Dynamic simulation of safety relief process under vacuum failure scenarios in large cryogenic system

Abstract

Large cryogenic systems are vital for large scale scientific and industrial facilities such as superconducting accelerators, fusion reactors and superconducting magnet systems. These systems operate at liquid helium or superfluid helium temperatures and contain large helium inventories, making them highly vulnerable to overpressure hazards during vacuum failure scenarios such as loss of insulation vacuum (LIV) and beam vacuum (LBV). An appropriately designed safety relief system is crucial for risk mitigation. Conventional safety device sizing approaches typically rely on conservative steady-state assumptions and overlook the dynamic nature of discharge processes, potentially leading to inappropriate valve selection and suboptimal system process design. To address this, a comprehensive dynamic simulation model of cryogenic safety relief processes was developed using EcosimPro software. The model includes detailed heat and mass transfer modelling of vacuum failure behaviour, cryogenic components modelling, and safety relief process modelling. The model was applied to a 2 K cryogenic system of Dalian Advanced Light Source (DALS) Test Facility project. Simulation results validated the existing safety configuration and demonstrated the necessity of dynamic analysis in ensuring the reliable and efficient design of safety relief systems. The methodology is broadly applicable to the design and optimization of cryogenic safety systems, offering high engineering value for future safety system designs and relief devices selection.