超临界CO_(2)管道停输过程温压及相态变化规律预测  

Prediction of change laws of temperature,pressure and phase state in supercritical CO_(2) pipeline shutdown process

作　　者：李欣泽 孙晨 刘晓飞 邹炜杰 姜星宇 郭良辉 董宝军 邢晓凯 LI Xinze;SUN Chen;LIU Xiaofei;ZOU Weijie;JIANG Xingyu;GUO Lianghui;DONG Baojun;XING Xiaokai(School of Engineering,China University of Petroleum(Beijing)at Karamay,Karamay 834000,Xinjiang,China;Xinjiang Key Laboratory of Multi-Medium Pipeline Safety Transportation,Urumqi 830011,Xinjiang,China;PetroChina Planning and Engineering Institute,Beijing 100083,China)

机构地区：[1]中国石油大学(北京)克拉玛依校区工学院,新疆克拉玛依834000 [2]新疆多介质管道安全输送重点实验室,新疆乌鲁木齐830011 [3]中国石油天然气股份有限公司规划总院,北京100083

出　　处：《低碳化学与化工》2025年第1期143-152,共10页Low-Carbon Chemistry and Chemical Engineering

基　　金：中国石油大学(北京)克拉玛依校区科研启动基金(XQZX20230021);新疆维吾尔自治区自然科学基金(2023D01A19);新疆维吾尔自治区“天池英才”引进计划;新疆天山创新团队“油气高效管输技术研究与应用创新团队”(2022TSYCTD0002);新疆维吾尔自治区“一事一议”引进战略人才项目(XQZX20240054);克拉玛依市创新环境建设计划(创新人才)(20232023hjcxrc0001)。

摘　　要：不同于原油、天然气管道,超临界CO_(2)管道在停输过程中,需要关注温度和压力共同作用下的CO_(2)相态变化。掌握停输过程管道各位置流体温压变化关系、初始气化工况点和气化程度,对实现管道安全状态预判具有重要意义。基于中国石油天然气股份有限公司新疆油田分公司百万吨级超临界CO_(2)管道示范工程KB CO_(2)管道,建立了管道水力热力模型并求解,获得了管道停输后全线压力、温度、密度、持液率及相态变化规律,发现流体密度值与单位温降对应的压降值存在正相关性。基于Peng-Robinson状态方程,得到流体气化前压力、温度和密度变化的函数表达式,该温压关系在CO_(2)相图中为相态迁移路径线的斜率值。该值主要受流体密度影响,流体密度500 kg/m^(3)、650 kg/m^(3)和800 kg/m^(3)对应的斜率值分别为0.213、0.325和0.473。同时,给出了流体初始气化时的温压计算公式和气化后持液率变化预测公式。CO_(2)相图中相态迁移路径线与气液平衡线的交点即为流体初始气化压力和温度点。CO_(2)流体气化后,压力和温度状态点将沿着气液平衡线移动,直到温度降至管道周围土壤环境温度。采用OLGA软件对推导出的计算公式进行了验证,计算值与模拟值的误差在±4.00%以内,说明公式具有较高的准确性。最后应用公式对示范工程停输过程安全状态进行了预测,发现管道起点发生气化时的压力最高,为避免管道任意点发生气化,需在管道压力降至7.0 MPa前进行再启动操作。Different from crude oil and natural gas pipelines,it is necessary to pay attention to CO_(2) phase change under the combined effect of temperature and pressure during the shutdown process of supercritical CO_(2) pipelines.It is of great significance to master the temperature-pressure change relationship,initial gasification pressure and temperature and gasification degree during shutdown process,in order to predict pipeline safety status.Based on the KB CO_(2) pipeline of PetroChina Xinjiang Oilfield Company’s million-ton supercritical CO_(2) pipeline demonstration project,the pipeline hydrothermal model was established and solved to obtain the change of pressure,temperature,density,liquid-holding rate and phase state in whole pipeline after shutdown,and it is found that there is a positive correlation between density of fluid and pressure drop corresponding to unit temperature drop.Based on the Peng-Robinson equation of state,the functional expressions of pressure,temperature and density changes before fluid gasification were obtained,and this temperature-pressure relationship can be expressed as the slope value of phase migration path line in CO_(2) phase diagram.This value is mainly affected by fluid density,and the slope values corresponding to fluid densities of 500 kg/m^(3),650 kg/m^(3)and 800 kg/m^(3) are 0.213,0.325 and 0.473,respectively.At the same time,the equations for temperature and pressure during initial gasification of fluid and the prediction equations for change of liquid-holding rate after gasification were given.The intersection point of phase migration path line and gas-liquid equilibrium line in CO_(2) phase diagram is the initial gasification pressure and temperature points of fluid.After the gasification of CO_(2) fluid,the pressure and temperature state points will be shifted along the gas-liquid equilibrium line until the temperature is reduced to temperature of soil around pipeline.The derived formulas were verified using the industry-recognised OLGA software,and the errors between

关 键 词：超临界CO_(2) 管道输送 停输过程 相变 

分 类 号：TE81[石油与天然气工程—油气储运工程]