Reactor mechanically mixed

Reactor Design. The continuous polymerization reactions in this investigation were performed in a 50 ml pyrex glass reactor. The mixing mechanism utilized two mixing impellers and a Chemco magnet-drive mechanism. 

This process, according to the manufacturer,54 has been developed in such a way that space requirements are kept to a minimum. A BIOPAQ IC reactor is used as the initial step in the treatment process. The name of this anaerobic reactor is derived from the gas-lift driven internal circulation that is generated within a tall, cylindrical vessel. These reactors have been operational in the paper industry since 1996. The second step in the purification process is a mechanically mixed and aerated tank. The aerating injectors can be cleaned in a simple way without the need to empty the aeration tank. Potential scaling materials are combined into removable fine particles. At the same time, the materials that may cause an odor nuisance are oxidized into odorless components. The process can be completed by a third and a fourth step. The third step focuses on suspended solids recovery and removal. The fourth step is an additional water-softening step with lamella separation and continuous sand filters in order to produce fresh water substitute. The benefits claimed by the manufacturer are as follows54 ... 

Tlie requirement for mechanical agitation can be avoided by using a fluidized bed reactor. In this type of reactor, the agitation and mixing are achieved by means of the moving liquid that carries the solids through the reactor or mixes with the particle phase. Thus, high heat and mass transfer rates are assured. 

On each of these, random and structured reactors behave quite differently. In terms of costs and catalyst loading, random packed-bed reactors usually are most favorable. So why would one use structured reactors As will become clear, in many of the concerns listed, structured reactors are to be preferred. Precision in catalytic processes is the basis for process improvement. It does not make sense to develop the best possible catalyst and to use it in an unsatisfactory reactor. Both the catalyst and the reactor should be close to perfect. Random packed beds do not fulfill this requirement. They are not homogeneous, because maldistributions always occur at the reactor wall these are unavoidable, originating form the looser packing there. These maldistributions lead to nonuniform flow and concentration profiles, and even hot spots can arise (1). A similar analysis holds for slurry reactors. For instance, in a mechanically stirred tank reactor the mixing intensity is highly non-uniform and conditions exist where only a relatively small annulus around the tip of the stirrer is an effective reaction space. 

Tower Reactor The tower reactor is convenient when working with flocculating yeast cells. The reactor consists of a cylinder provided with bottom and upper zones for feeding substrate and cells and sofid/liquid separation. The overall aspect ratio is of 10 1, with 6 1 for the reaction zone. A tower reactor does not use mechanical mixing, and is simpler to build. Cell concentrations up to 100 g/1 can be achieved with productivities 30-80 times higher than in batch reactors. The residence time is below 0.4 h and the yield up to 95% of the theoretical one. A design procedure is available [18]. 

The next section will first show the importance of flow in a concrete modelling problem such as the slip flow effect on the efficiency of a permanent mechanically mixed reactor. Then the characterization of the combined flow models where the slip flow occurs will be presented. 

The Slip Flow Effect on the Efficiency of a Mechanically Mixed Reactor in a Permanent Regime... 

In this section, we consider a permanent and mechanically mixed reactor, where a chemical transformation occurs and the consumption rate of one reactant is given... 

Mechanically Mixed Reactor for Reactions in Liquid Media... 

Experiments in a Batch System. In the experiments with molten catalyst, asphaltene and catalyst were mechanically mixed and placed in a reactor. In the experiments using a solvent, the catalyst was first impregnated on asphaltene and suspended in the solvent. 

An active catalyst for the conversion of butane to isobutane was obtained by mechanically mixing W03/Zr02 and Pt/Zr02 (0.5 wt% Pt) as shown in Table 17.8. The activity of Pt-W03/Zr02 prepared by co-impregnation of zirconia with W and Pt materials was lower than that of the mechanical mixture of W03/Zr02 and Pt/ Zr02 [202]. The reaction was carried out in a reactor in which two catalysts could... 

In slurry reactors (Fig. 8.8) small catalyst particles (10-100 pm) are suspended in a liquid phase by mechanical mixing. Stirring also improves the contact between the gas bubbles and the liquid phase and heat exchange with the surroundings. Slurry reactors can be operated in a batch, semi-batch or continuous mode. In the semi-batch mode often the gas-phase is supplied continuously. 

Tubular flow reactors are usually operated under steady conditions so that, at any point, physical and chemical properties do not vary with time. Unlike the batch and tank flow reactors, there is no mechanical mixing. Thus, the state of the reacting fluid will vary from point to point in the system, and this variation may be in both the radial and axial direction. The describing equations are then differential, with position as the independent variable. 

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