Energy and exergoeconomic analysis of the gas compression station: A case study

The aim of this study is to improve the gas turbine operating conditions, used in the gas compression station of Marand, from the energy, exergy and economic points. The most important problems of these turbines are the low thermal efficiency due to the high heat losses, consuming large amounts of natural gas at the gas turbine start-up time in the starter system, turbine dependence on external electrical energy sources, as well as the high costs of fuel supply for the turbine and power consumption in auxiliary equipments. In this study the application of heat recovery steam generator to reduce the heat losses and increase the efficiency of combined cycle besides the replacement of the inefficient existing starting system are suggested. Furthermore, the effects of inlet air temperature, load, pinch point and steam injection to the turbine combustor are investigated in the energy and exergy balance equations and the unit exergy cost rates. Moreover, the costs related to the start up of a gas turbine, the fuel consumption and electrical energy are estimated. Results reveal that suggestive system not only can make the gas compression station independent from the external energy sources, but it also can reinforce the efficiency of the system and reduce the carrying costs. As with the 0.5 kg.s(-1) steam injection to the combustion chamber of the gas turbine, at the inlet air temperature of 288 K and the pinch point of 10 K, the efficiency of the combined cycle increases 5 percent. Also the economic saving of this suggested system is about 79.68 dollars per each functional hour of the gas turbine and for the station running in its full load and design condition the amount of economic savings will exceed to 247 000 dollars in month.