The effect of the number of impeller blades on granular flow in a bladed mixer

Boonkanokwong, Veerakiet; Remy, Brenda; Khinast, Johannes G.; Glasser, Benjamin J.

doi:10.1016/j.powtec.2016.08.064

Cited by 70 publications

(16 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After 40 h of fermentation, the eight-blade impeller was found to give the highest ethanol concentration of almost 34 g/L, followed by the four-blade impeller (30 g/L), the Rushton blade (20 g/L), and then the two-blade impeller (18 g/L). This is because of the increase in radial and axial mixing intensity as the number of pitched blades increases [20]. The ethanol concentration of the biofuel obtained in this experiment was slightly smaller than that of the fermentation of waste coke [21] and corn stover [22].…”

Section: Effect Of Operating Conditions On Bioethanol Fermentationmentioning

confidence: 68%

Simulation of Mixing Intensity Profile for Bioethanol Production via Two-Step Fermentation in an Unbaffled Agitator Reactor

2020

View full text Add to dashboard Cite

Bioethanol synthesis techniques have been studied intensively due to the energy crisis and various environmental concerns. A two-step bioethanol production process was carried out multiple times in an unbaffled agitator tank. The parameters varied, including the fermentation temperature, the pH level, the amount of yeast, and the impeller type. Then, a simulation was used to obtain an image of the agitation behavior inside the agitator tank to compare the velocity profile of each type of impeller design. The impeller with eight blades was found to produce the highest flow velocity: 0.28 m/s. The highest concentration of bioethanol generated from the fermentation was 34 g/L, which was produced by using an eight-blade impeller at 30 °C, a pH level of 5, an agitation speed of 70 rpm, and 2 wt % yeast. The two-blade impeller produced the lowest bioethanol concentration, 18 g/L, under the same conditions. Ethanol concentration was found to peak at 40 °C and a pH level of 5. The geometry of the impeller, the fermentation temperature, and the pH level were each found to have a significant effect on the resulting bioethanol concentration according to the results of an ANOVA test. The amount of yeast had no effect on the fermentation reaction. Finally, the results demonstrated the possibility of using computational fluid dynamic modeling to determine the impeller’s behavior for the development of the bioethanol fermentation process. The simulation and experimental results from this research support the scaling up of a bioethanol production facility.

show abstract

Section: Effect Of Operating Conditions On Bioethanol Fermentationmentioning

confidence: 68%

Simulation of Mixing Intensity Profile for Bioethanol Production via Two-Step Fermentation in an Unbaffled Agitator Reactor

2020

View full text Add to dashboard Cite

show abstract

“…its packing fraction decreases. This effect was first noticed by Reynolds [39] and has been reported in the literature of sheared granular media [40][41][42][43][44][45] and flow in hoppers [46][47][48][49][50][51] or silos [52]. Shear-induced dilation occurs because when a granular medium is subjected to a local shear it must expand by creating more void spaces to allow the grains to pass by each other and overcome the grains interlocking.…”

Section: Mechanics Of Powder Spreadingmentioning

confidence: 79%

A DEM study of powder spreading in additive layer manufacturing

Fouda

Bayly

2019

Granular Matter

View full text Add to dashboard Cite

In this paper, discrete element method simulations were used to study the spreading of an idealised, blade based, powder coating system representative of the spreading of spherical, mono-sized, non-cohesive titanium alloy (Ti6AlV4) particles in additive layer manufacturing applications. A vertical spreader blade was used to accelerate a powder heap across a horizontal surface, with a thin gap between the blade and the surface, resulting in the deposition of a thin powder layer. The results showed that it is inevitable to deposit a powder layer with a lower packing fraction than the initial powder heap due to three mechanisms: shear-induced dilation during the initiation of powder motion by the spreader; dilation and rearrangement due to powder motion through the gap; and the inertia of the particles in the deposited powder layer. It was shown that the process conditions control the contribution of these three mechanisms, and that the velocity profile in the shear layer in front of the gap is critical to the final deposited layer packing fraction. The higher the mean normalised velocity in the shear layer the lower the deposited layer packing fraction. The gap thickness and the spreader blade velocity affect the properties of the deposited layer; with the former increasing its packing fraction and the latter decreasing it. The analysis presented in this study could be adapted to powders of different materials, morphologies and surface properties. Keywords Additive manufacturing (AM) • Powder spreading • Discrete element method (DEM) • Dilation • Metal powders • Powder bed fusion List of symbols d Particle diameter t Time v velocity x, y, z Cartesian coordinates δ Gap thickness Δ Change in packing fraction Packing fraction Subscripts 1, 2, 3 First, second and third packing fraction reduction mechanisms, respectively back Interrogation region at the back of the spreader front Interrogation region in front of the spreader p Particle w Spreader ∞ Final

show abstract

“…As a consequence, the powder forming these vertical walls cannot be in contact with blades by slipping or shearing. Along with this phenomenon, a moving of blocs of particles in front of blades may take place, impeding the creation of a wider contact network of particles, which could exist in free-flowing systems interacting with impeller blades (Boonkanokwong et al 2016). Therefore, our measurements are in agreement with Cavinato et al, since their range of filling ratio remains relatively small (less than 0.4), and in this range, we also observed an increase of power consumption with filling ratio, which is a behavior similar to that of free-flowing material.…”

Section: The Role Of Packing State In Cohesive Powders Rheologymentioning

confidence: 99%

Analysis of powder flow and in-system rheology in a horizontal convective mixer with reclining blades

Legoix

Gatumel

Milhé

et al. 2017

Particulate Science and Technology

View full text Add to dashboard Cite

A prototypal convective mixer, designed and built for this work, allows investigating powder rheology under various geometrical configurations. The configuration chosen here is a horizontal vessel with four rectangular blades. Two blade inclinations (0-33°) and three filling ratios are studied for two powders of different kind: a free-flowing powder (semolina) and a cohesive powder (lactose). For the smaller agitation speeds, the flow regime of the powder is rolling and is characterized by surface powder avalanches. For greater agitation speeds, the flow regime is cataracting, with particle projections that follow the blade movement. These flow regimes are identified for both powders and do not depends on the filling ratio. Rheological measurements evidence that the blade inclination has little impact on the mechanical power needed to stir the free-flowing powder. It has an impact observable on cohesive powders, especially for high filling ratios. A correlation between the power number and the Froude number is established and compared to previous results obtained on a different technology. It is of the form: N p à a.F r b . The dependencies of the coefficients a and b on the powder type and on the flow regime are quantified.

show abstract

The effect of the number of impeller blades on granular flow in a bladed mixer

Cited by 70 publications

References 52 publications

Simulation of Mixing Intensity Profile for Bioethanol Production via Two-Step Fermentation in an Unbaffled Agitator Reactor

Simulation of Mixing Intensity Profile for Bioethanol Production via Two-Step Fermentation in an Unbaffled Agitator Reactor

A DEM study of powder spreading in additive layer manufacturing

Analysis of powder flow and in-system rheology in a horizontal convective mixer with reclining blades

Contact Info

Product

Resources

About