Selection of a reactor configuration

When one has decided that at least two phases are to be contacted, there is the question of the choice of the configuration. The possibilities have been reviewed in section 4.3. Here a few examples will be given of aspects of selection for the most important multi-phase systems. The selection of the configuration can not always be made independently from the selection of the operation mode (section 9.4). 

In most solid/fluid processes the solid is brought into a granular form, and the solid particles are dispersed in the fluid. The gas or liquid phase may be passed through a stationary bed of solid particles, or the particles may be suspended in the fluid phase, such as in a stirred tank or a fluidized bed. These are to be preferred when a large solid surface area is required. 

Another possibility is to let the fluid flow parallel to a solid wall. This is practised in many electrolysis cells, in monolith (or parallel passage) catalysts. 

The three possible configurations of a liquid/gas system are a dispersion of gas in liquid (section 4.6.1), a dispersion of liquid in gas (section 4.6.2), and a parallel flow of gas and liquid (section 4.6.3). The main differences are  

For making a choice it is best to look at the main reaction first. If this is a relatively slow liquid phase reaction, it will require a certain liquid volume, so that a gas-in-liquid dispersion is generally the most suitable configuration. For suppressing competitive or consecutive reactions high liquid phase mass transfer coefficients are favourable (section 5.3.5). 

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Chapter 6 starts with criteria for the selection of a reactor configuration. Data are given for sizing reactors. Then the details are given for over 30 reactor configurations. 

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