3 replies to this topic

[amiestonia]

Hello all!

I have been compiling various hydrocraking process details, which are currently offered in the market. I have one issue over this which I would like some help.

Slurry bed and ebullated bed process are described as hydrocraking process, but many places hydrocraking reactor is shown as only a fixed-milti-bed reactor. I want to know that in case of slurry and ebullated bed process, how are they different from fixed bed? how do they manage the heat generated in reaction, which a fixed bed takes care via interbed gas quenching.

Thanks

[Technical Bard]

Slurry bed and ebullated bed process are described as hydrocraking process, but many places hydrocraking reactor is shown as only a fixed-milti-bed reactor. I want to know that in case of slurry and ebullated bed process, how are they different from fixed bed? how do they manage the heat generated in reaction, which a fixed bed takes care via interbed gas quenching.

Slurry and ebullated bed reactors use huge volumes of hydrogen in the feed. In an ebullated bed, the reactor is very well mixed, such that the reactor will be essentially isothermal and can be controlled by the feed furnace(s). Some slurry designs are the same, although I believe there is one slurry design that uses a plug-flow type reactor - and I don't know how they control the temperature along that reactor design.


Ebullated bed and slurry designs are used primarily for vacuum residue feeds that contain significant metals, CCR and asphaltenes, which would plug/poison a fixed catalyst bed very quickly. The advantage of these units is that the metals and coke/coke precursors will deposit on the catalyst / additive and are withdrawn from the reactor.

[amiestonia]

Thank you for this information.

Are Slurry bed and Ebullated bed similar in design and differ only in catalyst properties?

[Technical Bard]

Thank you for this information.

Are Slurry bed and Ebullated bed similar in design and differ only in catalyst properties?

It depends on the licensor. The Axens and CLG ebullated bed designs utilize a pump in the bottom of the reactor (one is internal, the other places it external to the reactor itself) to circulate the fluid and "ebullate" by increasing the liquid flux in the reactor over the "once through" option. These both use small catalyst particles that are added and removed via other nozzles on the reactor while it is running. The catalyst does not pass through the ebullating pump or leave with the reactor product.

The Slurry reactors are different. Most do not have pumps, and the catalyst/additives are included in the feed and are recovered from the product stream. These catalysts/additives are often much smaller than the catalyst pieces used in the ebullated bed because they need to entrain in the product. I believe this is true of both the UOP/CANMET and ENI designs.