Nitrogen rejection processes are usually needed for two natural gas sources: sub-quality natural gas reserves and produced gas from enhanced oil/gas recovery technologies. The nitrogen content of natural gas in the former is usually constant during the project lifetime, but it varies from 5 to 70% during enhanced oil/gas recovery programs. This variation leads to different process flowsheets for nitrogen removal: single-column, double-column, three-column, and two-column processes. In order to determine which configuration is more suitable for a particular nitrogen content in a feed stream, we must minimize the energy requirement for each process. In this study, we merge all the four configurations into two categories: single-column and multi-column processes and then use the Particle Swarm Optimization algorithm to optimize process parameters for each process with the objective of energy consumption minimization. Finally, we use the exergy concept to analyze theoretically these different processes.

两种天然气来源通常需要采用脱氮工艺：劣质天然气储量和采用改进的油气回收技术生产的天然气。前者中天然气的氮含量通常在项目生命周期中保持恒定，但在提高油气采收率计划中，天然气的氮含量在5％至70％之间变化。这种变化导致脱氮的工艺流程不同：单塔，双塔，三塔和两塔工艺。为了确定哪种配置更适合进料流中的特定氮含量，我们必须使每个过程的能量需求最小化。在这项研究中，我们将所有四种配置合并为两类：单列和多列过程，然后使用粒子群优化算法为每个过程优化过程参数，以实现能耗最小化。最后，我们使用火用概念从理论上分析这些不同的过程。