Turbine Agitator Research Articles

The Effect of Scalling-Up and Hydrodynamic Properties of Stirring System on the Kinetics of Vegetable Oil Hydrogenation

The stirring system of classical turbine agitator beside the anchor agitation system was studied from the point of view of the effect of their hydrodynamic properties on the kinetics of sunflower oil hydrogenation, It was found out that the anchor agitator makes up a higher gas hold-up than the turbine one and its efficiency from the view of reaction kinetics is higher. On changing the geometrical parameters of anchor agitator - by reducing its blade height - its hydrodynamic properties change considerably, and its efficiency decreases. The scaling-up of the stirring system did not manifest itself in the reaction rate in case of the turbine agitator. With the anchor agitator, the scaling-up resulted in the confirmation of its specific effect on the reaction kinetics, viz., on exceeding the limiting value of stirring frequency, the dramatic loss in efficiency took place.

Power, gas dispersion and homogenisation characteristics of Scaba SRGT and rushton turbine impellers.

The Scaba SRGT agitator with six blades when gassed draws between 1 and 0.8 times the ungassed power in fluids of low and moderate viscosity respectively. Under similar conditions, the gassed Rushton turbine draws 0.5 to 0.4 times the ungassed power. In addition, some three times more gas can be handled at the same ungassed power by this SRGT before flooding occurs. The increased hold-up achieved by the 6SRGT is commensurate with the increased power input and it is argued that the potentially extra power available should be able to give a similarly enhanced kLa. The 6SRGT agitator also gives an equivalent homogenisation performance to a standard Rushton turbine agitator of the same size at the same gassed power input. When gassed reactors are fitted with motors of sufficient power to be capable of running at full speed when ungassed, this agitator offers simple retrofitting possibilities potentially leading to considerably enhanced performance.

Search for optimal geometry of a conical turbine agitator for heat transfer in stirred vessels

AbstractSimultaneous measurements of power consumption P and heat transfer coefficient α for a jacketed, baffled, agitated vessel of diameter D = 0.45 m, equipped with a conical turbine, were carried out. The following geometric parameters of the agitator were tested: diameter d, blade width b and number Z, and distance from the bottom of the vessel to the lower edge of the blade h. The results of these investigations were generalized mathematically. On the basis of optimization, the best geometric parameters with respect to heat transfer are proposed for the conical turbine agitator.

Comparison of Ozone and Oxygen Mass Transfer in a Laboratory and Pilot Plant Operation

Abstract Mass transfer of ozone and oxygen to water was investigated both in pilot plant countercurrent bubble column and in a Rushton type laboratory stirred reactor supplied with a variable speed turbine agitator. A comparison was made for different hydrodynamic conditions with the main task of developing an engineering approach for determination of the physical volumetric mass transfer coefficient (KL oa), specific interfacial area (a), and physical masstransfer coefficient (KLO). The mass transfer characteristics of ozone and oxygen can be determined quickly in a pilot plant or laboratory apparatus, and employed to optimize the performance ofthe full scale water treatment plant.

Growth of hybridoma cells under different agitation conditions

The effect of mechanical agitation on hybridoma cell growth was examined in laboratory scale vessels. At an agitation rate four times that required to keep the cells in suspension, both growth rate and growth extent were reduced. However, using the minimum agitation rate required to suspend cells, no adverse effect on cell growth was observed even with a turbine agitator.

Comparisons between cellulase production by Aspergillus fumigatus in agitated vessels and in an air‐lift fermentor

Aspergillus fumigatus was cultured in disc-turbine-agitated vessels and in an air-lift fermentor. In the agitated vessels the yield of cellulase was reduced when the agitation rate was increased, although extracellular protein levels rose. The enzyme complex itself was shown to be exceptionally stable under conditions similar to those in the agitated vessels, so probably shear damage to the mycelium had occurred, liberating intracellular contents. These appeared to contain an inhibitor that could be removed by fabricated inorganic protein absorbents, such as kieselguhr and alumina. However, the inhibitor was not likely to be protease, since only relatively low levels could be detected and its identity has not been established. The use of an air-lift fermentor avoided the shear effects due to use of the disc turbine agitator in the conventional fermentors, and yields of enzyme were then found to increase by about 20%, maximum yields being obtained at maximum K(L)a values.

Fluid motion and mixing in a gas-liquid contactor with turbine agitators

Gas bubble distributions, estimated from local holdup measurements, and flow profiles near the vessel wall, deduced from wall pressure measurements, we Typical findings were that (1) the flow field under the impeller was quite similar to that for unaerated agitation, (2) the circulation flow of liquid Mixing measurements under aeration for comparison with single-phase measurements obtained at lower speeds to maintain the same total power input confir

Carrier mediated extraction: application of double emulsion technique for mercury removal from waste water

Extraction of mercury(II) cations from low-pH aqueous solutions by means of a double emulsion technique was studied in a laboratory scale, 2 l turbine agitator. A 10% solution of long-chain fatty acids (oleic and linolic) in normal paraffins (C 11C 15) was used as the intermediate phase. The optimal operational conditions for fast and complete removal of mercury, providing a 1000 fold concentration increase of the metal in the receiving, encapsulated phase, were obtained.

Characterizing the effect of feed rate in continuous flow vessels having turbine agitators

Characterizing the effect of feed rate in continuous flow vessels having turbine agitators

Liquid pressure and peripheral velocity distribution developed by a turbine (blade) agitator

Liquid pressure and peripheral velocity distribution developed by a turbine (blade) agitator

Real and pseudo-turbulence in the discharge stream from a rushton turbine

The trailing vortex system leaving the blade tips dominates the velocity field in the vicinity of a turbine agitator. This paper relates velocity measurements made with a stationary conical hot film probe to the known flow field defined relative to the impeller. It is shown that the ordered pseudo turbulence deviates so much from isotropic conditions that the usual interpretation in terms of the turbulence parameters of scale intensity is of doubtful value in this region.

The trailing vortex system produced by Rushton turbine agitators

Further studies of the discharge from a six blade Rushton turbine are reported. Photographic velocity measurements have been used to examine the trailing vortex system in water and aqueous glycerol. An analysis of the vortex field in terms of a solution to the simplified Navier-Stokes equations shows reasonable agreement with the measured velocity profiles. Pressure field determinations at two different scales prove that Reynolds number alone is a sufficient scale-up parameter. The centrifugal accelerations and shear rates associated with the trailing vortices are shown to be much greater than previous literature has implied. Although restricted to single phase flow the results presented are of importance to most applications of disc turbines to dispersion operations.

Internal gas recycling in a bubbling (contact) apparatus with turbine and propeller agitators

Internal gas recycling in a bubbling (contact) apparatus with turbine and propeller agitators

Vývoj větracích systemů s turbínovými míchadly v ČSSR.

Vývoj větracích systemů s turbínovými míchadly v ČSSR.

Effect of agitation on selectivity in the hydrogenation of soybean oil

SummaryA total of 12 hydrogenations were conducted in the pilot plant. The conditions were such that analyses of the data would furnish information as to the effect of 6 variables on the course of the reaction. The most reliable estimates were obtained for the effect of increasing, by agitation, the dispersion of hydrogen in the oil. The dispersion was accomplished by converting from a simple turbine agitator to a gas dispersing type with easily fabricated parts. This change resulted in a more selective reaction with respect to unsaturates. The change can also result in a shorter reaction time, or in the consumption of less power. Judging from its effects on the course of hydrogenation, agitation cannot simply be defined in terms of speed.

Agitation. Power Requirements of Turbine Agitators

Agitation. Power Requirements of Turbine Agitators