Agitators selection

Proper agitator selection is very important to provide good contact between the phases. Firstly, the catalyst particles must be kept uniformly suspended in the reaction medium. When a gaseous reactant is used, agitation is of primary importance in facilitating the gas-to-liquid mass transfer. In addition, good agitation is needed for optimum temperature control. 

Agitator Selection and Design, Engineering Equipment Users Association, Constable (1963). 

ENGINEERING EQUIPMENT USERS SSOaW ON (1965) Agitator Selection and Design, Constable. 

EEUA (1962) Agitator Selection and Design, Handbook 9, London, Constable. PALMER, M. H. and WEAVER, D. S. (1988) Shaft Design Guide, FMP Report 033. BHR Group Ltd. Cranfield, Bedford, September. 

Agitator selection and viscosity ranges. The viscosity of the fluid is one of several factors affecting the selection of the type of agitator. Indications of the viscosity ranges of these agitators are as follows. Propellers are used for viscosities of the fluid below about... 

Equation (8.2-11) is an adaptation of the classical Dittus and Boelter equation for straight pipes. Further information on this topic can be found in Holland and Chapman [1966]. Various aspects of agitator selection are dealt with by Gates et al. [1975]. 

The most frequent site for crystal encrustation is on a compatible solid surface within a zone of high supersaturation and low agitation. Selection of a less compatible material having a smooth surface can avoid the major excesses of encrustation. Duncan and Phillips (1979) and Shock (1983), respectively, reveal a connection between the metastable zone width of crystallizing solutions and their propensity to encrust. It is well known that judicious crystal seeding can also help minimize encrustation. Simple laboratory tests are recommended to determine all these issues before the plant is built. 

Conditions of hydrogenation also determine the composition of the product. The rate of reaction is increased by increases in temperature, pressure, agitation, and catalyst concentration. Selectivity is increased by increasing temperature and negatively affected by increases in pressure, agitation, and catalyst. Double-bond isomerization is enhanced by a temperature increase but decreased with increasing pressure, agitation, and catalyst. Trans isomers may also be favored by use of reused (deactivated) catalyst or sulfur-poisoned catalyst. 

Continuous-Flow Stirred-Tank Reactor. In a continuous-flow stirred-tank reactor (CSTR), reactants and products are continuously added and withdrawn. In practice, mechanical or hydrauHc agitation is required to achieve uniform composition and temperature, a choice strongly influenced by process considerations, ie, multiple specialty product requirements and mechanical seal pressure limitations. The CSTR is the idealized opposite of the weU-stirred batch and tubular plug-flow reactors. Analysis of selected combinations of these reactor types can be useful in quantitatively evaluating more complex gas-, Hquid-, and soHd-flow behaviors. 

Selected for clinical trials as a compound to calm agitated patients, imipramine was relatively ineffective. However, it was observed to be effective in the treatment of certain depressed patients (38). Early studies on the mechanism of action showed that imipramine potentiates the effects of the catecholamines, primarily norepinephrine. This finding, along with other evidence, led to the hypothesis that the compound exerts its antidepressant effects by elevating norepinephrine levels at central adrenergic synapses. Subsequent studies have shown that the compound is a potent inhibitor of norepinephrine reuptake and, to a lesser extent, the uptake of serotonin, thus fitting the hypothesis that had been developed to explain the antidepressant actions ofMAOIs. 

The thermal duty here is the opposite of solidification operations. The indirect heat-transfer equipment suitable for one operation is not suitable for the other because of the material-handling rather than the thermal aspects. Whether the temperature of transformation is a definite or a ranging one is of little importance in the selection of equipment for fusion. The burden is much agitated, but the beds are deep. 

From these data, plots are made of volumetric efficiency and agitation speed at each throughput level from these plots the condition which gives the maximum volumetric efficiency is selected for scale-up. 

Pai+icle size enlargement equipment can be classified into several groups, with advantages, disadvantages, and applications summarized in Table 20-36. Comparisons of bed-agitation intensity, compaction pressures, and product bulk density for selected agglomeration processes are highlighted above in Fig. 20-71. 

Volumetric or gravimetric feeders may be used, but volumetric feeders are usually selected only for installations where comparatively low feed rates are required. Dilution does not appear to be important, therefore, control of the amount of water used in the feeding operation is not considered necessary. Inexpensive hydraulic jet agitation may be furnished in the wetting chamber of the feeder as an alternative to mechanical agitation. The jets should be sized for the available water supply pressure to obtain proper mixing. 

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