Background:

This mega integrated refining and petrochemical complex features a vast array of process units with enormous overall capacity, resulting in a highly complex site-wide system design. Based on relief load data provided by licensors and flare load superposition criteria specified under Chinese industry standard SH/T 3009-2013, the preliminary calculated total flare relief rate was extremely substantial. The initial engineering design required ten 1.8 m diameter flare main headers. Even when excluding the general power failure scenario for refining and aromatics units, the projected flare load remained excessively high, leading to prohibitive capital expenditure for the full flare system. 

Solution：

In full compliance with international standard API 521, SimTech deployed all permitted methodologies and mitigation strategies specified in the standard. We conducted comprehensive evaluation and optimization covering all plant units via a systematic toolkit—including steady-state process simulation, static relief load analysis, dynamic simulation, dynamic relief load analysis, and flare load mitigation solutions based on High Integrity Protection Systems (HIPS).

Static relief load analyses were performed to validate all design scenarios and assumptions, cross-checking the relief load figures submitted by the licensors. Dynamic modeling captured real-world dynamic behaviors such as reboiler pinch effects. Compared with overly conservative static relief load analysis results, the total relief load was reduced by approximately 50%. Additional load reduction was achieved through the implementation of HIPS and other engineered mitigation measures, delivering a drastic cut to the overall required flare capacity

Benefit:

lThermal Radiation & Footprint Mitigation: Significant reduction in total flare thermal radiation output and heat radiation radius, eliminating the critical risk of flare radiation overlapping with the tank farm zone under the original design.

lInfrastructure & Piping Reduction: The quantity of 1.8 m diameter flare main headers was reduced from the initial 10 down to only 4.

lCAPEX Savings: Capital cost savings alone exceeded RMB 100 million.