average particle size

[rgrokkam]

Hello
For the vessel shown in the attachment, size of the particles is different and the liquid entry is from the bottom. I want to calculate the minimum fluidization velocity from Ergun equation. To estimate the average particle diameter, I doubt the use of sauter mean diameter. Can I use the mass mean diameter? I appreciate the forum's suggestion in this problem.
Thanks,

 

[shahyar]

1. As far as know, Ergun formula is for calculating pressure drop around beds. Min fluidization velocity is calculated by another formula.
2. In practice, we use average diameter(a rough number), but the best number would be "sauter mass mean diameter".

 

[rgrokkam]

Thanks Shahyar for your post.
Ergun equation is for pressure drop in packed beds. But the equation can be rearranged.
DP/L = g*(1-e)*(density of particle - density of liquid). where e is the voidage.

There are layers of particles, each with different diameter. ( I mean its not a mixture )In this case can I go ahead with sauter mass mean diameter?