Testing a Low Temperature Application Corrosion Inhibitor in the Upper Mahiao Power Plant Condensates

Abstract

The power plant condensates coming from the Upper Mahiao Power Plant is highly saturated with dissolved CO2 and H2S gases, making the condensates acidic with and corrosive to the carbon steel pipeline that is used to transport these condensates from a spray tower to the injection wells. Currently, the power plant condensates are treated with caustic soda (NaOH) to raise the fluid pH. At elevated pH level, corrosion is controlled since the corrosive species present are buffered. However, the caustic soda solution is difficult to handle due to its highly corrosive nature. Also, its present cost in the market is escalating. Thus, a low temperature application corrosion inhibitor was tested and dosed at the carbon steel condensate pipeline downstream of the spray tower, to possibly find an alternative corrosion inhibition treatment that is both effective and cost competitive to the current caustic soda dosing. The inhibitor is a filming amine which coats the pipe wall with an amide film and thereby protects it from corrosion attack. On-line corrosion rate measurements were conducted while the dosage rates were optimized to find the optimum dosing concentration in the line.