The Link Between the Corrosion and calcium carbonate scaling susceptibilities of heat transfer surfaces

Abstract

The nucleation o f CaCO, scales on copper, graphite, aluminium and mild steel heat transfer surfaces at surface temperatures 54-56 "C, f r o m turbulent solutions ( R e 22,000) of bulk temperature 30 "C, has been studied using thermal resistance and corrosion potential measurements and scanning electron microscopy. The rate of CaCO, scale nucleation and growth decreases in the order mild steel > aluminium > copper and graphite. Scale nucleation apparently proceeds from the very outset, throughout an apparent thermal induction period, the end o f which appears to be associated with the development of nuclei into aragonite clusters. The differing scaling susceptibilities o f the materials are directly related to their corrosion susceptibilities. Studies on aluminium highlight the importance o f the nature and integrity of surface oxide films in determining scaling susceptibility. Under the conditions examined, scales consist primarily of aragonite, with small amounts of calcite and vaterite. Mild steel surfaces apparently favour growth of "flower" vaterite.

Effect of water chemistry on calcium carbonate deposition on metal and polymer surfaces

“…A considerable body of knowledge exists for scaling of metals e.g., [4][5][6][7][8][9][10][11], but less is known about the scaling of polymers, which are gaining acceptance in a variety of water applications, including solar hot water systems [12,13]. In this paper, we compare the scaling behaviors of polypropylene tubes, a candidate polymer for solar water heating, and copper tubes, a traditional material for the same application.…”

Water soluble copolymers for calcium carbonate and calcium sulphate scale control in cooling water systems

“…Deposition of these materials on heat exchange surfaces can lead to loss of system efficiency, unscheduled shutdown, and ultimately to system failures or clogging of filters, obstruction of fluid flow, reduction in cooling efficiency, localized corrosion attack, wear of metal parts, and loss of production and economy 1–3. The scale formation depends on concentration of lattice forming ions, dissolved and suspended solids, pH, flow velocity, evaporation rate, pressure, etc 4, 5. Scales can be controlled by (1) altering the system design and operating parameters, (2) altering the nature of feed waters, and (3) using chemical treatment methods.…”

Scale Prevention With Special Reference to Threshold Treatment

“…(II) (12) SCALE PREVENTION TO THRESHOLD TREATMENT 223 The constant E pj[AAt)/A(t)] only depends on the specific batch of seed crystals and ) hence it will be the same for all experiments performed on the same batch of seed crystals, regardless the amount of seed crystals or the concentration of the solution at time zero. So for each batch of seed crystals a unique R-f3 curve will be obtained.…”