Parametric and heuristic optimization of multiple schemes with double-reheat ultra-supercritical steam power plants

Abstract

Improvement of energy conversion efficiency in modern steam thermal power plants and minimization of the impact on the environment can be both achieved using ultra-supercritical (USC) parameters and schemes with double-reheat of steam. A methodology is proposed to analyze the energy conversion processes of the double-reheat steam cycles with USC parameters and determine their optimal design. Three types of thermodynamic cycles were considered: a single-reheat benchmark cycle and two double-reheat cycles with different positions of the deaerator. This model finds the best configuration of the preheating system and the optimum reheating steam parameters. Parametric and heuristic multi-objective optimization of energy processes were used for multi-thermodynamic cycles, a synthesis Pareto frontier being computed from the Pareto of the individual cycles to find the best overall solutions. The results prove the benefits of double-reheat cycles for USC parameters, except for low main steam temperatures, where single-reheat cycles are recommended. The solution with the deaerator supplied with steam from the intermediate pressure turbine is usually recommended. For the same specific investment, a 1.22% relative gain of net efficiency was obtained for the double-reheat cycle compared to the single reheat benchmark cycle.