An Advanced Surge Dynamic Model for Simulating Emergency Shutdown Events and Comparing Different Antisurge Strategies

The compressor surge is a phenomenon which has to be avoided since it implies the deterioration of performance and leads to mechanical damage to the compressor and system components. As a consequence, 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 model using 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. Simulations were carried out at 17,800 and 19,800 rpm; the comparison with experimental data showed the accuracy of the model in simulating different opening rates and different sizes of the recycle valve, at both low and high suction pressure (HSP). Moreover, different actions for recovering/preventing surge were 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.