About half of the heat released by the burners is utilized by the reformer tubes. The remaining heat is carried by the flue gases that leave the radiant section of the reformer and is recovered by the convection coils to preheat other process streams (IPTS/EC, 2007 p.40). When the flue gas temperature is considerably reduced, the flue gases are released into the atmosphere. 

The heat requirements of the radiant section determine the overall fuel consumption of the furnace. By decreasing the duty of the radiant section by extended preheating of the reformer feed gas before it reaches the catalyst tubes, the overall fuel consumption can be decreased (OPET Network, 1998). 

As the fuel gas for the primary reformer burners is typically supplied to the ammonia plant battery limits at close to or below ambient temperature, heating this stream with low level heat recovery from the coolest portion of the reformer convection zone represents a particular option. In India, preheater for reformer fuel gas has been installed in four plants (FAI, 2013).

Redesigning the convection section will typically result in lower steam generation. Therefore, to optimize the energy efficiency improvements, this concept will have to be combined with a reduction in steam consumption (i.e. lower steam/carbon ratio, improved efficiency steam turbine) (A2A Toolkit).