Burning iron powder in a coal combustion chamber

Kurzfassung

One of the greatest challenges of modernizing the energy supply is the need for large-scale seasonal energy storage. Renewable energy must be available in a form in which industry-relevant capacities can be stored over longer periods of time. Metal fuels can play a significant role here. In this concept, energy is released through the combustion of metal powder. To ensure climate neutrality, green hydrogen can be used to reduce the resulting metal oxides. Research and industry are investigating the possibility of commissioning power plants for iron combustion; we are also dedicating ourselves to this approach by investigating the retrofitting potential of existing coal-fired power plants. The aim of this work is to obtain initial empirical evidence of the flame behaviour. The main question is the stabilization of the flame under varying operating conditions. For this purpose, we are using the MB1500 experimental combustion chamber designed for the investigation of pulverized lignite combustion, with a fuel heat output of up to 15 kW, which is hereby given a new application as the "Zittau Iron Combustion Chamber" (ZIICC). The ZIICC is a vertically aligned micro-combustion chamber that simulates the combustion behaviour of industrial combustion chambers. Firstly, the feasibility of iron powder combustion will be demonstrated by first mixing iron powder with pulverized lignite and then burning it in its pure form to generate a self-sustaining flame. Here, we will discuss the differences observed between pulverized lignite firing and iron powder combustion. Next, the oxygen content in the flue gas, or more specifically the associated feed mass flow of the iron powder, will be varied, generating primarily process and operational data. The differences in ignition behaviour between two different particle sizes will be investigated. Finally, we discuss the phenomenon of "fouling", which has thus far only been observed in such bottom-up burners. The insights gained from these experiments will aid us in achieving our end goal of retrofitting coal-fired power plants to burn iron instead.