Analysis of formation and growth process of ash deposition on the convective heating surface of a 400t/d MSW incinerator based on different operating days

To elucidate the mechanism of ash deposition produced by MSW incineration, samples from a mechanical grate (MG) type MSW incinerator were collected and characterized by SEM-EDS, XRF, and XRD. After 172 days of continuous operation, ash deposition on the walls of the HTR and SH3 tubes reached 33 mm and 18 mm. The rate of ash deposition at the HTR position can reach 0.625 mm/d, followed by the SH3 position, which reaches 0.229 mm/d. ECO has the minimum deposition rate, which is 0.02 mm/d. The shedding factor is proposed to describe the shedding phenomenon of ash deposition, and the absolute value of the shedding factor at the HTR position is the largest, which is 2.55 × 10–3 mm/d2. Cl was enriched in deposition sample at SH3, accounting for 10.62%. Alkali metal salts form the initial layer, which is influenced by the temperature of the tube wall. The chemical reaction heat of the sulfation process, which causes ash deposition containing molten or semi-molten material, promotes the sintering effect. The S/Cl molar ratios calculated for ash deposition at HTR and SH3 were 6.9 and 1.4, predicting ash deposition and strong corrosion of the tube walls.