| Abstract |
The varying levels of pH and dissolved C02 and H2S in power plant condensates (temperature of 34-90░C) affect the corrosion rates along the condensate lines of the different power plants in the Leyte Geothermal Production Field. This is due to the controlling effect of pH to the active species of dissolved H2S and COP in solution. In cases where pH is less than 5.5, dissolved 602 is mostly in the form of H2CO3 and dissolved sulfides in the form of H2S and native sulfur. All of these species are highly corrosive to carbon steel line. This condition was demonstrated by the rapid corrosion rate in Upper Mahiao condensate line. Between pH of 5.5 and 7.5, dissolved C02 is mostly in the form of HCOj and dissolved H2S occurs as HS'. The corrosion rates of carbon steel caused by this fluid depend on the amounf of dissolved gases in the solution. The condensates are corrosive if dissolved 602 is greater than 30 ppm and H2S greater than 1.5 ppm. For example, the Malitbog power plant, where pH is around 6.5 but COP is above 36 ppm and H2S is above 1.5 ppm, has more rapid corrosion rate than the TlPF power plant, whicl? has fluid pH of around 6.0 but has a lower level of dissolved gas. In cases where pH is above 7.5) corrosion rate seem to be insignificant because dissolved 6 0 2 is in the form of 6Q2(,@ and H2S is in the form of HS. These are the conditions in Ma han agdong, where con densat e pH ranges from 7.0 to 8.5 and no leakage has occurred along the lines. |