Controlling particle adhesion of synthetic and sewage sludge ashes in high temperature combustion using metal oxide nanoparticles

Abstract

During combustion, ash particles can adhere to the internal walls of the plant due to partial melting and generate a liquid bridge force at the high operating temperatures. The adhered ashes inhibit energy recovery and stable operation of the plant. To achieve highly efficient energy recovery during combustion, it is necessary to investigate suitable methods to control adhesiveness according to each operational case. Herein, the ability of small amount (1–3 wt%) of nanoparticles (NPs: SiO2 NPs, Al2O3 NPs, and Fe3O4 NPs) as additives to control the adhesiveness at high temperatures was investigated. The controllability of each type of NP with respect to the adhesiveness of various synthetic ashes, which served as model compounds, was evaluated to clarify the role played by the different NPs. To demonstrate the practical utility of the NPs as additives, ash samples derived from the incineration of sewage sludge were investigated. Given the chemical complexity of the ash systems, it was discovered that a chemical effect and an increase in the porosity of the powder bed can effectively decrease the adhesiveness of ash particles produced at high temperatures.