Analysis of the defluidization behaviour of industrial reactive powders at high temperature

The Chemical Industry Association reports that most of chemical products currently in production involve the use of particles at some stage in the manufacturing process. Particle science and technology are essential to the improvements of many types of consumer products and tackle most contemporary grand challenges, such as in advanced manufacturing, sustainable energy, waste management, and food preservation. To this end, fluid bed reactors are usually used, due to their particular benefit in high temperature systems. However, fluid bed operations at elevated temperatures are usually limited by a tendency of the particles to form agglomerates, thus causing the bed to defluidize. This may occur at temperatures well below the normal particles’ melting point, and it has been encountered in different processes, including the carbochlorination reaction involving titaniferous materials. Several previous studies on the effect of temperature on fluidization behaviour highlighted how the phenomena involved are complex and how such changes of fluidization behaviour cannot be fully explained by considering only hydrodynamic forces. This phenomenon is a result of a strong particle-particle interaction causing more rapid rate of sintering, but it is still challenging to perform a direct quantification of these interactions and of their changes with temperature. The objective of this paper is to report experimental observations on the effect of temperature on the flow and fluidization behaviour of mixtures of carbon coke and titaniumores. To this end, a simple approach for the early detection of agglomeration in the regimes of incipient fluidization - where the carbon combustion causes defluidization- will be followed. Such a monitoring approach is based on the simultaneous measurements of local temperatures and the pressure drop across the particles bed.