Premix and Postmix Burners
1. Introduction
The way air and fuel are mixed in a burner directly determines combustion efficiency, flame stability, and emission levels.
Industrial combustion systems generally operate under two different principles: Premix (pre-mixed) and Postmix(diffusion-type) burners.
Each system serves a distinct purpose — Premix burners are designed for high efficiency and low emissions, while Postmix burners are optimized for high-temperature performance and fuel flexibility.
2. Premix Burners – Pre-mixed Systems
In premix burners, fuel and air are blended before entering the combustion chamber.
The mixing process occurs inside a venturi, mixer block, or injection manifold, ensuring a uniform mixture.
Advantages:
Homogeneous mixture enables complete combustion.
Achieves low NOₓ emission levels.
Very stable, short, and controllable flame.
Excellent for modulating and precise control systems.
Disadvantages:
If the air–fuel ratio is not precisely maintained, backfire (flashback) may occur.
Requires continuous pressure balance between gas and air.
Typical Applications:
Condensing boilers
Small and medium-capacity industrial burners
Processes requiring low-emission operation
3. Postmix Burners – Diffusion Systems
In postmix burners, fuel and air mix inside the combustion chamber.
Fuel is injected through nozzles or ports and mixes with the incoming air at the point of ignition.
Advantages:
Capable of reaching very high flame temperatures.
Flexible air-to-fuel ratio allows wider operating range.
Compatible with multiple fuels (natural gas, LPG, heavy oil, waste oils, etc.).
Suitable for heavy-duty and high-temperature processes.
Disadvantages:
The air–fuel mixture is less homogeneous than in premix systems.
Generally produces higher NOₓ emissions.
Typical Applications:
Large industrial boilers
Furnaces and heat-treatment lines
High-temperature process burners
4. Premix vs Postmix – Comparison Summary
| Feature | Premix Burner | Postmix Burner |
|---|---|---|
| Mixing Location | Before combustion | Inside combustion chamber |
| Flame Type | Short, homogeneous | Long, intense |
| Emission Level | Low NOₓ | Moderate–High NOₓ |
| Control Accuracy | High | Medium |
| Fuel Compatibility | Gaseous fuels | Gas + liquid fuels |
| Typical Use | Condensing & modulating systems | Industrial process heat |
5. Conclusion
Premix and Postmix technologies represent two different engineering philosophies.
Premix systems provide precision, efficiency, and low emissions, while Postmix designs deliver power, flexibility, and durability.
At InnoBurn, we combine the strengths of both to engineer high-performance, low-emission, and energy-efficient burner solutions tailored to industrial needs.