APPLICATION OF VARIOUS DYNAMIC ANALYSES IN SOLVING STRUCTURAL VIBRATION PROBLEMS TWO CASE STUDIES

摘要

Various analytical tools have been used in structural modeling and modification of two power plant equipment. A vertical Auxiliary Condensate Extraction pump in a CANDU nuclear generating station and a Combustion Air fan structure in a fossil generating station with high vibration levels were studied. Detailed spectral analyses concluded that both systems have resonant frequencies near their motor running speeds that amplify the unbalance response of the motor to an unacceptable level. Both systems with appropriate boundary conditions were modeled using a commercial finite element program. Modal analyses were performed and found to be in a good agreement with the measured natural frequencies. To detune the systems resonant frequencies, numerous structural modification techniques were considered and studied. Once a practical and cost effective structural modification was decided, frequency response analyses were performed on both equipment. To satisfy nuclear regulatory requirement, additional seismic analysis was conducted using Design Basis Earthquake (DBE) criteria established by the nuclear plant. Recommended modification on the fossil unit has been implemented with great success and is underway for the nuclear unit.