Case study of surge avoidance design for centrifugal compressor systems during emergency shut-down (ESD)

Compression systems with centrifugal compressors are widely used in gas involving processes. Surge protection system design is crucial in avoiding any damage in abnormal circumstances such as emergency shutdown (ESD), start-up, coast-down operation, and normal shutdown. We analyzed four cases of existing centrifugal compressor systems, three CO2 compression systems and one off-gas compression system, to study the surge protection availability during ESD. All compression systems were working well at normal operating condition, but some systems could not avoid surge during ESD. To check the surge cases, the surge criteria flowchart was suggested and surge analysis through dynamic simulation was done using a commercial process simulator. To avoid a surge during ESD, a sensitivity analysis was done while considering the following process parameters: pre-stroke time, anti-surge valve (ASV) type, capacity, and stroke time. We optimized ASV design using response surface method with two selected parameters from the sensitivity study, ASV capacity and stroke time. Finally, the installation of the hot gas recycle system was analyzed to avoid surge occurrence.