---
title: "Duct burner"
description: "A duct burner is an auxiliary natural-gas or distillate-oil burner installed in the inlet duct of an HRSG to add heat to the gas-turbine exhaust before it enters the first tube bank. Duct burners are used for:"
canonical_url: "https://sylio.co/glossary/duct-burner"
last_updated: "2026-06-28T02:29:33.592Z"
---

A **duct burner** is an auxiliary natural-gas or distillate-oil burner installed in the inlet duct of an [HRSG](/glossary/heat-recovery-steam-generator) to add heat to the gas-turbine exhaust before it enters the first tube bank. Duct burners are used for:

- Steam-flow boosting beyond the gas-turbine-only HRSG capacity
- Cogeneration peak shaping where process steam demand exceeds nominal HRSG output
- Cold-start steam-temperature ramp control

## Effect on fouling

Duct-burner firing raises the temperature and changes the gas composition entering the [finned-tube](/glossary/finned-tube-harp-tube) banks. On natural-gas-only HRSGs, this adds little fouling; on duct burners firing oil or in any unit firing back-up fuel, particulate loading rises substantially and convective-pass fouling accelerates.

## Cleaning implications

HRSGs that operate with regular duct-burner firing on liquid fuels usually need more aggressive [sonic-horn](/glossary/sonic-horn) coverage on the HRSG harps than gas-only HRSGs do.

## Related terms

- [Heat Recovery Steam Generator (HRSG)](/glossary/heat-recovery-steam-generator)
- [Combined-cycle gas turbine (CCGT)](/glossary/combined-cycle-gas-turbine)
- [Finned tube / harp tube](/glossary/finned-tube-harp-tube)