Nowadays, the world energy production is still based on the exploitation of fossil fuels, mainly oil, coal, and natural gas, responsible for large greenhouse emissions in the environment. According to the measures proposed by the European Green Deal to meet the carbon neutrality by 2050, the decarbonisation of the energy production processes represents a top priority. Hydrogen represents a carbon-free energy carrier, useful to drive the society toward a decarbonized-economy. The novelty of this work is represented by the experimental generation of clean hydrogen by a two stages plant constituted of a biogas/biomethane steam reformer and a Pd-Ag membrane separator, meanwhile applying on this simple case the methodology of the exergy analysis, identifying the main losses and suggesting improvements. Hence, it deals with the exergy analysis of the whole system with the process intensification operated by the membrane separator adopted instead of using several stages to separate/purify hydrogen − as conventionally done after the reforming stage (two water gas shift reactors, high and low temperature, followed by a pressure swing adsorption stage) − with the objective of recovering decarbonized hydrogen coming from the biogas/biomethane steam reformer, meeting the European targets indicated by the Clean Hydrogen Alliance. This approach allowed to understand the amount of irreversibilities present in such a system as well as how the thermal efficiency may be influenced by a number of parameters, constituting globally a baseline for the scaling up of this process technology from lab to bench/pilot scale. The best results of this work highlight that the utilization of biomethane in the feed stream to generate hydrogen resulted to be a better choice than biogas in terms of thermal efficiency (based on the lower heating value) of the whole system, equal to 73 % at 773 K, while the highest percentage of exergy destruction was concentrated in the condensation stage, with values varying between 76 % and 93 %, depending on the feed stream typology. The two stages system was able to meet the “decarbonized hydrogen production target 2027”, with a hydrogen recovery of 90 % and a purity of 99.9999 %. Last but not least, the overall exergy destroyed efficiency of the overall system in the two analyzed cases was 92 % (biomethane feed stream) and 88 % (biogas feed stream), respectively.

中文翻译：

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用于沼气/生物甲烷脱碳制氢的重整器 + 膜分离器装置：结合能源效率和火用分析的实验研究


如今，世界能源生产仍然以石油、煤炭和天然气等化石燃料的开采为基础，造成环境中大量温室气体排放。根据欧洲绿色协议提出的到2050年实现碳中和的措施，能源生产过程的脱碳是当务之急。氢代表一种无碳能源载体，有助于推动社会走向脱碳经济。这项工作的新颖性体现在由沼气/生物甲烷蒸汽重整器和 Pd-Ag 膜分离器组成的两级装置实验性产生清洁氢气，同时在这个简单的案例中应用了火用分析的方法，确定了主要损失和改进建议。因此，它处理整个系统的火用分析，采用膜分离器操作的过程强化，而不是像重整阶段之后传统的那样使用多个阶段来分离/纯化氢气（两个水煤气变换反应器，高和低）温度，然后是变压吸附阶段） - 目的是回收来自沼气/生物甲烷蒸汽重整器的脱碳氢，满足清洁氢联盟指定的欧洲目标。这种方法可以了解此类系统中存在的不可逆性数量以及热效率如何受到许多参数的影响，从而构成了将该工艺技术从实验室扩大到实验室/中试规模的全球基线。 这项工作的最佳结果强调，就整个系统的热效率（基于较低的热值）而言，利用进料流中的生物甲烷来产生氢气是比沼气更好的选择，在773 K，而火用破坏的最高百分比集中在冷凝阶段，其值在 76% 到 93% 之间变化，具体取决于进料流类型。两级系统能够满足“2027年脱碳制氢目标”，氢气回收率为90%，纯度为99.9999%。最后但并非最不重要的一点是，在两个分析案例中，整个系统的总体火用破坏效率分别为 92%（生物甲烷原料流）和 88%（沼气原料流）。