Aspen HYSYS-based Modeling of Liquefied Natural Gas Production from an Indigenous Natural Gas Source

Pakistan is currently facing a serious energy shortage due to a lack of domestic technology and local expertise in key engineering fields. Pakistan contains rich natural gas reserves. Most natural gas contains a high percentage of light hydrocarbons and low percentages of carbon dioxide and nitrogen. Natural gas liquids are hydrocarbons that alter the hydrocarbon dew point (HCDP) of natural gas. Therefore, to raise the hydrocarbon dew points and generate revenue, these hydrocarbon dew points must be removed before further transportation. In this study, a steady-state, single-stage industrial process model was developed to remove natural gas liquids (NGLs) from natural gas. Process flow diagrams (PFDs) for two ISS configurations, the turbine expander (TE) and the gas subcooling process (GSCP), are integrated into the Aspen HYSYS V10 standard process simulator. The program uses the Peng-Robinson formula of state as the fluid package. The performance of the two processes was evaluated based on three different natural gas sources: Sohi, Qadirpur, and Zamzam. Based on feed composition. The effects of feed flow rate, input temperature, and pressure were studied. An economic and cost assessment of these two operations was also performed. The HHV values of NGL generated from Qadirpur, Zamzama, and Sui gas in TE configuration are 1.38 ×106, 1.51×106 and 2.3×106KJ/kgmole KJ/kg.mol, respectively. The HHV values of the return gas in TE configuration at Qadirpur, Zamzama, and Sui were estimated to be 7.68×105, 6.78×105, and 8.53×105KJ/kg.mol, respectively. Feed pressure significantly affects the production of natural gas liquids and electricity requirements. It was noticed that the production of NGL increased non-linearly with increasing input pressure. The GSCP configuration led by Sui shows the highest capital cost of $12.1 million, while the TE configuration led by Zamzama shows the lowest capital cost of $11.4 million.