Title: Exergy destruction associated with maximising C₂ recovery in an existing NGL facility

Authors: Karim Gaber Zaki; Ahmed Fayez Nassar; Reem S. Ettouney; Mahmoud A. El-Rifai

Addresses: Cairo University, Street, Giza, 12612, Egypt ' Cairo University, Street, Giza, 12612, Egypt ' Cairo University, Street, Giza, 12612, Egypt ' Cairo University, Street, Giza, 12612, Egypt

Abstract: This study addresses increasing C₂ recovery in an existing NGL plant through a set of operating conditions modifications targeting the decrease of the demethaniser temperature. The CO₂ freezing problem associated with the reduction in temperature is first studied. Reducing the demethaniser pressure and temperatures of the low-temperature separator and reflux enabled to increase the C₂ recovery from 59% to 94% with an increase in energy consumption by 16.5 MW. This however required the addition of a sweetening unit and a consequent additional increase in energy consumption by 31.8 MW. The exergy destruction and efficiency associated with revamp were also studied.

Keywords: demethaniser; CO₂ freeze; C₂ recovery; NGL; exergy; simulation; retrofitting; cryogenic separation; cold energy recovery; thermal integration.

DOI: 10.1504/IJEX.2026.152055

International Journal of Exergy, 2026 Vol.49 No.3, pp.194 - 210

Received: 17 Mar 2025
Accepted: 10 Jun 2025
Published online: 04 Mar 2026 *

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