基于热流逸效应的燃煤电厂烟气二氧化碳分离系统

分离捕集CO₂是实现“双碳”目标的重要途径之一。常规的CO₂分离方法普遍能耗较高，若能以余（废）热为动力来分离CO₂则可综合利用能源、降低能耗。本文针对高碳排放但却拥有丰富余（废）热资源的燃煤电厂，提出了一种基于热流逸效应的烟气CO₂分离系统，并建立了相应的分离过程数学模型和系统性能评价指标。分析表明，CO₂的浓度和回收率均随热流逸式气体分离器串联级数的增加而升高，但浓度和回收率达到某一阈值后效果不再明显；典型的1000MW燃煤电厂烟气经该系统中串联的24级分离器处理后，CO₂的物质的量分数最高可达98.89%，回收率达72.53%。此外，该系统可梯级利用烟气的余热，?效率为64.8%，单位能耗为0.047GJ/tCO₂， 与传统CO₂分离方法相比具有一定节能潜力。利用热流逸效应分离CO₂符合当下净零碳排放的政策导向，为CO₂的分离捕集提供了新思路。

Thermal-transpiration-effect-based carbon dioxide separation system for flue gas from coal-fired power plant

CO₂ separation and capture are one of the important ways to achieve the goal of “carbon peak and carbon neutrality”. Conventional CO₂ separation methods are highly energy-consuming in general. CO₂ separation employing waste heat can realize comprehensive utilization of energy so as to reduce energy consumption. Since coal-fired power plants emit lots of CO₂ and are abundant in waste heat resources as well, a thermal-transpiration-effect-based separation system for flue gas from coal-fired power plant was proposed with the establishment of corresponding mathematical model and performance evaluation indicators. The concentration and recovery rate of CO₂ rise as the thermal-transpiration-effect-based separators increased in series, but the improvement of separation effect was not significant when the concentration and recovery rate reached a certain threshold, respectively. After the flue gas from a typical 1000MW coal-fired power plant was processed by the 24 gas separation units in series of the proposed system, the maximum CO₂ concentration and CO₂ recovery rate could approach to 98.89% and 72.53%, respectively. In addition, the system can realize the energy cascade utilization of flue gas with the exergy efficiency of the system of 64.8% and the unit energy consumption of 0.047GJ/tCO₂, which meant the proposed system was potentially energy-saving compared with the traditional CO₂ separation ways. CO₂ separation employing thermal transpiration effect agreed with the current policy orientation of net zero carbon emissions and can provide an innovation for CO₂ separation and capture.