Due to the constantly increasing environmental requirements, the reduction of emissions, especially carbon dioxide (CO2) but also carbon monoxide (CO), and nitrogen oxides (NOX) by energetic optimization measures is a permanent topic of interest. This requires flow and numerical modelling for the energetic optimization and for an enhanced emission reduction of energy-intensive aggregates. A further criterion is the quality requirements of the process to improve the qualitative parameters of the process.

Objectives and Motivation

  • Development of fast computing 1D models for tunnel kilns and continuous heat treatment lines
  • Reduced computing time of a NOx post processor
  • Improving the temperature distribution and increasing the energy efficiency of the walking beam furnace as well as energy improvement measures for the rotary kiln
  • Development of a catalyst for the oxidation of CO to CO2 in sinter exhaust gas for a low temperature range (200° to 250°C)


Since numerical models for mass and energy balances have been published in the late 1970s, there has been a steady development of these methods, which, however, usually do not consider spatial distributions of reactive species in energy intensive processes. The innovation in the current Project 3.3 lies in the development of an aggregate specific 1D resolution compromise by using the implicit finite volume method.

As part of previous projects, a post processor for modeling NOX concentrations was developed at the Chair of Thermal Processing Technology (Montanuniversität Leoben), which enables precise prediction of the concentrations in a fraction of calculation time compared to conventional models being therefore applicable to large industrial processes. In this Project 3.3, further methods are examined to reduce the computing time and these methods will be implemented in the post processor. The three approaches to be investigated include internal optimization by reducing the floating point operations using tabulated values, the generation of optimized computing networks for the NOX post processor during the flamelet calculation, and the development of a model for the generation of optimized chemical initial conditions.

Moreover, the observation of a walking beam furnace and a rotary kiln is carried out by using CFD (Computational Fluid Dynamics). CFD models are the state-of-the-art; however, it is necessary to develop new models to illustrate the process. The already developed model for the description of the walking beam furnace will be further optimized focusing on a reduction of the computing time by adaptive networks. At the same time, the energy improvement cycle based on the existing model will be started. In addition, a model with reasonable computing time must be developed to depict the rotary kiln serving as the basis for the detailed energetic process observation.

Project 3.3 also deals with the catalytic oxidation of carbon monoxide CO in sinter exhaust gas. The aim is to develop a catalyst on a laboratory scale that can be operated in the low temperature range (200 °C to 250 °C). The laboratory tests will be accompanied by diagnostic studies on sulphur chemistry. Furthermore, an energy balance of the CO catalysis is planned.

Results and application

The focus of this Project is on the reduction of emissions through energy optimization. After the evaluation of 1D models for tunnel kilns and continuous heat treatment lines, they will be implemented in a graphical user interface being easy to handle.

With the NOX Post Processor 2.0, an industrial burner design was improved in the first funding period. This Post Processor is used in an improvement cycle to reduce NOX emissions from industrial aggregates.

The dated observation of a walking beam furnace and a rotary kiln by means of CFD allows a profound and detailed understanding of the physical and chemical processes in the aggregates. This enables the definition of energy improvement measures and their effectiveness will be verified by the model.

Furthermore, a theoretical plant concept of a CO-catalysis will be defined for a sinter plant exhaust gas cleaning system.