These heaters are the most commonly used for heat duties up to 40-45 MW unless the specific process characteristics require 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 either with or without a convection section. The all-radiant heater is less expensive but characterized by low efficiency. A convection section is generally justified, except for very small heaters (less than 1 MW) or in locations where fuel costs are extremely low.
The main advantage of this kind of heater is its overall small dimension that requires a relatively reduced plot area compared to the others.
This kind of design is typically suitable for process services such as reboilers, hot oil heaters, heat transfer medium heaters, feed preheaters, regeneration gas heaters, and light crude heaters.