Both substances adhere, but there are significant differences in the order of adhesion, the rate of accumulation, and the severity of the problem:

They primarily adhere in large quantities to the spray nozzles.

Fine organic flocs continuously flow at high speed through the spray pipes and the small orifices of the nozzles as part of the circulating fluid:

These flocs are sticky; upon contact with metal surfaces, they adhere and accumulate, gradually reducing the diameter of the outlet orifices. In mild cases, this results in uneven spray distribution and turbulent boiling within the chamber; in severe cases, the spray nozzles become completely blocked, leading to a decrease in circulation flow rate and salt accumulation due to flow deviation in the heat exchange channels.

Since the spray nozzles are part of the liquid-phase channel, the flocs remain fully submerged in the slurry and are continuously transported, causing blockages to develop at the fastest rate.

Secondary adhesion to the demister screen results from accumulation caused by secondary entrainment.

During normal, stable evaporation, most flocs are carried away by the liquid and rarely drift on their own to the gas-phase mesh;

only when vacuum fluctuations or violent boiling with foaming and material entrainment occur do flocs rise, entrained by foam and droplets, and adhere to the demister screen wires.

Flocs combine with salt crystals to form composite scale, which clogs the mesh openings, increasing resistance to gas flow and further exacerbating negative pressure fluctuations and material carryover—this constitutes secondary blockage.

Simple Comparison

Spray nozzles: Flocs are continuously transported by the liquid phase, causing the earliest and fastest blockage, which directly disrupts heat exchange within the chamber;

Demister screens: Accumulation occurs only when flocs are entrained by foam, representing secondary blockage resulting from worsening foaming conditions.