Agglomeration equipment operation variables

The spray flux captures the impact of equipment operating variables on nucleation, and as such is very useful for scale-up if nucleation rates and nuclei sizes are to be maintained constant. The overall impact of dimensionless spray flux on nucleation and agglomerate formation is illustrated in Fig. 21-106, with agglomerates increasing with increased spray flux as clearly governed by Eq. (21-106) for the case of rapid drop penetration. 

Considerable effort has been made in the examination of the deposition of oxides of iron onto surfaces, since this has considerable relevance to the operation of boiler plant. Williamson [1990] has reviewed some experimental magnetite (FejOJ deposition data. He draws attention to the wide discrepancies in the results even for similar systems as may be seen from examination of Table 7.3. He attributes the discrepancies to inadequate control of one or more of the less obvious variables in the system such as the water chemistry (even deionised water is likely to "pick up" COj from the atmosphere with an effect on the pH). A fixed particle size distribution is extremely difficult to maintain in an experimental system due to potential agglomeration and is likely to be time dependent. Even particle concentration may not be uniform due to settlement in the parts of the equipment where velocities are low. Experimentally the consistency of these variables are difficult to determine. 

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