Abstract:

Global CO₂ emissions continue to rise, leading to frequent climate problems. With the goal of "carbon peak and carbon neutralization", it has become an urgent issue to capture CO₂ from the flue gas of coal-fired power plants in an efficient and cost-effective way. The development of traditional chemical absorption method is seriously restricted by its high energy consumption, high cost and volatile solvent. The membrane carbon capture is considered as the most promising capture method because of its advantages such as simple operation, low energy consumption and small environmental pollution. Membrane-based carbon capture is considered as the most promising capture method because of its low capture cost and environment-friendly features. In this paper, a gas separation membrane model is established and solved with PI hollow fiber membrane as the separation membrane. And with the target of carbon dioxide capture in flue gas of coal-fired power plants, the membrane separation processes with different configurations of carbon dioxide capture are solved by multi-island genetic algorithm, and the key parameters (membrane area, operating pressure) in the separation process are optimized. The results show that in the two stage-one step membrane separation process, when the operating pressure of the first stage membrane and the second stage membrane are 5.8 bar and 7.1 bar, respectively, and the area of the first stage membrane and the second stage membrane is 448000 m² and 180000 m², the unit capture cost is 27.36 USD/t CO₂. Compared with two stage-two step membrane separation and several other traditional CO₂ capture methods (MEA method and phase change absorption method), the capture cost and energy consumption of CO₂ by two stage-one step membrane separation is the lowest. This study will provide a basis for achieving low energy consumption and low cost for CO₂ capture.

Key words: CO₂ capture, membrane separation, carbon reduction, numerical simulation, optimal design

摘要：

全球CO₂的排放量不断升高，导致气候问题频发。“双碳”目标下，如何高效、低成本地捕集燃煤电厂烟气CO₂已经成为迫在眉睫的问题。传统的化学吸收法由于能耗高、成本高、溶剂易挥发等问题严重制约了其发展，而膜法碳捕集因为其操作简单、能耗低、环境污染小等优势被认为是最有前景的捕集方式。本文以PI中空纤维膜为分离膜，建立和求解了气体分离膜模型。并以燃煤电厂烟气CO₂为捕集目标，利用多岛遗传算法求解了膜分离捕集CO₂工艺的不同配置，并优化了分离过程中的关键参数(膜面积、操作压力)。结果显示：在二级膜分离工艺中，二级一段膜分离工艺的第一级膜和第二级膜操作压力分别为5.8 bar和7.1 bar，第一级膜和第二级膜的面积分别为448000 m²和180000 m²时，单位捕集成本为27.36 USD/t CO₂。与二级二段膜分离以及其他几种传统的CO₂捕集方法(MEA法、相变吸收法)相比，二级一段膜分离捕集CO₂的捕集成本和能耗均最小。本研究将为CO₂捕集实现低能耗和低成本化提供依据。

关键词: 二氧化碳捕集, 膜分离, 碳减排, 数值模拟, 优化设计