Published by David Bizley,
Reinhard Ringdorfer, Unitherm Cemcon, explains how the development of new satellite burner systems has allowed cement plants to push the limits of AF utilisation.
The usage of alternative fuels in liquid and solid form is an integral part of every cement process. Initially the cement kiln was used as an incinerator. Since landfilling was no longer allowed, other methods of waste disposal had to be found. The cement kiln with its high temperatures was a perfect candidate, and cement plants were paid to dispose of the waste.
Over the years the incentive has changed, but alternative fuels are still used in the kiln and calciner to a high extent. Since secondary fuels are nowadays considered CO2 neutral, the use of these fuels reduces production costs and helps cement producers to decarbonise their production.
Ever since cement plants started using alternative fuels, Unitherm has been a disruptive pioneer in the market, introducing new technologies to push the limits of AF utilisation.
While liquid secondary fuels are rather easy to burn with the right equipment, solid secondary fuels haven proven more difficult. In 2001, with the introduction of the Pneumo-Swirl (PS), the first attempt was made to influence the flight behaviour of the fuel particles. This device, located at the exit of the solid secondary fuel channel causes the fuel particles to a swirl and mixes them with the primary fuel.
In 2007 the PS was supported by the Pneumo-Injector (PI), which gave the operator the ability to accelerate the particle exit velocity and therefore affect the throwing length of the particles. Bigger particles especially could be thrown farther into the kiln, avoiding reducing conditions in the sintering zone.
Both devices were used in numerous burners, ensuring a successful operation with the combustion of solid secondary fuels.
The latest development was the introduction of the Pneumo-Deflector© in 2011 (patent no. E 2 633 235 B1). Solid secondary fuel particles can be deflected above the kiln axis via bores in the outlet nozzle of the fuel, the required air is supplied by the primary air fan and the intensity can be adjusted via valve. Since then, this innovative solution has been further optimised using CFD and has proven to be most successful, enabling the operator to increase the amount of secondary fuel of the same quality while maintaining a high clinker quality.
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Read the article online at: https://www.worldcement.com/special-reports/14022022/satellite-success/
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