Research on the application of magnetic separation technology for the removal of black powder in natural gas pipelines

Objective Black powder, primarily composed of magnetic corrosion products, accumulates in natural gas pipelines, causing various issues when its concentrations exceed specific limits, including frequent blockages of filter elements and abnormal shutdowns of compressors. This paper explores methods for applying magnetic separation technology to effectively separate magnetic particles, which is significant for ensuring the safe, stable, and efficient operation of natural gas pipeline networks.

Methods A three-dimensional model was developed using the finite element simulation software COMSOL to replicate magnetic system matrices. A parametric scanning technique was employed to investigate interactions among multiple magnetic systems under various layouts. A subsequent quantitative analysis was conducted by varying magnetic spacings to examine the magnetic field distribution patterns of the matrices at different positions within the magnetic separators. Furthermore, the results were utilized to optimize layout parameters for the magnetic system matrices. Additionally, an experimental platform was established to test the separation efficiency of the magnetic systems under different matrix layout parameters and to validate the simulation results.

Results As the spacing of magnetic systems increased, the magnetic induction at the corresponding position of the magnetic conduction block diminished due to the repulsive effect between like poles. Conversely, the magnetic induction at the position of the Nd-Fe-B magnet increased because of the superposition of magnetic fields. When the spacing of magnetic systems varied from 35 mm to 85 mm, the average magnetic induction generated by the magnetic system matrices initially increased and then decreased. The separation efficiency of the magnetic matrices was found to be proportional to the average magnetic induction when the matrices were employed to trap magnetic particles. At a spacing of 65 mm, the average magnetic induction of the magnetic systems and the spatial volume covered by the stronger magnetic field within the magnetic separators reached their respective maxima, measuring 6.76 × 10⁻² T and 12.7 × 10⁵ mm³, which corresponded to the highest separation efficiency of the magnetic system matrix at 80.37％. These results highlight the optimal structural parameters of the magnetic system matrix.

Conclusion The optimized magnetic matrix is effective in capturing magnetic corrosion products within natural gas pipelines, thereby extending the service life of filtration and separation equipment. This optimization contributes to a significant reduction in the operational and maintenance costs of natural gas transmission stations, making the resulting matrix promising for large-scale engineering applications.