液态乙烷管道相变工况低温特性探讨

The Study of Low Temperature Characteristics of Liquid Ethane Pipeline Under Phase Change Condition

液态乙烷管道因介质轻质组分含量极高,物理性质活泼,虽在稳态输送时可依据现行相关规范保证单相输送,但在特殊工况下极有可能发生相变,造成较低温度,需在管道低温设计时引起重视。基于液态乙烷管道工艺设计方法,结合液态乙烷物理性质,探讨了造成液态乙烷管道低温工况的诱因,分析并选用了适于多相分析的商用软件,模拟了某液态乙烷管道在特殊相变工况下的低温问题。研究表明:典型液态乙烷产品在绝热膨胀至常压后,温度将降至-77℃;常规的液相管道模拟软件无法识别由于相态变化引起的低温;水击工况具有快速降压的特点,水击点下游是发生乙烷管道低温问题的主要区域;减缓水击强度和适当提高运行压力是降低乙烷管道低温问题的主要手段。该研究成果可为液态乙烷管道的设计提供相关参考和借鉴。

Due to the high content of light hydrocarbon components for the liquid ethane pipeline,the physical characteristic of medium is lively. Although the single-phase transportation can be ensured under the current design standard,the phase change is likely to occur under special conditions,resulting in lower temperature. Thus,it is worth of the attention of pipeline low-temperature design. Based on the liquid ethane pipeline process design method and the physical characteristic of liquid ethane,the causes of the low temperature conditions of liquid ethane pipeline are discussed. The commercial software suitable for multiphase analysis is selected to simulate a liquid ethane pipeline low temperature problem under special phase change condition. The results show that the temperature of the typical liquid ethane products will decrease to-77 ℃ after adiabatic expansion to normal pressure. The conventional liquid pipeline simulation software cannot perform the simulation for the low temperature caused by the phase change. The water hammer has the characteristics of rapid pressure depression. Downstream of the water hammer point is the main area of the ethane pipeline low temperature occurrence; slowing down the water hammer momentum and appropriately improving the operating pressure are helpful to mitigate the low temperature issue of ethane pipeline. The research results of this paper can provide reference for the design of liquid ethane pipeline.