Abstract Steam Rankine cycle is the most widely used power cycle for the electric power generation and its process modification can effectively improve the power generation efficiency. To evaluate the thermal performance of these process modifications, the “thermal cycle splitting analytical method” was proposed and illustrated by general formulas. In this analytical method, the modifications of the thermal power cycle are classified into two types, i.e., “power boosting” and “heat saving”; then, the modified cycle is split into a basic cycle and one/several equivalent power cycle(s) (EPC) with simpler thermodynamic process; finally, the effect of the modification can be reflected by the split EPCs, which will not need the overall system simulation. Based on the proposed analytical method, the high-temperature EPCs and low-pressure EPCs were split from the reheat and regenerative cycles, respectively, and the corresponding models for evaluating the efficiency of the modified cycle were developed. Then, the proposed analytical method was utilized to investigate several representative modifications of a typical 1000 MW-stage supercritical power plant, including the cycle itself modification (double reheat, multi-stage regeneration, outer steam cooler, regenerative turbine) and the external heat integration (boiler cold-end energy integration, coal pre-drying and solar-aid power generation), and the obtained results showed a high accuracy through comparing with the overall system simulation. The proposed analytical method might provide a new perspective to analyze the energy saving mechanism of the complex thermal power cycles in a clearer and simpler way.

中文翻译：

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一种评估改进蒸汽朗肯循环性能的通用简单方法：热循环分裂分析法

摘要 蒸汽朗肯循环是发电中应用最广泛的动力循环，其工艺改进可有效提高发电效率。为了评估这些工艺改进的热性能，提出了“热循环分裂分析方法”，并通过通用公式进行了说明。在该分析方法中，对火力循环的修改分为“增电”和“节热”两种；然后，修改后的循环被分解为一个基本循环和一个/几个具有更简单热力学过程的等效功率循环（EPC）；最后，修改的效果可以通过拆分的EPCs来体现，不需要整个系统的仿真。基于所提出的分析方法，将高温EPCs和低压EPCs分别从再热循环和再生循环中分离出来，并建立了相应的改进循环效率评估模型。然后，利用所提出的分析方法研究了典型 1000 MW 级超临界电厂的几种代表性改造，包括循环本身改造（双再热、多级再生、外蒸汽冷却器、蓄热式汽轮机）和外部热集成（锅炉冷端能量集成、煤预干燥和太阳能发电），与整体系统仿真相比，所得结果具有较高的精度。