Multiple reference frame (MRF), computational fluid dynamics, Euler multiphase flow model and standard K- ε turbulence model were used to investigate the …
Brewing fermentations have traditionally been undertaken without the use of mechanical agitation, with mixing being provided only by the fluid motion induced by the CO2 evolved during the batch process. This approach has largely been maintained because of the belief in industry that rotating agitators would damage the yeast. Recent studies …
Summary. Stirred tank reactors are widely used in the chemical and allied industries. They offer excellent flexibility in meeting varying demands of a reaction. The …
Abstract. In this work, suspension of high-concentration slurry in the presence of gas was investigated using different baffling configurations, particle sizes, …
The aim of this paper is to study the effect of agitator's types on the turbulent flows in stirred tanks without and with baffles. The hydrodynamics behavior induced by four different agitator's types: a Rushton turbine (RT), a circular blade turbine (CBT), a diverging triangular blade turbine (DTBT) and converging triangular blade turbine (CTBT) are …
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44(12), 2781–2796 ... E.U. Nagamine, Effect of low off-bottom impeller clearance on the minimum agitation speed for complete suspension of solids in stirred …
The parity plot (Figure 13a) of the proposed equation (eq 5 using parameters in the column "DT" of Table 7) for the DT impeller has a much smaller spread (R 2 = 0.86) compared to the parity plot ...
By using mixing intensification involving high solids concentration as a means to achieve process intensification for the mineral process industry is discussed here. Improving agitator energy efficiency is essential for operating at high solids concentrations. It is shown that improved agitator energy efficiency can be achieved by removing baffles …
In high solid loading stirred tank, accumulation of solid in the bottom of the tank makes it difficult to achieve efficient mixing. ... C D = 24 α l Re s 1 + 0.15 α l Re s 0.687, Re s < 1000 0.44, Re s > 1000 where Re s is the Reynolds number. ... High solids concentration agitation for minerals process intensification. AIChE J., 57 (9) (2011 ...
The pulp that fully stirred by high-efficiency agitation tank is subjected to a flotation process of one roughing + two beneficiation + three sweeps to obtain qualified concentrate. (5) Morocco 500TPD silver processing plant ... and the slurry is fed into the high-concentration agitation tank for stirring, and then enters the grinding and ...
The solids concentration profiles in a slurry mixing tank with mechanical agitation have been measured by using a photo-electric method. The concentration profile has been explained by the sedimentation-dispersion model in which the slurry flow in a stirred tank with a flat-disk turbine or a marine propeller is assumed to be dominated …
Improving agitator energy efficiency is essential for operating at high solids concentrations. It is shown that improved agitator energy efficiency can be achieved by removing baffles and using higher power number impellers at high solids loadings. Power consumption (50–80%) reductions were demonstrated in the experiments.
Solid suspension and gas dispersion in gas-solid-liquid stirred vessels with high solid concentration / Meysam Davoody. Mechanically agitated vessels are used …
Abstract. By using mixing intensification involving high solids concentration as a means to achieve process intensification for the mineral process industry is …
agitators with shorter blades are used at high speeds for liquids with a very wide range of viscosities. Normally, the turbines have four or six blades. Various types of paddle agitators are often used at low speeds between about 20 and 200 rpm. At low speeds mild agitation is obtained in an unbaffled vessel. At higher speeds baffles are
Njs, the minimum agitation speed to just suspend dispersed solids in stirred liquids is commonly measured experimentally using the visual method, consisting of determining the agitation speed N at ...
Semantic Scholar extracted view of "Reconstitution of dairy powders to high solids content in a stirred-tank: the effect of agitation." ..., title={Reconstitution of dairy powders to high solids content in a stirred-tank: the effect of agitation.}, author={John Fitzpatrick and K. Weidendorfer and Ernest Teunou}, journal={Milchwissenschaft-milk ...
Drewer GR, Ahmed N, Jameson GJ. Suspension of high concentration solids in mechanically stirred vessels. AIChE Symp Ser 1994; 136: 41–48. ... Koutsakos E. Solids suspension and distribution in liquids under turbulent agitation. Chem Eng Sci 1989; 44: 529–542. 10. ... Graham L, Parthasarathy R, Nguyen B. High solids concentration …
The impact of agitation rate and sparged aeration on BM-hMSC expansion in conventional stirred tank bioreactors was assessed. It was found that a decrease in impeller speed to below NJS caused ...
in a stirred vessel, while for non-Newtonian case, such as the biopolymer fluid adopted in this study, with higher concentration and complex rheology characteristics solutions,
Brewer's spent grain components (cellulose, hemicellulose and lignin) were fractionated in a two-step chemical pretreatment process using dilute sulfuric acid and sodium hydroxide solutions. The cellulose pulp produced was hydrolyzed with a cellulolytic complex, Celluclast 1.5 L, at 45 °C to convert the cellulose into glucose. Several …
This study focused on designing a high concentration medium agitation system for such a process using the commercial computational fluid dynamics package Fluent (V. 6.2.20) and its preprocessor ...
Successful k L a estimations have been demonstrated for fermentation processes under relatively low agitation speeds; [14, 20, 26-28] however, this paper aims to provide strongly aerobic fermentation mass transfer behavior analysis with high agitation speeds, that is, up to 1200 RPM stirring speeds in a 1-L three-impeller vessel.
The maximum velocity criteria was applied within the high-velocity area, and the boundary of the agitation zone was identified where the velocity magnitude reached the maximum value. As shown in Fig. 6 (b), the boundary of the agitation zone at Z/H = 0.6 was identified as R = 0.168 m, where the loop-averaged velocity magnitude reached 0.43 …
Summary. Stirred tank reactors are widely used in the chemical and allied industries. They offer excellent flexibility in meeting varying demands of a reaction. The most common version of the tank or vessel is a vertical cylindrical tank with a dish end at the bottom. Impellers commonly used in stirred tank reactors are divided into radial …
The agitation was provided by a shaft which was placed in vertical axis of the tank and driven by a 3.0 kW motor. ... systems handling high concentration slurries (up to 40% v/v) in the presence ...
Suspension of ultrahigh concentration solids in an agitated vessel. Steven Wang, Steven Wang. Division of Earth Science and Resource Engineering, …
In past decades a lot of researches on the bio-hydrogen production in the suspended growth reactor such as continuous stirred-tank reactor have been carried, however most of them are almost vertical continuous stirred-tank reactor (VCSTR) [31], [32], [33], [34].The structure and impeller of the vertical continuous stirred-tank reactor …
The present work focuses on the determination of gas holdup, Sauter mean bubble diameter (d 32) and gas–liquid interfacial area (α g−l) for radial- and mixed-flow impellers under various operating conditions in a three-phase stirred vessel.d 32 values were determined for a wide range of solids concentration (0.01–0.25 v/v) using an …
Luo et al. 9 investigated the effects of geometrical and physical factors on light particles dispersion in stirred tank by agitation characteristic curve, ... the high concentration area of the bottom particles increases; when the height from the bottom increases from 220 mm to 280 mm, the high concentration area of particles is reduced ...
Tests showed that swirling flow could provide more energy efficient suspension compared with draft tubes or multiple impeller designs. It is demonstrated that SF is capable of suspending solids at very high concentration, which is impractical with …
Request PDF | Agitation energy efficiency in gas-solid-liquid stirred vessels operating at ultra-high solids concentrations | In this work, suspension of high-concentration slurry in the presence ...
Stirred tank bioreactors provide high values of mass and heat transfer rates and excellent mixing. ... and different techniques for measuring the dissolved oxygen concentration can be used. ... of 0-200 rpm and continues with inefficient enhancement that starts from 300 rpm and does not reach to plateau in high agitation speeds.
Drewer GR, Ahmed N, Jameson GJ. Suspension of high concentration solids in mechanically stirred vessels. AIChE Symp Ser 1994; 136: 41–48. ... Koutsakos E. …
Similarly, when the impeller is fixed on a tilted shaft, it is called the inclined-shaft or angled-shaft agitation. This scheme is mainly used in the unbaffled stirred tank [44] or disposable aerated stirred bioreactor for the cultivation of animal cell [45]. By adopting this strategy, an energy-saving and efficient mixing can be achieved.