Indirect fired HTM heaters use fired fuel to heat up the HTM (heat transfer medium) and supply the heated HTM to the required process section to provide heat energy. Indirect fired HTM heaters share similar components with direct fired heaters, but they have extra modules such as storage tank, expansion tank and pump skid to store and circulate the HTM.
As compared to a direct fired heater which has a single process port-in/port-out connection, an indirect fired HTM heater creates a sustainable loop to power up individual heating needs from different process sections. The HTM(s) will ultimately be collected at one common point for re-heating. This offers more flexibility in process designs.
The governing code for an indirect fired HTM heater is API 560 or DIN 4754.