Abstract
Effect of fines content (weight % of particles with diameter less than 45 μm) on bed fluidity was determined to get a base for good fluidization quality in the fluid catalytic cracking (FCC) unit. The fines content in equilibrium FCC catalysts (Ecat) from commercial units were controlled by adding or removing the fines to simulate commercial situation. To get the fluidity values (Umb/Umf) of seven different FCC catalysts (2 Ecats and 5 fresh catalysts) and their mixture, minimum fluidization velocity (Umf) and minimum bubbling velocity (Umb) were measured in a fluidized bed reactor (0.05 m ID). The fluidity decreased with loss of fines content and increased with increments of makeup of fresh catalysts or additive with the controlled fines content. The fluidities of catalysts increase with increases of normalized particle diameter variation by the fines addition. The obtained fluidities have been correlated with the fines contents and the catalyst and gas properties. The proposed correlation could guide to keep good catalyst fluidity in the FCC unit.
Highlights
Fluid catalytic cracking (FCC) processes are used to upgrade heavy hydrocarbon fractions into valuable light fractions, such as propylene, gasoline, and gas oil, etc. [1]
It is very important to investigate the effect of fresh catalyst and additive addition on the catalyst fluidity in an equilibrium FCC catalysts (Ecat) fluidized bed, to ensure stable operation even under changing operating conditions of the FCC unit
The effect of fines in the catalysts on the fluidity has been well defined from a lot of studies with varying fines content in given FCC catalysts and the correlation derived from the results [7]
Summary
Fluid catalytic cracking (FCC) processes are used to upgrade heavy hydrocarbon fractions into valuable light fractions, such as propylene, gasoline, and gas oil, etc. [1]. Whitcombe et al [8] showed that previous correlations on fluidization characteristics did not predict well experimental data of Ecat due to metal contamination on the catalyst surface It indicates that the fluidity correlation should be improved with experimental data of Ecat only and Ecat-fresh catalyst mixtures for reliable prediction and its application. It is very important to investigate the effect of fresh catalyst and additive addition on the catalyst fluidity in an Ecat fluidized bed, to ensure stable operation even under changing operating conditions of the FCC unit. The fluidities of commercial fresh and equilibrium FCC catalysts with various contents of fine particles were measured to investigate the effect of fresh catalyst and additive addition for maintaining good fluidization quality of the FCC unit. A guidance for control of bed fluidity has been proposed based on the correlation
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