5 replies to this topic

[Sagar Nawander]

In our process, for acetylene Hydrogenation we are using downflow reactor (though its a gas phase reaction)...

Any idea for that ?

[PingPong]

Except fluidized bed or ebulated bed reactors, all reactors with catalyst beds are downflow. At least, I have never seen otherwise.

 

Upflow would have risk of catalyst entrainment (and catalyst fines), especially if there were an upset.

[thorium90]

Yup, its definitely always downflow. It keeps the catalyst nicely packed and compact. Upflow can cause fluidization, potential channelling etc.

[Sagar Nawander]

Agreed..
but is there any thumb rule for this?

and when we shall go for upflow mode ?

 

thanks

[PingPong]

Rule of thumb: all fixed bed catalytic reactors are designed for down flow.

 

I can't think of any reason why one would design a fixed bed reactor for upflow.

[rahulavyas]

Hi,

 

1. Catalyst entrainment (Damage to catalyst due to attriation) is major issue in upflow reactors which used solid catalyst.

2. the only Up flow reactor Ihave come across is used in Alkylation unit where in Hydrogen Fluoride(Liquid phase) is used as catalyst to alkylate the feed, here it's more of intimate contact and mixing which takes place than reaction. hence these reactors are also caleed as Alky Mixers rather than reactors