An analysis of the changes of the composition of natural gas transported in high-pressure gas pipelines

Natural gas consumption in Poland in the last few years equaled to about 15 billion m3. About 67–71% of annual gas consumption was covered by import, whereas the remaining 29–33% came from home production. The basic element providing energy safety of each country is proper diversifi cation of sources and directions of deliveries. In the case of natural gas the most important factor is the properly developed transport infrastructure. With the increased predicted natural gas deliveries to Poland, the national pipeline network started to dynamically develop. It began from the construction of connections between systems, the main tasks of which was the integration of Europe’s natural gas markets, through parallel investments in the transport and distribution, and fi nishing with the construction and development of underground gas storages. Stabilized, high methane natural gas is delivered to Poland, though with the increasing natural gas import from other directions than east one could expect gas of a diff erent composition. This stems from the fact that the Europe’s market is serviced by various gas suppliers, i.e. from deposits localized in diff erent regions of the world. Gas composition depends on its source and has a decisive infl uence on the thermodynamic and hydraulic properties. The content of heavy hydrocarbon gases increases the calorifi c value of the gaseous fuel, whereas the high content of inorganic components lowers the amount of energy obtained in the course of natural gas combustion; as a side eff ect, environmentally hazardous chemical compounds are formed. As far as gas transport is concerned, too high content of heavy hydrocarbon gases (propane, butane, pentane) is disadvantageous. In high pressure conditions the C3–C5 class gases