Q & A > Question Details
In our diesel hydrotreating unit, we treat a mix of LVGO, LCGO, and CDU Gasoil. what is the optimum cut off temperature for this feed and why? Normally we cut off the feed at 260C. Right or not?
Also we have a NHT unit; we cut off the feed also at 240-260C. Why?
15/04/2020 A: Ahmed Abd Elkader , EPROM , Ahmedkader127@gmail.com
Generally, the cut off temperature for feed for a DHTU is 260C. At this temperature, hydroprocessing reactions decrease so the product becomes off-spec .
This also applies to a NHTU . But you must keep in mind to keep naphtha in the vapour phase
13/04/2020 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
High temperature sulfur corrosion normally becomes a concern above 240-260C. If your metallurgy is not adequate for the amount of sulfur in the feed then you need to limit the feed temperature to avoid excessive corrosion rates.

Modified McConomy curves are typically used to estimate corrosion rates ahead of the hydrogen injection location, and the Couper-Gorman curves are used downstream of the hydrogen injection location.