Flare gas recovery by liquid ring compressors-system design and simulation

Abstract

Flare gas emission is a critical issue in the oil and gas industry due to its significant environmental impacts. While there are currently available solutions that can minimize the environmental risks of such emission sources, the implementation of these technologies generally brings additional economic and environmental challenges. Among the available technologies, the liquid ring compressor (LRC) is a promising option as it can compress and treat the flare gas simultaneously. However, there are several fundamental questions regarding the best operating conditions as well as the appropriate integration of such devices into a flare gas recovery system. This paper deals with the design of a flare gas recovery system consisting of liquid ring compressors and an aqueous amine solvent for the abatement of acid gases, mainly hydrogen sulfide. Three different system configurations are investigated to find the optimal system layout for the efficient and continuous recovery of flare gas in a refinery complex. In the first configuration, a simple compressor arrangement is considered without an amine recycling line between the compression stages. The second configuration involves an amine recycling line between the compression stages. Appropriate heat exchangers are added to cool down the amine recycling line in all compression stages in the last configuration. Results show that the amine consumption in the third configuration is 67% and 44% lower than the amine consumption in the first and second configuration, respectively. However, due to the additional cooling duty, the total required power in the third configuration increases by about 58% and 53% compared to the first and second configurations, respectively.