1 reply to this topic

[DuncanN]

Hi there, I'm currently studying particle technology and don't know how to arrive at an answer for this question:

A fixed bed reactor is made of spherical catalyst particles with radius of 1mm and density of 1500kg/m3, filled into a cylindrical vessel with diameter of 10cm. the solid volume fraction in the catalyst bed is 0.5.

(a) Calculate what length of the fixed bed is needed to get the total particle surface area in the bed equal to 10m2.

I have tried setting the area (10m2) equal to the equation for the surface area of a cylinder but the length then comes to some ridiculous. I have calculated the total particle surface area per unit volume to be 1500m-1.

the flow rate through the bed is 100ml/min

( Calculate the mean residence time of the liquid in the fixed bed.

i know the residence time = V/q but obviously need the length to find V.

Thanks for your help.

[Wit Knien]

I'm not sure if I'm correct on this one, just trying to help.

If the solid volume fraction is 0.5 , you'll need twice the amount of volume of the spheres. Spheres with a diameter of 1 mm have a Volume of V = 4.18879E-6 m³ , a surface area of A = 0.00125664 m². I'd simplify things and divide the 10m² by the surface area per, get the amount of spheres you need and then multiply those by the volume, times 2 because of the solid volume fraction and then calculate the rest.