These heaters are the most commonly used for heat duties up to about 40-45 MW (unless specific process characteristics requires coil drainability, vertical flow pattern or double firing). In the radiant section, tubes stand or hang vertically, in a circle around the floor-mounted burners. Firing is parallel to the radiant section tubes. Vertical-cylindrical heaters can be designed both with and without a convection section. The all-radiant heater are less expensive, but characterized by low efficiency. A convection section is generally justified, except for very small heaters (less than about 1 MW) or in locations where fuel costs are extremely low. Main advantage of this kind of heater is the reduced plot area requirement (and overall dimensions) compared with other kind of heaters.
This kind of design is typically suitable for process services as Reboilers, Hot Oil Heaters, Heat Transfer Medium Heaters, Feed preheaters, Regeneration Gas Heaters and Light Crude Heaters.