Low-Cost Plasma Spray Coatings for Metal Components in Biomass Conversion Systems

Driven by growing concerns over climate change, the US leadership in renewable technologies, and the significant potential of green jobs in a future bioenergy economy, there is now a renewed urgency for developing sustainable bioenergy and bioproducts. As the use of biomass increases for power, products and fuels, one major remaining challenge is the lifetime and reliability of the combustors in the harsh conditions in the reacting zone high-temperature typically >600C, with some local hot spots up to ~800 to 900C). Currently biomass is limited to a few percent of feedstock in co-fired power stations because of severe gaseous and salt corrosion of steel components, which results in shutdowns and high maintenance costs, and new solutions are needed to enhance reliability of these components under operating conditions. In this project, HiFunda will develop and demonstrate an innovative plasma spray process for applying low cost durable ceramic coatings to low cost steel parts in biomass combustors combustors to enhance their performance in operating conditions, and reduce the lifetime cost of these components. In Phase I project, compositions that have adequate thermal expansion matching with typical steels used in biomass combustors will be identified through a systematic evaluation process. Processing parameters for that can be used to produce dense, thin ceramic coatings of these down-selected compositions on low cost steel substrates will be identified, and their thermal cycling durability will be demonstrated. Finally, the ability of these coated steels to provide significantly reduced corrosion under simulated biomass combustor environments will be demonstrated. The coatings developed through this project can be used to significantly enhance the reliability of steel components used for biomass combustion, and ultimately enable greater adoption of biomass technologies for power and fuel production. Biomass is the only renewable energy source that can offer a substitute for fossil-based, liquid transportation fuels in the near to mid-term. The United States could produce more than one billion tons of sustainable biomass that can be used to produce reduced-carbon-emission fuel for cars, trucks, and jets; make chemicals; and produce renewable power to supply the grid. This can create new domestic economic opportunities and jobs in agriculture, manufacturing, and service sectors, while reducing future climate impacts. In addition, the coating technology developed will also find applications in a number of other areas where high temperature hot corrosion of steel is problematic including conventional coal and natural gas based power generation.