Abstract
Natural gas is carried through transit pipelines at high pressure (5–7 MPa) from production sites to consuming points. In the place of consumption or crossing into a lower pressure pipeline, the pressure of the gas must be decreased. This pressure reduction occurs in places named city gate stations (CGS) as the gas passes through throttling valves. The gas must be heated before it enters throttle valves to ensure that it remains above the hydrate formation zone and dew point so that no liquid or solid phase condenses at the output temperature. Currently, in all of Iran’s CGSs, the gas is preheated through bath type heat exchangers (known as line heater), which burn a portion of the gas for providing heating duty to warm up the natural gas. As a low temperature heat is required for preheating the natural gas in a CGS, a solar collector array is proposed to be utilised in the CGS in order to displace the heating duty of the heater and to reduce the amount of fuel consumption. The proposition includes a modified design of an in use CGS to take advantage of freely available solar heat.
This work was supported by the Mazandaran Gas Company.