A CASE HISTORY FOR THE MITIGATION OF SALT WATER INTRUSION INTO A BOILER STEAM CYCLE

摘要

On May 22, 1998, Bridgeport Harbor Station Unit No. 3 operated for nearly four (4) hours with saltwater intrusion into theboiler water and steam systems via a condenser tube leak. After deliberate and detailed study with world-renown corrosioninspection and mitigation experts and EPRI, a plan of action was developed to mitigate the salt water intrusion from theboiler waterwall and steam system, in order to place these portions of the unit in a 'before incident' condition. The boilerwaterwall system was thoroughly recirculated and flushed with condensate, and then chemically cleaned prior to service. Acomplete turbine overall has been undertaken, a portion of which includes thorough blasting, surfactant soaking, rinsing anddrying of all stages of steam buckets, diaphragms, and turbine blading. A multi-stage high velocity water flush wassuccessfully completed to mitigate saltwater intrusion into the superheat and reheat steam systems. This paper describes thevarious processes used to successfully return the unit to normal, full load operation, with particular emphasis on the multi-stage high velocity water flush of the steam cycle.