天然气外输管道黑粉分布规律及清除措施

Distribution and remove measures of black powder in natural gas pipeline

关键词:  天然气  外输管道  黑粉  腐蚀  防治  清管

Key words:  natural gas  transportation pipeline  black powder  corrosion  prevention and control  pigging

摘要:

黑粉在天然气外输管道中积聚,会造成仪表阀门堵塞、输送介质污染、管输量下降等一系列问题,因此,有必要开展管道中黑粉组成和分布情况研究。结合外输管线的清管作业情况,分析了管道不同部位的黑粉组成、分布和形态。同时,对管输天然气历年气质情况进行了分析,确定了黑粉组成及其在管线中的分布规律,分析了黑粉形成原因。结果 表明:黑粉偏向在距气源较近、地势低洼处的管道中聚集；其主要组成为FeCO₃,还含有一定量的Fe₃S₄、FeS、S、SiO₂、Fe₂O₃等,其中FeCO₃、Fe₃S₄、FeS主要由天然气生产设备或管道发生CO₂和H₂S腐蚀所形成,而S、SiO₂、Fe₂O₃则由上游气源携入或来自管线施工残留物。根据黑粉的组成和其在管道中的分布特点,提出了黑粉防治措施建议:从源头上杜绝设备和管道的腐蚀；对老旧天然气外输管线应定期组织清管,清管时选用合适的清管工艺。

Abstract:

The accumulation of black powder in transportation pipeline would induce a series of problems, such as blockage of the instrument and valves, pollution of the conveying gas and loss of pipe transporting volume. Therefore, it is necessary to study the composition and distribution of black powder in transportation pipeline. Based on the operation of pigging, the composition, distribution and form of the black powder at different locations in natural gas transportation pipelines were investigated. Correspondently, gas quality of the pipelines in recent years were analyzed as well, leading to the understanding on the composition, distribution, and the possible causes of the black powder in the pipelines. The results showed that black powder prefers to accumulate at the low-lying places closing to gas source. The black power is mainly composed of FeCO₃, and mounts of Fe₃S₄, S, SiO₂ and Fe₂O₃. Among which, FeCO₃, Fe₃S₄, and FeS were mainly formed by CO₂ and H₂S corrosion of pipeline steel, while S, SiO₂, Fe₂O₃ were carried by the upstream gas flow or from the construction residues. The prevention and control measures of black powder were proposed according to the composition and distribution features of black powder in transportation pipeline, including preventing the corrosion of equipment and pipes from the source, cleaning the old natural gas pipeline regularly, and selecting suitable procedures for pigging operation.