Optimization of inlet conditions of hot steam injection into the non-equilibrium condensing steam

Abstract

Injecting hot steam into the cascade flow is one of the procedures for resisting losses and damages caused by condensation. In the current study, utilizing a 3D (three-dimensional) geometry for steam turbine blades, the hot steam has been injected into the steam cascade via the embedded channel. In the power plant industry, the hot steam injection process is done in two ways: constant pressure with a reservoir or constant mass flow rate utilizing a control valve. Therefore, considering these two methods and the TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) optimization method, the best temperature for injecting hot steam into non-equilibrium steam in a constant steam turbine blade has been gained. At the optimal temperature of 540 K at the constant pressure mode, Er (erosion rate ratio) and Lr (condensation loss ratio) were obtained as 66.6% and 30.7%, respectively, and Kr (kinetic energy ratio) showed a 0.6% growth in the hot steam injection mode, in comparison with the original mode. In addition, the economic cost of hot steam injection was calculated as 0.457 ($/hour). By the TOPSIS optimization method, the optimal temperature of hot steam injection, utilizing the constant mass flow rate method, has been obtained as 460 K, and the Er, Lr, and Kr values were 31.2%, 66.1%, and 88.48%, respectively at the optimal temperature. Moreover, the economic cost was 0.43 ($/hour). It is easier to control the steam injection by the constant mass flow rate method utilizing a control valve; therefore, the 460 K temperature and constant mass flow rate method are introduced as the optimal method.