Characterization and parametric study of the flow properties of cohesive powders at temperatures up to 850 ºC
Tutor / director / evaluadorDegn Jensen, Anker
Tipo de documentoProyecto/Trabajo final de carrera
Condiciones de accesoAcceso abierto
In connection with the design of a new preheater for the application in the cement manufacturing plant which does not use a cyclone tower, particle beds may be formed inside the equipment when raw meal is heated up to approximately 850 ºC. Experiences and equipment design from the industry show that congested particles that cause blockages are often occurring, especially at temperatures above 600 ºC – 700 ºC. For this reason, the study of the flow properties of the raw meal, so that the design of the new preheater can ensure a correct operation, is highly important. Therefore, the aim of this thesis was to study which parameters affect the flow properties of the bulk solids and, more specifically, to experimentally determine the dependence of the raw meal flow properties with the temperature using different testing methods carried out at temperatures up to 850 ºC, which needed to be previously designed and developed. The methods used for the flowability characterization were the uniaxial shear test, the rheological shear test and the poured angle of repose measurement. Precisely, the rheological shear test was an innovation on this thesis, since until the date a rheometer had not been used with this purpose. The results obtained with the flowability testing methods concluded that the raw meal flow behavior is kept nearly constant until a temperature around 700 ºC, and from that temperature onwards an increase of the cohesion is achieved, decreasing is flowability. This results matched with another results obtained with coal fly ash found in the literature. Besides, in terms of the effectiveness and reliability of the methods, the uniaxial shear test and the rheological shear test seemed to be fairly adequate for the particle characterization at high temperatures.