Flare gas recovery (FGR) is known as an option to reduce greenhouse gases (GHG) from oil and gas refineries. The major concerns about environmental impacts of GHG emission lead refineries to deploy different FGR methods, most of which requiring new equipment and high cost of design and construction. In this paper, feasibility of three methods for FGR is evaluated in a giant gas refinery in Iran. The first two methods considered liquefaction and LPG production by implementing flare gases as feed for existing LPG unit. Different parameters were studied in feed liquefaction and LPG production. The third studied option is using a three-stage compression unit to compress the flare gases. Finally, an economic evaluation was performed to find the most profitable method. Based on simulation results, the 0.75-barg pressure of flash drum leads to maximum LPG production. For FGR, the 1barg pressure of flash drum recovered the most CO2-equivalent from releasing into the atmosphere, which is more than 205 ton/day. The economic evaluation shows that rate of return (ROR) for liquefaction unit and LPG production unit are more than 200% for different scenarios and are higher than compression. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.