Acid cleaning of scale

Definition

Acid cleaning uses concentrated hydrogen ions to dissolve mineral scale from equipment surfaces. Inhibited hydrochloric acid was circulated through a chiller condenser barrel at a target pH of 1 to remove calcium carbonate scale.

High hydrogen concentrations attack the ionic lattice between calcium and carbonate, converting carbonate to bicarbonate, then to carbonic acid, then releasing carbon dioxide gas as the solid dissolves into solution. At pH 1 hydrogen dominates so completely that carbonate cannot exist, but the same aggression attacks metal, removing years of working life in an afternoon. Calcium climbs and pH creeps from 1 to about 2.5 as hydrogen is consumed, signaling completion.

Related concepts

Corrosion inhibitor · Neutralization · Ionic lattice

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Part of The Blueprint of Water · 🛠️ operations