Thermo‐Fluid Dynamics Study of Oxy‐MILD combustion of pulverized coal in furnaces and in a novel concept of boiler

Abstract

The thermal power plant for the generation of electricity, which uses coal as a primary energy source, presents multiple issues linked to the emission of pollutants and greenhouse gas (CO2) into the atmosphere. Furthermore, the conventional boilers greatly contribute to the increase of these harmful substances. The aim of this work is to propose and analyze the possibility of combining two new combustion technologies: the so-called oxy and MILD combustion. The rst one, allows to capture the carbon dioxide, while the second one provides several advantages, not only because it reduces the emission of nitrogen oxides, but also because it is characterized by uniform ows in the combustion chamber. Therefore, the challenge is to combine the two technologies with applications in furnaces and a new concept of boiler. For the latter, the planned applications include the ultra-super critical plants. For this reason, numerical simulations have been carried out by means of technical CFD (Computational Fluid Dynamics) because it is hard to provide large-scale tests. The initial phase of the work involves the application of the two technologies in furnaces. The rst one focuses on the MILD combustion by analyzing di erent positions of the pulverized coal jet, while the second one focuses on the application of the combination of the two technologies in order to analyze their e ects in terms of temperature and species concentration distributions. The next phase of the work, instead, has a focus on an innovative boiler. The testing of di erent geometrical solutions and models of char combustion has also allowed to study their e ects in terms of temperature, combustion products concentrations, burnout and, above all, wall heat ux. These latter results have been compared with the ones of traditional boilers and the results reported in the literature. The nal aim of this work is to analyze the advantages deriving from the combination of two technologies into a new concept of boiler, in order to reduce pollutant emissions, greenhouse gases and obtain a better performance than the one at the current state of the art.