超压泄放装置尺寸计算理论与方法研究OA

To resolve the confusions arising from the determination of reference conditions,identification of medium phase states,real-gas correction,and selection of two-phase-flow calculation approaches during the sizing of overpressure relief devices,literature review,theoretical formula collation and comparison of standard calculation methods are adopted in this work.The calculation methods of mass flux and relief area are analyzed for liquids,gases,saturated steam,near-critical fluids and two-phase-flow media.The results indicate that the sizing of relief devices should take the operating condition corresponding to the maximum allowable accumulation pressure as the primary reference state,and the discharge coefficient shall be introduced to perform engineering correction on the adiabatic or isentropic nozzle model.For gas relief,the correction formula derived from the ideal-gas assumption can be used for engineering estimation when the inlet compressibility factor Z ranges from 0.8 to 1.1.When the isentropic expansion coefficient n replaces the ideal-gas specific-heat ratio k,the applicable interval can be extended to approximately 0.5～1.1.For saturated steam,piecewise correlations of mass flux can be established on the basis of the KN value within the pressure range of 0.105～22.0 MPa,and the calculation deviation can be controlled within±3%.For media prone to flashing or phase change,two-phase-flow methods including the HDI,HEM and Omega methods should be selected preferentially according to phase-state criteria.This paper defines the applicable boundaries and selection principles of sizing methods for various media,and can provide technical references for the engineering design and standard implementation of safety valves,bursting discs and other overpressure relief devices.