Flowability characterization of torrefied biomass powders: Static and dynamic testing

Pachón‐Morales, John; Colin, Julien; Casalinho, Joël; Perré, Patrick; Puel, François

doi:10.1016/j.biombioe.2020.105608

Cited by 10 publications

(9 citation statements)

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“…For all three materials, there is a systematic bias when comparing to a linear trend, and the measured cohesion appears to have a power law or exponential-type growth with increasing pre-shear stress. The flowability of the powder is qualitatively interpreted through the ratio of the major principal stress to the unconfined yield strength, where higher values indicate more free-flowing solids (Dietmar, 2008;Miccio et al, 2011;Pachón-Morales et al, 2020). The highest flowability was measured in the largest particle size, while the lowest was in the small particles, while the distribution has a value closer to the smaller particles than the large (i.e., the sample flowability is given by S4 > S6 >~S2).…”

Section: Schulze Ring Shear Testermentioning

confidence: 99%

“…Typically, granular tests preformat the granular solids to yield a given internal stress and particle packing (void volume) configuration. By preformatting the material over a range of internal stresses and measuring the force required to initiate motion, one can characterize apparent internal friction, bulk cohesion, and the unconfined yield strength and major principal stresses through a Mohr's circle analysis (Comanici and Barsanescu, 2018;Westover and Hartley, 2018;Pachón-Morales et al, 2020). Compared to granular testers, rheometers are more common due to their ease of use and ability to quantify the shear behavior of both viscous fluids and semi-solid materials (such as yield stress fluids).…”

Section: Introductionmentioning

confidence: 99%

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Multiscale Shear Properties and Flow Performance of Milled Woody Biomass

et al. 2022

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One dominant challenge facing the development of biorefineries is achieving consistent system throughput with highly variant biomass feedstock quality and handling performance. Current handling unit operations are adapted from other sectors (primarily agriculture), where some simplifying assumptions about granular mechanics and flow performance do not translate well to a highly compressible and anisotropic material with nonlinear time- and stress-dependent properties. This work explores the shear and frictional properties of loblolly pine at multiple experimental test apparatus and particle scales to elucidate a property window that defines the shear behavior over a range of material attributes (particle size, size distribution, moisture content, etc.). In general, it was observed that the bulk internal friction and apparent cohesion depend strongly on both the stress state of the sample in granular shear testers and the overall particle size and distribution span. For equipment designed to characterize the quasi-static shear stress failure of bulk materials ranging from 50 to 1,000 ml in test volume, similar test results were observed for finely milled particles (50% passing size of 1.4 mm) with a narrow size distribution (span between 10 and 90% passing size of 0.9 mm), while stress chaining and over-torque issues persisted for the bench-scale test apparatus for larger particle sizes or widely dispersed sample sizes. Measurement of the anisotropic particle–particle friction ranged from coefficients of approximately 0.20 to 0.45 and resulted in significantly higher and more variable friction measurements for larger particle sizes and in perpendicular alignment orientations. To supplement these laboratory-scale properties, this work explores the flow of loblolly pine and Douglas fir through a pilot-scale wedge-shaped hopper and a screw feeder. For the gravity-driven hopper flow, the critical arching distance and mass discharge rate ranged from approximately 10 to 30 mm and 2 to 16 tons/hour, respectively, for both materials, where the arching distance depends strongly on the overall particle size and depends less on the hopper inclination angle. Comparatively, the auger feeder was found to be much more impacted by the size of the particles, where smaller particles had a more consistent and stable flow while consuming less power.

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Section: Schulze Ring Shear Testermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multiscale Shear Properties and Flow Performance of Milled Woody Biomass

et al. 2022

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“…Intensively torrefied samples were less prone to flow in terms of event frequency, followed by the mildly torrefied sample, the raw sample and finally the non-cohesive glass beads. A comprehensive critical analysis on the use of the f parameter as indicator of flowability has been made in previous research [91]. The identification of the type of events is also important to conclude on flowability when using this indicator.…”

Section: Experiments Dem Simulationsmentioning

confidence: 99%

Potential of DEM for investigation of non-consolidated flow of cohesive and elongated biomass particles

Pachón‐Morales

Perré

Casalinho

et al. 2020

Advanced Powder Technology

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The evaluation of the flow properties of biomass powders is essential for the design of handling systems within a thermochemical valorization context. The Discrete Element Method (DEM) is a valuable tool for simulating the bulk behavior of granular materials that has rarely been used for biomass feedstocks. This work focuses on the numerical investigation of the flow of raw and torrefied biomass particles in a loose and dynamic conditioning using a rotating drum. The relevance of DEM parameters calibrated using bulk experiments (angle-of-repose, bulk density, retainment ratio) is tested by comparison with experimental data obtained using a rotating drum system. The calibrated DEM material model considers the elongated, submillimetric and cohesive nature of the biomass powder. Several flowability descriptors (Upper Angle of Stability, size of avalanches, fraction of revolution to trigger events and irregularity of the free surface) are evaluated using both experimental data and DEM simulations. DEM results reproduced well the experimental trends and distinguished between the different cohesive extent of the samples. DEM is therefore a relevant technique for assessing flowability of biomass powders in a non-consolidated dynamic flow. This paves the way for investigating the effects of particle characteristics on bulk flow, which are briefly discussed.

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“…A number of attempts have been made to numerically simulate such a flow [14][15][16][17]. Further development of biotechnology has increased interest in experimental and numerous studies of avalanche motion in a rotating chamber of granular biomass [18][19][20]. However, the results obtained relate only to flows of single-fraction granular loading, mainly at slow rotation of the chamber and low Froude numbers Fr<<1.…”

Section: Introductionmentioning

confidence: 99%

The effect of the filling degree of the tumbling mill chamber on the bifurcation value of the froude number

Deineka¹,

Naumenko²,

Myronenko³

2021

TT: PhE

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The influence of the filling degree of the drum chamber on the bifurcation value of the Froude number in the case of self-excitation of self-oscillations of a two-fraction granular charge with a minimum swing is considered. Such a pulsating mode of the charge movement is used in the self-oscillating grinding process in a tumbling mill. The coarse fraction that simulated the milling bodies consisted of spherical particles of an incoherent granular material with a relative size in the chamber ψb=0.00733. The fine fraction, simulating the material to be ground, was cement with a relative particle size ψm≈0.092∙10-3. The value of the adopted analogue of the kinematic viscosity of the two-fraction granular loading approached the value of 10-3 m2/s. The main variable factor in experimental studies was the filling degree of the drum chamber with loading at rest κb=0.25, 0.35, and 0.45. An additional factor was the degree of filling the gaps between the spherical particles of the coarse fraction with particles of the fine fraction κb=0, 0.25, 0.5, and 1. The method of visual analysis through the transparent end wall of the chamber of transient processes of the loading behavior with a smooth change and fixation of the velocity was applied. The bifurcation minimum value of the rotation speed was recorded, at which the steady-state circulation mode of the load movement turns into a transient pulsation one with a minimum swing. A decrease in the bifurcation values of the Froude number Frb on the cylindrical surface of the chamber with an increase in κb has been established. An increase in the intensity of the decrease in Frb with an increase in κm was revealed. The recorded effect is due to an increase in the connected properties of a two-fraction loading during self-excitation of self-excited oscillations with an increase in κb and κm. The numerical values of the boundaries of the range of bifurcation values of the Froude number for a tumbling mill Frb=0.0484–1.17 have been determined. The obtained Frb range corresponds to the Reynolds value in the range Re=40–197. The maximum Frb value is obtained with coarse grinding. An increase in the likelihood of self-excitation of self-oscillations of the intra-chamber loading with a decrease in the fineness of grinding was revealed

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Flowability characterization of torrefied biomass powders: Static and dynamic testing

Cited by 10 publications

References 50 publications

Multiscale Shear Properties and Flow Performance of Milled Woody Biomass

Multiscale Shear Properties and Flow Performance of Milled Woody Biomass

Potential of DEM for investigation of non-consolidated flow of cohesive and elongated biomass particles

The effect of the filling degree of the tumbling mill chamber on the bifurcation value of the froude number

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