Development of an attrition evaluation method using a Jet Cup rig

Abstract

Particles attrition is an important phenomenon to account for when developing and scaling up new fluidized bed processes. Most of the time, little amount of particles is available at the early development stage and only lab scale experiments can be carried out. Most of the available tools and methodologies to investigate attrition at small scale were developed for the FCC process on group A particles. However, attrition also needs to be evaluated for new applications such as Chemical Looping Combustion (CLC) with different particle properties.In this work, we propose a method using a jet cup apparatus that aims to compare attrition rate of solids having different properties. Materials studied in this paper are a Group A FCC catalyst (Dp50 of 70μm, grain density of 1450kg/m3) and a Group B CLC oxygen carrier (Dp50 of 180μm, grain density of 3600kg/m3). Based on experimental data and CFD modeling, comparative testing conditions could be defined in order to apply the same mechanical stress for all solids tested. Classical attrition indexes usually quantify the generation of fine particles below 40μm which does not describe fully attrition of Group B powders. Therefore, a new attrition index was defined to calculate the total amount of particles generated by attrition over the entire size range of all solids tested. Finally, the attrition rates of both materials were compared applying the methodology developed. It was found that attrition rate is less important for the oxygen carrier. It is important to notice that attrition due to thermal or chemical stresses is not investigated in this study and needs separate evaluation.