A. Sand, H.Z. Kuyumcu, J. Rosenkranz
Luleå tekniska universitet
Conference in Minerals Engineering
Within stamp-charged coke making a large volume of coal is compacted to one single coal cake before entering the coke oven chamber. This is done by means of several falling stampers in a stamping machine having a mould nearly of the oven’s dimensions. Producing a high quality coke also from inferior coals requires a cake density of approximately 80% of the coal density. Besides that the industrial stamp-charging process demands a minimum mechanical strength of the coal cake to move it from the stamping mould into the oven chamber without failure. Densification and the build up of cake strength were investigated earlier in stamping tests using a micro-stamping device [1-2]. The quantities derived from these tests (as e.g. cake density or porosity) represent average values for the entire cake. Statements describing the local compaction state at different heights are difficult to achieve without destructing the cake.In order to gain better insight into the densification process and the inner structure of the coal cake a computational model based on the discrete element method, DEM, has been set up using 2 and 3-dimensional simulation software. The stamper’s position and velocity as well as the force acting on the stamper were monitored and the model’s response was compared against measurement data from laboratory stamping tests.It was possible to reproduce the force and displacement pattern of the stamper in response to the visco-elastic properties of the cake using standard DEM bonding and contact models. Furthermore, the rearrangement of particles in response to the compaction by the stamper was tracked by calculating their displacement at the point the stamper hit the coal surface. The latter can also be used as indicators of particle deformation or breakage. By defining control points at different heights the particle displacement, stress and strain rates, porosity could be studied at different heights.
coal compaction, dem, stamping