In this study, the sintering of kaolin and the resulting impact on alkali capture efficiency in a pilot scale real flame combustion test rig using beech wood as fuel was studied. Pre-experiments of the thermal sintering behavior of kaolin in an electrically heated furnace with residence times between 30 s and 1 h and temperatures between 790 – 1400 °C under calcination conditions were performed. Subsequent measurements of the resulting BET surface area (Brunauer-Emmet-Teller method using N2 adsorption) of the kaolin samples were carried out. The temperature profile in the top-down fired biomass combustion test rig (BoCTeR) was measured with an IFRF-type suction pyrometer when combusting beech wood powder. Additional measurements with natural gas as a reference case were conducted as well. Additional pre-experiments were made injecting kaolin particles directly into a natural gas flame at different reactor heights. Those kaolin particles exposed to high temperatures in the natural gas flame were collected and subsequently analyzed for the BET surface in order to evaluate the corresponding degree of sintering. The main test series comprises of a similar setup combusting beech wood powder instead of natural gas. The alkali sorption capacity of the used kaolin is indirectly measured by the combustion aerosol reduction performance determined with an ELPI. The main goal of this work is to show the optimization potential when using kaolin as Al/Si-based additive during pulverized-fuel combustion of biomass by using the most suitable temperature window for the kaolin injection. Preliminary results are promising and show that the amount of kaolin can be significantly reduced achieving similar fine particle concentrations by using the optimal injection position for the additive.     «

In this study, the sintering of kaolin and the resulting impact on alkali capture efficiency in a pilot scale real flame combustion test rig using beech wood as fuel was studied. Pre-experiments of the thermal sintering behavior of kaolin in an electrically heated furnace with residence times between 30 s and 1 h and temperatures between 790 – 1400 °C under calcination conditions were performed. Subsequent measurements of the resulting BET surface area (Brunauer-Emmet-Teller method using N2 adso...     »