Fines generation

Eor irregular or spherical bodies, a cylindrical container is loaded with a 100 gram or larger sample and a pistonlike cover is placed on top of the sample. The container is placed in a hydraulic press and a predeterrnined amount of force is appHed to the cover at a controUed rate. The sample is removed from the container and screened to remove cmshed particles (fines). The bulk cmsh strength is reported in terms of percent fines generated by a specified force. 

Modify the FCCU to allow the use of catalyst fines - Some FCCUs can be modified to recycle some of the catalyst fines generated. 

Sishtla, C., Findlay, I, Chan, I., and Knowlton, T. M., The Effect of Temperature and Gas Velocity on Fines Generation in Non-Reactive Fluidized Beds of Coal Char, Fluidization VI, (J. R. Grace, L. W. Shemilt, and M. A. Bergougnou, eds.), Banff, Alberta, Canada (1989)... 

Like catalytic cracking, hydrocracking processes generate toxic metal compounds, many of which are present in spent catalyst sludge and catalyst fines generated from catalytic cracking and hydrocracking. These include metals such as nickel, cobalt, and molybdenum. 

In order to predict the total level of degradation of fines for coal handling systems of the Gladstone port, a study was commenced to examine the mechanism of lump degradation and to reduce the fines generation. The effect of different types of surface onto which the coal with initial fines was... 

The results of cushioning effects of both types of coal in Figs. 6 and 7 shows that the initial fines with lump coal does not reduce much fines generation when dropped on coal... 

Fig. 8. Comparison of percentage of fines generation of three impact surfaces of South Blackwater coal tested with cushioned coal sample.

Non-cushioned coal sample of both types of coal dropped on different impact surfaces produced higher percentage of fines than the sample of cushioned coal, initial 10% fines, initial 30% fines and initial 50% fines. The cushioning effects of South Blackwater and Ensham coal with initial 10% fines dropped on steel surface produced more fines than conveyor surface and coal surface. The cushioning effect of fines on coal surface was least compare to other two impact surfaces. There was no significant difference of fines generation in between the three impact surfaces tested with a sample of initial 30% fines of both types of coal. The degradation model was used satisfactorily for South Blackwater coal on different impact surfaces. 

Bulk crush strength is commonly measured by placing a representative sample in a cylinder, applying a constant force with a piston, and mesuring the amount of fines generated. Many different variants are possible and no generally accepted method is yet available. The bulk crush strength is defined empirically and the re-... 

After subjecting a sample containing 20 wt% Ni+V to an attrition testp the fines generated by attrition testing (about S wt% of the sample), as well as the extrudates before and after attrition, were analyzed by a number of techniques to deternine the chemical changes responsible for the high attrition loss,... 

Figure 11-27 Fines generated by sonication can adhere to other particles.

Controlling the effect of locally higher supersaturation may be particularly important in cases where the goal is to minimize fines generation. Efforts to decrease the average supersaturation in the vessel may fail to reduce the number of fines produced. Often the key is rather to eliminate or moderate the local maximum supersaturation, say in the vicinity of a feed point or in the boiling zone of an evaporative vessel. 

Figure 12. Process comparison based on percent fines generation (from chord length mean PSD)...

Dust cloud ignition Rotary atomizer Yes Nozzle atomizer Yes (countercurrent) Mostly in the upper section and in the dust recovery section In the bed, no just above bed and in dust recovery section, probably yes Within the dryer due to fines generated as a result of attrition and breakage... 

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