Design Considerations and Operation of Condenser Bypass Systems in Combined Cycle Power Plants: Part 1

As many Combined Cycle Power Plants have come into operation over the last 10 years, premature condenser tube failures have been experienced at several installations. This paper reviews factors and mechanisms contributing to such failures. The steam turbine condenser must operate under a demanding, wide range of conditions. Tubes within the condenser experience cyclic stresses, direct contact from admission of high-energy steam into the condenser, and the effects from a wide service range beginning with start-up and commissioning through continuous or intermittent daily operation. A number of factors go into properly designing condenser related sub-systems as required by the functional operation of the combined cycle plant. The condenser bypass system is a critical component directly affecting the operation, maintenance and control of conditions experienced by the condenser. Part 1 of this paper identifies related problems experienced, in the field, within the condenser considering operation and maintenance, and also provides design considerations to avoid occurrence of tube failures. Part 2 of this paper addresses many key points for consideration with respect to the design and implementation of the high-energy bypass system leading into the condenser.