Economizers on Fired Heaters
Figure 3200-5 illustrates how economizers can reduce fired heater flue gas temperatures from a range of 700°F to 1200°F to the range of 300°F to 700°F.
The flue gas outlet temperature depends on:
• The pressure of the steam generated in the economizer, and
• The need to burn higher sulfur fuels as a back-up in the future. Lower temperatures could cause corrosion in the cold end of the waste heat recovery equipment.