Nozzle design for fluidized bed reactor. HELP NEEDED.

[amockalypsenow]

Hi Engineering gurus,

I am tasked with designing a nozzle for a kind of fluidized bed reactor, which will have high temp oil flowing through it and a catalyst of around 1.5mm diameter. The vessel will be a cylinder of 40cm d. x 250cm l.

Problem is, it needs to be back-flushed so must have some kind of mesh or single unit design that inhibits the catalyst from passing through the nozzle.

I'm trying to find out information about how having a mesh in front of this nozzle will modulate the flow of oil into the vessel.

I'm also considering using a laminar flow-esque system of ports ala (Although with a much higher number of ports):

(

https://www.google.com/patents/US5472145)

What would the practical differences be between a convergent divergent nozzle going through a screen and some sort of laminar flow type nozzle with ports that will inherently restrict the catalyst objects from back flushing?

I really appreciate the help here, this is really outside of my wheelhouse and I don't know where to begin looking into this.

 

[jari001]

I just want to clarify something (for myself most likely); you don't want catalyst to ever go into the vessel, or you don't want it to leave the vessel via this nozzle once it's in there?

**Assuming you mean catalyst should not enter the vessel**
If you used a nozzle that acts like a filtering element, how would it be cleaned?

Are you limited to how much pressure drop, velocity gain/loss, temperature gain/loss you can have due to this nozzle?


It has been my experience that catalyst material can be physically settled out after mixing is stopped, filtered out, crystallized out, or just left in the product (e.g. Ti catalyst in plastic used for shopping bags). This is because of my ignorance, but what is preventing the use of standard nozzles for FBRs?

 

[amockalypsenow]

It's a bit a of a unique design- different in design to typical fluid bed reactors. It will be fluid moving through a relatively densely packed bed.

The nozzle will not be doing any filtering, it will just have an in-built perforation to contain the catalyst beads INSIDE the vessel. There will be a back-flushing operation taking place.

Thanks for your help, I'm in over my head at my job, and just trying to do my best.

 

[jari001]

I would think the mesh, to effectively filter the catalyst particles, would give you flow property issues. Do you know or can ask others what specific performance is needed from this nozzle (e.g. a specific distribution pattern, some minimum velocity or dP)?

I'm not well versed in this area either, so I think your best bet might be to see what standard designs are available for the application that is closest to yours and try to incorporate the relevant details into your design.

 

[amockalypsenow]

Thanks Jari,

The fluid velocity I'm estimating is around: 13.3 m/s (44 f/s)

Looking for somebody that will be able to help with this.