Reactors with mainly axial flow

In reactors with mainly axial flow, axial mixing can often be described with good accuracy, and the effects are usually limited. 

An analysis is made of the factors which pose a limit to representative downscaling of catalyst testing in continuous fixed-bed reactors operated with either gas or gas-liquid flow. Main limiting factors are the axial dispersion and, in the case of gas-liquid operation, also the contacting of the catalyst. The effects of catalyst and reactor geometries are quantified, and boundaries for safe operation are indicated. 

Another often-used reactor type (especially for relatively long-lasting derivatization reactions) is the open tube with liquid or gas segmentation [94]. Segmentation prevents the formation of a parabolic flow profile (axial dispersion), and peak dispersion is due mainly to the phase separator, which is responsible for removal of the segments prior to detection. The principle of segmentation was first used by Moore and Stein [102], who developed an amino acid autoanalyzer (ninhydrin reaction) in 1958. 

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