· Phase 1: Static relief analysis.
Guided by the principles and methodologies specified in API STD 521, this phase lays the foundation for all subsequent work. Engineers analyze process flows and control systems, identify applicable relief scenarios and corresponding design assumptions for each protected equipment item, and calculate relief loads accordingly. SimTech performs all calculations via its self-developed SimTech Relief software.
· Phase 2: Dynamic relief analysis.
This phase adopts rigorous first-principles dynamic simulation under the guidance of API STD 521 to simulate and analyze overpressure upset conditions and transient relief behaviors of protected equipment. Dynamic simulation represents the state-of-the-art technical approach for relief analysis and is explicitly recommended in the latest edition of API STD 521 (7th Edition, 2020).
· Phase 3: Relief Load Mitigation.
This stage focuses on cutting total relief discharge. Site-specific mitigation measures including process & equipment modifications and High Integrity Protection Systems (HIPS) overpressure interlocks are deployed to eliminate or reduce discharge volumes during overpressure incidents, thereby lowering overall relief loads. Follow-up deliverables may cover safety valve sizing verification, steady-state hydraulic calculation of flare vent headers, and dynamic hydraulic & heat transfer analysis of vent piping.
By adopting scientific, rigorous and systematic methodologies to calculate and optimize unit flare gas relief loads, the requirement for constructing new flare systems can be minimized or even eliminated, delivering capital cost savings ranging from tens of millions to hundreds of millions of RMB.
It eliminates multiple bottlenecks associated with flare systems, including excessive thermal radiation, land occupation constraints, flare stack height limitations and environmental emission compliance issues.
Comprehensive scientific calculation and thorough evaluation of the full plant relief system enable identification and rectification of potential safety hazards, ensuring full compliance with the latest international standards and emergency regulatory requirements.
A complete digital model of the relief system is established to quantify the maximum total relief load of the unit and generate clear, quantitative basic data. It provides reliable technical support for corporate decision-making covering future capacity expansion, flare system optimization and integration, avoiding over-investment or under-designed facilities.
The process unit and flare system simulation models built during the project serve as core digital assets of the plant. They continuously deliver tangible value across the full lifecycle, including design verification, operator training, commissioning optimization, process tuning, performance monitoring, online optimization and revamp scheme evaluation.