输气管道投产置换过程气体混合规律研究

目前国内输气管道置换工艺主要依据人工经验进行，存在较大的盲目性，导致天然气管道投产成本较高，安全风险较大，有必要对输气管线安全投产工艺进行科学、系统的研究，实现输气管道的安全、高效、经济投产模式。文章讨论了现有置换工艺中不同的置换方式，认为不加隔离器的置换方法具有置换效率高、费用低以及安全可靠等优点，是一种有前途的新工艺、新方法。同时，为确保置换过程的安全性，针对置换过程中注氮量确定的盲目性问题，采用模拟试验方法，研究了天然气与氮气、氮气与空气混合段在不同流速和背压下长度的变化规律，从而为确定合理的用氮量提供了理论依据。

STUDY ON GAS MIXING REGULATION OF GAS DISPLACEMENT OPERATION FOR GAS TRANSMISSION PIPELINE COMMISSIONING

Presently, Chinese gas displacement technology for the natural gas transmission pipeline is mainly performed in accordance with manual experience which has great blindness. It has led to higher commissioning cost and risk. Thus, it is necessary to conduct scientific and systemic researches on the gas pipeline commissioning technology to realize the safe, efficient and economical gas pipeline commissioning mode. Different kinds of gas displacement manners in existence were discussed. The displacement technique without pigs has some merits such as higher displacement efficiency, lower commissioning cost and safety etc, which made it a promising technology. Meanwhile, to secure the safety of gas displacement, simulated test method is carried out to study the regulation of length change of air and nitrogen blend section and nitrogen and natural gas blend section under different flow velocities and back presses. It avoided the blindness of nitrogen injection capacity during the gas displacement operation. Therefore, the scientific basis was provided to ensure reasonable nitrogen injection capacity.