Objective With the rapid development of intelligent pipelines and smart pipeline network construction, coupled with the widespread application of unattended station operation technologies, the automatic offtake system plays an increasingly significant role at natural gas pipeline stations.

Methods This paper delves into the challenges posed by the conventional offtake system at an in-service natural gas pipeline station, such as frequent manual operations and imprecise control. A comprehensive analysis was conducted, covering aspects such as the control logic governing the offtake system, the degree of automation in the station control system, the operational convenience of offtake branches, operational safety, and cost-effectiveness. Consequently, a retrofit scheme was proposed for the automatic offtake system, leveraging the existing SCADA system at the station. The proposed design includes devising the control logic for the automatic offtake system and configuring the SCADA system, based on the existing station control system(AB PLC). This retrofit facilitates the introduction of four primary automatic offtake control modes: non-uniformity coefficient, residual mean, constant-pressure control, and volume-limit transmission shutdown. Furthermore, several supplementary control functions are integrated, comprising undisturbed offtake branch switching, PID regulation, automatic offtake startup/shutdown, low-flow protection, low-pressure protection, and transmission shutdown for overpressure prevention.

Results Following the retrofit of the automatic offtake system, this natural gas pipeline station has been restored to continuous and stable operation. The retrofit led to a substantial reduction in the frequency of patrol inspections and manual operations while improving automation levels and the precision of offtake control. The design's compatibility with the station control PLC, owing to its low processing demands, makes it ideal for establishing automatic offtake systems for new pipelines and upgrading existing ones at operational pipeline stations.

Conclusion The proposed retrofit design for the automatic offtake system at natural gas pipeline stations is demonstrated to be efficient in reducing investment costs and construction periods. Furthermore, it is beneficial in achieving unattended station operation, thereby enhancing regional management for pipeline operators.