近年来,沼气作为天然气替代品的使用受到了极大的关注。通常,除了甲烷(CH4),沼气含有二氧化碳(CO2),以及少量的杂质,例如,硫化氢(H2S),氮气(N2),氧气(O2)和挥发性有机化合物(VOCs)。沼气净化的最新趋势之一是膜工艺的应用。然而,在使用膜升级之前,文献报道对沼气预处理的具体要求含糊不清。因此,本研究的主要目的是全面审查和讨论使用单膜分离装置进行沼气升级的最新成就。进行文献综述以表明,近年来,为此目的使用聚合物膜已经取得了相当大的进展。例如,已经证明,具有溶胀的聚酰胺(PA)层的薄膜复合(TFC)膜的应用确保了原始沼气的成功升级,并且消除了对其预处理的需要。进行文献综述的重要性是得出的推论,即在单个步骤中进行的沼气富集可以获得可用于家庭用途的升级沼气。然而,这种解决方案可能不足以以高回收效率获得高纯度气体。因此,为了获得可用于天然气应用的沼气,可能需要膜级联。此外,据记载,大量的实验研究集中在合成沼气的升级上;同时,原始沼气的数据非常有限。此外,人们注意到,虽然陶瓷膜显示出几个优点,它们在单膜系统中的应用的实验研究被忽略。总结文献数据,可以得出结论,为了彻底评估提出的问题,需要在中试系统中使用聚合物和陶瓷膜对原始沼气进行升级的长期实验研究。提出的文献综述具有实际意义,因为它将有利于支持用于沼气升级的膜工艺的发展。
In recent years, the use of biogas as a natural gas substitute has gained great attention. Typically, in addition to methane (CH4), biogas contains carbon dioxide (CO2), as well as small amounts of impurities, e.g., hydrogen sulfide (H2S), nitrogen (N2), oxygen (O2) and volatile organic compounds (VOCs). One of the latest trends in biogas purification is the application of membrane processes. However, literature reports are ambiguous regarding the specific requirement for biogas pretreatment prior to its upgrading using membranes. Therefore, the main aim of the present study was to comprehensively examine and discuss the most recent achievements in the use of single-membrane separation units for biogas upgrading. Performing a literature
review allowed to indicate that, in recent years, considerable progress has been made on the use of polymeric membranes for this purpose. For instance, it has been documented that the application of thin-film composite (TFC) membranes with a swollen polyamide (PA) layer ensures the successful upgrading of raw biogas and eliminates the need for its pretreatment. The importance of the performed literature
review is the inference drawn that
biogas enrichment performed in a single step allows to obtain upgraded biogas that could be employed for household uses. Nevertheless, this solution may not be sufficient for obtaining high-purity gas at high recovery efficiency. Hence, in order to obtain biogas that could be used for applications designed for natural gas, a membrane cascade may be required. Moreover, it has been documented that a significant number of experimental studies have been focused on the upgrading of synthetic biogas; meanwhile, the data on the raw
biogas are very limited. In addition, it has been noted that, although ceramic membranes demonstrate several advantages, experimental studies on their applications in single-membrane systems have been neglected. Summarizing the literature data, it can be concluded that, in order to thoroughly evaluate the presented issue, the long-term experimental studies on the upgrading of raw biogas with the use of polymeric and ceramic membranes in pilot-scale systems are required. The presented literature
review has practical implications as it would be beneficial in supporting the development of membrane processes used for
biogas upgrading.