Attrition of fluid cracking catalyst in fluidized beds
- Univ. of Surrey, Guildford (United Kingdom)
Particle attrition in fluid catalytic cracking units causes loss of catalyst, which could amount to a few tonnes per day! The dependence of attrition on the process conditions and catalyst properties is therefore of great industrial interest, but it is however not well established at present. The process of attrition in the jetting area of fluidised beds is addressed and the attrition test method of Forsythe & Hertwig is analysed in this paper. This method is used commonly to assess the attrition propensity of FCC powder, whereby the attrition rate in a single jet at very high orifice velocity (300 m s{sup -1}) is measured. There has been some concern on the relevance of this method to attrition in FCC units. Therefore, a previously-developed model of attrition in the jetting region is employed in an attempt to establish a solid basis of interpretation of the Forsythe & Hertwig test and its application as an industrial standard test. The model consists of two parts. The first part predicts the solids flow patterns in the jet region, simulating numerically the Forsythe & Hertwig test. The second part models the breakage of single particles upon impact. Combining these two models, thus linking single particle mechanical properties to macroscopic flow phenomena, results in the modelling of the attrition rate of particles entrained into a single high speed jet. High speed video recordings are made of a single jet in a two-dimensional fluidised bed, at up to 40500 frames per second, in order to quantify some of the model parameters. Digital analysis of the video images yields values for particle velocities and entrainment rates in the jet, which can be compared to model predictions. 15 refs., 8 figs.
- OSTI ID:
- 430463
- Report Number(s):
- CONF-960730-; TRN: 96:006490-0004
- Resource Relation:
- Conference: 5. world congress of chemical engineering, San Diego, CA (United States), 14-18 Jul 1996; Other Information: PBD: 1996; Related Information: Is Part Of The 5th World Congress of chemical engineering: Technologies critical to a changing world. Volume VI: 2nd international particle technology forum, Track 2; PB: 685 p.
- Country of Publication:
- United States
- Language:
- English
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