Landfill gas (LFG) produced from municipal solid waste substrates represents an important source of RNG and the market for its upgrade is facing significant challenges in terms of energy consumption and operating costs. To ensure higher CH₄ yields and avoid its release in the atmosphere, the LFG is collected below the atmospheric pressure by the use of a vacuum pump that results in the contamination of the LFG by air and particularly N₂. Most of the proposed solutions, propose a two-step separation process in which the CO₂ removal takes place in the first one while N₂ removal in the second. This study focuses on the removal of the N₂ from a decarbonated methane stream by a four-step PSA cycle. The impact of several parameters on process performance has been investigated using numerical simulations with the aim of simplifying the unit design and operational performances. In particular we investigate the effect of the pressure at the end of the desorption step showing that it is possible to operate the cycle with the desorption pressure slightly above atmospheric one. This allows avoiding the use of a dedicated vacuum pump with, however, a penalty in the energy required.

由市政固体废物底物产生的垃圾填埋气（LFG）代表了RNG的重要来源，其升级市场在能源消耗和运营成本方面面临着严峻的挑战。为了确保较高的CH ₄收率并避免其在大气中释放，通过使用真空泵将LFG收集到大气压以下，这会导致LFG受到空气特别是N ₂的污染。大多数提出的解决方案都提出了一个两步分离过程，其中在第一个过程中发生了CO _2的去除，而在第二个过程中发生了N _2的去除。这项研究的重点是去除N ₂通过四步PSA循环从脱碳甲烷流中分离出甲烷。为了简化单元设计和操作性能，已经使用数值模拟研究了几个参数对过程性能的影响。特别地，我们研究了解吸步骤结束时压力的影响，结果表明可以在略高于大气压的解吸压力下操作该循环。这样可以避免使用专用的真空泵，但是会消耗所需的能量。