To avoid discontinuation during long-term continuous operation in plants, a reliable monitoring system for the state diagnosis is strongly expected. However, occurring troubles of various facilities in a plant aren’t simple. We proposed a sophisticated estimation method to diagnose the state for reciprocating compressors. Our monitoring system uses both the measuring data in the factory and the analytical results based on the mathematical model, which can express the dynamic behavior about the reciprocating compressor. The mathematical model has multi degrees of freedom and the model parameters are identified to estimate the state change. To realize the reliable monitoring, we have to establish estimation and diagnosis method for any change of the operation state.
In this paper, we discuss estimation method of the rigidity in connecting and sliding portions by using the measuring data during operation of the reciprocating compressor in case of changing a connecting parts. We identified parameters of spring constant, by which one can be obtained the frequencies of eigenvalue analysis correspond to some natural frequencies determined based on an optimal problem. Moreover, we analyzed frequency responses of the model using the identified parameters and compared the frequency responses of the model with those of experimental results.