HRSG Duct Burner & Supplemental Firing Calculator
Calculate supplemental duct burner fuel firing duty (MMBtu/hr and MWth), turbine exhaust gas temperature rise, and added steam generation per ASME PTC 4.4.
Turbine Exhaust Gas (TEG) Flow
Firing Duty & Added Steam
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Frequently Asked Questions
Why do HRSG duct burners not require external combustion air fans?
Gas turbine exhaust contains 12% to 15% unused oxygen by volume. Duct burners fire directly into this hot, oxygen-rich exhaust stream, acting as a massive preheated combustion air supply.
What is the maximum allowable duct burner firing temperature?
Standard HRSGs limit firing to 750°C–850°C without requiring specialized refractory lining. Beyond 900°C, carbon steel casing and superheater tube alloy metallurgy must be heavily upgraded.
What is the efficiency of supplemental firing in a combined cycle plant?
Supplemental duct firing converts fuel energy into steam at nearly 100% incremental thermal efficiency because the turbine exhaust gas is already at 500°C–600°C, eliminating standard combustion air preheat losses.