Particle Loaded Gases in Turbines and Components

The Institute of Thermal Turbomachinery and Machine Dynamics can draw upon a very long experience in the design of heat recovery turbines in fluid catalytic cracking plants (FCC). These contain a fluid bed in order to regenerate the spent catalyst by burning deposited carbon under pressure in the air stream. The aluminia and silica particles of this sandy catalyst are thus subjected to repeated heat cycles and degrade in size by thermal stress fatigue thus elutriating fine particles. The hot gas is cleaned by several cyclones but still particles in a far higher concentration than usually accepted pass through these special turbines. The first multistage FCC gas turbine was designed by H. Jericha in 1968. The multistage flow concept proved adequate and resulted in a record blade life of 75000 hrs. Mass balance, size and density distribution of the particles passing through the turbines are known, so that the observed erosion grooves can be compared with flow calculations, computed particle trajectories and metal erosion theory on a statistical basis. The same theory is applied to wood burning gas turbines in order to establish design rules for new gas turbines working under erosive conditions.