运用等熵闪蒸法的安全阀计算  

Calculation of pressure relief valve utilizing isentropic flash method

作　　者：吴晓欣 Wu Xiaoxin(SINOPEC Guangzhou Engineering Co.,Ltd.,Guangzhou,Guangdong 510620)

机构地区：[1]中石化广州工程有限公司,广东省广州市510620

出　　处：《炼油技术与工程》2023年第9期25-29,共5页Petroleum Refinery Engineering

摘　　要：介绍了石油化工装置中安全阀设计的内容,考察了国外某新建炼油厂柴油加氢精制装置冷高压分离罐顶循环氢出口管线上的安全阀,结合等熵闪蒸的方法对冷高压分离罐火灾工况下高温高压的泄放介质进行模拟计算,可得到更准确的安全阀计算面积,确定安全阀喉径。结合管道轴测图对安全阀进出口管线进行水力学计算,确定进出口管径并指导安全阀选型。安全阀进口段压力降应小于安全阀定压的3%,避免安全阀震颤造成损坏。安全阀出口段的泄放背压与安全阀定压比值可指导安全阀的选型,保证安全阀正常起跳:普通工况下,小于定压的10%,火灾工况小于定压的21%,可选择普通式安全阀;大于10%且小于50%,应选择平衡式安全阀;大于50%,应选择先导式安全阀。This paper introduces the general design process of pressure relief valve in petrochemical units.An example of sizing the pressure relief valve which locates on the recycle gas discharge line at the top of the cold high pressure separator of diesel hydrotreating unit overseas is also introduced.When considering external fire case of the cold high pressure separator,isentropic flash method is utilized for the simulation of relieving fluid under high pressure and high temperature.With this method,the calculated relief area is more accurate and used for determination of the valve orifice size.Conduct hydraulic calculation on the suction and discharge pipelines of the pressure relief valve based on isometric diagrams to determine the size of pipelines and guide the valve type selection.For the suction pipelines,the total pressure loss should not exceed 3%of the pressure relief valve set pressure which prevents valve failure from chattering.For the discharge pipelines,the ratio of calculated built-up backpressure to pressure relief valve set pressure is used for valve type selection.This guarantees the pressure relief valve will pop open normally under set pressure.If the ratio is less than 10%for normal cases and less than 21%for external fire cases,conventional type valve can be used.If the ratio is more than 10%but less than 50%,balanced type valve should be used.And if the ratio is more than 50%,pilot-operated type valve should be used.

关 键 词：等熵闪蒸法 安全阀 计算 泄放量 泄放面积 工况分析 水力学计算 

分 类 号：TQ055.81[化学工程]