Development of an attrition evaluation method using a Jet Cup rig

Benjamin Amblard (1) , Stéphane Bertholin (1) , Carole Bobin (1) , Thierry Gauthier (1)

1 IFPEN - IFP Energies nouvelles

There is presently very little information available concerning long term operation with group B oxygen carriers for the Chemical Looping Combustion (CLC) process. It is therefore difficult to predict the attrition at industrial scale based on existing tools and methodologies for the different oxygen carriers available. The CLC process is similar in its configuration to the Fluid Catalytic Cracking (FCC) process with particles circulating in a loop between different reactors. Therefore for the CLC process development perspectives, it is interesting to compare the different oxygen carriers with a FCC catalyst of which data at industrial scale are available. A method to compare the mechanical resistance to attrition of solids from different fluidization groups was developed in this work. In order to deal with small amount s of particle samples, experiments are conducted using lab scale testing with a Jet Cup rig. Two solids of interest were considered in this study, a Group B oxygen carrier with a density of 3600 kg/m 3 and a mean particle diameter (dp 50) of 180 microns, and a group A FCC equilibrium catalyst with a particle density of 1450 kg/m 3 and a mean particle diameter (dp 50) of 70 microns. First, we defined a new attrition index that does not depend upon a given particle size. This index is based on the total percentage of particles generated by attrition and it is called TPGI (Total Particles Generated Index). This index also gives the possibility to estimate the maximum diameter of particles generated by attrition. It was found that attrition in the jet cup is proportional to the contact frequency between the air jet and the particles. Therefore it is necessary to estimate the particles circulation within the air jet for each solid tested in order to make sure that particles go through the same mechanical stress. For this purpose, a CFD study using Barracuda™ was carried out on the two solids of interest. CFD results showed that in order to have the same circulation of particles in the air jet, therefore the same mechanical stress, tests should be carried out with the same initial volume of particles. It is important to notice that this conclusion is valid for the two solids of interest, another CFD study should be done for solids with different properties. Finally, the particles mechanical resistance is characterized by the TPGPI increase rate with respect to the test duration. This parameter is then be used to compare the solids tested, the oxygen carrier being more resistant than the FCC catalyst in this study case.

Mots clés: Attrition; Jet Cup; Chemical Looping Combustion; Fluid catalytic cracking; Computer Fluid Dynamic

Domaines: Catalyse

Benjamin Amblard, Stéphane Bertholin, Carole Bobin, Thierry Gauthier. Development of an attrition evaluation method using a Jet Cup rig. Powder Technology, 2015, 274, pp.455-465. ⟨10.1016/j.powtec.2015.01.001⟩. ⟨hal-01149043⟩