段塞流捕集器控制系统方案研究

Schematic study on control system of slug catcher

多相混输管线在海上油气输送领域的应用越来越广泛,为了控制多相混输过程中产生的段塞流而引起的捕集器内液位和压力波动,本研究基于某海上气田混输管线实际工况,利用OLGA软件建立了该气田混输管线及段塞流捕集器混输过程多相流动仿真模型,在此基础上设计了单回路控制、选择性控制、前馈-反馈选择性控制等3种控制系统方案,并从系统的跟踪性能展开分析,对比了不同控制系统捕集器液位、压力及液相出口流量的闭环响应曲线,结果表明,前馈-反馈选择性系统在动态阶段由于前馈回路的存在,曲线的过渡过程最短,波动最小,且进入稳态后的曲线表现最为平稳,故推荐选用前馈-反馈选择性控制作为目标气田段塞流捕集器的控制方案。采用该方案可及时有效地稳定捕集器的液位及压力,并带有捕集器液位及出口管线流量防超限功能,能很好地满足实际安全生产要求。本文为多相混输过程中段塞流捕集器控制系统的设计提供了借鉴。

Multiphase mixed pipeline is more and more widely used in offshore oil and gas transportation.In order to control liquid level and pressure fluctuation in slug catcher caused by slugging flow during multiphase mixed transportation,based on the actual working condition of a mixed pipeline in an offshore gas field,the multiphase flow simulation model of mixed pipeline and slug catcher in this gas field is established by OLGA software,and on this basis,single-loop control,override control,and feedforward-feedback override control in the slug catcher are designed.Three control system schemes are analyzed from the tracking performance of the system.The closed-loop response curves of liquid level,pressure and liquid outlet flow of catcher in different control systems are compared.The results show that the curve of feedforward-feedback override system has the shortest transition process and the smallest fluctuation in the dynamic stage due to the existence of feed-forward loop,and the curve shows the most stable performance after entering the steady state.Therefore,feedforward-feedback override control is recommended as the optimal control scheme of slug catcher in the target gas field.With this scheme,the liquid level and pressure of the catcher can be stabilized timely and effectively,and the fluid level of the catcher and the flow rate of the outlet pipeline can be controlled within the limitations,which can well meet the actual production safety requirements.This paper provides a reference for the design of slug catcher control system in multiphase mixed transportation.