Acid gas cleaning is one of the natural gas processing steps where the acid gases are removed to satisfy the quality of the sweet gas. Conventionally, this is achieved by processing the sour gas through an acid gas removal (AGR) unit to produce the desired sweet gas while concentrating the H₂S gas in the acid gas enrichment unit. Together with achieving the required high heating value of 930 BTU/SCF in the sweet gas, it is also desired from the process that the acid gases must contain 30–55% H₂S content before feeding to the sulfur recovery unit. In addition, the waste gases sent to the thermal oxidizer must not contain more than 2000 ppmv H₂S. However, these requirements put a constraint on the process operational flexibility especially when the feed gas has a high CO₂ content. In this study, a novel acid gas cleaning design has been proposed that can significantly reduce the energy requirement while maintaining all the streams’ design specifications. The proposed design recommends first producing acid gas with the required purity and then producing the sweet gas in another AGR unit. The results show that the proposed design requires 22% lower operational energy compared to the base design. The economic analysis reflects a saving of more than $7.25 million in total annual cost compared to the conventional design.

中文翻译：

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酸性气体清洗装置的设计改进，可提高天然气处理性能

酸性气体清洁是天然气处理步骤之一，其中去除酸性气体以满足甜气的质量。通常，这是通过在酸性气体浓缩单元中浓缩H ₂ S气体时，通过酸性气体去除（AGR）单元处理酸性气体以产生所需的甜味气体来实现的。除在甜味气体中达到所需的930 BTU / SCF的高发热量外，从工艺中还希望酸性气体在送入硫磺回收装置之前必须包含30-55％的H ₂ S含量。此外，送入热氧化器的废气不得含有超过2000 ppmv H ₂然而，这些要求限制了工艺操作的灵活性，特别是当原料气具有高的CO ₂含量时。在这项研究中，提出了一种新颖的酸性气体清洁设计，该设计可以显着降低能耗，同时保持所有物流的设计规格。提出的设计建议首先生产具有所需纯度的酸性气体，然后在另一个AGR装置中生产甜味气体。结果表明，与基础设计相比，拟议的设计所需的运行能耗降低了22％。经济分析表明，与传统设计相比，每年可节省725万美元以上。