Burner Types

Chapter from the Fired Heaters Design Guide.

BURNER TYPES & SELECTION

Burner Classification

Burner Type	NOx Level	Mechanism	Flame Shape	Advantages	Limitations	Typical Application
Conventional (raw gas)	100-300 ppmv	Premixed or diffusion flame	Short, intense	Simple, reliable, low cost	High NOx emissions	Older heaters, no NOx limits
Low-NOx (staged air)	40-80 ppmv	Staged air injection	Longer, cooler	Moderate NOx reduction	Longer flame, may need larger firebox	Most new refinery heaters
Low-NOx (staged fuel)	30-60 ppmv	Staged fuel injection	Staged combustion zones	Good NOx with compact flame	More complex fuel manifold	Moderate NOx requirements
Ultra-Low-NOx	5-25 ppmv	Internal flue gas recirculation + staging	Very long, diffuse	Lowest NOx achievable	Longest flame, complex, expensive	Strict air quality districts (SCAQMD)
Combination (oil + gas)	Varies by mode	Dual fuel capability	Fuel-dependent	Fuel flexibility	Oil atomization maintenance	Refineries with fuel oil available
Floor-fired (vertical)	Varies	Upward-firing from floor	Vertical, tall	Even heat distribution, natural draft	Requires vertical cylindrical heater	Reformer furnaces, vertical heaters
Wall-fired (horizontal)	Varies	Side-firing from walls	Horizontal	Compact, good for box heaters	Complex burner arrangement	Cabin/box-type heaters

Burner Troubleshooting Quick Reference

Problem	Symptom	Likely Cause	Corrective Action	Safety Concern
Flame impingement	Hot spots on tubes, coke	Dirty tips, misalignment, excess fuel	Clean/replace tips, realign, adjust fuel	Tube failure risk
Flame lifting	Flame detaches from burner	Too much primary air, low fuel pressure	Reduce air register, check fuel P	Flameout risk → explosion
Flame rollover	Flame exits firebox opening	Insufficient draft, too much fuel	Increase draft, reduce firing rate	Personnel safety hazard
Yellow/luminous flame (gas)	Soot, smoke	Insufficient air, fuel quality change	Increase air, check fuel composition	Soot in convection = fire risk
Pulsation/rumble	Low-frequency oscillation	Combustion instability, draft issues	Adjust air/fuel ratio, check dampers	Structural fatigue
Uneven firing	Temperature imbalance across firebox	Fuel distribution, plugged tips, draft pattern	Balance fuel headers, clean tips	Local overheating

Source: Fired_Heaters_Design_Guide_v1.xlsx · sheet “Burner Types”

© 2026 Inflection Point Engineering, LLC. All rights reserved. The content of this page — including calculation methods, reference data, written analysis, interactive tools, and source code — is the intellectual property of Inflection Point Engineering, LLC and is protected under applicable copyright, trademark, and trade secret laws. Unauthorized reproduction, redistribution, modification, or derivative use in whole or in part is prohibited without prior written consent.

Disclaimer. This material is provided for informational and educational purposes only and does not constitute professional engineering advice. Calculations, reference data, and methodologies are based on published standards and accepted engineering practice but are not a substitute for engineering judgment, site-specific analysis, or review by a licensed Professional Engineer. Inflection Point Engineering, LLC makes no warranties, express or implied, regarding the accuracy, completeness, or fitness for a particular purpose of any content presented here, and shall not be liable for any direct, indirect, incidental, or consequential damages arising from its use. Users assume all risk associated with applying this content to real-world design, operations, or decisions.