超临界CO2循环冷端温度优化研究

超临界CO₂循环冷端排出的热量温度较高,优化冷端温度对于提高循环的效率有重要作用。为了获得最佳的全年平均效率,有必要引入人工制冷,使超临界CO₂循环运行在更优化的冷端温度下。针对550℃/20 MPa参数的分流再压缩方式的超临界CO₂循环,通过热力学方法,分析了自然冷却和人工制冷组合条件下,冷端温度为5~35℃的不同工况下全年平均循环效率,并对冷端温度优化方法的适用性和经济性进行了研究。选取优化的冷端温度,将自然冷却和人工制冷相结合,可提高机组的全年平均效率。对于我国北方地区,冷端温度优化方法有较佳的适用性。引入人工制冷导致机组设备投资增加,但是机组运行效率的提高带来更多的发电收入,并在机组全寿期产生可观的收入增量。

Study on Cold End Temperature Optimization of Supercritical CO2 Cycle

Supercritical CO₂cycle has a high cold end temperature.Optimizing the cold end temperature plays an important role in improving the cycle efficiency.In order to obtain the best annual average efficiency,it is necessary to introduce artificial refrigeration to make the supercritical CO₂cycle run at a more optimized cold end temperature.For the supercritical CO₂recompression cycle with parameters of 550℃/20 MPa,the annual average cycle efficiency under different cold end temperature of 5 to 35℃,with the combination of natural cooling and artificial refrigeration was analyzed by thermodynamic method,and the feasibility and economic analysis of the cold end temperature optimization method were studied as well.The annual average efficiency of the unit can be improved by choosing the optimal cold end temperature and combining natural cooling with artificial refrigeration.For northern China,the cold end temperature optimization method has better feasibility.The artificial refrigeration increases the investment of unit equipment,but the improvement of operation efficiency brings more power generation revenue and moreover increases the net income of the unit during its life cycle.