Discrete-Ordinates Modelling of the Radiative Heat Transfer in a Pilot-Scale Rotary Kiln

Abstract

This paper presents work focused on the development, evaluation and use of a 3D model for investigation of the radiative heat transfer in rotary kilns. The model applies a discrete-ordinates method to solve the radiative transfer equation considering emission, absorption and scattering of radiation by gas species and particles for cylindrical and semi-cylindrical enclosures. Modelling input data on temperature, particle distribution and gas composition in the radial, axial and angular directions are experimentally gathered in a down-scaled version of a rotary kiln. The model is tested in its capability to predict the radiative intensity and heat flux to the inner wall of the furnace and good agreement was found when compared to measurements. Including the conductive heat transfer through the furnace wall, the model also satisfactorily predicts the intermediate wall temperature. The work also includes a first study on the effect of the incident radiative heat flux to the different surfaces while adding a cold bed material. With further development of the model, it can be used to study the heat transfer in full-scale rotary kilns.

Heat Transfer Conditions in Hydrogen-Fired Rotary Kilns for Iron Ore Processing

“…The rotary kiln modeling tool used within this work has been developed in our previous work based on a full-scale kiln 17 and a pilot-scale kiln. 18 The model describes the heat transfer within the kiln, to the kiln inner surfaces, and to the pellet bed material, including radiation from the flame and kiln wall, convection from the warm gases, and conduction between the bed and wall, as illustrated in Figure 2. The heat of reaction from the exothermic oxidation of magnetite to hematite, Reaction R.1, obtained from Forsmo et al, 19 is included as a source term in the model.…”