Impeller Speed

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Jacob A. Moulijn - One of the best experts on this subject based on the ideXlab platform.

  • Gas−Liquid Mass Transfer in Benchscale Stirred TanksFluid Properties and Critical Impeller Speed for Gas Induction
    Industrial & Engineering Chemistry Research, 2006
    Co-Authors: Martinus Mathilda Pieter Zieverink, Michiel T. Kreutzer, Freek Kapteijn, Jacob A. Moulijn
    Abstract:

    This work is concerned with the gas−liquid mass transfer in stirred tanks with gas-inducing Impellers. Experiments were performed to determine the critical Impeller Speed for the onset of gas induction and the mass-transfer group kLa, using water, n-hexadecane, toluene, acetone, and sunflower oil at various temperatures as liquids and hydrogen and nitrogen as gases. The use of different liquids and gases allowed the influence of fluid properties on the mass transfer to be studied. Special emphasis is on reducing the experimental effort in downscaling, i.e., the use of benchscale autoclaves to mimic industrial conditions. In benchscale tanks, the capillary pressure is significant, with respect to the static liquid pressure at the Impeller, and must be taken into account to describe the critical Impeller Speed for gas induction. Downscaling implies relatively low mass-transfer rates, which can be achieved by operating close to the critical Impeller Speed. The critical Impeller Speed must be included in mode...

  • gas liquid mass transfer in benchscale stirred tanksfluid properties and critical Impeller Speed for gas induction
    Industrial & Engineering Chemistry Research, 2006
    Co-Authors: Martinus Mathilda Pieter Zieverink, Michiel T. Kreutzer, Freek Kapteijn, Jacob A. Moulijn
    Abstract:

    This work is concerned with the gas−liquid mass transfer in stirred tanks with gas-inducing Impellers. Experiments were performed to determine the critical Impeller Speed for the onset of gas induction and the mass-transfer group kLa, using water, n-hexadecane, toluene, acetone, and sunflower oil at various temperatures as liquids and hydrogen and nitrogen as gases. The use of different liquids and gases allowed the influence of fluid properties on the mass transfer to be studied. Special emphasis is on reducing the experimental effort in downscaling, i.e., the use of benchscale autoclaves to mimic industrial conditions. In benchscale tanks, the capillary pressure is significant, with respect to the static liquid pressure at the Impeller, and must be taken into account to describe the critical Impeller Speed for gas induction. Downscaling implies relatively low mass-transfer rates, which can be achieved by operating close to the critical Impeller Speed. The critical Impeller Speed must be included in mode...

  • Critical Impeller Speed (NSG) for solid suspension in sparged stirred vessels fitted with helical coils
    Industrial & Engineering Chemistry Research, 2005
    Co-Authors: Bhaurao P. Nikhade, Jacob A. Moulijn, Vishwas G. Pangarkar
    Abstract:

    An attempt has been made to investigate the effect of the presence of a helical coil, used in specific cases to increase the heat-transfer rate, on the critical Impeller Speed (NSG) for a solid sus...

Martinus Mathilda Pieter Zieverink - One of the best experts on this subject based on the ideXlab platform.

  • Gas−Liquid Mass Transfer in Benchscale Stirred TanksFluid Properties and Critical Impeller Speed for Gas Induction
    Industrial & Engineering Chemistry Research, 2006
    Co-Authors: Martinus Mathilda Pieter Zieverink, Michiel T. Kreutzer, Freek Kapteijn, Jacob A. Moulijn
    Abstract:

    This work is concerned with the gas−liquid mass transfer in stirred tanks with gas-inducing Impellers. Experiments were performed to determine the critical Impeller Speed for the onset of gas induction and the mass-transfer group kLa, using water, n-hexadecane, toluene, acetone, and sunflower oil at various temperatures as liquids and hydrogen and nitrogen as gases. The use of different liquids and gases allowed the influence of fluid properties on the mass transfer to be studied. Special emphasis is on reducing the experimental effort in downscaling, i.e., the use of benchscale autoclaves to mimic industrial conditions. In benchscale tanks, the capillary pressure is significant, with respect to the static liquid pressure at the Impeller, and must be taken into account to describe the critical Impeller Speed for gas induction. Downscaling implies relatively low mass-transfer rates, which can be achieved by operating close to the critical Impeller Speed. The critical Impeller Speed must be included in mode...

  • gas liquid mass transfer in benchscale stirred tanksfluid properties and critical Impeller Speed for gas induction
    Industrial & Engineering Chemistry Research, 2006
    Co-Authors: Martinus Mathilda Pieter Zieverink, Michiel T. Kreutzer, Freek Kapteijn, Jacob A. Moulijn
    Abstract:

    This work is concerned with the gas−liquid mass transfer in stirred tanks with gas-inducing Impellers. Experiments were performed to determine the critical Impeller Speed for the onset of gas induction and the mass-transfer group kLa, using water, n-hexadecane, toluene, acetone, and sunflower oil at various temperatures as liquids and hydrogen and nitrogen as gases. The use of different liquids and gases allowed the influence of fluid properties on the mass transfer to be studied. Special emphasis is on reducing the experimental effort in downscaling, i.e., the use of benchscale autoclaves to mimic industrial conditions. In benchscale tanks, the capillary pressure is significant, with respect to the static liquid pressure at the Impeller, and must be taken into account to describe the critical Impeller Speed for gas induction. Downscaling implies relatively low mass-transfer rates, which can be achieved by operating close to the critical Impeller Speed. The critical Impeller Speed must be included in mode...

Jyeshtharaj B. Joshi - One of the best experts on this subject based on the ideXlab platform.

  • CFD simulations of gas-liquid-solid stirred reactor: prediction of critical Impeller Speed for solid suspension
    Chemical Engineering Science, 2007
    Co-Authors: B. N. Murthy, R.s. Ghadge, Jyeshtharaj B. Joshi
    Abstract:

    In this work, simulations have been performed for three phase stirred dispersions using computational fluid dynamics model (CFD). The effects of tank diameter, Impeller diameter, Impeller design, Impeller location, Impeller Speed, particle size, solid loading and superficial gas velocity have been investigated over a wide range. The Eulerian multi-fluid model has been employed along with the standard k-e turbulence model to simulate the gas-liquid, solid-liquid and gas-liquid-solid flows in a stirred tank. A multiple reference frame (MRF) approach was used to model the Impeller rotation and for this purpose a commercial CFD code, FLUENT 6.2. Prior to the simulation of three phase dispersions, simulations were performed for the two extreme cases of gas-liquid and solid-liquid dispersions and the predictions have been compared with the experimental velocity and hold-up profiles. The three phase CFD predictions have been compared with the experimental data of Chapman et al. [1983. Particle-gas-liquid mixing in stirred vessels, part III: three phase mixing. Chemical Engineering Research and Design 60, 167-181], Rewatkar et al. [1991. Critical Impeller Speed for solid suspension in mechanical agitated three-phase reactors. 1. Experimental part. Industrial and Engineering Chemistry Research 30, 1770-1784] and Zhu and Wu [2002. Critical Impeller Speed for suspending solids in aerated agitation tanks. The Canadian Journal of Chemical Engineering 80, 1-6] to understand the distribution of solids over a wide range of solid loading (0.34-15 wt%), for different Impeller designs (Rushton turbine (RT), pitched blade down and upflow turbines (PBT45)), solid particle sizes (120-1000 μm) and for various superficial gas velocities (0-10 mm/s). It has been observed that the CFD model could well predict the critical Impeller Speed over these design and operating conditions.

  • Critical Impeller Speed for solid suspension in gas inducing type mechanically agitated contactors
    Canadian Journal of Chemical Engineering, 1997
    Co-Authors: K. Saravanan, A.w. Patwardhan, Jyeshtharaj B. Joshi
    Abstract:

    Critical Impeller Speed for solid suspension (NCS), has been measured in gas inducing mechanically agitated contactors (GIMAC) fitted with two Impellers. Five different Impeller designs were employed. It was found that the multiple Impeller system having both pitched blade downflow turbines was the most energy efficient for the suspension of solid particles. The interImpeller clearance (C3), and the Impeller bottom clearance (C1) were found to be important parameters. Further, for this optimum combination, the design of the lower Impeller was optimized in terms of Impeller diameter (D), blade width (W), blade angle (A), and the number of blades (nb). An empirical model has been proposed based on the mechanism of fluidization. La vitesse de turbine critique pour la suspension des solides (NCS) a ete mesuree dans des contacteurs agites mecaniques a induction de gaz (GIMAC). Cinq turbines differentes ont ete employees. On a trouve que le systeme ayant des turbines a pales inclinees a ecoulement descendant etait le plus efficace du point de vue energetique pour la suspension de particules solides. La distance entre les turbines (C3) et le degagement sous la turbine (C1) se sont averes des parametres importants. En outre, pour cette combinaison optimale, la conception de la turbine inferieure a ete optimisee en termes de diametre de turbine (D), de largeur des pales (W), d'angle des pales (A) et de nombre de pales (nb). On propose un modele empirique base sur le mecanisme de fluidisation.

  • Effect of addition of alcohol on the design parameters of mechanically agitated three-phase reactors
    Chemical Engineering Journal, 1992
    Co-Authors: V. B. Rewatkar, Jyeshtharaj B. Joshi
    Abstract:

    Abstract The effect of the presence of isopropyl alcohol on the design parameters of gas-liquid-solid systems has been studied in a vessel with an internal diameter of 0.57 m. A pitched blade downflow turbine was used as an Impeller. Isopropyl alcohol concentration was varied from 0 to 2 vol.%. Air and quartz particles of 2000 μm in size were used as the gas and solid phase, respectively. The solid loading (X) was varied from 0 to 15 wt.%. The Impeller Speed and superficial gas velocity were varied in the range of 2.4 to 10 rev s−1 and 0 to 9.4 mm s−1 respectively. The variations of power number and mixing time with respect to Impeller Speed were found to be similar. The effect of isopropanol concentration on the power consumption, liquid phase mixing time, critical Impeller Speed for gas dispersion, critical Impeller Speed for solid suspension and fractional gas hold up have been studied.

  • Critical Impeller Speed for solid suspension in mechanically agitated three-phase reactors. 1. Experimental part
    Industrial & Engineering Chemistry Research, 1991
    Co-Authors: V. B. Rewatkar, K. S. M. S. Raghava Rao, Jyeshtharaj B. Joshi
    Abstract:

    The critical Impeller Speed for suspension of solid particles has been measured in mechanically agitated three-phase contactors of 0.57-, 1.0-, and 1.5-m i.d. Tap water and quartz particles were used as the liquid and solid phases, respectively. Air was used as the gas phase. The Impeller Speed was varied from 0.5 to 13.33 revolutions/s. The superficial gas velocity and solid loading were varied in the ranges 0-32 mm/s and 0.34-50% w/w, respectively. Three types of Impellers, namely, disk turbine (DT), pitched turbine downflow (PTD), and pitched turbine upflow (PTU) were employed

Vishwas G. Pangarkar - One of the best experts on this subject based on the ideXlab platform.

  • Critical Impeller Speed (NSG) for solid suspension in sparged stirred vessels fitted with helical coils
    Industrial & Engineering Chemistry Research, 2005
    Co-Authors: Bhaurao P. Nikhade, Jacob A. Moulijn, Vishwas G. Pangarkar
    Abstract:

    An attempt has been made to investigate the effect of the presence of a helical coil, used in specific cases to increase the heat-transfer rate, on the critical Impeller Speed (NSG) for a solid sus...

  • CRITICAL Impeller Speed FOR SOLID SUSPENSION IN MULTI-Impeller AGITATED CONTACTORS: SOLID-LIQUID SYSTEM
    Chemical Engineering Communications, 1995
    Co-Authors: N. N. Dutta, Vishwas G. Pangarkar
    Abstract:

    Abstract The critical Impeller Speed for suspension of solid particles (N js ) has been measured in multi-Impeller mechanically agitated contactors of 0.15 and 0.30m id and 1.0 m height. Three types of Impellers, i.e. disk turbine (DT), pitched turbine downflow(PTD) and pitched turbine upflow(PTU) were used. The number of Impellers used in the 0.3 m and 0.15 m id reactors were three and four, respectively. The distance maintained between two Impellers was equivalent lo the tank diameter. The effect of Impeller type and diameter, particle size and loading, and clearance of the bottom Impeller from the reactor bottom was studied and results compared with those of single Impeller agitated contactors. PTD Impeller was found to be more efficient for solid suspension. The N js values obtained in reactors with multiple Impeller are essentially the same as those observed in single Impeller reactor and the bottom Impeller plays dominant role in determining the N js , values. An empirical correlation has been propo...

  • Critical Impeller Speed for solid suspension in multi‐Impeller three phase agitated contactors
    Canadian Journal of Chemical Engineering, 1995
    Co-Authors: N. N. Dutta, Vishwas G. Pangarkar
    Abstract:

    The critical Impeller Speed for solid suspension in gas-liquid-solid systems has been measured in multi-Impeller agitated contractors of 0.15 and 0.30 m and ID and 1.0 m height. Three types of Impellers, i.e. disk turbine (DT), pitched turbine downflow (PTD) and pitched turbine upflow (PTU) were used. Air, deionised water and sand particles were used as the gas, liquid and solid phases, respectively. The superficial gas velocity and solid loading were varied in the ranges 0–15 mm/s and 0.5 to 10% w/w, respectively. The effects of Impeller type and its diameter, particle size and loading and gas flow rate were studied. Some measurements of gas hold-up and mixing time were also made in order to get some insight of the hydrodynamic behaviour of the reactor. The critical Impeller Speed for solid suspension in the presence of gas (nisg) was found to be more than that in the absence of the gas and the increase of critical Speed correlated well with the gas flow rate. The influence of particle—liquid parameters on solid suspension Speed in the gassed system was similar to but relatively weaker than that in the ungassed condition.

  • critical Impeller Speed for solid suspension in multi Impeller three phase agitated contactors
    Canadian Journal of Chemical Engineering, 1995
    Co-Authors: N. N. Dutta, Vishwas G. Pangarkar
    Abstract:

    The critical Impeller Speed for solid suspension in gas-liquid-solid systems has been measured in multi-Impeller agitated contractors of 0.15 and 0.30 m and ID and 1.0 m height. Three types of Impellers, i.e. disk turbine (DT), pitched turbine downflow (PTD) and pitched turbine upflow (PTU) were used. Air, deionised water and sand particles were used as the gas, liquid and solid phases, respectively. The superficial gas velocity and solid loading were varied in the ranges 0–15 mm/s and 0.5 to 10% w/w, respectively. The effects of Impeller type and its diameter, particle size and loading and gas flow rate were studied. Some measurements of gas hold-up and mixing time were also made in order to get some insight of the hydrodynamic behaviour of the reactor. The critical Impeller Speed for solid suspension in the presence of gas (nisg) was found to be more than that in the absence of the gas and the increase of critical Speed correlated well with the gas flow rate. The influence of particle—liquid parameters on solid suspension Speed in the gassed system was similar to but relatively weaker than that in the ungassed condition.

Peter Kleinebudde - One of the best experts on this subject based on the ideXlab platform.

  • Is the adjustment of the Impeller Speed a reliable attempt to influence granule size in continuous dry granulation
    Advanced Powder Technology, 2018
    Co-Authors: Haress Mangal, Peter Kleinebudde
    Abstract:

    Abstract As the field of continuous manufacturing of solid pharmaceutics is developing, the interest in implementing continuous granulation methods is growing. Process analytical technology tools should be integrated to ensure the monitoring of the product quality and therefore enforce control strategies. Three single materials which are often used in dry granulation and additionally two formulations, one containing ibuprofen and the other acetaminophen were processed at various process parameters. They all differed in their compaction and fracture behavior. A statistical analysis of the influence of process parameters was executed, to work out which parameters could be used for a granule size control approach in continuous dry granulation. Thereby, the specific compaction force and the Impeller Speed were found to be significant factors in each design of experiment. However, the Impeller Speed was evaluated as the only suitable parameter to control granule size, as an impact on granule density is unlikely. Nevertheless, some restrictions such as an upper Impeller Speed limitation to avoid excessive fines and a lower Speed limitation to impede a downturn of the throughput, have to be considered. Furthermore, a decreasing median granule size was observed at higher throughputs for plastically deforming materials and formulations.

  • Melt pelletisation of a hygroscopic drug in a high shear mixer ☆: Part 2. Mutual compensation of influence variables
    European Journal of Pharmaceutical Sciences, 2000
    Co-Authors: R Thies, Peter Kleinebudde
    Abstract:

    The process of melt pelletisation in a Diosna P10 high shear mixer was examined for sodium valproate and glycerol monostearate. The effects of binder concentration, Impeller Speed and massing time on mean granule size, size distribution and liquid saturation were investigated. Spherical pellets of almost similar size and size distribution were obtained after 20 min of massing time, with a binder content from 3.1 to 14.1% w/w by adjusting the Impeller Speed. Granule growth was observed at low levels of binder concentration and liquid saturation (

  • Melt pelletisation of a hygroscopic drug in a high shear mixer: Part 2. Mutual compensation of influence variables
    European Journal of Pharmaceutical Sciences, 2000
    Co-Authors: R Thies, Peter Kleinebudde
    Abstract:

    The process of melt pelletisation in a Diosna P10 high shear mixer was examined for sodium valproate and glycerol monostearate. The effects of binder concentration, Impeller Speed and massing time on mean granule size, size distribution and liquid saturation were investigated. Spherical pellets of almost similar size and size distribution were obtained after 20 min of massing time, with a binder content from 3.1 to 14.1% w/w by adjusting the Impeller Speed. Granule growth was observed at low levels of binder concentration and liquid saturation (