For modeling processes in rotary kilns, reduced mathematical models are developed for heat transfer, flame spread and for the movement of material . On the basis all processes are simulated.
It describes the influence of the length, the diameter, the rotational speed and the degree of filling of the rotary kiln as well as the properties of the material, among others. For the transverse transport mathematical models are derived, which described the slip line, the speed profiles and the local mass flows. The theoretical results are in relatively good agreement with our own and other readings. For further measurements, there is a joint research project with Prof. Dr. P. Walzel of the University of Dortmund. The flame spread is calculated with the CFD program system FLUENT.
Under investigation is the influence of the air preheating, the fuel type of material (coal, oil, gas), the twist and the burner construction. On the basis of known theories relationships between the variables and the type of fuel are derived. To describe the complicated mechanism of heat transport, models for transport over the wall and in the moving bed are worked out depending on the material properties of the wall or the bulk material.
The experimental determination of heat transfer a test furnace will be used (internal diameter 400 mm). The furnace can be continuously measured up to 1100 ° C in the radial and axial temperature field. In addition, the axial course of the gas concentrations can be detected. The furnace can be operated in parallel and counter flow. The speed and inclination can be adjusted.
Using the example of the lime kilns flow, temperature and concentration fields are simulated in reactive packings. The CFD program system FLUENT is used to calculate the flame spread in the bed of the radial and axial injection of various fuels . It examines the following: the influence of the length / diameter ratio of the furnace , the injection speed, the gap degree , the air preheater is warming and the volume flow ratio among others.
The cross-flow in tunnel is simulated using CFD. This produced with hot fans flow of heat transfer is increased. The optimum between heat transfer and pressure loss is modeled in terms of energy savings.
For a tunnel kiln for firing bricks , a new concept is developed , which is based on the Solid - recuperation . The air for cooling is used directly to preheat the bricks. This stove requires only about 50 % of the energy of conventional brick kilns. Für den Wärmeübergang über die Transportrolle wurde ein vereinfachtes mathematisches Modell entwickelt, mit dem dieser in Abhängigkeit der Drehzahl, der Materialeigenschaften, des Durchmessers und der Wanddicke dargestellt werden kann. Demnach behindern die Transportrollen den Wärmeübergang bei keramischem Gut. Bei metallischem Gut ist dagegen der Wärmeübergang auf der Unterseite höher als auf der Oberseite.
The Institute of Fluid Dynamics and Thermodynamics (ISUT) at the University of Magdeburg “Otto von Guericke” is responsible for teaching and research in all areas of fluid dynamics, thermodynamics and combustion.