关键词: 二氧化碳, 分离, 微尺度, 热流逸效应, 余热利用, 能源效率

Abstract:

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.

Key words: carbon dioxide, separation, microscale, thermal transpiration effect, waste heat utilization, energy efficiency