“Development of Simultaneous Non-Corrosive and Biodegradable Descaling and Inhibition System Solution”

Abstract

Calcareous scales can form in industrial and domestic pipelines, heat exchangers, desalination plants, or cooling towers, causing obstruction and flow reduction, high-pressure drops, low heat transfer coefficients, and other harmful effects, resulting in a negative economic impact. The composition of calcareous scales varies depending on the type and quality of the water in which they form and usually consists of carbonate minerals. In this study, we evaluated an organic acid mixture that is environmentally friendly, descaling solution to remove calcareous scales on embedded domestic pipelines. The results presented include speciation diagrams of the descaling solution at different concentrations in contact with calcium carbonate using the software MEDUSA. The results indicate that stable citrate and phosphate complexes are formed at 1 < pH < 4. XRD and FTIR analyses of the recrystallized scales from embedded pipelines in the descaling solution show different calcium carbonate polymorphs. The LPR technique allows us to calculate the corrosion rates of embedded carbon pipeline sections in contact with the descaling solutions at different concentrations. A corrosion rate reduction of 39 % was observed for 0.1 M descaling solution compared with 0.1 M HCl. Two distinct inhibitors were evaluated: one derived from the leaves of Agave Americana, and another from an ionic liquid known as 1-Pentadecyl-3-methylimidazolium bromide. The findings indicate an efficiency range of approximately 34-50% for the agave extract, whereas the ionic liquid exhibited superior performance, achieving efficiencies of 65 to 87%, both cases below the expected values of 90%. Furthermore, simulations of pressure drop in pipelines with calcareous carbonate deposits were conducted using the COMSOL Multiphysics 5.5 software. Thanks to the use of an adaptable mesh, it was possible to predict the dissolution kinetics and the dominant velocity and pressure profiles within the encrusted pipes. An instrumented testing apparatus was designed to investigate the dissolution rate under different flow conditions.