输气管道氮气置换过程气体混合规律数值模拟

Numerical simulation on gas mixing rule in course of nitrogen isolation gas displacement technology for commissioning of gas transmission pipeline

目前,国内输气管道投产置换时,注入氮气用量主要依据人工经验确定,存在一定的盲目性.文章以长呼天然气输送管道投产为背景,对该管道投产置换过程进行了计算机数值模拟,获得了气体置换速度对混合段长度的影响规律,即气体的置换速度在2.81～6.50 m/s范围内,混合长度随着流速的增加而增大,但混合长度的增长率随流速的增加而降低.

At present, during the displacement for the commissioning of gas transmission pipeline, the injection capacity of nitrogen is defined chiefly by the man-made experience, so it has some blindness. How to define the optimum injection capacity of nitrogen in the course of the displacement for the commissioning of gas transmission pipeline is an urgent problem to be solved in the oil pipeline engineering field. In this paper, taking the commissioning of Changqing oilfield to Huhehaote gas transmission pipeline as back- ground, the displacement course for commissioning of this pipeline is simulated. The influence rule of gas mixed section length due to displacement velocity has been obtained. Namely, in the scope of gas displacement velocity from 2.81 m/s to 6.50 m/s, along with increase of displacement velocity, gas mixed section length enlarges, but its increase rate redneces.