The conventional process employed for the removal of N₂ in a natural gas upgrading facility is cryogenic distillation (CD) and entails a significant investment outlay. Operation of the CD unit occurs at approximately 40 bar and − 120 °C, provided by a suitable refrigeration system. At such a low temperature, significant pre-treatment of the feed gas is required to prevent hydrate formation, solidification of CO₂ and heat exchanger corrosion damage from mercury. In the current study, the conventional nitrogen removal unit (NRU) using CD is compared to the use of an optimized 9-step pressure vacuum swing adsorption (PVSA) detailed process model employing a Takeda carbon molecular sieve as the adsorbent. The PVSA unit preferentially adsorbs N₂ based upon kinetic selectivity of the carbon molecular sieve. Nitrogen rejection by PVSA allows a higher tolerance to the contaminant levels over CD. The impact of this advantage on the overall performance of the entire natural gas upgrading process is evaluated by analysing, in HYSYS, the unit operations upstream and downstream of the CD unit. By employing dimethylethanolamine solvent for acid gas scrubbing and relocating the C₂₊ fractionation unit upstream of the NRU, the natural gas upgrading process is shown to be more profitable for the production of pipeline gas from raw natural gas at flow rates of up to 40 MMscfd (versus the currently accepted breakeven at 15 MMscfd) using PVSA instead of CD for the NRU.

在天然气提质设备中用于除去N ₂的常规方法是低温蒸馏（CD），需要大量的投资。CD单元的运行在约40 bar和− 120°C的温度下进行，由合适的制冷系统提供。在这样的低温下，需要对进料气进行大量的预处理，以防止水合物的形成，CO _2的固化和热交换器对汞的腐蚀破坏。在当前的研究中，使用CD的传统脱氮装置（NRU）与采用武田碳分子筛作为吸附剂的优化的9步变压真空吸附（PVSA）详细过程模型的使用进行了比较。PVSA单元优先吸附N ₂基于碳分子筛的动力学选择性。PVSA的脱氮功能可以使CD上的污染物含量更高。通过在HYSYS中分析CD装置上游和下游的装置操作，可以评估此​​优势对整个天然气提质过程的整体性能的影响。通过使用二甲基乙醇胺溶剂进行酸性气体洗涤，并将C ₂₊分馏单元重新放置在NRU的上游，天然气提纯工艺对于从原始天然气中以最高40 MMscfd的流量生产管道气显示出更大的收益。 （相对于当前接受的15 MMscfd收支平衡），对于NRU，使用PVSA而不是CD。