Processo Integrado para Produção de H2 Offshore via Reforma a Vapor de Metano com Captura de CO2

Abstract

The hydrogen production from steam methane reforming (SMR) with carbon capture, blue H2, is considered a transition route to the exclusive green H2 production. Blue H2 can be supplied on a large scale by improving existing technologies, adopting new technologies, or integrating the processes involved. Offshore H2 production has advantages in relation the availability of natural gas and water, and the possibility of capturing and injecting CO2 into mature oil production wells (CCS). The objective of this work is to evaluate and compare the offshore H2 production from an energy and CO2 emission point of view by steam methane reforming with carbon capture by chemical absorption and by supersonic separation. A model for the integrated system involving the processes of H2 production, seawater desalination, carbon capture and CO2 compression was developed and simulated using Aspen Plus® and Hysys® software. The results were verified using data from the literature. From the mass and energy balances, was possible to quantify the thermal and electrical demands of the processes and a simplified utility plant was used to produce the demanded streams. The integrated process of converting natural gas into H2 using chemical absorption for carbon capture, seawater desalinization and CO2 compression presented an efficiency of 49%, considerably lower than the efficiency obtained by the integrated system using supersonic separation (69%). Considering the specific CO2 emission factor of the whole integrated H2 production system, 8.13 kgCO2/kgH2 was obtained with chemical absorption and 4.56 kgCO2/kgH2 using supersonic separation. The CO2 emission from the direct use of methane (56.10 kgCO2/MJGN) is lower than the CO2 emission from the H2 generated in the integrated offshore H2 production system via SMR with carbon capture by chemical absorption (67.71 kgCO2/MJH2) and higher than the CO2 emission from the integrated system with supersonic separation (37.97 kgCO2/MJH2). Was observed that the specific energy consumption of the chemical absorption process is 50% higher than that of supersonic separation, because chemical absorption is supplied by a large thermal demand. In terms of natural gas consumption in the integrated system, using supersonic separation required 50% less fuel than adopting chemical absorption. Therefore, the developed analyses indicated that the supersonic separation technology presents lower energy consumption, reduced CO2 emissions, besides presenting advantages associated with its modularity and better use of space, favoring its installation on offshore platforms.