Corrosion management of condenser tubes in power generating station – field trail

Abstract

This article presents the corrosion monitoring of condenser tubes in power generating station. The cooling water is used for condensing low pressure (LP) steam and several additives are systematically injected into cooling water for corrosion protection without affecting the performance of anti-scalant. Firstly, 10 ppm of mixture consisting of organophosphonate + HEDP (1-hydroxyethylidine-1, 1-diphosphonic acid) + zinc, 2 ppm of bio-dispersant and 6 ppm of mixture consist orthophosphate + zinc were dosed into cooling water. It was referred as mixture 1. Secondly, 5 ppm of pyrophosphate was further injected into cooling water in addition to mixture 1 referred as mixture 2. Lastly, 10 ppm of polymeric dispersant was dosed subsequently into cooling water referred as mixture 3. All three different conditions obtained from three mixtures were taken as plant trail for 1 month separately to establish the field condenser performance to maintain scale deposition and to prevent tubes against internal water corrosion. An addition of polymer dispersant showed improved corrosion protection due to formation of crystalline calcium phosphate layer which could act as anti-scalant as well as anti-corrosive layer. Moreover, heat transfer had been achieved by presence of co-polymer. The field trail of selected additive injection and examination of formed scales deposits may provide good insights on corrosion management of actual cooling water system.