Increased use of alternative fuel in the main firing system of rotary cement kilns

When producing cement, most of the thermal energy is required for burning the cement clinker in rotary kiln plants. At present, fossil fuels and alternative fuels (or secondary fuels) are used in parallel for this purpose. As energy costs represent a large part of the overall costs of cement production, the cement industry has always been keen to reduce and optimise fuel requirements. These efforts mainly focus on the use of alternative fuels as a replacement for fossil fuels.

The operating characteristics and thus also the alternative fuel substitution rate are determined not only by the properties and quantities of the fuels, but also by the design of the plant and burner, the method of supplying cold primary air and hot secondary air in the burner/kiln hood area and the fuel supply method. A negative effect on the clinker properties and the availability of the kiln plants should be avoided.

The experience gained so far with the optimisation of the use of alternative fuels comes from certain specific works and can accordingly only be applied to other works to a limited extent. The aim of the project is therefore to define the sensitivities of and relationships between the various influencing factors in a form applicable to plants in general. This shall be achieved on the basis of  plant experiences, as well as on existing and new plant measurements and CFD simulation. . This involves numerical simulation of the combustion of alternative fuels in rotary kiln plants with various plant geometries and operating parameters and checking by way of plant trials. The most suitable model combinations will be determined for such simulations in the context of the rules of "Best Practice".

The findings will be compiled in a manual for process and building technology measures to increase the use of alternative fuels in rotary kiln firing systems for plant operators and plant manufacturers.

Supported by

The IGF project 18862 N of VDZ gGmbH is supported by the AiF within the framework of Industrial Collective Research (IGF) of the Federal Ministry of Economic Affairs and Energy on the basis of a decision of the German Bundestag.


Dr. Stefan Schäfer

Dr. Stefan Schäfer

+49-211-45 78-252

+49-211-45 78-296


10/2015 - 03/2018

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IGF Project 17189 N: Development of a high-efficiency SNCR process with staged combustion for reducing NOx and NH3 emis-sions in cement industry rotary kiln plants with precalcination