Application of Dynamic Simulation for the Design of the LNG Inlet Gas Compressor Anti-Surge Protection

Abstract An inlet gas compressor system is simulated in Aspen HYSYS Dynamics v12.1. The emphasis of the simulation is to design the system to prevent or mitigate surges during an emergency shutdown (ESD). The dynamic simulation aims to assess the performance of the anti-surge control valve (ASCV), to add and size a cold gas bypass valve (CGBV) or hot gas bypass valve (HGBV) if the ASCV is insufficient, to determine the corresponding bypass valve size, and to select which bypass valve configuration is appropriate. An ASCV accompanied by an 8” HGBV is shown to be the recommended anti-surge protection configuration to mitigate surge due to its faster response and is more appropriate for motor-driven compressors which slow down more quickly during ESD. The ASCV provided by the compressor vendor with the recommended 8” HGBV can mitigate the effects of compressor surges during an emergency shutdown scenario.