In our kero minus hydrotreater unit, employing Albemarle catalyst, I witnessed an abnormal behaviour in preheat exchanger and HP separator.
A pressure gauge is installed at downstream of tube side of last preheat exchanger that essentially indicates pressure drop in tube side (Reactor downstream) of exchangers. The said gauge has hunting of approximately about 1 bar. I first wonder why is this happening as there is no chance for continuous pressure fluctuations in the circuit. I also presumed gauge to be faulty and asked maintenance section to replace it, but the problem still prevails.
Then I found the level fluctuations of the approximately same kind in HP separator. The level transmitter in our DCS didn't indicate this rise and fall, but the level glass proves this abnormality.
I am unable to understand this behaviour and seek experts advice.