Suspending solid particles in an agitated tank with axial-type impellers

Musil, Ladislav; Vlk, J.; Jiroudková, H.

doi:10.1016/0009-2509(84)80168-2

“…Baldi et al (1978), Subbarao and Taneja (1979), Bohnet and Niesmak (1980), Einenkel (1980). Chapman et al (1983), Musil et al (1984), and Chudacek (1985) all have investigated solids suspension. These studies have been critically reviewed by Joshi et al (1982) and Gray and Oldshue (1986).…”

Section: Previous Workmentioning

confidence: 99%

Critical impeller speed for solid suspension in mechanically agitated contactors

Rao

¹

,

Rewatkar

²

,

Joshi

³

1988

View full text Add to dashboard Cite

Critical impeller speed for the suspension of solid particles, N,,, has been measured in 0.3, 0.4,0.57, 1 .O, and 1.5 m ID mechanically agitated contactors. Tap water and quartz particles (100, 340, 700, 850, 2,000 pm) were used as liquid and solid phase, respectively. The impeller speed was varied from 3.5 to 13.3 r / s and solid loading from 0 to 50 wt. YO.Three types of impellers were employed: disk turbine, pitched turbine downflow, and pitched turbine upflow. The impeller diameter to vessel diameter ratio was varied in the range 0.175 to 0.58 and the impeller blade width to impeller diameter ratio was varied in the range 0.25 to 0.4. The impeller clearance from the tank bottom was varied from 0.5 to 0.167 of tank diameter. The effect of impeller blade thickness was also studied.The pitched-blade impellers were found to be more efficient than a conventional disk turbine, and the pitched turbine downflow type was found to be more efficient than a pitched turbine upflow impeller. An attempt has been made to explain the mechanism of suspension on a rational basis and a correlation has been proposed for the estimation of Ncs that is expected to be useful in design.

show abstract

“…The criteria to explain particle distribution in the mixing tank are not clear. Musil et al (1984) came forward with a method based on variation in particle concentration close to the tank base with increase in impeller speed. This method can be used for opaque system.…”

Section: Models and Methods For Characterizing Just Suspension Speed (Njs)mentioning

confidence: 99%

Using tomography and computational fluid dynamics to study the performance of a maxblend impeller for solid-liquid mixing operations

Mishra¹

2021

Preprint

0

View full text Add to dashboard Cite

A thorough literature review suggests that no comprehensive research work has been done regarding the characterization of the local solid concentrations in a slurry reactor equipped with a Maxblend impeller. The aim of this research work was to assess the mixing performance of a Maxblend impeller in a slurry reactor through electrical resistance tomography (ERT) and computational fluid dynamics (CFD). The mixing efficiency of the Maxblend impeller for solid-liquid mixing operation was compared to those measured for the A200 (an axial-flow impeller) and the Rushton turbine (a radial-flow impeller). The tomography images were employed to assess the particles distribution inside the slurry reactor. The CFD model was created using the Eulerian and Eulerian (E-E) method, standard k-ε turbulence model, and sliding mesh (SM) technique for simulating the two-phase fluid flow, turbulence effects, and stirrer rotation, respectively. The validated CFD model was utilized to obtain the particle concentration profiles and to determine the local particle distributions attained by the Maxblend impeller. The data were utilized to analyze the impacts of various important parameters such as the agitation speed, particle concentration, particle diameter, specific gravity of the particle, and the use of baffles on the mixing efficiency of the Maxblend impeller in terms of the extent of homogeneity and mixing index. The particle distribution in the slurry reactor furnished with a Maxblend impeller was also assessed through clouding height and just suspended agitation speed approaches in this study. The results from this study showed that the assessment of the optimum impeller speed is extremely important to enhance the local mixing quality in the mixing vessel. Experimental tests demonstrated that maximum homogeneity attained by the Maxblend impeller was higher than those for the A200 and Rushton impellers.

show abstract

“…The criteria to explain particle distribution in the mixing tank are not clear. Musil et al (1984) came forward with a method based on variation in particle concentration close to the tank base with increase in impeller speed. This method can be used for opaque system.…”

Section: Models and Methods For Characterizing Just Suspension Speed (Njs)mentioning

confidence: 99%

Using tomography and computational fluid dynamics to study the performance of a maxblend impeller for solid-liquid mixing operations

Mishra¹

2021

Preprint

0

View full text Add to dashboard Cite

A thorough literature review suggests that no comprehensive research work has been done regarding the characterization of the local solid concentrations in a slurry reactor equipped with a Maxblend impeller. The aim of this research work was to assess the mixing performance of a Maxblend impeller in a slurry reactor through electrical resistance tomography (ERT) and computational fluid dynamics (CFD). The mixing efficiency of the Maxblend impeller for solid-liquid mixing operation was compared to those measured for the A200 (an axial-flow impeller) and the Rushton turbine (a radial-flow impeller). The tomography images were employed to assess the particles distribution inside the slurry reactor. The CFD model was created using the Eulerian and Eulerian (E-E) method, standard k-ε turbulence model, and sliding mesh (SM) technique for simulating the two-phase fluid flow, turbulence effects, and stirrer rotation, respectively. The validated CFD model was utilized to obtain the particle concentration profiles and to determine the local particle distributions attained by the Maxblend impeller. The data were utilized to analyze the impacts of various important parameters such as the agitation speed, particle concentration, particle diameter, specific gravity of the particle, and the use of baffles on the mixing efficiency of the Maxblend impeller in terms of the extent of homogeneity and mixing index. The particle distribution in the slurry reactor furnished with a Maxblend impeller was also assessed through clouding height and just suspended agitation speed approaches in this study. The results from this study showed that the assessment of the optimum impeller speed is extremely important to enhance the local mixing quality in the mixing vessel. Experimental tests demonstrated that maximum homogeneity attained by the Maxblend impeller was higher than those for the A200 and Rushton impellers.

show abstract

Suspending solid particles in an agitated tank with axial-type impellers

Cited by 14 publications

References 5 publications

Critical impeller speed for solid suspension in mechanically agitated contactors

Critical impeller speed for solid suspension in mechanically agitated contactors

Using tomography and computational fluid dynamics to study the performance of a maxblend impeller for solid-liquid mixing operations

Using tomography and computational fluid dynamics to study the performance of a maxblend impeller for solid-liquid mixing operations

Contact Info

Product

Resources

About