Variety of Processes through the Fluid Bed Technology

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Playing with Parameters

In addition, it is possible to influence the properties of the product decisively by adjusting the parameters. The most important aspect is that the process moisture is in proportion to the structure of the granules. This can be influenced mainly through the process inlet air temperature and the liquid spray rate. The higher the moisture is during the agglomeration process, the more liquid bridges exist between the particles and the more solid bonds are created, resulting in a large and porous agglomerate. If, however, the process takes place at relatively dry conditions, the portion of fine material, and with it the bulk density, increases.

The moisture level in the process can be determined by the spray rate and drying velocity, which depends on the saturation level of the process air. By increasing the spray rate, more moisture is supplied to the process, which, in turn, facilitates the creation of liquid bridges. Courser and, in some cases, also denser granulates are created.

The atomisation pressure also has a considerable influence on the process. If the nozzle pressure is increased smaller droplets are produced and due to their larger surface, reduce the drying time and cause the formation of granulates with an increased amount of fines.

In general, a higher inlet air temperature reduces the evaporation time of the liquid and causes a faster hardening. The liquid bridges between the particles dry more quickly so that the probability of particle to particle contacts led to successful binding is reduced and preferable particles with a smaller grain size are created.

In addition, the particle size is defined by the air volume flow. With an increasing air velocity, the intensity of motion between the particles increases further. The high velocity causes increased abrasion of the agglomerates which have already been created and reduces the bonding capability of the spraying liquid, limiting the growth of the particles.

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