Acid Corrosion Analysis in the Initial Condensation Zone of a H₂O/CO₂ Turbine

• Main Authors: Ziyue Ma, Xiaofang Wang, Jinguang Yang, Wei Wang, Wenyang Shao, Xiaowu Jiang
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Energies
• Subjects: H₂O/CO₂ turbine; initial condensation zone; acid corrosion; numerical simulation; performance degradation
• Online Access: https://www.mdpi.com/1996-1073/14/11/3323

A supercritical H₂O/CO₂ turbine is a key piece of equipment for the coal gasification in the supercritical water (CGSW) cycle to achieve conversion of heat into power. Compared with a traditional steam turbine, the working medium of an H₂O/CO₂ turbine has a relatively high CO₂ concentration. In the initial condensation zone (ICZ), steam condenses into droplets on the turbine blades and the droplets combine with CO₂ to form carbonic acid, which corrodes the turbine blades. In order to research the characteristics of acid corrosion in the ICZ of a H₂O/CO₂ turbine, the acid corrosion rate of the blades in the ICZ of the H₂O/CO₂ turbine was calculated and analyzed based on the three-dimensional CFD (3D CFD) method and a one-dimensional numerical model of CO₂ corrosion. The results suggest that acid corrosion rates decrease stage by stage in the ICZ due to the reduction in temperature and pressure. Rotor blades in the first stage in the ICZ suffer the worst and form a corrosion zone at the trailing edge of the blade and on the pressure surface. The decline of efficiency caused by corrosion settles down to a relatively steady value of 0.6% for a 10 year service time. Moreover, the corrosion area for the last two stages shrinks with the service time due to the rearward movement of the ICZ.