D3.1 Refining boundaries of the CLpre process

Abstract

Fluidized bed reactors offer some advantages, including high heat and mass transfer rates, while eliminating the need for energy-intensive agglomeration steps, such as pelletizing. This report provides an insight into the process design and reactor configuration for the chemical looping pre-heating and pre-reduction (CLpre) process using biomass waste as fuel and iron ore as an oxygen carrier, with particular focus on expectable thermodynamic driving forces and kinetic behavior of reduction reactions of iron oxides. The technology has been discussed as a method of supplying the required process heat for iron ore pre-heating, pre-reducing iron oxides and enabling efficient CO₂ capture to generate negative emissions. Two main findings can be extracted from the investigations carried out in the course of the deliverable: - It can be concluded that hematite is most likely to be reduced to magnetite during the CLpre process, which results in a reduction degree of approx. 11%. Further reduction to wüstite may be theoretically possible, but seems to be unlikely. - For the CLpre process and the expected achievable reduction degrees, the available amount of reducing gas is most likely the limiting step during ore reduction in the fuel reactor, which operates as a typical bubbling bed under atmospheric pressure. Future investigations of the process concept will focus on the mass and energy balance of the CLpreprocess within the identified limitations with regard to thermodynamics.