Economic investigation of replacing high-pressure pipelinewith low-pressure one in fourth main gas pipeline of Iran

Nowadays, transmitting hydrocarbon gases for consumption as a clean fuel in pipeline is common but very expensive. Certainly, in competition market reducing production cost is very important. Two important parameters affecting the transmitting costs are pipeline and compressor station costs, which include purchase, installing and maintenance costs that a little change in those makes evident change in investment cost. Natural gas transmission cost can be decreased by choosing smaller diameter pipeline and increasing operating pressure at constant flow rate, simultaneously. Higher pressure can more compress the gases to occupy less volume that reduce necessary power of compressors, but it needs thicker pipeline. Although pipe cost decreases with smaller pipe diameter but it increases with thickening the pipe. These opposite effects should be considered simultaneously. This paper investigates economically replacing high-pressure small diameter pipeline with low-pressure large diameter one in case of fourth main gas pipeline of Iran (IGAT4). 1305 psia and 2500 psia as low and high inlet pressures respectively in a range of common pipe diameter between 36 to 64 inches have been investigated to specify the best economic case. Results show that 48 inches high-pressure pipeline has the lowest total capital investment and it is economical than currently designed pipeline (56 inches, low-pressure).

Keywords:

Economic , IGAT4 , Natural gas , Pipeline , Transmission