In CO₂ capture retrofit unit of existing coal-fired power plants, energy level mismatch between extraction steam from turbines and CO₂ regeneration process always results in large exergy destruction and low thermal efficiency. Thus, a new CO₂ capture system driven by double absorption heat transformer is proposed. Through the absorption heat transformer, low-temperature steam is upgraded into a higher energy level to match the temperature of CO₂ regeneration. Also, flue gas heat is partly recovered to preheat the circulating water from CO₂ capture process to further decrease system energy penalty. Aspen Plus 11.0 is used to simulate the system and parameters of key processes are validated by experimental values. It is shown that with 90% CO₂ capture, the thermal efficiency of the power plant with proposed CO₂ capture system is enhanced by 1.25 percentage points compared with traditional method. And the efficiency enhancement of the proposed system has a trend of increase first and then decrease with CO₂ capture rate growth. For a 350 MW coal-fired power plant, the optimum CO₂ capture rate is 53.65% and the corresponding efficiency enhancement is 2.06 percentage points. Exergy analysis shows that the exergy destruction in CO₂ separation and steam condensation process can decrease by 49.5% in the proposed system, and thereby the exergy efficiency is 1.85 percentage points higher than the conventional method. Furthermore, the cost of CO₂ avoided and cost of electricity of the proposed system will be reduced by 10.7 $/t-CO₂ and 1.9 $/MW h, respectively.

在现有燃煤电厂的CO ₂捕集改造单元中，涡轮抽汽与CO ₂再生过程之间的能级失配总是导致大的火用破坏和低热效率。因此，提出了一种由双吸收式热转换器驱动的新型CO ₂捕集系统。通过吸收式热转换器，低温蒸汽被提升到更高的能量水平，以匹配CO ₂再生的温度。另外，烟气的热量被部分回收以从CO _2中预热循环水捕获过程以进一步降低系统能量损失。Aspen Plus 11.0用于模拟系统，关键过程的参数已通过实验值进行了验证。结果表明，采用90％的CO ₂捕集，与传统方法相比，采用建议的CO ₂捕集系统的电厂热效率提高了1.25个百分点。提出的系统效率的提高具有随CO ₂捕集率的增长先升高后降低的趋势。对于一个350 MW的燃煤电厂，最佳的CO ₂捕集率为53.65％，相应的效率提高为2.06个百分点。火用分析表明，CO ₂的火用破坏所提出的系统的分离和蒸汽冷凝过程可以减少49.5％，因此，火用效率比常规方法高1.85个百分点。此外，避免的CO ₂成本和拟议系统的电力成本将分别降低10.7 $ / t-CO ₂和1.9 $ / MW h。