The feasibility study, exergy, and exergoeconomic analyses of a novel flare gas recovery system

Abstract

One of the challenging issues that has always attracted the attention of the experts is how to control and reduce greenhouse gas emissions because of their overwhelming negative environmental impacts. Although burning the hazardous gaseous products in the flare systems boosts the safety of gas and oil fields and diminishes the internal pressure of the extraction systems, it has a catastrophic impact on the surrounding environment. In this study, a new system was designed to recover flare gas. In this system, ejectors and compressors are used in parallel to compress flare gas. One of the aims of this system is to minimize environmental disadvantages and prevent the waste of national capital. The described system is firstly simulated using the HYSYS software based on Peng–Robinson state equations. The efficiency and exergy destruction can be calculated through exergy analysis, which is the second step in the process. Finally, by considering investment and fuel cost to each exergy flow, exergoeconomic analysis was evaluated. From the exergy analysis results, it can be concluded that the ejectors have the highest exergy efficiency (99.87%) compared with other devices in the process, and their total exergy destruction rate is 8458.35 kW. Findings from exergoeconomic analysis suggest that the highest exergy destruction cost for flare system is associated with EJ-3 ejector which is 89.01 USD/h. Furthermore, a sensitivity analysis was applied to specify the dependency of the exergy and exergoeconomic results of this process on the flow rate of recovered gas and flare gas pressure as important input plant feed parameters. By this study, we aim to evaluate the feasibility of the implementation of this system in an industrial plant.