Considerable ongoing risk of condenser in-leakage exists at Otahuhu B (OTB) Power Station. The condenser cooling water used at OTB station is corrosive brackish water with exceedingly high sodium and chloride concentrations. Significant signs of corrosion inside the condenser have been found recently. In the event of condenser in-leakage, the salt contaminants in the cooling water will directly enter the Heat Recovery Steam Generator (HRSG) with the potential for significant and costly damage resulting in a long plant outage. A dynamic mathematical model was developed in the thesis to analyse the consequences of condenser in-leakage at OTB station. The analysis results show that the tolerance of the condenser to any leakage of cooling water is almost zero. Because the existing condensate monitoring system is not designed to detect contamination in this time frame, a new fast response system is required to detect condenser in-leakage immediately. A new dedicated fast response condensate monitoring system has been engineered and installed at OTB station as a part of the project scope. The new system dramatically reduces the response time to condenser in-leakage events. Critical instruments utilise multiple redundancy schemes to enhance the availability and reliability of the system. In addition, action level voting, timing, and alarming has been automated to assist operators in making correct decisions. The new condensate monitoring system is presently fully functional. The project has successfully achieved the objective of controlling the risk of condenser in-leakage events and minimising damage and negative effects on the plant.
| Identifer | oai:union.ndltd.org:ADTP/241426 |
| Date | January 2008 |
| Creators | Zhang, Heng |
| Publisher | Massey University |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
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