长输原油管道末站余压发电工艺设计与分析

Analysis of the Process for Generating Electricityfrom Residual Pressure in A Long-distance Crude Oil Pipeline

  • 摘要: 【目的】在长输原油管道的日常运行中,管道末站若存在剩余压力(余压),通常需要通过减压阀减压。在减压过程中,大量能量浪费在减压阀上,若余压较大还会引起较大噪声。国内外液体管道的余压多在输水或化工设备管道中应用,在长输原油管道中的相关研究较少。为实现长输原油管道节能、增效,将末站余压发电以供给站内生活用电,探究其工艺可行性。【方法】在某现役长输原油管道末站余压发电能力分析基础上,提出将减压阀并联液力透平发电装置以实现余压发电,并利用SPS仿真软件着重分析不同流量下投用液力透平发电装置对全线管路水力特性的影响规律,重点关注全线压力和末站流量的变化。同时,对比基于高选/低选(HS/LS)逻辑的PID复合控制系统,确定了能保障全线管路水力安全的控制逻辑,以避免在液力透平发电装置投用后,所致上游高点处运行压力不足,进而引发油品汽化等危险工况。最后,将投资回收期和二氧化碳减排量作为指标,综合分析了不同流量下余压发电的经济与环境效益。【结果】在高运行流量2 200 m3/h下,液力透平发电装置能满足末站一天生活用电需求,且不会引发上游管路高点汽化,同时高流量下的动态投资回收期最短、二氧化碳减排量最大。即高运行流量可使得余压发电获得更好的经济性、更强的稳定性、更高的环境效益。在中低运行流量下,存在不能满足部分高峰用电需求的情况,且在无合理站场控制前提下,中低流量会引发上游管路高点发生汽化。经模拟分析比选,确定液力透平发电装置前调节阀宜选用低选(LS)的控制逻辑,可保障全流量工作范围内全线管路水力安全。【结论】该长输原油管道末站余压发电工艺具有可行性,在回收减压能量的同时可保证全线管路水力安全,且具有一定的经济和环境效益,可为长输原油管道的余压发电推广提供工程借鉴。

     

    Abstract: 【Objective】In the daily operation of long-distance crude oil pipelines, if there is residual pressure (surplus pressure) at the terminal station, it is usually necessary to reduce the pressure through a pressure reducing valve. During the pressure reduction process, a large amount of energy is wasted on the pressure reducing valve, and if the surplus pressure is large, it may also cause significant noise. The utilization of residual pressure in liquid pipelines is mostly applied in water transmission or chemical equipment pipelines at home and abroad, but there are few studies on the utilization of residual pressure in the field of long-distance crude oil pipelines. To achieve energy conservation and efficiency improvement in long-distance crude oil pipelines and enhance resource utilization, generating electricity from the residual pressure at the terminal station to supply the station's domestic electricity is a feasible approach. However, the technical feasibility of this process still needs to be thoroughly explored. 【Methods】This study first evaluated the potential for residual pressure power generation at an operational long-distance crude oil pipeline terminal station. Based on this assessment, installation of a hydraulic turbine in parallel with the existing pressure-reducing valve is proposed. Using the SPS simulator (SYNERGI PIPELINE SIMULATOR 10.4), the impact of operating the hydraulic turbine power generation unit at different flow rates on the hydraulic characteristics of the entire pipeline was analyzed. Emphasis was placed on changes in pressure throughout the pipeline and flow rate at the terminal station. A PID composite control system based on high-select/low-select (HS/LS) logic was compared to identify a control strategy that ensures hydraulic safety across the pipeline. This prevents hazardous conditions such as crude oil vaporization at upstream high points due to insufficient operating pressure after the hydraulic turbine unit is activated. Finally, the payback period and CO2 emission reduction were used as indicators to evaluate the economic and environmental benefits of residual pressure power generation under different flow conditions. 【Results】The results show that at a high operating flow rate of 2 200 m³/h, the hydraulic turbine power generation device can meet the daily electricity demand for living at the terminal station without causing vaporization at the high points of the upstream pipeline. Meanwhile, the dynamic investment payback period is the shortest and the carbon dioxide reduction is the largest under high flow conditions. This indicates that a high operating flow rate is conducive to achieving better economic efficiency, stronger stability, and higher environmental benefits for the pressure difference power generation. Under medium and low operating flow rates, there is a risk of not meeting some peak electricity demands, and without reasonable control at the station, medium and low flow rates may cause vaporization at the high points of the upstream pipeline. Through simulation analysis and comparison, it is determined that the control logic of the regulating valve before the hydraulic turbine power generation device should be set to low selection (LS) to ensure the hydraulic safety of the entire pipeline within the full flow range. 【Conclusion】The analysis conclusion indicates that the pressure recovery power generation process at the terminal station of the long-distance crude oil pipeline is feasible. It can not only recover the energy from pressure reduction but also ensure the hydraulic safety of the entire pipeline. Moreover, it has certain economic and environmental benefits. This can provide an important engineering reference for the application of hydraulic turbine power generation devices in long-distance crude oil pipelines to achieve pressure recovery power generation and improve energy utilization efficiency.

     

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