A new mathematical framework for optimal synthesis, design, and operation of triple-pressure steam-reheat combined-cycle power plants (CCPP) is presented. A superstructure-based representation of the process, which embeds a large number of candidate configurations, is first proposed. Then, a generalized disjunctive programming (GDP) mathematical model is derived from it. Series, parallel, and combined series-parallel arrangements of heat exchangers are simultaneously embedded. Extrinsic functions executed outside GAMS from dynamic-link libraries (DLL) are used to estimate the thermodynamic properties of the working fluids. As a main result, improved process configurations with respect to two reported reference cases were found. The total heat transfer areas calculated in this work are by around 15% and 26% lower than those corresponding to the reference cases.

This paper contributes to the literature in two ways: (i) with a disjunctive optimization model of natural gas CCPP and the corresponding solution strategy, and (ii) with improved HRSG configurations.

提出了一种新的数学框架，用于优化三压力蒸汽-再热联合循环电厂（CCPP）的合成，设计和运行。首先提出了一个基于上层结构的过程表示，其中嵌入了大量候选配置。然后，从中得出一个广义的析取规划（GDP）数学模型。同时嵌入热交换器的串联，并联和组合串联-并联布置。在GAMS外部从动态链接库（DLL）执行的外部函数用于估计工作流体的热力学性质。作为主要结果，发现了相对于两个报告的参考案例的改进的过程配置。

本文通过两种方式为文献做出了贡献：（i）具有天然气CCPP的分离优化模型和相应的解决方案，以及（ii）具有改进的HRSG配置。