An Advanced Surge Dynamic Model for Simulating ESD Events and Comparing Different Anti-Surge Strategies

Abstract

Despite advancements in research and industry, compressors still have to operate in the stable region of the characteristic curves otherwise, at low flow ranges, they enter an unstable regime. The worst instability that can arise in industrial compressors is called surge, which involves the whole system in view of the fact that it generates dangerous pressure and mass flow fluctuations. Thus, this phenomenon has to be prevented since it implies the deterioration of performance and leads to mechanical damage to the compressor and system components. It is clear that, currently, compression system models have a crucial role in predicting the phenomena which can occur in the compressor and pipelines during operation. In this paper, a dynamic model, developed in the Matlab/Simulink environment, is further implemented to allow the study of surge events caused by rapid transients, such as emergency shutdown events (ESD). The aim is to validate the experimental data obtained in a single stage centrifugal compressor installed in the test facility at Southwest Research Institute. The test facility consists of a closed loop system and is characterized by a recycling circuit, and thus a recycling valve, which is opened in case of surge or driver shutdown. In this work, the recycling circuit is implemented in the model as well, and comparisons between recorded data and simulations were carried out. Moreover, different actions for recovering/preventing surge are simulated by controlling different valves along the piping system and by adding a check valve immediately downstream the compressor. The results demonstrated the fidelity of the model and its capability of simulating piping systems with different configurations and components, also showing, qualitatively, the different effects of some alternative actions which can be taken after surge onset.