Q & A > Question Details
In hydrotreator, why do we consider hot separator top pressure as a system pressure? Why do we not consider reactor top pressure or reactor bottom pressure or inlet hydrogen pressure?
05/12/2017 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
There are two ways to look at the issue:
1. Correlations based on pilot plant and commercial experience must be based on some pressure. Each licensor has selected a reference pressure, whether it be reactor inlet, separator, or wherever.
2. Vessel pressure ratings and relief valve settings relate to the location of the relief valve relative to the vessel being protected (heat exchangers are considered vessels, too). That reference point may be the effluent exchanger on the feed side, if that is where the PSV is located. The separator has a design pressure and MAWP and a PSV protecting that vessel as well.