Burner Basics - Industrial Burners (Nozzle and Premix)

Burner Characteristics & Selection
Several burner characteristics come into play in making the proper selection for an oven or furnace.

• Btu capacity
• Flame configurations
• Heat release intensity
• Turndown ratio
• Air emissions
• Flame velocity
• Flame color (luminous or clear)
• Ability to burn standby fuels

Btu Capacity:
Burner firing capacity is usually the first characteristic to consider. No single burner can cover the entire range of Btu inputs required by various industrial processes, so burner types are built in families of different sizes. This permits designers to choose the correct size for an application.

Getting a good match between the burner's flame characteristics and the furnace or oven is the fastest, most efficient heat transfer, providing good temperature uniformity.

Flame Dimensions & Shape
The flame size and shape have to match the needs of the application.

Burner Heat Release Concentration
The concentration of the heat released by the burner must match the characteristics of the process.

Low temperature, lightly-loaded processes like bakery ovens need a relatively small amount of heat distributed over a wide area. This calls for line burners, ribbon burners and other designs that spread small flames over several feet of burner.

High temperature, heavily-loaded applications, like metal melters and forging furnaces, require a large amount of heat energy packed into a relatively small area. Burners for these furnaces usually have compact, intense, fast-mixing flames.

Burner Turndown Ratio
Burner turndown is the maximum firing rate divided by its minimum firing rate. It's an indication of the burner's flexibility in responding to variations in heat requirements. The burner system turndown must match or exceed the heat requirement turndown of the process.

One way to stretch the turndown of a burner is to operate with excess air at certain firing rates. In general, the larger the ratio flexibility of the burner, the greater its turndown capability.

Burner Exhaust Emissions
Burner exhaust emissions (NOx, carbon monoxide and unburned hydrocarbons) have become a major consideration. In fact, in some areas, they are the most important selection criteria. Regulations may require the use of special low emission burners for a job, even though they may not be the first choice from a heat application standpoint.

Burner Flame Velocity
Burner flame velocity may be an important selection factor. High velocity burners have become popular in recent years for certain applications requiring faster heat transfer and good temperature uniformity.

Burner Flame Color
Burner flame color isn't as important a factor as it used to be. In high temperature applications (where most of the heat is transferred by radiation), many customers believe a luminous yellow flame transfers heat faster and more uniformly.

Clear blue flames are strongly preferred in applications like paint curing and food processing because they indicate clean, soot-free combustion.