Abstract:

Flare system is a necessary auxiliary production facility for large-scale petrochemical plant. It is also an important safety and environmental protection measure. However, flare design standard SH 3009—2013 “Design specifications for combustible gas discharge system in petrochemical engineering” and the international standard API 521 “Pressure-relieving and Depressuring Systems” are mainly based on industry practices and engineering experience currently. Therefore, when the flare system needs installation or extension, there will be higher risk, especially when the diameter and layout of pipe line cannot be changed. This paper presented a general method for the risk assessment of the flare system for the renovation or expansion of combined petrochemical plant. The key parameters of the flare system were obtained by the superposition algorithm of simultaneous discharge of multiple discharge sources before and after the reconstruction and expansion. This paper used Aspen flare-net software for numerical simulation and case study. The numerical results of the back pressure and noise of the safety valve of flare system caused by the newly installed device in the plant, the corresponding safety risks, and the release combinations that may lead to safety risks of flare system were obtained. The results provided quantitative decision basis for discharge load management, and the application effect and effectiveness of the proposed method were illustrated.

Key words: quantitative risk assessment, flare system, plant reconstruction or expansion, discharge load management, numerical simulation

摘要：

火炬是大型石油化工联合装置必备的辅助生产设施，同时也是重要的安全环保措施。但目前火炬的设计标准《石油化工可燃性气体排放系统设计规范》（SH 3009—2013）或者国际标准《泄压和减压系统》（API 521）主要还是基于行业惯例和工程经验。新增装置或扩建装置会对火炬系统造成较大的风险影响，尤其是在火炬系统管网管径及管网布置不改变或无法改变的情况下。本文提出了一种针对石化联合装置进行改扩建对火炬系统风险评估的通用方法，采用改扩建前后发生多泄放源同时泄放的叠加方法流程来获得火炬系统关键参数。采用Aspen Flare-net软件进行数值模拟和案例研究，获得了厂区新增装置导致的火炬系统安全阀背压、噪声等数值结果及对应的安全隐患，并得到了全部可能导致火炬系统安全隐患的泄放组合，为泄放负荷管理提供了量化决策依据，同时说明了所提方法的应用效果和有效性。

关键词: 量化风险评估, 火炬系统, 装置改扩建, 泄放负荷管理, 数值模拟