小容量超临界二氧化碳燃煤发电系统的 一维设计及回热器紧凑性分析
One dimensional design of small capacity supercritical CO2 coal fired power generation system and analysis of regenerator compactness
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摘要: 超临界二氧化碳(S-CO2)循环因其高效、紧凑、灵活的优势,有望成为新一代发电动力循 环。 选用三压缩末级部分压缩的循环结构,将其应用到 20 MW S-CO2 燃煤发电系统中,并对发电 系统的关键部件进行一维设计。 设计结果表明,透平和压缩机尺寸整体较小,尺寸优势明显,相比 水机组具备明显的竞争力;基于不同容量锅炉的体积变化规律,合理推断由于炉内 CO2 工质换热系 数较小,使得 S-CO2 锅炉相比水机组锅炉体积有所增加;基于印刷电路板换热器的回热系统占地较 大,在本文设计条件下回热器总体积约为 18.95 m3 ,远超现有水机组回热器总体积,问题显著。 因 此,进一步从回热器换热效果角度探究了回热系统特性,讨论了现有技术面临的困难与瓶颈,发现 循环热效率与回热系统体积存在着较强的制约关系,进而对回热系统进行了成本分析,在考虑基础 建设费及人工费后,回热系统的投资成本约为 9 347.47 万元,初始投资成本较高。 同时发现,印刷 电路板换热器在缩小回热系统体积方面的潜力有限,因此仍需研发新的换热器形式,实现换热系数 的量级性提升。 最后,针对回热系统体积问题,提出了 S-CO2 燃煤发电系统的一体化布置方案,通 过空间布置的优化实现了系统的整体紧凑性。 我国正在推进中等容量 S-CO2 燃煤发电系统示范, 此项研究为示范电站建设提供了新的技术思路。Abstract: Supercritical CO2(S-CO2)cycle is expected to be the next generation power cycle for electricity generation because of its high efficiency,compactness and flexibility. In this study,a tri⁃compression with last⁃stage partial com⁃ pression S-CO2 cycle was applied to a 20 MW S-CO2 coal⁃fired power generation system,and the one⁃dimensional de⁃ signs of components were conducted. It is shown that the size of turbine is significant smaller than that of the tradition⁃ al steam turbine,thus it has obvious competitiveness compared with the water steam unit. Based on the volume change law of boilers with different capacities,it is reasonably inferred that the volume of S-CO2 boiler is larger than the steam boiler due to the smaller heat transfer coefficient of the CO2 in the boiler. The regeneration system based on the prin⁃ ted circuit heat exchanger covers a large area with a volume around 18.95 m3,which is far more than the existing re⁃ generation system of the water steam unit and the problem is significant. Therefore, this study further explored the characteristics of the regeneration system from the perspective of the heat transfer of the regeneration, discussed the difficulties faced by the existing technology,and found that there is a strong constraint relationship be⁃ tween the cycle thermal efficiency and the volume of the regeneration system,and then conducted an economic analysis of the regeneration system. After considering the infrastructure and labor costs,the investment cost of the regeneration system is about 93 474 700 yuan,which is a high initial investment cost. It was also found that the printed circuit heat exchanger has limited potential to reduce the size of the regeneration system, thus new heat exchanger types still need to be developed to increase the magnitude in heat transfer coefficient. Finally,to address the size problem of the regeneration system,this study proposed an integrated arrangement scheme for the S-CO2 coal⁃fired power gen⁃ eration system, which achieves the overall compactness of the system by optimizing the space arrangement. Currently,the demonstration of S - CO2 coal⁃fired power plants is promoted in China, and this research provides some novel technical ideas for the demonstration system.