Analysis of the Behavior of the Ash Depending on the Temperature of Combustion and Air Supply System

The choice of the appropriate combustion technology is primarily related to the overall physico-chemical properties of fuel, primarily the properties of solid fuel, which also contains a mineral matter. The higher the content of fly ash in the fuel, the more complex the choice of the appropriate combustion technology. In addition to knowledge about the chemical composition of ash and the ash melting temperatures, the choice of combustion technology also requires knowledge about the behavior of ash in this process at different temperatures and technical-technological conditions in the furnace. This paper presents the results of laboratory research on the behavior of fly ash during the combustion of Bosnian coals from Middle Bosnian mining basin, and co-firing coal with waste woody biomass. The research was conducted on reactor installed in the laboratory for coal and biomass combustion at the Faculty of Mechanical Engineering, University of Sarajevo. The test fules powdered were subjected to pulverized combustion with a variable combustion temperature, the excess air ratio and the system of air supply into the reaction zone. During the test regime, samples of ash deposits from the reaction zone from different places and samples of slag and ash at the reactor outlet were collected. In assessing the behavior of ash in the process and the tendency to slagging/fouling heating surfaces in the boiler, in addition to the classic criteria applied for these purposes, the criteria determined in the overall previous research in the laboratory for coal and biomass combustion were applied. These criteria also include the influence of process temperature on the ash behavior in the process.