This kind of heater is typically used in all-vapor, non-coking services, such as octanizers, where very low coil pressure drops are available. This design is based on a cabin fired heater (FH) with vertically oriented “hoop/arbor” tubes. This arrangement allows for a very low process mass velocity because of the high number of parallel flow passes.
The radiant section consists of separated zones, divided by free-standing brick walls, where the process charge is reheated several times, based on the plant’s needs. Flue gases from all radiant zones pass through a common convection section, used for preheating services or to produce steam.
Typical duties for this kind of heater range from 20 MW to 100 MW. Typical process services employed are octanizer heaters or reactor feed heaters.