Julio Augusto Mendes da Silva

ENERGY AND EXERGY PERFORMANCE OF THREE FPSO OPERATIONAL MODES

Floating, Production, Storage and Offloading (FPSO) is a floating facility used in primary petroleum processing. In Brazil, most FPSOs have been installed in Campos Basin and new facilities may be implemented in the pre-salt area are projected to boost the Brazilian oil production. Crude oil composition has a significant influence on the operational mode of the FPSO. In this study, three operational modes of a FPSO are assessed: the first mode is used when the crude oil has the maximum water and CO2 contents, the second mode is implemented for a composition of 50% basic sediment and water (BSW) in the crude oil, and the third mode is operated when the crude oil has the maximum oil and gas fractions. The FPSO facility configuration changes with the operational mode, and it is possible to have gas export, gas injection, and CO2 injection, in order to achieve the functional conditions established by the FPSO operator. Energy and exergy criteria have been applied to evaluate and compare the performance of components and systems of the three operational modes of the FPSO. The processing and utilities plants have been modeled and simulated by using Aspen HYSYS. Results indicate that higher oil content in the crude oil increases the power consumption, the exergy requirement and the destroyed exergy of the FPSO.

ON THE EXERGY DETERMINATION FOR PETROLEUM FRACTIONS AND SEPARATION PROCESSES EFFICIENCY

Petroleum separation processes are intensive in exergy use. However, only a very small fraction of the consumed exergy is converted into products. Due to the significant magnitude difference between consumed exergy and processed exergy, as well as to the unknown molecular structure of the involved streams, the calculation of specific exergy and of exergy efficiency is a delicate topic that involves significant uncertainties. Comparison and explanation of five different ways to perform exergy evaluation of petroleum separation processes are conducted. The indication of advantages and disadvantages of each formulation is presented. The chemical and physical exergy calculation for petroleum and its fractions are covered. An application is performed and the results are discussed.

Carbon footprints for the supply of electricity to a heat pump: Solar energy vs. electric grid

The carbon footprint is one of the most commonly employed environmental indicators used to evaluate the environmental impacts associated with a process or a product. The energy sector is responsible for more greenhouse gas emissions than any other sector. This has raised concerns about the consequences of the high consumption of non-renewable resources and increased the search for renewable energy sources. Renewable energy sources, such as photovoltaic solar energy, enable diversification of the global energy system. In this study, a comparative environmental analysis was performed for a heat pump utilized for dehumidification and heating purposes. The carbon footprints associated with two different scenarios for the supply of electricity to a heat pump were calculated. The first scenario used electricity from the national electric grid (Brazilian electricity mix), and the second scenario used electricity from a photovoltaic solar energy system connected to the grid. Photovoltaic solar energy presented a ...

Application of Thermoeconomics for CO2 Allocation for Net Power and Useful Heat in a Gas Turbine Cogeneration System

Thermoeconomics is a discipline that connects Thermodynamics and Economics concepts, usually used for rational cost assessment of the final products of a thermal plant, by means of a model which describes the cost formation process of the overall system. Generally, exergy or monetary costs of the external resources are distributed to the final products. However, environmental consideration can be incorporated in the models to calculate the environmental costs, such as specific CO2 emission of each final product. This work aims at demonstrating how the thermoeconomic models can be adapted or modified in order to allocate the overall CO2 emission of a gas turbine cogeneration system to the final products (net power and useful heat), in order to determine the specific CO2 emission (g/kWh) of each product. This subject is an important step in the applications of Life Cycle Assessment in plants with two or more products and also to quantify the environmental cogeneration advantage. It also reveals that any thermoeconomic model can be adapted for allocation of the overall CO2 emissions or any other pollutant to the final products of a multi-product plant.