Development and optimization of an integrated process configuration for natural gas liquefaction (LNG) and natural gas liquids (NGL) recovery with a nitrogen rejection unit (NRU)

In this study a novel integrated process including recovery of natural gas liquids, natural gas liquefaction and nitrogen rejection unit is investigated and analyzed. Natural gas is often associated with nitrogen and hydrocarbon heavy compounds. Recovering such heavy liquids can be necessary. Nitrogen of the natural gas when its content is more than 4 percent (mole fraction) must be removed. Because operating temperature of the LNG, NGL and NRU processes are lower than −100 °C there a good potential to integrate these processes. Process integration declines the energy consumption and number of the required equipment. The results show that the new integrated process has specific power of 0.359 (kWh/kg-LNG) and recover NGL more than 90%. Sensitivity analysis shows that this process is capable of eliminating nitrogen from the natural gas at a concentration of 4%-15%.