A case study on suspended particles in a natural gas urban transmission and distribution network

Suspended particles are well known to cause serious problems in natural gas pipelines and related equipment. In this study, suspended particles in the natural gas transmission and distribution network of the city of Kerman, Iran were investigated. Particle concentration and size distribution were measured, under isokinetic conditions, in different locations of the natural gas pipeline network. The particle samplings were carried out in two seasons: summer, when there is the lowest consumption, and winter, when there is the highest consumption of urban natural gas in the year. Additional particle characterization was carried out by scanning electron microscopy coupled with energy dispersion X-ray (SEM/EDX) and X-ray diffraction (XRD) analyses. The particle concentration was found to be significantly higher in winter months as compared to summer. The approximate range of particle concentrations in summer was from 0.12 at the end of the pipeline to 4.7 at the network entrance, and from 0.30 to 22.1 in winter. The particle size distribution showed a higher frequency of smaller particles in winter than in summer season. Larger particles were more likely to exist at the network entrance as compared to the network pipeline exit. The results showed that the average particle size ranged from 181 µm at the network end to 253 µm at the entrance in summer, and from 74 µm to 209 µm in winter. The filtration performance was found to be rather inefficient according to the particle concentration in the natural gas flow, although it decreased along the pipeline to the end of the network. The results of particle characterization confirmed the presence of corrosion products in the suspended particles.