海底凝析气管道工艺计算模型的建立与应用

Establishment and Application of Technological Calculation Model for Conden-sate Gas in the Submarine Pipeline

根据海底凝析气管道的输送特点,从凝析气两相流流型判断、凝析气输送工艺计算数学模型的建立、不同稳态工艺计算类型的数值算法等三个方面进行了研究,编制了相应的计算机程序。用平湖至上海和JZ20—2凝析气管道的生产数据,对所选计算模型的正确性和可靠性进行了检验,检验结果表明,与国外多相流软件PIPEPHASE和热力学模拟软件HYSIM的计算偏差均在10％以内。实例计算结果证明,所提出的计算模型对海底凝析气管道的工艺计算具有足够的计算精度,能正确模拟出实际管道的沿线压力、温度、持液率、气液相速度的变化规律,对管内流型、水合物形成区域的预测也符合实际情况。

In the course of pipeline transportation of condensate gas, wet gas often occurs to the behaviors of retrograde condensation due to the changes of pressure and temperature along the pipeline,so its flow belongs to the category of low liquid holdup two-phase flow,and the process calculations are not in correspondence with usual natural gas pipeline. According to the transporting feature of submarine pipeline, the theoretical studies including flow regime prediction, establishment of hydrodynamic and thermodynamic models and computer modeling of different technological calculation methods are conducted in the paper. And meanwhile the steady computer programs for technology calculation are developed. The reliability and precision of the models are demonstrated by comparing with producing data of JZ 20-2 and Pinghu-Shanghai offshore pipelines,and the relative derivation between the results of models and the same kind of foreign software PIPHASE &. HYSIM are all within 10%. The example analysis indicates that computing results with a high relatively accuracy are obtained with the calculating models proposed in this paper,and these models can simulate the change laws of pressure drop,temperature drop,liquid holdup and velocities of gas and liquid along practical producing pipeline. In the aspect of judgment of hydrate forming zones and flow pattern prediction, the validity of the method are verified, but the calculating value of accumulated amount of liquid in the pipeline is smaller.