Experimental validation of a multiphase flow model of a lab-scale fluidized-bed gasification unit

Porcu, Andrea; Xu, Yupeng; Mureddu, Mauro; Dessì, Federica; Shahnam, Mehrdad; Rogers, William A.; Sastri, Bhima; Pettinau, Alberto

doi:10.1016/j.apenergy.2021.116933

Cited by 20 publications

(6 citation statements)

References 71 publications

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“…To assist in such optimization efforts, particle modeling must be integrated into reactor-scale modeling in order to optimize the performance of a thermochemical reactor system. This is often estimated by using an analytical shrinking core-type model in biomass combustion 85 and gasification, 86 originally presented by Wen. 87 However, the shrinking core is not relevant for biomass pyrolysis without oxidation.…”

Section: Bioenergy Processesmentioning

confidence: 99%

Bridging Scales in Bioenergy and Catalysis: A Review of Mesoscale Modeling Applications, Methods, and Future Directions

et al. 2021

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Between the molecular and reactor scales, which are familiar to the chemical engineering community, lies an intermediate regime, here termed the “mesoscale,” where transport phenomena and reaction kinetics compete on similar time scales. Bioenergy and catalytic processes offer particularly important examples of mesoscale phenomena owing to their multiphase nature and the complex, highly variable porosity characteristic of biomass and many structured catalysts. In this review, we overview applications and methods central to mesoscale modeling as they apply to reaction engineering of biomass conversion and catalytic processing. A brief historical perspective is offered to put recent advances in context. Applications of mesoscale modeling are described, and several specific examples from biomass pyrolysis and catalytic upgrading of bioderived intermediates are highlighted. Methods including reduced order modeling, finite element and finite volume approaches, geometry construction and import, and visualization of simulation results are described; in each category, recent advances, current limitations, and areas for future development are presented. Owing to improved access to high-performance computational resources, advances in algorithm development, and sustained interest in reaction engineering to sustainably meet societal needs, we conclude that a significant upsurge in mesoscale modeling capabilities is on the horizon that will accelerate design, deployment, and optimization of new bioenergy and catalytic technologies.

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Section: Bioenergy Processesmentioning

confidence: 99%

Bridging Scales in Bioenergy and Catalysis: A Review of Mesoscale Modeling Applications, Methods, and Future Directions

et al. 2021

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“…Because of complex gas–solid dynamics and chemical reactions involved in the rotary drum, which are difficult to be captured by measurement tools, numerical simulation has become a powerful tool to supplement more details inside the reactor. A wide range of numerical models have been proposed, among which computational fluid dynamic (CFD) models can predict both the multiphase flow dynamics and chemical reactions, which are helpful for profoundly understanding the particle motion as well the conversion mechanism. , …”

Section: Introductionmentioning

confidence: 99%

“…A wide range of numerical models have been proposed, 7 among which computational fluid dynamic (CFD) models can predict both the multiphase flow dynamics and chemical reactions, which are helpful for profoundly understanding the particle motion as well the conversion mechanism. 8,9 With regard to the CFD investigation of biomass conversion, considerable progress has been made in multiphase flow models, such as the multifluid model (MFM), 10 the multiphase particlein-cell model (MP-PIC), 11 and the CFD coupled with discrete element model (CFD-DEM). 12 In general, MFM treats both gas and solid phases as continua, so information of individual particles is omitted.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Biomass Pyrolysis in a Rotary Drum by Coupling CFD-DEM with a One-Dimensional Thermally Thick Model

Wang

Yang

2022

Energy Fuels

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A reactive computational fluid dynamic-discrete element model (CFD-DEM) is coupled with a one-dimensional thermally thick model to simulate biomass pyrolysis in a three-dimensional rotary drum reactor. Furthermore, a diffusion-based voidage algorithm and a competitive pyrolysis scheme are also implemented. After validation, the integrated model is applied to explore the effects of the drum rotating speed and the filling level. The particle distribution and motion, heat transfer, and conversion behavior are selected as indicators. Results show that the particle inventory within the central transverse section is affected by both the mechanic effect of rotation and the axial conveying due to the product gas flux. The angle of repose for the central section first increases and then decreases with rotating speed, while increasing the filling level reduces the angle of repose and delays the bed sinking. Moreover, the particles at the bed surface are energetic and thus the area of high-value granular temperature is distributed along the bed surface. The particle accumulated displacement increases and the particle residence time at the wall reduces with the rotating speed and the filling level. In addition, the specific heat conduction rate can be promoted by decreasing the rotating speed and the filling level. A higher rotating speed or a lower filling level is favorable for particle mixing and thus makes particles heat up uniformly. Finally, a higher rotating speed or filling level exerts a negative impact on biomass conversion. These findings are helpful for better understanding biomass pyrolysis in a rotary drum reactor.

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“…A gas–solid circulating fluidized bed (CFB) system, as a typical chemical reactor, has been widely applied into industrial processes such as oil catalytic cracking, Fischer–Tropsch synthesis, and coal combustion. , The most valuable area of potential applications for CFB is in coal gasification and biomass gasification for power generation, chemical production, and synthesis gas. − Recently, the CFB technology is a promising approach that allows effective gas–solid contact for emission control and chemical looping processes for carbon capture and utilization. − Based on the gas–solid flow directions, operations of a CFB reactor can be achieved either in a riser − where both the gas and solid flow upward counter to the gravity or in a downer , where both the gas and solid flow downward concurrent with the gravity. Normally, most of the reactions like the catalytic cracking and fuel combustion processes take place in the riser reactor since it provides good gas–solid contact, large throughput, proper residence time of the reaction, and flexible operating ranges.…”

Section: Introductionmentioning

confidence: 99%

Cluster Identification by a k-means Algorithm-Assisted Imaging Method in a Laboratory-Scale Circulating Fluidized Bed

Wang

Lan

Sun

et al. 2021

Ind. Eng. Chem. Res.

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Particle clusters for FCC particles in a gas–solid circulating fluidized bed with a 12.4 m high riser and a 5 m high downer were identified from the images of the gas–solid flow by a k-means machine learning algorithm-assisted processing method. An optimal k value of 3 was determined and justified by several evaluation criteria for the k-means algorithm. The solid holdup obtained from the processed images agrees well with that from the optical fiber method. The particle cluster characteristics between the riser and downer, such as the cluster solid holdup, equivalent diameter, velocity, and frequency, were extracted from the processed images and then compared in detail for the first time. The cluster solid holdup and the cluster velocity in the riser (εcl = 0.05–0.20, V cl = 4–10 m/s) are much higher than those in the downer (εcl = 0.005–0.020, V cl = 2–5 m/s). The cluster equivalent diameter and the cluster frequency in the riser and downer are similar (d cl = 2–10 mm, f cl = 100–400 Hz). Empirical correlations of the cluster characteristics with the local flow conditions and the operating parameters in both the riser and downer are further studied.

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Experimental validation of a multiphase flow model of a lab-scale fluidized-bed gasification unit

Cited by 20 publications

References 71 publications

Bridging Scales in Bioenergy and Catalysis: A Review of Mesoscale Modeling Applications, Methods, and Future Directions

Bridging Scales in Bioenergy and Catalysis: A Review of Mesoscale Modeling Applications, Methods, and Future Directions

Simulation of Biomass Pyrolysis in a Rotary Drum by Coupling CFD-DEM with a One-Dimensional Thermally Thick Model

Cluster Identification by a k-means Algorithm-Assisted Imaging Method in a Laboratory-Scale Circulating Fluidized Bed

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