EFFECT OF PH-VALUE ON FOULING BEHAVIOR OF HEAR EXCHANGERS

For the experiments a CaCO3/H2O solution was used with a pi-I-range be tween pH 6 and pH. to which is relevant in cooling water systems. For pi-I-values above 6 aqueous solutions of CaCO3 cause an increase of th e fouling resistance. With increasing pH-value the number of free hydr ogen ions decreases, which keep the calcium ions in solution. The rati o of free hydrogen ions can be described by the saturation index which is calculated by the reaction equations and the equilibrium constants . It can be seen, that the saturation index is proportional to the dep osition rate of the solid. The deposition can be calculated by the rat e of reaction that is determined experimentally. The comparison of res ults of fouling experiments carried out with different pH-values shows good agreement with calculated data.