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I'm currently working on a VGO hydrocracker simulation. I want to know some common problems in normal industrial operation in this kind of process.
 
Answers
20/08/2014 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Comments on operation only, not design, construction or maintenance challenges:
The conversion is very sensitive to the average weighted bed temperature. Fresh feed and bottoms recycle are both on flow control for that reason, and the response of the quench instrumentation is important. With the bottoms recycle on flow control, the bottoms level of the column where the recycle pump takes suction can move quickly with changes in conversion. Such changes can be caused by otherwise minor things like a sudden rain shower. That level must be maintained without upsetting trays or losing pump suction. Instrumentation alone is not as adequate as operator experience. The operator reacts quickly to avoid such upsets. He or she makes precise changes in furnace outlet temperature in order to allow the recycle pump to remain on flow control.