Characterization of municipal solid waste combustion in a grate furnace

The objective of this paper is to evaluate the combustion process of municipal solid waste combustion in a grate furnace both experimentally and numerically by using data of a reference experiment with over-stoichiometric primary air supply. Measurements were carried out inside the combustion chamber of a pilot plant by monitoring temperatures and sampling gaseous combustion products along the bed surface. The data were assessed using elemental and energy balances. Experimental data of the axial temperature profiles of the flue gas, the fuel bed and the grate bars, as well as local gas flows and the flue gas composition measured above the fuel bed along the grate were used to describe the conversion process, including drying and carbon burnout. These data served as input to model the thermo- and fluid dynamic processes of the gas phase above the bed inside the combustion chamber. For this purpose the commercial code FLUENT was employed to carry out the simulations. Thus, the turbulent temperature, flow and species distributions in the combustion chamber of the pilot waste incinerator TAMARA were predicted. The results of the FLUENT modeling showed that under the prevailing conditions the flue gas burnout is almost completed before entering the first flue due to high temperatures, effective mixing and sufficient residence times of the flue gas inside the combustion chamber. This agrees well with the experimental results inside the first flue. On the basis of the above mentioned results, design and parametric studies can be carried out in a more efficient way by saving cost and time.