Objective In the daily operation of long-distance crude oil pipelines, residual pressure (differential pressure) at the terminal is typically reduced using pressure-reducing valves, which dissipates significant energy and generates substantial noise. While the utilization of residual pressure is common in water delivery and chemical pipelines, its utilization in long-distance crude oil pipelines is less studied. To achieve energy saving and efficiency improvement of long-distance crude oil pipelines, this study investigates the technological feasibility of harnessing the residual pressure at the terminal to generate electricity for on-site use.

Methods Based on an analysis of the power-generation potential from residual pressure at the terminal of an existing long-distance crude oil pipeline, the installation of a hydraulic turbine power generator in parallel with the pressure-reducing valve was proposed to utilize residual pressure for power generation. The influence of the hydraulic turbine power generator on the pipeline’s hydraulic characteristics under varying flow rates was analyzed using SPS software, with particular attention given to changes in pressure along the pipeline and flow rate at the terminal. Meanwhile, the control logic for ensuring the hydraulic safety of the entire pipeline was determined by comparing PID composite control systems based on high-selection/low-selection (HS/LS) logic, so that dangerous conditions such as oil vaporization caused by insufficient operating pressure at upstream high points after the hydraulic turbine power generator was put into use could be avoided. Finally, the investment payback period and carbon dioxide emission reduction were used as indicators to comprehensively evaluate the economic and environmental benefits of residual pressure power generation under different flow rates.

Results At a high operating flow rate of 2 200 m³/h, the hydraulic turbine power generator could fully meet the terminal’s daily electricity demand without causing vaporization at upstream high points. Additionally, this flow rate yielded the shortest investment payback period and the greatest reduction in carbon dioxide emissions, indicating that higher flow rates enhanced economic efficiency, operational stability, and environmental benefits. At medium and low flow rates, peak electricity demand might not be met, and without proper station control, vaporization could occur at upstream high points. Through simulation analysis and comparison, it was determined that low-selection (LS) control logic should be applied to the regulating valve upstream of the hydraulic turbine power generator to ensure hydraulic safety across the full flow range.

Conclusion Power generation using residual pressure at the terminal of long-distance crude oil pipelines is feasible. While recovering energy that might be lost during pressure reduction, it ensures the hydraulic safety of the entire pipeline, and offers economic and environmental benefits. This study provides valuable engineering reference for the wider adoption of this technology in long-distance crude oil pipelines. (16 Figures, 5 Tables, 22 References)