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 …
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Abstract. In this work, suspension of high-concentration slurry in the presence of gas was investigated using different baffling configurations, particle sizes, …
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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 ...
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Abstract. By using mixing intensification involving high solids concentration as a means to achieve process intensification for the mineral process industry is …
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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 ...
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The synthesis was carried out in 700 mL of orange juice in a 1 L jacket glass mechanic stirred-batch reactor. The agitation was done using two Scaba impellers 4 cm in diameter and 1cm wide for mechanical stirring. The last topic described the process, with synthesis at 25 and 30°C. ... Comparing MAG30 and MEC30, the first presented a high ...
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The efficiency of mixing operation in the stirred tank reactor (STR) depends mainly on the impeller diameter, the agitation speed, and the numbers of impellers (Noor et al., 2003). High agitation speed is preferred because vigorous agitation promotes the formation of an emulsion system with reduced droplet sizes.
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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 ...
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Drewer GR, Ahmed N, Jameson GJ. Suspension of high concentration solids in mechanically stirred vessels. AIChE Symp Ser 1994; 136: 41–48. ... Koutsakos E. …
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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 ...
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In anaerobic digestion biogas plant industry, high-efficiency agitation system in the Continuously Stirred Tank Reactor (CSTR) is vital for encouraging mixing between substrates and bioliquids with low energy consumption. This study numerically investigated the downward pumping agitation system in an industrial CSTR test site to …
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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 tanks. Chem. Eng. Sci. 53(9), 1757–1775 (1998) ... Suspension and liquid homogenization in high solids concentration stirred chemical reactors. Chem. Eng. Res. Des.
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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,
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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 …
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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 ...
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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 …
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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 ...
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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 …
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Solid suspension and gas dispersion in gas-solid-liquid stirred vessels with high solid concentration / Meysam Davoody. Mechanically agitated vessels are used …
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It can be estimated that N js ~ 190–200 rpm, largely independent of the concentration, except at a very high value of 1300 g/L. P js, the power at JS condition, increased from 120 W for concentrations less than 1000 g/L, to 200 W at 1100 g/L, and then sharply elevated to 700 W at 1300 g/L (0.54 v/v).
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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.
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The physical properties of the milk powders are presented in Table 1. They are both non-agglomerated milk powders. Honey was used to mimic high viscosity solutions and was obtained from Boyne Valley, Ireland. Stirred-tank agitation system. A 3-l unbaffled vessel with internal diameter T = 125 mm was used for the experiments. The …
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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.
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Later, Buurman et al. (1986), working with small and large scale vessels stirred by pitched blade turbines (PBT), reported the presence of a relatively homogeneous high-concentration layer in the lower part of the vessel, whose extension was found to depend on agitation speed as well as on stirrer and vessel size and system physical …
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Good solid-liquid mixing homogeneity and liquid level stability are necessary conditions for the preparation of high-quality composite materials. In this study, two rotor-stator agitators were utilized, including the cross-structure rotor-stator (CSRS) agitator and the half-cross structure rotor-stator (HCSRS) agitator. The performances of the two types …
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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 …
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Particle suspension in high-concentration slurries has been studied using radial-, mixed-, and axial-flow impellers. Impeller power measurements in this study were linked to the mass of solids suspended in the agitation system rather than the suspension volume. This approach was based on the consideration that the rate of dissolution or …
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Experimental results of gas hold-up, power consumption and residence time of gas bubbles in a gas-solid-liquid system produced in an agitated vessel equipped with a high-speed impeller and a vertical tubular coil are presented in this paper. Critical agitator speed, needed for the dispersion of gas bubbles and solid particles in liquid were also …
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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 …
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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 ...
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3.44: 0.1126: Cell density pre- induction (OD 600 nm) 1: 149.46: ... In stirred tank bioreactors, agitation and aeration are essential operational parameters in scaling up aerobic biosynthesis systems and ... Another study showed aeration rates to be a significant factor for high enzyme yields in a stirred tank bioreactor 55. Effect of aeration ...
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The jet-flow HSM can complete suspension task at high solids concentration exceeding 40 wt%. The N js and the P js of jet-flow HSM would obviously increase with increasing the solids concentration. Besides, the N js and the P js for downforce rotor are the smallest compared with vertical rotor and lifting rotor, and the N js reduces while the …
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Investigations of suspension characteristics are based on the so-called 1-s criterion, representing a state in which the entire surface area of the particles just becomes available for mass ...
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AIChE Journal is an official chemical engineering journal of the American Institute of Chemical Engineers, covering the very latest technological advances.
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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 …
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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
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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 …
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The present work studies two mixing systems specifically for viscoplastic fluids. Such a situation occurs for instance in an emulsion copolymerization process at high concentrations. A rheological characterization of this emulsion has been performed by Marouche et al. [16]. The mixing systems investigated are flat-bottomed vessels …
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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.
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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 …
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