Crude Oil Processing Reactor: Desalter, Hydrotreater and FCC Pre-Treatment Design What is a crude oil processing reactor? A crude oil processing reactor is a vessel in a refinery where crude or its fractions are chemically transformed before or during upgrading, and it appears at four critical points: the electric desalter, which removes salt and water at 120-150°C; the hydrotreater, which reacts the oil with hydrogen at 300-450°C and 30-150 bar to remove sulphur, nitrogen