Shape of the catalyst bed

Frequently, experimenters who wanted to use just a little catalyst tried to narrow down the basket cross-section by making an insert (a bushing.) This is not the right choice, illustrated by the following calculation. 

AP will be sixteen times higher and for L/dp of four times longer, the total AP will be 4 16 = 64 times larger. For A and C, if the volumetric flow remains unchanged through a one-quarter flow cross-section, u increases four times, and increases sixteen times. No small pump exists that can take the temperature and pressure of this system. 

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