天然气过滤分离器紧急泄放系统设计

Design for the Emergence Relief System of the Nature Gas Filter Separator

天然气过滤分离器火灾工况下壁温和容器内气体温度随火焰持续燃烧逐渐增高,操作温度可能会超过设计温度,容器未发生超压而管口法兰已发生破裂,造成可燃介质外泄,加剧周边环境恶化。针对此工况下安全阀无法起到保护设备安全的问题,采用规范法和动态模拟法分别计算天然气过滤分离器火灾工况的泄放压力和泄放温度,得到泄放过程的温度-压力曲线,指出安全阀无法对该系统超温工况提供足够保护的局限性。在调研规范及行业经验的基础上,提出设置降压系统来处理火灾高温工况的方法,实时模拟泄放过程中流体的压力、温度、流量等参数随时间的动态响应过程,计算出限流孔板的喉径面积。分析结果表明,对于储存超临界流体、气体或盛有高沸点液体的容器的工艺系统,发生火灾时应考虑借助水喷淋、降压系统等保护措施;采用动态模拟法可实时模拟热力学参数随泄放时间的变化,其更符合流体的实际泄放工况,同时准确计算出经济合理的限流孔板喉径面积。

The wall temperature and the gas temperature in the natural gas filter separator increase gradually with the continuous combustion of the flame during fire scenarios.The operation temperature may exceed the design temperature and lead to the flange rupture without overpressure,resulting in the leakage of combustible media and aggravating the adverse environment around.In view of the problem that the safety valve could not protect the safety of the equipment under this condition,the relieving operation pressure and temperature of the natural gas filter separator under fire scenarios are calculated by the standard method and the dynamic simulation method respectively,and the temperature-pressure curve of the discharge process is obtained.It is found that the safety valve could not provide sufficient protection for the over-temperature condition of the system.Based on the research of standards and industry experiences,it is put forward that the depressurization system should be set to deal with the fire at high temperature scenarios.The dynamic response processes of the fluid pressure,temperature and fluid flow in the process of depressurization process are simulated in time,and the throat area of the restriction orifice is gained by calculation.The analysis results show that in the case of fire,the water spray and depressurization system should be taken into consideration for the vessels containing supercritical liq-uid,gas or liquid with high boiling point.The dynamic simulation method could simulate the changes of the thermodynamic parameters with the relieving time accurately,which is more suitable for the actual relief conditions of fluid and can accurately calculate the economical and reasonable throat area of the restriction orifice.