operating parameters (co = 250 mg/L; mo = 2.5 g; vt = 0.11 m/s), the adsorption saturation level of the liquid–solid fluidized bed reached 0.95, which was higher than that of the traditional fixed bed (0.91), indicating good MP adsorption performance. This study provides a new technical approach for MP removal from aquatic environments that is conducive to the industrial application of fluidized beds in the field of wastewater treatment.

Development and validation of filtered drag models for fluidization of low-density Geldart A particles

Filtered drag models have been extensively developed and applied in coarse grid simulation of fluidized beds. However, existing filtered drag models were mainly developed using the particle properties of Fluid Catalytic Cracking (FCC), and these models were found to perform less satisfactorily in predicting flow fields for low-density particles. To broaden the applicability of filtered drag models, this study developed a novel filtered drag model tailored explicitly for low-density Geldart A particles. Additionally, this study investigated the differences in filtering outcomes using various filter types. Statistical analyses revealed significant differences between filters, particularly between the median and other filters. The statistical skewness distribution of the filtered quantity datasets can lead to differences in results between median and mean filters. After analyzing one-marker and two-marker models, it was found that filter type has a more pronounced influence on model performance prediction differences at small filter sizes, while it becomes insignificant at larger filter sizes. Validation studies in fluidized bed simulations found that the two-marker model established based on the Median filter performs best in predicting performance. It is also found that more substantial drag corrections are required in the extremely dense phase domain for low-density particle fluidization systems.

Investigating hydrodynamics and gas diffusion coefficient in CFB of binary particles with significant differences in particle properties

A composite fluidized bed (SCFB), which integrated the bubbling fluidization and circulating fluidization into one bed, was developed in this work. Wavelet transform was employed to analyze time-series signals of the pressure fluctuations and the steady-state tracer injection technique was used to study the gas diffusion coefficient in SCFB. The energy contribution in BFB and CFB mainly concentrated on the macrostructures, while that in SCFB was caused principally by the mesostructures as gas velocity was high. The circulating particles could effectively reduce particle aggregates and promoted a uniform distribution of heavy particles in the bottom region. Radial dispersion coefficients in SCFB were greater than that in BFB and CFB, demonstrating that the circulating particles enhanced gas mixing in SCFB. The ratio of Da/Dr in SCFB was less than that in BFB, indicating that gas-solid flow in SCFB was more closely to the mixed-type flow compared to the BFB.

A detailed process model of biomass gasification in bubbling fluidized bed: integration of hydrodynamics into reaction modeling

A detailed process model of biomass gasification in bubbling fluidized bed: integration of hydrodynamics into reaction modeling