Exergoeconomic Analysis of a Cogeneration Plant on a Brazilian Pre-Salt FPSO Considering Different Fuel Gas Compositions

Rodrigo Dias¹; Waldyr Luiz Ribeiro Gallo¹

¹ State University of Campinas

Baixar PDF doi:10.20906/CPS/CILAMCE2015-0174

Resumo

Natural gas has often been used as a power supply in oil platforms due to its abundance and flexibility. Nowadays, major concerns over enviromental issues, and consequently, efficiency of energy conversion have taken the analysis to the next level, which relates strongly with the rational consumption of fossil fuels, such as natural gas, because of the low efficiencies yet experienced. The goal of this work is to provide a complete analysis of a cogeneration plant at a Brazilian pre-salt oil offshore platform composed of four gas turbines for power generation (100 MW installed) and heat exchangers fed by the exhaust gases, transferring recovered energy to process water; this picture of the plant shows an efficiency of only around 55%, which is very low for cogeneration. To accomplish that, an exergetic and thermoeconomic analysis will be essential in order to point out where the most part of irreversibilities are generated and the most costly flows are located, in energetic or monetary terms, despite of presenting the allocation of CO2 emissions between heat and power. The analysis will be extended to two cases of fuel composition, according to the local characteristics of the field and the period of production.

Palavras-chave: Exergy; Thermoeconomics; Natural Gas; Cogeneration