INFLUENCE OF BIOFUEL COMBUSTION PRODUCTS ON THE INTEGRITY OF FUEL UNIT LININGS. PART 1. EXPERIMENTAL STUDY OF THE INTERACTION BETWEEN SUNFLOWER MEAL ASH AND REFRACTORY AND INSULATING MATERIALS OF THE SIO₂-AL₂O₃ SYSTEM

Global decarbonization and the transition to renewable energy high-light the need to predict the thermochemical stability of industrial furnace linings when biomass is used as fuel. Biomass, including wood, agricultural residues, and energy crops, has a specific chemical composition. Its ash contains large amounts of alkali oxides (Na2O, K2O), alkaline earth oxides (CaO, MgO), phosphates, and silicates. At high temperatures, these components form aggressive melts. Such melts attack refractory surfaces and accelerate their degradation. This study presents experimental results on the interaction of sunflower meal ash with refractories and aluminosilicate mineral fibers. The focus is on how chemical composition and structure affect durability and service life. Acidic refractories based on silica and alumina (ultra-light foam-diatomite brick CPD-400, lightweight chamotte brick ShL-1.0, heavy chamotte brick ShA, chamotte-alumina plate ShPGT, and aluminosilicate ceramic fiber mat LYTX 512) proved unstable in contact with alkaline melts formed by biomass ash. Interaction begins at 1160 °C, regardless of chamotte density. Heating to 1240 °C for one hour produces pronounced erosion in all tested refractories. The key factor determining resistance is density and structure. Ultra-light materials (CPD-400, fiber-based refractory) show much lower resistance than lightweight and heavy materials. A more uniform structure, as in ShL-1.0, provides better resistance than heavy chamotte ShA, where filler grains remain intact but the matrix vitrifies deeply. Alumina content also plays an important role. CPD-400, with less than 5 % Al2O3, showed the lowest resistance. ShPGT, with about 40 % Al2O3 and similar density to CPD-400, performed much better, even surpassing heavier ShL-1.0 and ShA bricks (≤ 30 % Al2O3). However, the ultra-light fiber refractory, despite its high Al2O3 content (> 40 %) and additional 7 % ZrO2, demonstrated the poorest resistance. This confirms that density and structure are more decisive than chemical composition. Bibl. 40, Tab. 2, Fig. 8.