Extreme Duoflex burners

Rotary kiln burners produce some of the world’s largest single flames next to space rockets. And as kiln demands continue to grow, the burner designs are following suit. A new milestone has recently been achieved with the manufacturing of a 230 MW Duoflex burner – the largest firing capacity yet. All Duoflex burners are tailored to meet the requirements of individual plants, and they’re designed for a number of traditional and alternative fuel firing possibilities.

FLSmidth’s Duoflex burner was successfully launched over ten years ago and has since become an industry standard all over the world. And it continues to evolve in terms of capacity, application, size and flexibility. FLSmidth’s largest version, at 230 MW, is three times the size of the average burner. During operation, the burner consumes up to 40 tonnes of coal per hour and is central to a new 13,000 tonne per day clinker production line for a Chinese cement producer. Weighing more than 12 tonnes, this burner is large, but even larger models are available for certain applications.

The Duoflex is not just about capacity – it also offers flexibility. With Duoflex, plants can burn both traditional and alternative fuels. In fact, Duoflex burners can handle multiple fuels at once, such as a mixture of liquid, solid and gaseous fuels. To date the largest number of fuel firing possibilities in one Duoflex burner is six. And, as featured in the November 2008 issue of Highlights, the next generation of Duoflex burners – the G2 – has been developed to make even greater use of alternative fuels.

Surviving in the kiln’s harshest environment
The burner is situated in a kiln’s most hostile environment. Extreme temperatures above 1500° C engulf the free-hanging burner pipe, and the burner is constantly exposed to the wear and tear of dust and various chemicals arising from fuels and fumes. For maximum resilience, Duoflex burners have a unique double supporting structure inside to ensure a rigid burner pipe with minimum deflection.

The range to meet the industry’s needs

Duoflex burners come in various capacities and sizes. FLSmidth’s smallest Duoflex burner, designed for use in minerals applications, is only 9 MW and has a burner pipe diameter of 350 mm and a length of 4.5 m. By contrast, the largest burner pipe diameter yet is 1350 mm with a length of 7 m. Special process requirements for certain projects have demanded even longer burner pipes – in these cases up to 12 m from flange to burner tip. The outer burner pipe diameter of these burners is 750 mm, as shown in the model below.

Duoflex kiln burners continue to be a huge success. FLSmidth has installed 364 units worldwide since 1997, and 25 of these are large burners with capacities exceeding 150 MW. And with a 230 MW size now in our arsenal, the Duoflex burner is capable of supporting even the greatest kiln requirements.