Controlling of Calcium Carbonate Scale Deposition on the Piping System with Laminar Flow and in the Presence of Citric Acids

Abstract

Scale of calcium carbonate deposited on the pipe wall was investigated in the present study. The presence of scaling inside pipes is serious problems in industries which increase maintenance cost. In the experimental work, the scale-forming solution was prepared by mixing equimolar solutions of CaCl2 and Na2CO3 with a concentration of 3,000 ppm of Ca2+. The solution flew in the pipe at laminar mode at temperature: 30, 40, 50 and 60°C. Other parameters selected in this experiment were the addition of additives : citric acid (C6H8O7) with concentration of 5 ppm, 10 ppm and 20 ppm. The citric acid was selected to inhibit the crystal growth. The scale growth was continuously observed by measuring the conductivity of the solution coming out of the pipe. It was found that in all the experiments, the conductivity decreased abruptly after a certain induction period. The higher temperature produced, the more mass of the scale obtained indicating that the increasing temperature promoted the scale formation. Scale formed was then evaluated using SEM/EDX and XRD analysis. The result showed that the scale has a plate like morphology and the crystalline phase of the scale was found to be mostly calcite. The presence of citric acid seems to change the morphology of the crystals.