Hydrodynamically deposited CaCO3 and CaSO4 scales

A laboratory study was carried out to explore the effect of solution hydrodynamics on the deposition of calcium carbonate scale on Stainless Steel 316 and calcium sulfate scale on aluminum substrates using a rotating cylinder electrode apparatus. The results of the study indicate a strong influence of solution hydrodynamics on the deposition rate of these scales. Furthermore, the analysis of the data obtained in the study shows a good agreement with the theoretical prediction of a diffusion controlled process. Morphological examinations of the deposited crystals conducted on the exposed specimens by scanning electron microscopy revealed a variety of crystal shapes comprising: dendrites, sand-rose, half-moon, rhombic, hexagonal or prismatic needles/rods like crystals growing at nucleating sites and branching out randomly over the substrates. Secondary growth on the already existing primary crystals was also identified.