Investigations on Fluid Catalytic Cracking (Part 7)

Abstract

Although the particle size distributions and shapes of catalysts used in the fluid catalytic cracking process greatly affects the flow, catalysts with a wide range of particle size distribution are actually being used. Therefore, the authors have made studies on the characteristics of micro spherical catalyst particles in various particle size range as a start to determine the effects which particle size distributions and density changes bear upon the flow. These studies have indicated that;(1) In the past it was very difficult to determine the coefficient to express the density and shapes in relation with the flow. However, it was possible to obtain a value to express the physical characteristics, through the formula for the pressure drop of the fixed bed.(2) Catalysts now being used in the units were segregated into several groups in accordance with particle sizes, and it was discovered that the individual apparent bulk density will decrease as the particle size increases.(3) The minute particles of catalysts have a tendency to abnormally expand to resemble channeling, and the course particles resemble slagging. However, by utilizing the expansion curves of the layers the relation of these tendencies were studied in respect to the particle size and types of catatlysts, and it was discovered that the particle size of 40 micron is the limit between channeling and abnormal expansion.