Questions for you: 1) How many tubes and what is the micron rating of the elements in your Ronningen Petter filter? 2) What is the temperature and flow rate of liquid to this system?
It would seem to me off the cuff that the current filter would backwash more frequently. You may want to shorten the time between backwashes to get a more consistent feed rate to the hydrocracker. But since your current filter normally needs 3-5 vessel volumes each to properly clean, you will have more backwash liquid to deal with.
We are replacing such systems with gas-assisted backwash filters that use sintered powder media nominally rated in low single digits. Suggested operating temperature is between 450-550F. This should prevent the asphatenes from binding to the media.
If there is consideration of replacing the current filter, we can provide lab analysis and a feasibility study. The initial capital costs are high by operating costs are minimal.