Design of natural gas pipeline purging pig based on Venturi principle

In the pigging process of the natural gas pipelines with more dust and impurities, the conventional mechanical pigs are usually faced with some problems. For example, cups and bristles are worn and deformed seriously and the pigging efficiency is low. In this paper, the pipeline with the characteristics of Venturi principle is integrated with the framework of pig in structural design according to the Venturi principle. Meanwhile, the corresponding guide support plate, seal drive cup, front purge nozzle and other important parts were designed. Then, the design scheme on this advanced pig was put forward. Finally, the computational fluid dynamics (CFD) method was used to simulate and analyze the pigging effect of this newly designed pig under the working conditions. It is shown that by virtue of Venturi principle, this pig can purge and swab the impurities in the pipeline section between two cups. In addition, high-speed jet from the front purge nozzle can form a full-coverage column purge area in front of the pig. And the purge speed is high enough to purge and carry the dust and impurities with the particle diameter less than 2.5 mm. Therefore, the pigging effect is good. The implementation of this design scheme is of great practical significance and value to improve the level of research and development and design technology of unconventional pig in China, promote the improvement of pigging efficiency of in-service natural gas pipelines and diversify the pigging methods.