Vertical Tube, Cylindrical Heater
This heater configuration is commonly used in hot oil services and other processes where the duties are usually small. However, large units, 100 million Btu/hr and higher are not uncommon. In the radiant section, the tubes may be in a circular pattern around the walls of the firebox or they may be in a cross or octagonal design in the firebox which will expose them to firing from both sides. Older designs have radiating cones in upper part of radiant section as well as longitudinal fins on upper parts of tubes. The shield and convection tubes, if any, mormally are horizontal.