Investigation and modelling of ash deposit induced dynamic alloy corrosion in thermal and chemical gradients

Addressing essential material challenges in sustainable energy, this project concentrates on high-temperature corrosion in waste-to-energy and biomass combustion systems, which currently limit operational efficiency. The corrosion issues mainly stem from ash deposits. Still, current research is hindered by two key gaps: reliance on simplified isothermal studies and the absence of comprehensive models that consider dynamic, coupled thermal and chemical gradients across the entire alloy-oxide scale-deposit system. Using a multiscale approach, this project aims to quantitatively clarify these complex, combined corrosion mechanisms. The research is organized into three interconnected experimental work packages (WP1-3) and one advanced modeling work package (WP4). The experimental investigations will employ innovative, gradient-controlled setups: a refined high-temperature method to measure the migration of corrosion products within dense deposits (WP1), a modified setup to evaluate the influence of temperature gradients on low-temperature hygroscopic corrosion (WP2), and a newly built system to analyze ash condensation kinetics on different oxide surfaces (WP3). The extensive data from WP1-3 will provide crucial validation and calibration data for the models. The key scientific innovation is WP4, which will develop a dynamic, multiscale computational model. Building on the PI’s prior work, this model will expand to continuously monitor local phase equilibrium and diffusion across all system interfaces (alloy, oxide scale, corrosion front, and ash deposit) under simultaneous thermal and compositional gradients. This quantitative framework will deliver the first comprehensive description of this complex phenomenon. The results will directly guide material selection, improve component placement in industrial boilers, and ultimately enhance the efficiency and reliability of sustainable thermal conversion processes.

Waste-to-energy and biomass power plants are an essential part for meeting climate goals and reaching circular economy. However, their efficiency is severely reduced due to high-temperature corrosion. This corrosion is mainly caused by the ash from the fuel and enhanced by extreme thermal and chemical gradients inside the boilers. This project, primarily carried out at Åbo Akademi University, is investigating the complex, dynamic mechanisms that lead to material failure. We use innovative, custom-built laboratory setups to generate new experimental data that simulates these harsh conditions. This data will be used to develop an advanced multiscale computational model to predict when and how materials will fail. The results will allow industries to select better, more reliable materials and optimize boiler operations, directly increasing the efficiency, safety, and reliability of sustainable energy production.