紧急放空系统限流孔板孔径HYSYS模拟计算

HYSYS simulation for the restriction orifice sizing in the emergency blowdown system in the gas and oil gathering station

关键词:  集输站场  紧急放空  限流孔板  HYSYS动态模拟 

Key words:  gathering station  emergency blowdown  restriction orifice  HYSYS dynamic simulation

摘要:

紧急泄放系统为油气集输站场中设备和管道提供安全保障,尤其火灾工况下,带压介质必须尽快泄放,以防止由于容器受热后强度降低引起的破裂或爆炸。限流孔板孔径是影响泄放速率的主要因素,值得深入研究,以满足极端工况的泄放要求。基于限流孔板尺寸计算方法现状和火灾工况特点,分析了现行算法在火灾工况下的适应性,并建立HYSYS动态模拟,计算了火灾工况下紧急放空系统限流孔板孔径。结果 表明,目前的限流孔板尺寸算法无法合理考虑火灾工况泄放过程中液相介质挥发和气相组分升温等情况；容器中的轻质液相组分在火灾工况下将大量挥发,常规算法得出的泄放元件尺寸无法满足此种情况下紧急泄压的需求；建立的动态泄放模型能够进一步模拟真实情况。研究成果为集输站场紧急放空系统的限流孔板合理设计提供了参考与借鉴。 

Abstract:

The emergency blowdown system provided safety guarantee for the pipes and equipments in the gas and oil gathering station. Especially under fire case, the pressurised medium must be relieved quickly to avoid the equipment rupture or explosion in consequence of the decreased material strength at high temperature. The blowdown rate is mainly influenced by the size of Restriction Orifice (RO), of which the calculation is worth deeply studying to meet the relief requirement under extreme conditions. In this paper, based on the current restriction orifice sizing method and the feature of fire cases, the adaptability of the current equation on fire case is analyzed, and the sizing method for fire induced relief is then optimized by using HYSYS dynamic simulation model. The results showed that the evaporation of light condensates and vapor thermal expansion under fire case could not be thoroughly taken into consideration with the current method. Thus, the determined orifice size from the current method could not meet the emergency blowdown requirements due to the huge evaporation rates of the light condensates after heated. Instead, the HYSYS dynamic simulation method could present more realistic simulation and its calculation results were more reasonable than the conventional methods. Overall, this study provided reference for restriction orifice sizing in emergency case.