Producing Electrical Power in Addition of Heat in Natural Gas Pressure Drop Stations by ICE

Abstract

Natural gas (NG) must be preheated before pressure reduction takes places at City Gate Stations (CGS). It ensures that gas remains above the hydrateformation zone and dew point, so no pipeline blockage occurs. The preheating consumes a considerable amount of NG as fuel. In order to operate the CGS more efficiently, a new idea is proposed in this study. The idea is to utilize a Combined Heat and Power (CHP) system in which an Internal Combustion Engine (ICE) acts as a prime mover. The ICE is driving a generator in addition of providing heat for preheating NG. To show the advantage of the proposed system, Mashhad CGS has been chosen as a case study. Results show that a CHP system with two 2.8 MW ICEs is the most appropriate system. The system has the minimum fuel consumption and payback period. Based on the Iranian natural gas consumption of 377 × 10 6 (m 3 /day) and by assuming the similar conditions for the other CGSs in Iran, the total amount of extractable electrical power from the CHP systems is predicted to be nearly 91.5 MW. That is equivalent to 802.14 GW.hr/year in 2010 with a yearly benefit about 45 million dollars. According to average annual growing rate of 2.4% of gas consumption in Iran, the predictions are performed until 2035.Keywords: Natural gas city gate station; Combined heat and power (CHP); Internal Combustion Engine; Optimization; Economic analysis LIST OF SYMBOLS dMarket interest rate (%) DPB Discounted payback ratio (year)