二次再热机组高效灵活发电创新理论与方法

为解决二次再热机组在频繁变负荷情况下经济性能偏低、灵活性较差等问题，研究了二次再热高效灵活发电创新理论和方法。基于单耗分析方法揭示了传统二次再热机组全工况能耗分布规律，并提出5种适应电网调峰要求的典型600 ℃等级及以上的先进二次再热超超临界燃煤发电系统，分别为集成回热式小汽机新型循环、机炉深度耦合集成新循环、采用新型CO₂工质的循环、带储能的二次再热循环系统以及太阳能热互补二次再热循环系统，阐述了各循环系统的集成思路、系统特点以及对提高机组经济性和灵活性的优势。结果表明：锅炉、汽轮机、回热加热器具有较大的节能潜力；优选的集成回热式汽轮机的二次再热循环系统发电效率比基准系统煤耗降低了2.15 g/（kW·h）；提出的采用机炉耦合技术的二次再热机组在THA工况下煤耗降低高达3.6 g/（kW·h）；采用CO₂工质的火电系统在变工况下依然具有较高的效率；带储能的二次再热循环系统具有较好的灵活性；太阳能热互补二次再热循环系统节能潜力显著，达到14.73 g/（kW·h）。

Innovative Theory and Methods for High-Efficiency and Flexible Power Generation of Ultra-supercritical Double-Reheat Coal-Fired Power Generation Unit

Regarding the problems such as low economic performance and lack of flexibilities during the operations of double-reheat ultra-supercritical coal-fired power generation unit under frequent load change conditions, this paper studies the innovative theory and methods for high-efficiency and flexible power generation of ultra-supercritical double-reheat coal-fired power generation unit. Firstly, on the base of the specific fuel consumption method, the energy consumption distribution regularities of a traditional double-reheat coal-fired power generation unit under different load conditions are revealed. Then five types of new advanced double-reheat coal-fired power generation systems are proposed in this paper, which are all designed with the main steam temperatures of over 600℃ and more advanced capabilities of accommodating the peak load regulations, i.e., double-reheat power generation cycle integrated with the regenerative small steam turbine, double-reheat power generation cycle with the deep coupling between the boiler and turbine system, new double-reheat power generation cycle with CO₂ as the working medium, double-reheat power generation cycle with energy storage system and double-reheat power generation cycle integrated with the solar energy, respectively. Their ideas of integration and characteristics of these new cycle systems in improving the economic performance and operation flexibility are elaborated in details. The research results are illustrated as follows:boilers, steam turbines and regenerative heaters have great energy-saving potential; the standard coal consumption rate of the optimized double-reheat power generation cycle with the regenerative small steam turbine is 2.15 g/(kW·h) lower than that of the reference system; the coal consumption of double-reheat power generation cycle with the deep coupling between the boiler and turbine system can be reduced by 3.6 g/(kW·h) under THA condition; the coal-fired power plant with CO₂ as the working medium still has high efficiency even under load variation conditions; the double-reheat power generation cycle with energy storage system has better flexibility, while the double-reheat power generation cycle integrated with the solar energy has significant energy-saving potential, which can reduce coal consumption by as much as 14.73 g/(kW·h).