天高线B段复线管道积液特性分析

Analysis of Liquid Accumulation Characteristics in Tian’gao Line Section B Double Pipeline

摘要: 针对天高线B段复线起伏管段的积液问题，本文基于管道实际运行参数，耦合Hysys相态分析与OLGA双流体多相流机制，建立了高精度的管道工艺及流动计算模型(平均计算偏差为1.26%)。基于该模型，系统研究了管线积液的分布特征及关键运行参数的影响规律。结果表明：当前工况下，管线积液受地形主导，主要富集于19处低洼管段(总积液量约3 m³)，其中T15处(距起点14,185 m)为最大积液风险点(0.945 m³)；积液量随气体流量、环境温度及出口压力的升高而减少，随入口温度及乙二醇注入量的升高而增加，但参数波动不改变积液的核心分布位置。分析认为，上述规律主要受控于温压条件改变引起的气液相平衡偏移，以及气相流速变化带来的携液剪切力差异。为进一步指导现场排液，本文结合临界携液流速分析，确定了当前工况下的临界携液界限(4.94 m/s)，并构建了拟合度高达0.99的积液预测模型。本研究阐明了该天然气管道内积液的形成与分布机制，可为管道积液的动态预测与清管作业参数优化提供理论支撑。

Abstract: Aiming at the liquid accumulation problem in the undulating sections of the Tian-Gao Line Section B looping pipeline, a high-fidelity process and flow model was established based on actual field parameters. By coupling HYSYS phase behavior analysis with the OLGA two-fluid multiphase flow mechanistic model, the computational reliability was verified with an average deviation of 1.26%. Utilizing this model, the distribution characteristics of liquid accumulation and the influence of key operating parameters were systematically investigated. The results indicate that under the current operating conditions, liquid holdup is predominantly governed by topography, concentrating at 19 low-lying sections with a total volume of approximately 3 m³. Notably, location T15 (14,185 m from the inlet) exhibits the highest accumulation risk, reaching 0.945 m³. Furthermore, the liquid accumulation volume is found to decrease with increasing gas flow rate, ambient temperature, and outlet pressure, whereas it increases with elevated inlet temperature and ethylene glycol injection rates. Importantly, these parameter fluctuations do not alter the core topographical distribution of the accumulated liquid. Mechanistic analysis reveals that these phenomena are primarily driven by shifts in vapor-liquid phase equilibrium induced by temperature and pressure variations, alongside differences in the interfacial shear stress dictating the gas phase’s liquid-carrying capacity. To provide actionable guidance for on-site liquid unloading, a critical liquid-carrying gas velocity threshold of 4.94 m/s was determined for the current conditions, and a highly accurate predictive model for liquid accumulation was developed (R² = 0.99). This study elucidates the formation and distribution mechanisms of liquid holdup in natural gas pipelines, providing a robust theoretical foundation for the dynamic prediction of liquid accumulation and the optimization of pigging operations.