Effect of reducing the pressure of the gas distribution network on the rate of gas loss, exergy destruction and network stability

Natural Gas (NG) is transported from producing regions to consumption regions by using transmission pipelines at high pressures. At consumption regions, the pressure of natural gas is dropped to 250 psi in City Gate Station (CGS). Then in Town Border Station (TBS), by reducing the pressure to 60 psi, gas is injected into the transmission lines. In the present study, the effect of reducing the pressure of the gas distribution network to less than 60 psi on the rate of gas loss, exergy destruction and network stability is studied. The experimental data has been measured for the city of Islamieh in South Khorasan province. Results show that by reducing the pressure from 60 psi to 30 psi, the rate of gas loss in winter and summer periods decreased by 35% and 73%, respectively. In addition, the maximum exergy destruction at a pressure of 60 psi occurs in the home regulators which cannot be recoverable. While at pressures below 60 psi, the greatest exergy destruction is occurred at the TBS. Therefore, at low pressures, the irreversibility can be reduced by installing a turbo expander instead of throttling valve. By examining the stability of the network, the reduction of distribution line pressure to 30 psi is proposed to the National Gas Company.