Thermo-Economic Evaluation of ORC System in Off-Shore Applications

This paper presents a study related with off-shore oil & gas production and processing facilities, where required energy, for electric power, mechanical power and process heat, is mostly produced using gas turbines, as the fuel source (natural gas) is available onsite. Since size and weight of all equipment on an offshore facility are critical, it becomes necessary for the facility engineering team to ensure that all equipment are sized and selected appropriately to obtain better return on the investment. Therefore, any approach which could help in utilizing energy resources effectively will influence the bottom-line of the project, namely reduced capital cost and/or increased return on investment. In this paper, one such approach of recovering power and thermal energy through the use of Organic Rankine Cycle system is discussed. A detailed thermo-economic analysis, conducted considering a system with four gas turbines operating, shows that power recovery equivalent to one topping gas turbine is achievable with a suitable working fluid. The presented thermo-economic analysis clearly shows that use of the Organic Rankine Cycle system for waste heat recovery is a technically viable and economically attractive solution for the offshore applications.