NATURAL GAS LEAK FROM UNDERGROUND PIPELINE

Abstract

Natural Gas (NG) accidents occur from either above or underground pipelines, resulting in financial losses, global greenhouse effect, and deaths when accidents occur in urban areas. This research investigates the fluid flow and mass flow rate of leaked natural gas from the underground pipeline in the porous medium of soil using two groups of computational fluid dynamics simulations. The first group of CFD simulations is used to be compared with the miniature-sized testbed experiments. The second group of CFD simulations is designed and executed for the actual field of buried natural gas pipelines to test the real situation of the leaked natural gas in porous soil media. For each run, the inlet site velocity is used as an adjustable parameter to test different mass flow rates with respect to the real soil conditions. The simulations and the miniature-sized testbed experiments show good agreements for the concentration evolution of the model gas for three different mass flow rates. For the actual field model, different leak rates, i.e., 10 mg/s, 100 mg/s, and 1000 at a soil permeability of 10-15 m2 are studied and compared. In addition, different soil permeabilities in the range of 10-14 m2 and 10-16 m2 are studied at a constant mass flow rate, and the results show the non-monotonic behavior of the CH4 mole fraction. Furthermore, constant wind speed and random wind are tested for the actual natural gas model.