The economic efficiency of the use of high-alloy materials in power plant construction

Increasing electrical power production from renewable sources has led to changing demands in the field of conventional power plants in recent years in Germany. Coal-fired power plants that have been designed for Base load operation must withstand frequent start-up and shut-down cycles at present and in the future. Therefore, thick-walled components have a negative impact on the required flexibility and the life expectancy of these components. The exchange (retrofit) of these components and the commercial impact on an economically optimized operation of the power plant, as well as the financial effect of the exchange of such critical components are investigated in this work. As an example a thick-walled steam outlet header was selected. Different materials and different loading characteristics (number of warm and hot starts) including start-up gradients were taken as variables during the optimization process. The component design is based on EN standards. Economic results of the retrofit of critical components were investigated with sensitivity studies. The results show, that material and manufacturing costs are less important compared to the loading characteristics (i.e. number of starts), the electricity price and the fuel costs. Even the change in the design specifications, with a resulting reduction in the wall thickness, leads to improved flexibility in the plant operation and an economic benefit, even without the use of different materials. Due to the modular design of the implemented methods, this optimization can be easily adapted to other components.