Enhancing the flexibility and safety of electric-resistance heating on thick-walled pressure parts of utility boilers in coal-fired power plants

In this paper, a method for electric-resistance heating is proposed to reduce the thermal stress generated at a thick-walled pressure component during cold start-up in a coal-fired utility boiler. The aims of this approach are to shorten the start-up time and enhance the flexibility of the utility boiler. While focusing on a steam-water separator in a supercritical utility boiler, the finite element method (FEM) is employed in this study to analyze the thermal and mechanical stress amplitude and fatigue lifetime consumption parameters during cold start-up. An analysis of practical and optimized cold start-up is conducted. This start-up process involves the application of electric-resistance heating to a steam-water separator to shorten the boiler water filling time. Experiments are performed to investigate the differences in the inner and outer wall temperatures and thermal stresses under non-heating and electric-resistance heating conditions for a thick-walled component in an experimental facility being input with high-temperature and high-pressure steam. The results show that electric-resistance heating may reduce the thermal stresses and the fatigue lifetime consumption levels in thick-walled components when applied during cold start-up, and the cold start-up times are significantly shortened. The feasibility of this approach in practical engineering is confirmed through experiments.