What is channeling in catalyst, what are indications and how it can be avoided?

[Nasir Hussain]

What is channeling in catalyst, what are indication and how it can be avoided?

[Nasir Hussain]

Catalyst Channeling is the formation of a specific flow path by process fluid through the catalyst bed. Channeling can either result in an increase in DP or a decrease in DP depending on what is causing it. If there is coking in the bed, then the flow will be forced through paths that are not coked. The reduction in flow area will cause a net increase in DP. If there are voids in the catalyst bed due to poor loading of the catalyst into the reactor, then the void spaces in the bed provide more open channels for flow. Flow takes the path of least resistance and much of the catalyst bed is effectively bypassed.
Channeling can be confirmed by checking radial temperature across catalyst beds. More than 6 degrees C temperature shows the channeling if the bed is dense loaded but in sock loading, the radial spread can be more than 6 C.
Channeling will result in poor catalyst activity due to improper use of the catalyst. In addition, there may be hot spot formation on the catalyst bed where the feed flow is very low. Moreover, the rate of coke formation will increase at places where the flow is low and the temperature is high.
Channeling in catalyst beds can be avoided by;
1. Operating the unit at more than turn downflows
2. Using high tech reactor internals
3. Using dense loading of catalyst

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