Investigation of the flow patterns and power requirements in agitated systems: effects of the design of baffles and vessel base

2020 ◽  
Vol 18 (9) ◽  
Author(s):  
Mohammed Foukrach ◽  
Houari Ameur
Keyword(s):  
Power Consumption ◽  
Power Input ◽  
Vessel Diameter ◽  
Flow Patterns ◽  
Cylindrical Vessel ◽  
Rushton Turbine ◽  
Conical Shape

AbstractThe flow patterns and power consumption of a six-blade Rushton turbine (RT) in a cylindrical vessel are characterized in this paper. We focus on the effects of the shape of the vessel base by studying two cases: a conical and a dished shape. In addition, the effects of the height of the vessel base (h2) are explored and four cases are considered, namely: h2/D = 1/10, 1/6, 1/5 and 1/3 (D: vessel diameter). In the second part of our investigation, a new design of baffles (a triangular-shaped baffle) is suggested and a comparison is made between the performance of the standard and the triangular baffles. The main findings revealed that the conical shape of the vessel base provides a slight enhancement in the axial circulation at almost the same power input for the dished bottomed vessel. For Re < 2 × 104, the power required by both types of baffles is the same; however, above this value of Re, a reduction by about 4% in power consumption is given by the standard baffles. Also, and for all shapes of baffles and vessel bases, a reduction in power consumption may be obtained by increasing the height of the vessel base.

Effects of vessel baffling on the drawdown of floating solids

2009 ◽  
Vol 63 (2) ◽  
Author(s):  
Joanna Karcz ◽  
Beata Mackiewicz
Keyword(s):  
Experimental Data ◽  
Power Consumption ◽  
Strain Gauge ◽  
High Speed ◽  
Vessel Diameter ◽  
Rushton Turbine ◽  
Agitated Vessel ◽  
Dimensionless Equation ◽  
Inner Diameter ◽  
Floating Particles

AbstractThe effects of baffling of an agitated vessel on the production of floating particles suspension are presented in this paper. Critical agitator speed, needed for particles dispersion in a liquid agitated in a vessel of the inner diameter of 0.295 m, was determined. The just drawdown agitator speeds were defined analogously to the Zwietering criterion. Specific agitation energy was calculated from the power consumption experimental data obtained by means of the strain gauge method. The experiments were carried out for twelve configurations of the baffles differing in number, length and their arrangement in the vessels. The following high-speed impellers were used: up- and downpumping six blade pitched blade turbines, Rushton turbine, and propeller. The impeller was located in the vessel in the height equal to two-thirds or one-third of the vessel diameter from the bottom of the vessel. The results were described in the form of a dimensionless equation.

scholarly journals Power Input of High-Speed Rotary Impellers

10.14311/280 ◽  
2001 ◽  
Vol 41 (6) ◽  
Author(s):  
K. R. Beshay ◽  
J. Kratěna ◽  
I. Fořt ◽  
O. Brůha
Keyword(s):  
Pitch Angle ◽  
High Speed ◽  
Power Input ◽  
Cylindrical Vessel ◽  
Turbulent Regime ◽  
Power Dependence ◽  
Rushton Turbine ◽  
Weak Influence ◽  
Turbine Impeller ◽  
Blade Pitch Angle

This paper presents the results of an experimental investigation of the power input of pitched blade impellers and standard Rushton turbine impellers in a cylindrical vessel provided with four radial baffles at its wall under a turbulent regime of flow of an agitated liquid. The influence of the geometry of the pitched blade impellers (pitch angle, number of blades) and the off-bottom impeller clearance of both high-speed impellers tested on the impeller power input is determined in two sizes of the cylindrical vessel (0.3 m and 0.8 m diameter of vessel). A strain gauge torquemeter is used in the small vessel and a phase shift mechanical torquemeter is used in the large vessel. All results of the experiments correspond to the condition that the Reynolds number modified for the impeller exceeds ten thousand. The results of this study show that the significant influence of the separating disk thickness of the turbine impeller corresponds fairly well to the empirical equations presented in the literature. Both the influence of the number of impeller blades and the blade pitch angle of the pitched blade impeller were expressed quantitatively by means of the power dependence of the recently published correlations: the higher the pitch angle and the number of blades, the higher the values of the impeller power input. Finally, it follows from results of this study that the impeller off-bottom clearance has a weak influence on the power input of the Rushton turbine impeller, but with decreasing impeller off-bottom clearance the power input of the pitched blade impeller increases significantly.

scholarly journals Effect of impeller blade curvature on the hydrodynamics and power consumption in a stirred tank

2020 ◽  
Vol 26 (3) ◽  
pp. 259-266
Author(s):  
Mohammed Foukrach ◽  
Houari Ameur
Keyword(s):  
Power Consumption ◽  
Power Input ◽  
Stirred Tank ◽  
Impeller Blade ◽  
Blade Height ◽  
Rushton Turbine ◽  
Turbulent Flow Regime ◽  
Axial Movement ◽  
Computational Fluid Dynamics Cfd ◽  
Cylindrical Tanks

The performance of curved bladed turbines (CBTs) for the agitation of Newtonian fluids in cylindrical tanks is investigated. The efficiency of CBT is compared with that of the standard Rushton turbine. Also, effects of the blade height of the new designed impeller are highlighted. The computational fluid dynamics (CFD) study is performed to observe the axial, radial and tangential components of velocities, flow patterns and power consumption. The obtained results revealed that the increase of blade curvature reduces the power consumption. Also, a slight decrease of power number is observed in the turbulent flow regime within unbaffled tanks. In a comparison between the cases studied, the best axial circulation of fluid is given by the impeller with flat blades. The increase of the height of curved blades has generated a stronger tangential flow and enhanced the axial movement of fluid particles, but with further penalty in power input.

Effect of Baffle Length on Power Consumption in Turbulent Mixing Vessel with Rushton Turbine Impeller

2011 ◽  
Vol 37 (2) ◽  
pp. 147-149 ◽  
Author(s):  
Yoshihito Kato ◽  
Noboru Kamei ◽  
Yutaka Tada ◽  
Azusa Nakaoka ◽  
Yuichiro Nagatsu ◽  
...  
Keyword(s):  
Power Consumption ◽  
Turbulent Mixing ◽  
Rushton Turbine ◽  
Turbine Impeller

scholarly journals Study of Pumping Capacity of Pitched Blade Impellers

10.14311/380 ◽  
2002 ◽  
Vol 42 (4) ◽  
Author(s):  
I. Fořt ◽  
T. Jirout ◽  
R. Sperling ◽  
S. Jambere ◽  
F. Rieger
Keyword(s):  
Laser Doppler Anemometry ◽  
Radial Profile ◽  
Axial Flow ◽  
Power Input ◽  
Vessel Diameter ◽  
Energetic Efficiency ◽  
Turbulent Regime ◽  
Flat Bottom ◽  
Mean Velocity ◽  
Liquid Suspensions

A study was made of the pumping capacity of pitched blade impellers in a cylindrical pilot plant vessel with four standard radial baffles at the wall under a turbulent regime of flow. The pumping capacity was calculated from the radial profile of the axial flow, under the assumption of axial symmetry of the discharge flow. The mean velocity was measured using laser Doppler anemometry in a transparent vessel of diameter T = 400 mm, provided with a standard dished bottom. Three and six blade pitched blade impellers (the pitch angle varied within the interval a Îá24°; 45°ń) of impeller/vessel diameter ratio D/T = 0.36, as well as a three blade pitched blade impeller with folded blades of the same diameter, were tested. The calculated results were compared with the results of experiments mentioned in the literature, above all in cylindrical vessels with a flat bottom. Both arrangements of the agitated system were described by the impeller energetic efficiency, i.e, a criterion including in dimensionless form both the impeller energy consumption (impeller power input) and the impeller pumping effect (impeller pumping capacity). It follows from the results obtained with various geometrical configurations that the energetic efficiency of pitched blade impellers is significantly lower for configurations suitable for mixing solid-liquid suspensions (low impeller off bottom clearances) than for blending miscible liquids in mixing (higher impeller off bottom clearances).

Scale process effect on the power consumption characteristics of a novel curved Rushton turbine within a reactor vessel

2021 ◽  
Vol 166 ◽  
pp. 109-120
Author(s):  
Ning Qiu ◽  
Peng Wang ◽  
Qiaorui Si ◽  
Willy E.K. Pettang ◽  
Shouqi Yuan
Keyword(s):  
Power Consumption ◽  
Reactor Vessel ◽  
Rushton Turbine

scholarly journals CFD simulation of flow patterns in unbaffled stirred tank with CD-6 impeller

2012 ◽  
Vol 18 (4-1) ◽  
pp. 535-546 ◽  
Author(s):  
Tamphasana Devi ◽  
Bimlesh Kumar
Keyword(s):  
Numerical Simulations ◽  
Cfd Simulation ◽  
Flow Patterns ◽  
Industrial Applications ◽  
Spatial Variations ◽  
Stirred Tank ◽  
Rushton Turbine ◽  
Stirred Vessels

Understanding the flow in stirred vessels can be useful for a wide number of industrial applications. There is a wealth of numerical simulations of stirring vessels with standard impeller such as Rushton turbine and pitch blade turbine. Here, a CFD study has been performed to observe the spatial variations (angular, axial and radial) of hydrodynamics (velocity and turbulence field) in unbaffled stirred tank with Concave-bladed Disc turbine (CD-6) impeller. Three speeds (N=296, 638 & 844.6 rpm) have been considered for this study. The angular variations of hydrodynamics of stirred tank were found very less as compared to axial and radial variations.

Comments on "Experimental Studies and CFD Modeling on the Effects of a Cut in the Baffle on Power Consumption"

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
Ivan Fort
Keyword(s):  
Power Consumption ◽  
Cfd Simulation ◽  
Experimental Studies ◽  
Power Input ◽  
Cfd Modeling ◽  
Turbulent Regime

Critical comments on results of the CFD simulation of the impeller power input in a cylindrical baffled vessel under turbulent regime of flow of agitated liquid.

scholarly journals The Effect of Experimental Conditions on Methane (95%)–Propane (5%) Hydrate Formation

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6710
Author(s):  
Sotirios Nik. Longinos ◽  
Mahmut Parlaktuna
Keyword(s):  
Power Consumption ◽  
Separation Factor ◽  
Induction Time ◽  
Hydrate Formation ◽  
Equilibrium Line ◽  
General View ◽  
Experimental Conditions ◽  
Rushton Turbine ◽  
Pitched Blade Turbine

In the present study, the effect of different kinds of impellers with different baffles or no baffle was investigated. Up-pumping pitched blade turbine (PBTU) and Rushton turbine (RT) were the two types of impellers tested. The reactor was equipped with different designs of baffles: full, half and surface baffles or no baffles. Single (PBTU or RT) and dual (PBTU/PBTU or RT/RT) use of impellers with full (FB), half (HB), surface (SB) and no baffle (NB) combinations formed two sets of 16 experiments. There was estimation of rate of hydrate formation, induction time, hydrate productivity, overall power consumption, split fraction and separation factor. In both single and dual impellers, the results showed that RT experiments are better compared to PBTU in rate of hydrate formation. The induction time is almost the same since we are deep in the equilibrium line while hydrate productivity values are higher in PBTU compared to RT experiments. As general view RT experiments consume more energy compared to PBTU experiments.

Limitations on locomotor performance in squid

1988 ◽  
Vol 64 (1) ◽  
pp. 128-134 ◽  
Author(s):  
R. K. O'Dor
Keyword(s):  
Power Consumption ◽  
Power Output ◽  
Striated Muscle ◽  
Anaerobic Power ◽  
Power Input ◽  
Limited Capacity ◽  
Striated Muscles ◽  
Additional Energy ◽  
Flow Power ◽  
Aerobic And Anaerobic

An empirical equation relating O2 consumption (power input) to pressure production during jet-propelled swimming in the squid (Illex illecebrosus) is compared with hydrodynamic estimates of the pressure-flow power output also calculated from pressure data. Resulting estimates of efficiency and stress indicate that the circularly arranged obliquely striated muscles in squid mantle produce maximum tensions about half those of vertebrate cross-striated muscle, that "anaerobic" fibers contribute to aerobic swimming, and that peak pressure production requires an instantaneous power output higher than is thought possible for muscle. Radial muscles probably contribute additional energy via elastic storage in circular collagen fibers. Although higher rates of aerobic power consumption are only found in terrestrial animals at much higher temperatures, the constraint on squid performance is circulation, not ventilation. Anaerobic power consumption is also among the highest ever measured, but the division of labor between "aerobic" and "anaerobic" fibers suggests a system designed to optimize the limited capacity of the circulation.

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