Box-type Heaters

A box-type heater is a heater whose structural configuration forms a box. There are many different designs for box-type heaters. These designs involve a variety of tube coil configurations, including horizontal, vertical, and arbor configurations.

This type of heater can have locations or zones of  different heat densities. The size and arrangement of the tubes in a box-type heater are determined by the type of operation the heater is meant to perform; for example, crude oil distillation or cracking, the amount of heating surface required, and the flow rate through the tubes. 

Box-type heaters are usually updraft, with gas- or oil-fired burners located in the end or side wall, the floor or downdraft with the roof. After the process convection section tubes, auxiliary tubes are often added to preheat combustion air or to generate or superheat steam. In Figure 2, the convection section is centered in the upper portion of the box-type heater and the radiant tubes are on the two side walls.