A PERFORMANCE STUDY FOR WESTERN DESERT GAS COMPLEX (WDGC) UNDER VARIOUS FEED CONDITIONS
Abo El-Nasr Mahran, Abd El-Rahman Sayed
Egyptian Natural Gas Company (GASCO) Cairo – Egypt
Email: abonasr_mahran@gasco.com.eg , arahman_sayed@gasco.com.eg
ABSTRACT
The train-C at Western Desert Gas Complex (WDGC) is NGLs (Natural Gas Liquids) recovery train located in Alexandria – Egypt. The train-C employs a mix of Refrigeration and Turbo-expander technologies as a Gas Sub-cooled Process (GSP) to NGL/LPG recoveries with fractionating the raw gas into residue gas, ethane/Propane Mixture, Propane, LPG, and Condensates products based upon boiling point differences. The train-C handles 300 MMSCFD and designed to maximize the recovery of produced Ethane and Propane mixture.
The plant’s feed Gas composition & conditions at train-C is changing over time which leads to make changes in plant operating conditions. Feed gas pressure decreased to 66 Kg/cm2 compared with 70.5 Kg/cm2 in design , an increase in feed CO2 content to be 4.8% instead of 3.7% and also an increase in feed methane (C1) content to be 82% instead of 79% which caused decrease Ethane/ Propane recoveries in current actual operating conditions.
In this paper, the train-C is simulated using a steady state simulator (Aspen HYSYS) & Peng–Robinson (PR) equation of state (EoS) considering Equipment’s design data and products specifications. The simulation was made with a number of possibilities options and optimizations can be done to produce additional C2 with/without simple retrofitting plant’s equipment’s & facilities. Heat integration with narrow minimum temperature approach for heat exchangers, reducing De-methanizer column pressure and change split going to the sub-cooler exchanger / turbo-expander are studied, few enhancement to ethane recovery is occurred. With installing new vessel to separate GSP stream leaded to decreasing vapor load in the upper section of De-methanizer which increased ethane recovery to acceptable level.
Keywords: – NGLs, GSP, Ethane recovery, Refrigeration technology, Turbo-expander technology