Reduction of transient vibration via structural dynamics modification for H_2 cooling pipe system in a power plant

摘要

H_2 is a coolant that is used the generator in large power plants to cool. Thus it is extremely important to get stable for the H_2 piping system. But there was extremely transient vibration on the H_2 cooling pipe system in a power plant. According to creating and analyzing a finite element model we found the natural vibration of the piping system approached the exciting characteristics from the turbine rotor. Because of the operational condition on the spot we just measured vibration of the piping system, the modal test was replaced to analyze the finite element model for the system. We tried to seek an optimal model to satisfy mode shapes and thermal effects by creating a revised FEM model, and modification was carried out on the basis of the result of the dynamic analysis. Finally we could get the stable state for the H_2 cooling pipe system. Therefore this paper shows that changing total modes of a piping system depends on simplifying the piping path or changing the number and position of supports but changing a local mode of the piping system depends on modifying a local path of the piping without the change of total modes.