“Fundamental investigations on the influence of fuel composition on the particle formation, the pollution and the high-temperature chlorine corrosion during the combustion of biogenic solid fuels for the development of a corrosion reduction concept.”
Reason behind the research
In light of finite fossil resources and progressive global warming, the “Energy Concept” and the “National Biomass Action Plan” have made it their goal to increase the share of renewable energy, as well as to increase the efficiency of energy supply. Biomass has the advantage of having a storable form for needs-based power and heat generation. The steam power process with and without heat extraction is the most developed and commercially available power generation method in which biomass is used. However, the composition of the biomass brings about a limitation of the live steam temperatures, which results in limited efficiency, due to the formation of corrosive particles and gases on the heat-transfer surfaces, which bring about pollution and high-temperature chlorine corrosion. The pollution and the corrosion damage are the main reasons for unplanned system delays, reduced plant availability and high service and maintenance costs.
The primary objective of the project is to enhance the efficiency of existing and planned biomass combustion facilities, focusing on the energetic usage of “difficult” biogenic fuels. Through the selective variation of individual fuel elements in a testing facility, and the simultaneous application of established corrosion, particle and flue gas measurement technologies, the entire process chain will be investigated under defined, constant combustion conditions, starting with the formation of corrosive particles in the flue gas - to the deposition of said particles on cooled surfaces - until the eventual corrosion. Through the identification of corrosive and inert particle and gas species and their influence on online-corrosion measurement, an assessment and an evaluation of the potential and risk of corrosion in the selected fuels should be made possible. Through the analysis of the substances contributing to the formation of corrosive particle and gas species, and their manipulation through the introduction of corrosion inhibiting substances such as sulfur and aluminum-silicate, concrete measures should be established to inhibit the formation of corrosive components through intermediate reactions. On the basis of the results thus obtained, a corrosion reduction concept should be developed, which should provide insight into which substances can be used to reduce chlorine corrosion, and to what extent reduction is possible. The concept, once completed, should provide a first insight into the reduction of high-temperature chlorine corrosion. With the raising of the efficiency of biomass power plants in mind, the corrosion-reducing response mechanisms should also be tested in superheater wall temperatures of 550 °C.
Contact: Andreas Stephan