Analysis and structure optimization of jetting pigging robot for black powder removal process in subsea nature gas pipeline

Over extended periods of operation, natural gas pipelines tend to accumulate significant amounts of black powder impurities along their inner walls. Many of these impurities exhibit corrosive properties, leading to pipeline degradation and posing a serious threat to the safety and reliability of energy transportation. The jet pigging robot also called as jet pig, a type of pigging robots, has been developed to address pipeline impurities. The conventional approach involves using a pigging robot to perform cleaning operations inside the pipeline. However, the speed of traditional pigging robots is difficult to control, often leading to safety risks such as blockages and reduced cleaning efficiency, as well as increased operational costs. In contrast, the jet pigging robot, equipped with a jet nozzle, emits a high-speed jet stream that effectively dislodges black powder particles, mitigating issues related to safety, efficiency, and cost. Therefore, optimizing the design of the jet pigging robot for black powder removal is of great significance. This study proposes a novel pigging robot jet structure and optimizes its dimensions using finite element simulation. The effects of key geometric parameters on flow velocity and turbulent kinetic energy are investigated. Simulation results indicate that a jet structure with a sealing disk hole inclination angle of 40° and a baffle spacing of 18 mm demonstrates effective wall-cleaning performance. At a bypass ratio of 9%, the structure exhibits high cleaning efficiency, while at a bypass ratio of 12%, it enhances operational safety and reduces the risk of blockages.